Publications by authors named "Ossama Al-Mefty"

126 Publications

Extirpation of Recurrent Petrous Apex Cholesterol Granuloma Through the Zygomatic Approach: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun 10. Epub 2021 Jun 10.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Petrous apex cholesterol granulomas are believed to result from blockage of the normal aeration of the petrous air cells, resulting in a repetitive cycle of mucosal engorgement, hemorrhage, and granuloma formation.1 The lesion usually progressively expands causing compressive symptoms. The thick granulomatous wall envelopes various ages of breakdown products, including a cholesterol-containing fluid, which is typically hyperintense on T1 and T2 weighted magnetic resonance imaging. Drainage procedures, regardless of the route (endoscopic, endonasal, or transtemporal), with or without stenting or marsupialization, will only temporarily drain this cholesterol-containing fluid, with consequently frequent recurrences.2-5 A total exoneration of the granuloma and obliteration of the cavity with vascularized tissue will assure a more durable outcome.1 The extradural zygomatic/middle fossa approach provides a short distance to the petrous apex and is purely extradural. By sectioning the zygoma, temporal lobe retraction is avoided.6 We present a case of a 29-yr-old male who presented in the year 2000 with progression of a left petrous apex cholesterol granuloma despite 2 previous drainage and stenting procedures.  The patient consented for surgery and photo publication. Images in video at 2:41 © JNSPG, republished from Eisenberg et al1 with permission.
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http://dx.doi.org/10.1093/ons/opab156DOI Listing
June 2021

Activity of PD-1 blockade with Nivolumab among patients with recurrent atypical/anaplastic meningioma: Phase II trial results.

Neuro Oncol 2021 May 20. Epub 2021 May 20.

Center for Neuro-Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.

Background: Programmed death-1 ligand (PD-L1) contributes to tumor immunosuppression and is upregulated in aggressive meningiomas. We performed a phase II study of nivolumab, a programmed death-1 (PD-1) blocking antibody among patients with grade ≥2 meningioma that recurred after surgery and radiation therapy.

Methods: Twenty-five patients received nivolumab (240 mg biweekly) until progression, voluntary withdrawal, unacceptable toxicity, or death. Tumor mutational burden (TMB) and quantification of tumor infiltrating lymphocytes (TIL) were evaluated as potential immunocorrelative biomarkers. Change in neurologic function was prospectively assessed using the Neurologic Assessment in Neuro-Oncology (NANO) scale.

Results: Enrolled patients had multiple recurrences including ≥3 prior surgeries and ≥2 prior courses of radiation in 60% and 72%, respectively. Nivolumab was well tolerated with no unexpected AEs. PFS-6 was 42.4% (95% CI: 22.8, 60.7) and the median OS was 30.9 months (95% CI: 17.6, NA). One patient achieved radiographic response (ongoing at 4.5 years). TMB was > 10/Mb in 2 of 15 profiled tumors (13.3%). Baseline TIL density was low but increased post-treatment in 3 patients including both patients with elevated TMB. Most patients who achieved PFS-6 maintained neurologic function prior to progression as assessed by NANO.

Conclusion: Nivolumab was well tolerated but failed to improve PFS-6, although a subset of patients appeared to derive benefit. Low levels of TMB and TIL density were typically observed. NANO assessment of neurologic function contributed to outcome assessment. Future studies may consider rationally designed combinatorial regimens.
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http://dx.doi.org/10.1093/neuonc/noab118DOI Listing
May 2021

Endoscopic-Assisted Keyhole Resection of a Recurrent Epidermoid Tumor: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E32-E33

Epidermoid tumors are benign lesions. Surgical resection is the only treatment option available for these lesions.1 The surgical approach should be tailored to the clinical and anatomic findings to achieve radical resection, preferably total removal of the content and the capsule to prevent recurrences.2 Total resection is frequently possible in de novo lesions using tailored skull base approaches and their combination as well as modern microsurgical techniques, including the endoscope-assisted tools.2,3 Giant recurrent tumors, however, are not amenable for total resection. Hence, the severe adhesions will lead to a higher morbidity as the epidermoid capsule becomes thicker and more fibrous after prior resections attempts.2,4 The extent of the resection should still be safely extended as much as possible to delay the interval between surgeries. Endoscopic techniques are of great help in achieving such results through a keyhole approach when conservative surgery is decided.3 We present the case of a 69-yr-old male with a past medical history of coronary heart disease, hypertension, hypothyroidism, and recurrent giant epidermoid cyst in the left cerebellopontine angle, with significant compression of the brainstem and extended into Meckel's cave, internal auditory canal, and jugular fossa. He underwent resection in 1983, 2004, and 2012. He presented with worsening gait, and multiple cranial nerves deficits. A minimally invasive approach through a keyhole craniotomy was performed given the age, comorbidity, and multirecurrent nature of his lesion. The patient consented to the intervention and publication of his image. He had a satisfying evacuation of his cyst content with transient facial and lower cranial nerve postoperative worsening.
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http://dx.doi.org/10.1093/ons/opab098DOI Listing
June 2021

Resection of Pontine Cavernoma Through the Anterior Transpetrosal Approach: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E26-E27

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

The pons is the most frequent local for brain stem cavernoma.1 Repeated hemorrhage of brainstem cavernoma is associated with significant and accumulative neurological deficits and thus requires treatment. According to the Swedish Karolinska's group of radiosurgery, "it could not be concluded whether GKRS affects the natural course of a CM. The incidence of radiation-induced complications was approximately seven times higher than that expected."2 Thus, microsurgical removal has become the mainstay of treatment. In our experience, the following details assist in obtaining favorable outcomes and avoiding postoperative complications3,4: (a) the entry into the cavernoma based on thorough knowledge of the microanatomy; (b) the detailed study of the images and the presentation of the cavernoma on or near the brain stem surface; (c) the resection of the live cavernous hemangioma and not the mere removal of the multiple aged organized hematomas; (d) the preservation of the associated venous angioma; (e) the direct and shortest access to the lesion provided by a skull base approach; and (f) the use of the available technology, such as intraoperative neuromonitoring and neuroimaging. We present the case of a 54-yr-old male with recent deterioration in year 2001, past repetitive episodes of gait imbalance, and speech difficulty over a 7-yr period from known pontine cavernoma. The anterior petrosal approach provided superb and direct exposure to the entry at the lateral pons and the cavernoma was totally removed with preservation of the venous angioma. His preoperative neurological deficit rapidly recovered. Patient consented to the procedure and photography. Images at 3:15 from Kadri et al, The anatomical basis for surgical presercation of temporal muscle. J Neurosurg. 2004;100:517-522, used with permission from JNSPG. Image at 3:27 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997, with permission.
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http://dx.doi.org/10.1093/ons/opab103DOI Listing
June 2021

Pineal Region Hemangioblastoma Resection Through Paramedian Supracerebellar Approach: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E34-E35

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Pineal region tumors remain challenging lesions to safely resect because of their central location.1 Patients frequently present with symptoms associated with hydrocephalus and brainstem compression.2 Local anatomy, primarily the tentorium angle and venous anatomy, plays a central role in the selection of the approach.3 The paramedian supracerebellar approach pioneered by Yaşargil in 19844 allows to access the pineal region through a less steep angle while avoiding the central thickened arachnoid and midline cerebellar and vermian veins.3 Although the author strongly prefers the advantageous three-quarter concord position, this early case was performed in a sitting position, which requires a bubble test to rule out the presence of a persistent foramen ovale. The preoperative pineal differential diagnosis should be exhaustive, including blood and cerebrospinal fluid (CSF) tumor markers in suitable cases. Hemangioblastomas are seldom found or expected in the pineal area, and the surgeon must be alarmed by their typical "cherry nodule" appearance.2,5 Their recognition prior to resection is paramount in avoiding excessive blood loss from tumor entry. Similar to arteriovenous malformations, hemangioblastoma surgical tenets include en bloc resection and preservation of the main draining veins until the last steps of the resection. Von Hippel-Lindau (VHL) syndrome genetic workup is necessary is similar patients, as more than 25% of hemangioblastomas are associated with VHL tumor suppressor gene mutations in chromosome 3.2 The patient consented to the surgery and use of her photography. Image at 2:41 from Ueyama et al, Bridging veins on the tentorial surface of the cerebellum: a microsurgical anatomic study and operative considerations, Neurosurgery, 1998, 43(5),3 used with permission from the Congress of Neurological Surgeons.
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http://dx.doi.org/10.1093/ons/opab104DOI Listing
June 2021

Simpson Grade I Removal of Tuberculum Sella Meningioma Through the Supraorbital Approach: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 May 14. Epub 2021 May 14.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

As described by Cushing1 in the chiasmatic syndrome, tuberculum sellae meningiomas induce progressive asymmetrical, incongruous visual loss, which would lead to blindness. The surgical removal of these lesions has been rewarding in regard to visual preservation, or recovery, and has passed the test of time. Optic canal extension, in one or both canals, is a consistent feature of these tumors, and removing the tumor from the optic canals is paramount in the treatment of these lesions.2 Despite the small target volume, radiosurgery is not applicable because of the lack of safe distance from the optic pathways. Tuberculum sella meningioma has been distinguished with good surgical outcomes and low recurrence rates; thus, Simpson grade I removal (tumor, dura, and bone invasion) confers a prospect of cure.  Safe and successful resection of tuberculum meningiomas is achieved through the skull base supraorbital approach3 with several critical objectives: (1) visualization of the tumor without brain retraction; (2) 270° opening of the optic canal proximally and distally for safe tumor removal; (3) preservation of the vascular supply to the optic pathways and pituitary; (4) microsurgical dissection under high magnification on a short working distance to the encased carotid and anterior cerebral arteries; (5) complete resection of involved dura and bone at the skull base, particularly laterally; and (6) a robust skull base reconstruction with a vascularized pericranial flap.4  We present the case of a 45-yr-old female with a tuberculum sella meningioma who underwent Simpson grade I removal with an uneventful outcome. The patient consented for surgery.  Image at 2:59 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998; Image at 9:33 public domain.4.
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http://dx.doi.org/10.1093/ons/opab133DOI Listing
May 2021

Transcavernous Resection of an Upper Clival Chondrosarcoma: "Cavernous Sinus as a Route": 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 05;20(6):E422-E423

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Complete resection of skull base chondrosarcomas offers the potential for a durable, or even lifelong, cure and is best achieved at the first surgery.1,2 When a skull base chondrosarcoma is located at the upper clivus and in the interpeduncular cistern and invading laterally toward the petrous apex and cavernous sinus, the traditional approaches, ie, endonasal endoscopic or middle fossa approaches, are not adequate for the exposure and resection. The transcavernous sinus approach has been utilized to remove tumor from the cavernous sinus and as a corridor to the interpeduncular cistern and upper clivus, originally described for the clipping of basilar apex aneurysms. We present a case of a chondrosarcoma centered in the upper clivus and eroding the right posterior clinoid, analogous to the location of a giant basilar apex aneurysm. Detailed study of the tumor extension, bony invasion, and relationship with neuroanatomy dictated the most effective surgical approach.3,4 Neuronavigation and intraoperative magnetic resonance imaging (MRI) facilitated the gross total resection of the tumor in the Advanced Multimodality Image-Guided Operating (AMIGO) suite. Achieving a gross total tumor removal of this World Health Organization (WHO) grade I chondrosarcoma, adjuvant irradiation can be withheld1 and the patient monitored with serial imaging. The patient did well after the surgery. The patient consented for surgery and the use of photography.
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http://dx.doi.org/10.1093/ons/opab043DOI Listing
May 2021

Integration of Microanatomy, Neuronavigation, Dynamic Neurophysiologic Monitoring, and Intraoperative Multimodality Imaging for the Safe Removal of an Insular Glioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E28-E29

Department of Neurosurgery, Brigham and Women's Hospital, Harvard School of Medicine, Boston, Massachusetts.

Insular gliomas are located amongst myriad critical neurovascular structures, including lenticulostriate vessels, long insular perforators, putamen, internal capsule, frontal and temporal opercula, and key fasciculi.1-6 Each of these critical structures engenders key function of the brain, which must be preserved. Although anatomic knowledge remains the cornerstone of insular glioma surgery, novel tools have been developed to aid the surgeon in identifying and preserving these essential structures. Modern surgery of the insular glioma calls for seamless integration of these techniques to maximize the safety and totality of insular glioma resection, which has been shown to improve length of survival and seizure control, while reducing risk of tumor transformation.7-10 Neuronavigation can be used to help plan the craniotomy to achieve adequate exposure and assist during tumor resection. Brain "shift" can be corrected by re-registration following intraoperative magnetic resonance imaging (MRI). Interval ultrasound imaging reflects real-time progressive tumor resection. Dynamic neurophysiologic monitoring using thresholding techniques guides the surgeon as he resects tumor at its depth and posterior pole-close to the internal capsule. Intraoperative magnetic resonance imaging depicts residual infiltrative tumor that may require additional resection. The patient is a 33-yr-old woman with progressive growth of a right insular tumor and has consented to surgery, photography, and video recording.  Figure at 1:57, © Ossama Al-Mefty, used with permission.
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http://dx.doi.org/10.1093/ons/opab050DOI Listing
June 2021

Surgical Treatment of Bilateral Optic Nerve Sheath Meningioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 05;20(6):E418-E419

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Even though intracranial meningiomas commonly invade the optic canals, true optic nerve sheath meningiomas are extremely rare. They are insidious lesions that frequently grow in 4 stages, leading to progressive visual loss.1-4 Frequently, management includes observation for asymptomatic patients, and fractioned stereotactic radiotherapy with progressive visual loss.1,3 However, surgery is avoided due to the risk of perioperative visual loss.2-4 However, many of these cases present in the early stage of tumor growth, where an arachnoidal plane is still present, and vision can be saved by microsurgical tumor resection.2 Here we present the case of a 33-yr-old female presenting with a 3-wk history of blurred vision. Neuroimaging depicted an enhancing lesion along both optic nerves consistent with bilateral optic nerve sheath meningioma. Neuroophthalmological examination showed inferior cut of visual field bilaterally, more extensive on the left eye. Acuity was 20/20 on both eyes. Microsurgical resection of the tumor was performed through left supraorbital craniotomy, with the goal of eliminating intracranial extension and stabilizing visual function.5 The optic canal was unroofed with diamond bit drill under copious irrigation. A remarkable improvement of her visual field was observed with maintenance of acuity at 20/20 on follow-up. As the patient is attempting pregnancy, she is closely monitored without radiation. Surgery can be offered as a primary treatment of optic nerve sheath meningiomas, especially in early stages, with likely preservation and, in some cases, improvement of visual function.6 The patient consented to the procedure and the use of image. Images at 1:46 and 3:48 reprinted from Al-Mefty O, Operative Atlas of Meningiomas. 1998: Raven Press; Philadelphia, PA, with permission from LWW. Image at 2:57 reprinted from Rassi et al2; © Anil Can, 2018, used with permission. Image at 9:27 in public domain/age.
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http://dx.doi.org/10.1093/ons/opab052DOI Listing
May 2021

Petrosal Approach for Giant Retrochiasmatic Craniopharyngioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 05;20(6):E420-E421

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Microsurgical resection of craniopharyngiomas poses significant challenges, which are amplified with tumors in the retrochiasmatic location and larger size. Traditional pterional trans-sylvian, subfrontal translamia terminalis, or interhemispheric approaches provide narrow surgical corridors with obstructed visualization of the tumor by the prefixed chiasm and slit optic carotid window.1-5 The superior extension of the tumor compressing the hypothalamus and third ventricle are likewise inaccessible. Dissection through these approaches requires crossing and manipulation of the already compromised optic apparatus with surgical instruments. Finally, the basilar artery and its perforating branches are often adherent to the posterior aspect of the tumor, and are invisible. Endonasal endoscopic techniques have been utilized as a surgical approach that accesses the tumor without crossing the optic apparatus; however, these approaches have a significant risk of cerebrospinal fluid leakage and require dissection of the basilar artery and hypothalamus from long distances with lengthy instruments.6-9 Frequently, the surgeon achieves only partial removal. The petrosal approach is ideal for tumors in the retrochiasmatic location.10-13 Advantages include unhindered access to the retrochiasmatic space without crossing the optic nerve and chiasm. The angle of approach allows visualization superiorly to the hypothalamus. Additionally, the approach shortens the distance to the tumor, allowing for delicate bimanual dissection of the tumor, especially at the basilar artery and hypothalamic interfaces. This video demonstrates three cases of retrochiasmatic craniopharyngioma resection through the petrosal approach, highlighting these advantages to optimize patient outcome. The patients and guardians consented for the surgery, photography, and publication of the patient's image. Figures from Al-Mefty et al11 used with permission from the Journal of Neurosurgery Publishing Group. Additional figures republished from Al-Mefty et al.12 "The petrosal approach for the resection of retrochiasmatic craniopharyngiomas," Neurosurgery, 2008, volume 62, issue 5 Suppl 2 (ONS), ONS331-ONS336, by permission of the Congress of Neurological Surgeons.
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http://dx.doi.org/10.1093/ons/opab045DOI Listing
May 2021

Zygomatic Approach to Cavernous Sinus Chordoma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr 30. Epub 2021 Apr 30.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Chordoma is not a benign disease. It grows invasively, has a high rate of local recurrence, metastasizes, and seeds in the surgical field.1 Thus, chordoma should be treated aggressively with radical resection that includes the soft tissue mass and the involved surrounding bone that contains islands of chordoma.2-5 High-dose radiation, commonly by proton beam therapy, is administered after gross total resection for long-term control. About half of chordoma cases occupy the cavernous sinus space and resecting this extension is crucial to obtain radical resection. Fortunately, the cavernous sinus proper extension is the easier part to remove and pre-existing cranial nerves deficit has good chance of recovery. As chordomas originate and are always present extradurally (prior to invading the dura), an extradural access to chordomas is the natural way for radical resection without brain manipulation. The zygomatic approach is key to the middle fossa, cavernous sinus, petrous apex, and infratemporal fossa; it minimizes the depth of field and is highly advantageous in chordoma located mainly lateral to the cavernous carotid artery.6-12 This article demonstrates the advantages of this approach, including the mobilization of the zygomatic arch alleviating temporal lobe retraction, the peeling of the middle fossa dura for exposure of the cavernous sinus, the safe dissection of the trigeminal and oculomotor nerves, and total control of the petrous and cavernous carotid artery. Tumor extensions to the sphenoid sinus, sella, petrous apex, and clivus can be removed. The patient is a 30-yr-old who consented for surgery.
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http://dx.doi.org/10.1093/ons/opab126DOI Listing
April 2021

Concomitant Embolization and Microsurgical Resection of a Giant, Hypervascular Skull Base Meningioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr 30. Epub 2021 Apr 30.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Some skull base tumors can be extremely hypervascular, incorporating multiple vascular territories and demonstrating arteriovenous shunting. Devascularization is a critical step undertaken early in meningioma surgery, necessary before the debulking that is required in skull base tumors. While devascularization can often be achieved with appropriate approach selection, bony drilling, and microsurgical cautery, preoperative embolization of meningiomas has an invaluable role in selected cases.1,2  Embolization, however, does have added risk, magnified in large tumors by the potential infarction with subsequent edema that can potentially lead to acute deterioration and neurosurgical emergency. Hence, to achieve devascularization of an extremely vascular tumor, embolization and surgical resection should be performed concomitantly, as one operation, in which embolization might be the first stage, or might be performed after the craniotomy flap is raised, if necessary.3 Naturally, this requires the multifaceted neurosurgical expertise of embolization and microsurgical resection, and the facility to perform such.  We present a case of a giant, hypervascular, radiation-induced, skull base meningioma with internal and external carotid artery supply in a young patient with deteriorating vision in his only eye. Selective embolization of the internal maxillary, middle meningeal, and middle cerebral artery blood supplies was performed. Microsurgical interruption of the ethmoidal artery blood supply was then performed. This hybrid approach safely and effectively devascularized the tumor and allowed for a complete resection of this high-risk tumor4 while minimizing risk to the ophthalmic artery and optic nerve.  The patient was consented for surgery.
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http://dx.doi.org/10.1093/ons/opab128DOI Listing
April 2021

Medial Acoustic Tumors: Special Considerations: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr 30. Epub 2021 Apr 30.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Medial acoustic tumors are a rare distinct type of vestibular schwannoma having distinguished clinical and radiological features.1 Originating medially in the cerebellopontine angle without extending into the lateral internal auditory meatus, they are frequently giant in size at presentation in younger patients with a relatively preserved hearing, while they have other neurological deficits from cerebellar or brainstem compression and associated hydrocephalus. Imaging typically shows a cystic tumor with local mass effect and an internal auditory canal filled with cerebrospinal fluid.1,2 Surgical resection of theses schwannoma is particularly challenging not only due to their size and hypervascularity, but also given their particular arachnoidal rearrangement inducing marked adherence to the brainstem and facial nerve.2  The treatment is surgical resection, despite, however, their giant size hearing preservation should be sought and is attainable.1-5 Transmastoid approach with squeletonization and reflection of the transverse sigmoid sinus provides lateral exposure avoiding cerebellar retraction.6 In this report, we demonstrate the specific surgical considerations applied to the resection of a giant medial acoustic tumor in a 40-yr-old patient presenting with ataxia, vertigo, facial paresthesia, and intact hearing. The patient agreed to the surgery and photography.  Image at 1:44 © Ossama Al-Mefty, used with permission; Image at 8:21 from Dunn et al,2 used with permission from JNSPG.
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http://dx.doi.org/10.1093/ons/opab129DOI Listing
April 2021

Radical Resection of a Giant Epidermoid Tumor Associated With Miniature Chordoma Utilizing a Combined Endoscopic-Microscopic Technique: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr 30. Epub 2021 Apr 30.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Epidermoid tumors arise from misplaced squamous epithelium and enlarge through the accumulation of desquamated cell debris.1 Notwithstanding the prevailing conservative attitudes to minimize morbidity, optimal treatment consists of total removal of the capsule2,3; therefore, giant and multicompartmental tumors are particularly challenging. The utilization of simultaneous endoscopic microscopic techniques by tandem endoscopic and microscopic dissection to overcome the shortcomings of both modalities, markedly enhances the ability of radical removal,4 thus eliminating or at least long-delaying inevitable recurrences with subsequent accumulated morbidity. The transmastoid approach by skeletonizing and reflexing the transverse-sigmoid sinus offers wide exposure of the cerebellopontine angle avoiding cerebellar retraction and allowing 4-hands dissection.5 The patient is a 17-yr-old male with a giant epidermoid tumor in the cerebellopontine angle, extending through the incisura. The patient underwent surgical resection with maximum pursuit of the epithelial capsule. After removing the epidermoid tumor, a miniature intra and extradural midclival tumor was encountered and removed with a proven pathology of chordoma. Patient did well postoperatively with relief of his hemifacial spasms. Patient consented for surgery and photograph publication. Image at 1:23, ©1997, O. Al-Mefty, used with permission. All rights reserved.
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http://dx.doi.org/10.1093/ons/opab130DOI Listing
April 2021

Total Petrosectomy for the Total Resection of Sphenopetroclival Meningioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E22-E23

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Sphenopetroclival meningioma is a most formidable meningioma. Many patients have few preoperative deficits and surgery has the potential of severe neurological complications. Surgical treatment is challenging due to brainstem compression, the involvement of multiple cranial nerves and cerebral vessels. Wide tumor exposure, multiple dissection axis, and short distance are paramount factors in the quest of achieving total removal of Simpson grade I, including the involved dura and bone. The posterior petrosal, transtentorial presigmoid approach offers a wide and shallow operative field.1-7 When the patient has hearing loss, extending the resection of the temporal bone provides unmatchable exposure facilitating safer and more complete tumor removal. This article demonstrates the removal of a sphenopetroclival meningioma through total petrosectomy with closing of the external auditory canal and preservation of the facial nerve in the Fallopian canal. A total resection of the tumor was achieved with long-term preservation of cranial nerve function. The surgical steps of total petrosectomy are shown, including the skin flap, combined middle and posterior fossa craniotomy, skeletonization of the sigmoid transverse sinus, radical mastoidectomy, dissection of the Fallopian canal, and drilling of the labyrinth, cochlea, and petrous apex for superb exposure.8 We demonstrate the intra-arachnoidal microsurgical dissection utilized for the radical resection of petroclival meningioma. This surgery performed in 1995 is a testament to the time-tested technique. The patient consented to the procedure and image use. Images at 1:33 and 3:57 © Ossama Al-Mefty, used with permission.
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http://dx.doi.org/10.1093/ons/opab089DOI Listing
June 2021

A Combined Microsurgical and Endovascular Approach to Giant Paraclinoid Aneurysm: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 05;20(6):E424-E425

Neurosciences Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Giant paraclinoid aneurysm remains a treatment challenge because of their complex anatomy and surgical difficulties stems frequently from a calcified or atherosclerotic aneurysmal neck and compression of the optic pathways.1-9 To improve exposure, facilitate the dissection of the aneurysm, assure vascular control, reduce brain retraction and temporary occlusion time, and enable simultaneous treatment of possible associated aneurysms, we combined the cranio-orbital zygomatic (COZ) approach9 with endovascular balloon occlusion of the internal carotid artery (ICA) and suction decompression of the aneurysm.4 The patient is a 50-yr-old female who presented with headache and hemianopsia. MRI, CT, and 4-vessel angiography revealed a giant right ophthalmic paraclinoid partially thrombosed aneurysm. Surgery was performed via right COZ approach with removal of the anterior clinoid. Unroofing the optic canal and opening the falciform ligament and the optic sheath, allowing the dissection and mobilization of the optic nerve from the aneurysm and the origin of ophthalmic artery. The endovascular team placed a deflated, double lumen balloon catheter in the ICA 2 cm above the common carotid bifurcation. Proximal control is achieved by inflating the balloon. Distal control is then gained by temporary clipping just proximal of the origin of PcomA.4 Retrograde suction decompression through the catheter partially collapses and softens the aneurysm.1,4,6-8 Carotid occlusion was applied twice, 2:47 and 2:57 min. Intraoperative angiogram revealed the obliteration of the aneurysm and the patency of the carotid and ophthalmic artery. The patient recovered well, and visual deficit resolved and was neurologically intact. Patient consented for surgery. Illustrations in video reprinted with minimal modification from Surgical Neurology, vol 50, issue 6, Arnautović KI, Al-Mefty O, Angtuaco E, A combined microsurgical skull-base and endovascular approach to giant and large paraclinoid aneuroysms, 504-518,4 Copyright 1998, with permission from Elsevier Science Inc.
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http://dx.doi.org/10.1093/ons/opab059DOI Listing
May 2021

Venous Anatomy Influence on the Approach Selection of a Petroclival Clear Cell Meningioma With Associated Multiple Spinal Meningiomas: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 05;20(6):E426-E427

Preoperative careful evaluation of the sigmoid transverse sinus and its tributary veins is paramount for the safe surgical planning of petroclival lesions.1,2 When the vein of Labbé is running within the tentorium, classic petrosal approach involving transection of the tentorium is modified to avoid the risk of postoperative morbid temporal lobe venous infarcts.1-3 Thus, the surgical plan should be tailored to the specific patient anatomy as demonstrated in the presented case during which a transmastoid approach was followed, in the same surgical setting, by a middle fossa approach to resect a large petroclival clear cell meningioma with extension into Meckel cave. These meningiomas are WHO grade II tumors with a propensity to local recurrence and cerebrospinal fluid seeding.4 SMARCE1 mutations define this subtype of meningioma, with frequent familial inheritance, and predispose patients to both skull base and spinal clear cell meningiomas.5,6 Maximal surgical resection is the best initial treatment option allowing to withhold or delay the use of radiation in tumors frequently encountered in young patients.7 In this report, we demonstrate the microsurgical techniques deployed to achieve maximal resection of a petroclival clear cell meningioma and associated lumbar and sacral spinal meningiomas in a 20-yr-old patient with a familial SMARCE1 mutation. The patient agreed to the surgical intervention and to the use of her image.
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http://dx.doi.org/10.1093/ons/opab072DOI Listing
May 2021

Recurrent Chordoma Resection in the Advanced Multimodality Image Guided Operating Suite: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr;20(5):E344-E345

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.

Recurrent skull base chordomas are challenging lesions. They already had maximum radiation, and in the absence of any effective medical treatment, surgical resection is the only treatment.1,2 Surgery on recurrent previously radiated chordomas, however, carries much higher risk and the likelihood of subtotal resection. Maximizing tumor resection allows longer tumor control.3-5 The Advanced Multimodality Image Guided Operating Suite developed at the Brigham and Women's Hospital, Harvard Medical School, with the support of the National Institutes of Health, provides an optimal environment to manage these tumors. It offers the capability to obtain and integrate multiple modalities during surgery, including magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT), endoscopy, ultrasound, fluoroscopy, and the ability to perform emergent endovascular procedures.5-7 The patient is a 39-yr-old male, presenting after 19 yr follow-up of a surgical resection and proton beam treatment for a skull base chordoma. He developed progressive ophthalmoplegia due to recurrence of his chordoma at the right petrous apex and cavernous sinus. Preoperative angiography demonstrated narrowing of the petrous segment of the right carotid artery suspect of radiation-induced angiopathy. The presence of radiation-induced angiopathy increases the risk of intraoperative carotid rupture, and the availability of endovascular intervention in the operative suite added favorable preparedness to deal with such complications if they happen. Given the clinical and radiological progression, surgical intervention was carried out through the prior zygomatic approach with the goal of performing maximum resection.8 The patient had an uneventful postoperative course and remained stable until he had a second recurrence 4 yr later. The patient consented to the procedure.
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http://dx.doi.org/10.1093/ons/opaa445DOI Listing
April 2021

Petrosal Approach With Preservation of the Superior Petrosal Sinus (the Graceful Petrosal) for Resection of Giant Trigeminal Schwannoma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 04;20(5):E342-E343

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.

Trigeminal schwannomas are benign tumors amendable to curative surgical resection.1 Excellent outcomes, with preservation and improvement of cranial nerve function, including trigeminal nerve function, have been reported with microsurgical resection through skull base approaches.2 Dumbell shaped tumors, involving the middle and posterior fossa, are more challenging.3 They are resected via a middle cranial fossa approach with the expanded Meckel cave providing access to the posterior fossa. However, tumors with a large caudal extension below the internal auditory meatus typically cannot be adequately accessed with this approach and the posterior petrosal approach is utilized.2 Specific venous anatomy might deter from cutting the tentorium. This article describes the surgical resection of a trigeminal schwannoma with a large posterior fossa component through a petrosal approach without cutting the tentorium.4 The patient is a 34-yr-old man who presented with headaches and gait disturbance. Neurological exam revealed hypoesthesia and hypoalgesia in the left V1 and V2 distributions. Magnetic resonance imaging (MRI) revealed a large dumbbell-shaped schwannoma causing brainstem compression. Magnetic resonance venography (MRV) demonstrated temporal lobe venous drainage into the superior petrosal sinus and tentorium proximal to the transverse sigmoid junction. A single temporal-suboccipital bone flap and a retro-labrynthine mastoidectomy were performed. The petrous apex was drilled and Meckle's cave opened. The presigmoid dura was opened and extended toward the petrous apex region beneath the tentorium. This provided access to and safe resection of the tumor. A gross total tumor resection was achieved. The patient remained stable neurologically and was without tumor recurrence at 3 yr postoperatively. The patient had consented to the procedure. Figures in video at 4:06 from Jafez et al, Preservation of the superior petrosal sinus during the petrosal approach, J Neurosurg. 2011;114(5):1294-1298, with permission from JNSPG.
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http://dx.doi.org/10.1093/ons/opaa427DOI Listing
April 2021

The Resection of a Thalamic Pilocytic Astrocytoma Through the Transchoroidal Fissure, Transcallosal Approach: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Apr;20(5):E346-E347

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Surgical resection is the primary treatment of pilocytic astrocytomas and total removal can be curative. However, these lesions occur in critical areas, such as the thalamus, being surrounded by critical life neurovascular structures, which imposes a surgical challenge.1-5 Exhaustive acquisition and meticulous interpretation of preoperative radiological exams; reliable surgical orientation based on profound microneurosurgical anatomic knowledge and judicious discernment of the neuroanatomic distortions on the surface and deep-seated structures inflicted by the neuropathological entity; embracing and comprehensive application of the vast scope of available intraoperative guidance imaging and neurophysiological monitoring; in alliance with the mastered carefully microsurgical technique supported by endoscopic visualization are the keystones to the pursed duet "cure with quality of life" in the treatment of these lesions. We present the case of a 17-yr-old young lady with a progressive motor deficit in her right hemibody for over 2 yr. Her radiological investigation demonstrated a left thalamic lesion displacing the projection fibers (corticospinal tract) within the internal capsule laterally. The patient consented to the surgical procedure. The surgical strategy, intraoperative findings, and microsurgical and endoscopic technique, as well as the postoperative radiological and clinical evaluation are presented. The patient gave her informed consent for the publication of the case.
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http://dx.doi.org/10.1093/ons/opab015DOI Listing
April 2021

Two-Stage Double Petrosal Approach for the Total Resection of Petroclival-Cavernous Meningioma: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 Jun;21(1):E30-E31

Department of Neurosurgery, Brigham and Women's Hospital, Harvard School of Medicine, Boston, Massachusetts, USA.

The utilization of skull base approaches has markedly facilitated the safe surgical removal of challenging petroclival meningiomas.1 The anterior petrosal approach has been utilized for tumors limited to the upper clivus, above the meatus, whereas the posterior petrosal approach has been the workhorse for the resection of larger tumors in the posterior fossa extending down the clivus.2 Giant cases with extension in the middle fossa, cavernous sinus, and ventral to the brain stem would benefit from a wider exposure than each of these approaches provide. This could be achieved by total petrosectomy. However, in patients with serviceable hearing anterior and posterior petrosals can be combined while preserving the hearing apparatus.2,3 This procedure is lengthy; hence, we tend to stage it in 2 subsequent days. The first stage is focused on the soft tissue and bone work including the mastoidectomy, sigmoid transverse sinus, and jugular bulb skeletonization, as well as anterior petrosectomy. The second stage is dedicated to tumor exposure through tentorial sectioning and microsurgical resection. We report the case of a 40-yr-old woman diagnosed with large left-sided petroclival meningioma with significant extension into the cavernous sinus and Meckel's cave. The patient had neurological deficits including cranial nerves, cerebellar dysfunction, and hydrocephalus, although her hearing was intact. Total tumor resection was achieved through the double petrosal approach in 2002. Extensive anatomic knowledge and thorough preoperative clinical and radiological evaluation, particularly the venous system, are key in the successful planning of this procedure. The patient consented for surgery and publication of their image.  Figures at 2:40 and 3:47, ©Ossama Al-Mefty, used with permission.
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http://dx.doi.org/10.1093/ons/opab049DOI Listing
June 2021

Surgical Management of Multifocal Trigeminal Schwannomas.

Oper Neurosurg (Hagerstown) 2020 Jul 27. Epub 2020 Jul 27.

Department of Neurosurgery, Clinical Neurosciences Center, University of Utah, Salt Lake City, Utah.

Background: Isolated trigeminal schwannomas occur in 0.07% to 0.3% of intracranial tumors and account for 0.8% to 8% of intracranial schwannomas and 1/3 of Meckel cave tumors. The presence of multisegmental schwannoma is rare, resulting in a limited understanding of its optimal management.

Objective: To describe potential surgical options to manage this rare entity.

Methods: A 2-institution retrospective review of all patients with pathologically confirmed trigeminal schwannoma managed with resection from January 2009 through January 2019 was conducted. A manual chart review was performed to verify patients' inclusion and collect data about age, sex, tumor size, tumor site, treatment modality, surgical approach, complications, and follow-up duration and status.

Results: A total of 4 patients (age range 12-50 yr) who underwent a variety of cranial and orbitocranial approaches for tumor resection were identified. Patients achieved good outcomes with improvement of visual outcomes. One case of infection and 1 case of partial tumor recurrence requiring reresection were identified.

Conclusion: Multisegmental trigeminal schwannoma is a rare and unique entity, often associated with trigeminal schwannomatosis. Interdisciplinary management has been shown to be the most effective method for improving patient outcomes with these complex and poorly understood diseases.
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http://dx.doi.org/10.1093/ons/opaa227DOI Listing
July 2020

Safe Zones for Temporal Muscle Hook Retraction: A Technical Note.

World Neurosurg 2020 10 27;142:63-67. Epub 2020 Jun 27.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Background: The temporal muscle (TM) needs to be dissected and reflected downward in some anterolateral cranial approaches, and failing to preserve its integrity could have severe functional and cosmetic consequences. Most articles focus on techniques to prevent vascular injury during retrograde dissection or techniques to preserve the facial nerve; however, information on how to take care of the muscle during hook retraction is limited. We presented an anatomic study of vascularization of the TM, and we established safe areas for muscular hook retraction.

Methods: We dissected 16 TMs in 8 cadaveric heads. The TM was reflected downward, and we measured the distance between the anterior branch of the posterior deep temporal artery (PDTA) and the frontozygomatic suture and the distance between the posterior branch of the PDTA and the external auditory meatus projection.

Results: The average distance between the anterior branch of the PDTA and the frontozygomatic suture was 19.5 mm (range, 14-26 mm). The average distance between the posterior branch of the PDTA and the external auditory canal was 37.1 mm (range, 31-43 mm). We established 2 safe zones for hook placement: an anterior safe zone 14 mm posterior to the frontozygomatic suture and a posterior safe zone 30 mm anterior to the external auditory meatus.

Conclusions: We delimited 2 safe zones for hook placement during TM retraction aiming to avoid direct vascular damage in anterolateral cranial approaches.
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http://dx.doi.org/10.1016/j.wneu.2020.06.187DOI Listing
October 2020

Petroclival meningiomas and the petrosal approach.

Handb Clin Neurol 2020 ;170:133-141

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States. Electronic address:

As with other meningiomas, the goal of petroclival meningioma treatment should be curative total removal by achieving a Simpson I resection of the tumor, dura, and bone. Petroclival meningiomas particularly pose a great technical challenge because of their deep location and intimate relation with vital neurovascular structures. They require adequate exposure and trajectory to achieve total removal while minimizing the manipulation and risk to critical neurovascular structures, such as the vertebrobasilar system, the brainstem, and the cranial nerves. Here, we describe the indications and technical nuances of the posterior and combined posterior-anterior petrosal approaches for petroclival meningiomas.
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http://dx.doi.org/10.1016/B978-0-12-822198-3.00035-5DOI Listing
April 2021

Creation of a novel trigeminal tractography atlas for automated trigeminal nerve identification.

Neuroimage 2020 10 20;220:117063. Epub 2020 Jun 20.

Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.

Diffusion MRI (dMRI) tractography has been successfully used to study the trigeminal nerves (TGNs) in many clinical and research applications. Currently, identification of the TGN in tractography data requires expert nerve selection using manually drawn regions of interest (ROIs), which is prone to inter-observer variability, time-consuming and carries high clinical and labor costs. To overcome these issues, we propose to create a novel anatomically curated TGN tractography atlas that enables automated identification of the TGN from dMRI tractography. In this paper, we first illustrate the creation of a trigeminal tractography atlas. Leveraging a well-established computational pipeline and expert neuroanatomical knowledge, we generate a data-driven TGN fiber clustering atlas using tractography data from 50 subjects from the Human Connectome Project. Then, we demonstrate the application of the proposed atlas for automated TGN identification in new subjects, without relying on expert ROI placement. Quantitative and visual experiments are performed with comparison to expert TGN identification using dMRI data from two different acquisition sites. We show highly comparable results between the automatically and manually identified TGNs in terms of spatial overlap and visualization, while our proposed method has several advantages. First, our method performs automated TGN identification, and thus it provides an efficient tool to reduce expert labor costs and inter-operator bias relative to expert manual selection. Second, our method is robust to potential imaging artifacts and/or noise that can prevent successful manual ROI placement for TGN selection and hence yields a higher successful TGN identification rate.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572753PMC
October 2020

Is Falcine Meningioma a Diffuse Disease of the Falx? Case Series and Analysis of a "Grade Zero" Resection.

Neurosurgery 2020 10;87(5):900-909

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.

Background: Falcine meningiomas have unique characteristics including their high rates of recurrence, association with high grade pathology, increased male prevalence, and potential for diffuse involvement of the falx.

Objective: To address these issues in a substantial series of falcine meningiomas and report on the impact of extent of resection for this distinct meningioma entity.

Methods: Retrospective analysis of characteristics and outcomes of 59 falcine meningioma patients who underwent surgery with the senior author. A "Grade Zero" category was used when an additional resection margin of 2 to 3 cm from the tumor insertion was achieved.

Results: For de novo falcine meningiomas, gross total resection (GTR) was associated with significantly decreased recurrence incidence compared with subtotal resection (P ≤ .0001). For recurrent falcine meningiomas, median progression-free survival (PFS) was significantly improved for GTR cases (37 mo vs 12 mo; P = .017, hazard ratio (HR) .243 (.077-.774)). "Grade Zero" resection demonstrated excellent durability for both de novo and recurrent cases, and PFS was significantly improved with "Grade Zero" resection for recurrent cases (P = .003, HR 1.544 (1.156-2.062)). The PFS benefit of "Grade Zero" resection did not achieve statistical significance over Simpson grade 1 during the limited follow-up period (mean 2.8 yr) for these groups.

Conclusion: The recurrence of falcine meningiomas is related to the diffuse presence of tumor between the leaflets of the falx. Increased extent of resection including, when possible, a clear margin of falx surrounding the tumor base was associated with the best long-term outcomes in our series, particularly for recurrent tumors.
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http://dx.doi.org/10.1093/neuros/nyaa038DOI Listing
October 2020

Anatomical assessment of trigeminal nerve tractography using diffusion MRI: A comparison of acquisition b-values and single- and multi-fiber tracking strategies.

Neuroimage Clin 2020 8;25:102160. Epub 2020 Jan 8.

Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.

Background: The trigeminal nerve (TGN) is the largest cranial nerve and can be involved in multiple inflammatory, compressive, ischemic or other pathologies. Currently, imaging-based approaches to identify the TGN mostly rely on T2-weighted magnetic resonance imaging (MRI), which provides localization of the cisternal portion of the TGN where the contrast between nerve and cerebrospinal fluid (CSF) is high enough to allow differentiation. The course of the TGN within the brainstem as well as anterior to the cisternal portion, however, is more difficult to display on traditional imaging sequences. An advanced imaging technique, diffusion MRI (dMRI), enables tracking of the trajectory of TGN fibers and has the potential to visualize anatomical regions of the TGN not seen on T2-weighted imaging. This may allow a more comprehensive assessment of the nerve in the context of pathology. To date, most work in TGN tracking has used clinical dMRI acquisitions with a b-value of 1000 s/mm and conventional diffusion tensor MRI (DTI) tractography methods. Though higher b-value acquisitions and multi-tensor tractography methods are known to be beneficial for tracking brain white matter fiber tracts, there have been no studies conducted to evaluate the performance of these advanced approaches on nerve tracking of the TGN, in particular on tracking different anatomical regions of the TGN.

Objective: We compare TGN tracking performance using dMRI data with different b-values, in combination with both single- and multi-tensor tractography methods. Our goal is to assess the advantages and limitations of these different strategies for identifying the anatomical regions of the TGN.

Methods: We proposed seven anatomical rating criteria including true and false positive structures, and we performed an expert rating study of over 1000 TGN visualizations, as follows. We tracked the TGN using high-quality dMRI data from 100 healthy adult subjects from the Human Connectome Project (HCP). TGN tracking performance was compared across dMRI acquisitions with b = 1000 s/mm, b = 2000 s/mm and b = 3000 s/mm, using single-tensor (1T) and two-tensor (2T) unscented Kalman filter (UKF) tractography. This resulted in a total of six tracking strategies. The TGN was identified using an anatomical region-of-interest (ROI) selection approach. First, in a subset of the dataset we identified ROIs that provided good TGN tracking performance across all tracking strategies. Using these ROIs, the TGN was then tracked in all subjects using the six tracking strategies. An expert rater (GX) visually assessed and scored each TGN based on seven anatomical judgment criteria. These criteria included the presence of multiple expected anatomical segments of the TGN (true positive structures), specifically branch-like structures, cisternal portion, mesencephalic trigeminal tract, and spinal cord tract of the TGN. False positive criteria included the presence of any fibers entering the temporal lobe, the inferior cerebellar peduncle, or the middle cerebellar peduncle. Expert rating scores were analyzed to compare TGN tracking performance across the six tracking strategies. Intra- and inter-rater validation was performed to assess the reliability of the expert TGN rating result.

Results: The TGN was selected using two anatomical ROIs (Meckel's Cave and cisternal portion of the TGN). The two-tensor tractography method had significantly better performance on identifying true positive structures, while generating more false positive streamlines in comparison to the single-tensor tractography method. TGN tracking performance was significantly different across the three b-values for almost all structures studied. Tracking performance was reported in terms of the percentage of subjects achieving each anatomical rating criterion. Tracking of the cisternal portion and branching structure of the TGN was generally successful, with the highest performance of over 98% using two-tensor tractography and b = 1000 or b = 2000. However, tracking the smaller mesencephalic and spinal cord tracts of the TGN was quite challenging (highest performance of 37.5% and 57.07%, using two-tensor tractography with b = 1000 and b = 2000, respectively). False positive connections to the temporal lobe (over 38% of subjects for all strategies) and cerebellar peduncles (100% of subjects for all strategies) were prevalent. High joint probability of agreement was obtained in the inter-rater (on average 83%) and intra-rater validation (on average 90%), showing a highly reliable expert rating result.

Conclusions: Overall, the results of the study suggest that researchers and clinicians may benefit from tailoring their acquisition and tracking methodology to the specific anatomical portion of the TGN that is of the greatest interest. For example, tracking of branching structures and TGN-T2 overlap can be best achieved with a two-tensor model and an acquisition using b = 1000 or b = 2000. In general, b = 1000 and b = 2000 acquisitions provided the best-rated tracking results. Further research is needed to improve both sensitivity and specificity of the depiction of the TGN anatomy using dMRI.
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http://dx.doi.org/10.1016/j.nicl.2019.102160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6962690PMC
January 2021

Brachytherapy with surgical resection as salvage treatment for recurrent high-grade meningiomas: a matched cohort study.

J Neurooncol 2020 Jan 19;146(1):111-120. Epub 2019 Nov 19.

Department of Radiation Oncology, Brigham and Women's Hospital, Boston, MA, USA.

Purpose: To evaluate surgical resection with brachytherapy placement as a salvage treatment in patients with recurrent high-grade meningioma who exhausted prior external beam treatment options.

Methods: Single-center retrospective review of our institutional experience of brachytherapy implantation from 2012 to 2018. The primary outcome of the study was progression free survival (PFS). Secondary outcomes included overall survival (OS) and complications. A matched cohort of patients not treated with brachytherapy over the same time period was evaluated as a control group. All patients had received prior radiation treatment and underwent planned gross total resection (GTR) surgery.

Results: A total of 27 cases were evaluated. Compared with prior treatment, brachytherapy implantation demonstrated a statistically significant improvement in tumor control [HR 0.316 (0.101 - 0.991), p = 0.034]. PFS-6 and PFS-12 were 92.3% and 84.6%, respectively. Compared with the matched control cohort, brachytherapy treatment demonstrated improved PFS [HR 0.310 (0.103 - 0.933), p = 0.030]. Overall survival was not statistically significantly different between groups [HR 0.381 (0.073 - 1.982), p = 0.227]. Overall postoperative complications were comparable between groups, although there was a higher incidence of radiation necrosis in the brachytherapy cohort.

Conclusion: Brachytherapy with planned GTR improved PFS in recurrent high-grade meningioma patients who exhausted prior external beam radiation treatment options. Future improvement of brachytherapy dose delivery methods and techniques may continue to prolong control rates and improve outcomes for this challenging group of patients.
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http://dx.doi.org/10.1007/s11060-019-03342-5DOI Listing
January 2020

Clinical Importance of CDKN2A Loss and Monosomy 10 in Pilocytic Astrocytoma.

Cureus 2019 May 23;11(5):e4726. Epub 2019 May 23.

Neuro-Oncology, Dana-Farber / Brigham and Women's Cancer Center, Harvard Medical School, Boston, USA.

This case of a radiation-naive patient with pilocytic astrocytoma highlights how deletions of CDKN2A (cyclin-dependent kinase Inhibitor 2A) and PTEN (phosphatase and tensin homolog) portended a poor clinical outcome. Pilocytic astrocytomas are grade 1 tumors usually occurring in children and young adults with KIAA1549-BRAF fusion defining the majority of pilocytic astrocytomas. The presence of CDKN2A and PTEN loss may be associated with aggressive biology in pilocytic astrocytoma and further studies should include comprehensive genomics in a larger series of adult pilocytic astrocytoma to evaluate this previously unreported finding. Providers need to be aware of this possibility given the potential for poor outcomes.
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http://dx.doi.org/10.7759/cureus.4726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6649926PMC
May 2019

Tentorial Venous Anatomy: Cadaveric and Radiographic Study with Discussion of Origin and Surgical Significance.

World Neurosurg 2019 Nov 9;131:e38-e45. Epub 2019 Jul 9.

Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts, USA.

Background: Described variations of tentorial venous anatomy impact surgical sectioning of the tentorium in skull base approaches; however, described configurations do not consistently explain postoperative complications. To understand the outcomes of 2 clinical cases we studied the tentorial venous anatomy of 2 cadavers.

Methods: The venous anatomy of the tentorium isolated in 2 uninjected fresh cadaver head specimens with preserved bridging veins was observed by transillumination before and after methylene blue injection of the dural sinuses and tentorial veins. Our findings in cadavers were applied to explain the clinical and radiologic (magnetic resonance imaging and computed tomographic venography) findings in the 2 cases presented.

Results: A consistent transtentorial venous system, arising from transverse and straight sinuses, communicating with supra- and infratentorial bridging veins was seen in the cadaver and patient radiography (magnetic resonance imaging and computed tomographic venography). Our first patient had a cerebellar venous infarct from compromise of the venous drainage from the adjacent brain after ligation of a temporal lobe bridging vein to the tentorium. Our second patient suffered no clinical effects from bilateral transverse sinus occlusion due to drainage through the accessory venous system within the tentorium.

Conclusions: Herein, we elaborate on transtentorial venous anatomy. These veins, previously reported to obliterate in completed development of the tentorium, remain patent with consistent observed configuration. The same transtentorial venous system was observed in both cases and provided insight to their outcomes. These findings emphasize the importance of the transtentorial venous system physiologically and in surgical approaches.
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http://dx.doi.org/10.1016/j.wneu.2019.06.232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819248PMC
November 2019