Publications by authors named "Ramez W Kirollos"

39 Publications

Predictors of 30-day postoperative systemic complications in geriatric patients undergoing elective brain tumor surgery.

J Clin Neurosci 2021 Mar 15;85:72-77. Epub 2021 Jan 15.

Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Division of Neurosurgery, Department of Surgery, National University Hospital, National University Health System, Singapore.

Little evidence exists to guide the preoperative selection of elderly brain tumor patients who are fit for surgery. We aimed to evaluate the safety of brain tumor resection in geriatric patients and identify predictors of postoperative 30-day systemic complications. We conducted a retrospective cohort study of 212 consecutive patients at or above the age of 60 years who underwent elective brain tumor resection between 2007 and 2017. The primary outcome measures analyzed were perioperative systemic complications within 30 days after the operation. A total of 212 geriatric brain tumor patients were included. Fifty-two (24.5%) had a 30-day systemic complication. Among them, 29 (13.7%) had systemic infections, 13 (6.1%) had perioperative seizures, 10 (4.7%) had syndrome of inappropriate antidiuretic hormone secretion (SIADH), five (2.4%) had deep venous thrombosis (DVT), four (1.9%) had perioperative stroke, three (1.4%) had acute myocardial infarction (AMI) and three (1.4%) had central nervous system (CNS) infections. One patient (0.5%) died. Perioperative stroke was predicted by previous stroke (p = 0.040), chronic liver disease (p < 0.001) and vestibular schwannoma (p = 0.002 with reference to meningiomas). Perioperative AMI was predicted by co-existing ischemic heart disease (p = 0.031). Systemic infection was predicted by female gender (p = 0.007) and preoperative Karnofsky Performance Scale (KPS) score < 70 (p = 0.019). DVT was predicted by GBM (p = 0.014). In conclusion, brain tumor surgery can be safe in carefully-selected geriatric patients. The risk factors identified in this study would be helpful to select suitable candidates for surgery.
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http://dx.doi.org/10.1016/j.jocn.2020.12.023DOI Listing
March 2021

A critical appraisal of Monro's erroneous description of the cerebral interventricular foramina: Age-related magnetic resonance imaging spatial morphometry and a proposed new terminology.

Clin Anat 2020 Apr 22;33(3):446-457. Epub 2020 Jan 22.

Division of Neuroimaging and Neurointervention, Stanford Initiative for Multimodality neuro-Imaging in Translational Anatomy Research (SIMITAR), Department of Radiology, Stanford University School of Medicine, Stanford, California.

Anatomic connections between the cerebral lateral and third ventricles have been mischaracterized since Monro's original erroneous description of his eponymous foramina (FoMs) as being only one T-shaped passage. Accurate knowledge of the in vivo three-dimensional (3D) configuration of FoM has important clinical neuroendoscopic, neurosurgical, and neuroimaging implications. We retrospectively analyzed volumetric high-resolution brain magnetic resonance imaging of 100 normal individuals to characterize the normal spatial anatomy and morphometry for each FoM. We measured the true anatomical 3D angulations of FoMs relative to standard neuroimaging orthogonal planes, and their minimum width, depth, and distance between the medial borders of bilateral FoMs. The right and left FoMs were separate, distinct, and in a V-shaped configuration. Each FoM was a round, oval, or crescent-shaped canal-like passage with well-defined borders formed by the semicircular concavity of the ipsilateral forniceal column. The plane of FoM was angled on average 56.8° ± 9.1° superiorly from the axial plane, 22.5° ± 10.7° laterally, and 37.0° ± 6.9° anteriorly from the midsagittal plane; all these angles changing significantly with increasing age. The mean narrowest diameter of FoM was 2.8 ± 1.2 mm, and its depth was 2.5 ± 0.2 mm. Thus, the true size and orientation of FoM differs from that depicted on standard neuroimaging. Notably, in young subjects, FoM has a diameter smaller than its depth, a configuration akin to a short, small canal. We propose that the eponym "Monro" no longer be associated with this structure, and the term "foramen" be abandoned. Instead, FoM should be more appropriately renamed as the "interventricular canaliculus," or IVC, for short.
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http://dx.doi.org/10.1002/ca.23560DOI Listing
April 2020

Use of an Offsite Intraoperative MRI Operating Theater for Pediatric Brain Tumor Surgery: Experience from a Singapore Children's Hospital.

World Neurosurg 2020 Mar 23;135:e28-e35. Epub 2019 Oct 23.

Neurosurgical Service, KK Women's and Children's Hospital, Singapore; Department of Neurosurgery, National Neuroscience Institute, Singapore; SingHealth Duke-NUS Neuroscience Academic Clinical Program, Singapore.

Background: Intraoperative magnetic resonance imaging (iMRI) has been recognized as a useful adjunct for brain tumor surgery in pediatric patients. There is minimal data on the use of an offsite intraoperative magnetic resonance imaging operating theater (iMRI OT), whereby vehicle transfer of patients is involved. The primary aim of this study is to validate the feasibility of perioperative patient transfer to use an offsite iMRI OT for patients with pediatric brain tumor. Secondary objectives include the assessment of tumor resection efficacy and perioperative outcomes in our patient cohort.

Methods: This is a retrospective, single-institution clinical study of prospectively collected data from Singapore's largest children hospital. Variables of interest include issues encountered during interhospital transfer, achievement of surgical aims, length of stay in hospital, and postoperative complications. Our findings were compared with results of related studies published in the literature.

Results: From January 1, 2009 to December 31, 2018, a total of 35 pediatric operative cases were performed in our offsite iMRI OT. Within this cohort, 24 of these were brain tumor surgery cases. For all the patients in this study, use of the iMRI OT influenced intraoperative decisions. Average ambulance transport time from parent hospital to the iMRI OT was 30.5 minutes, and from iMRI OT back to the parent hospital after surgery was 27.7 minutes. The average length of hospitalization stay was 7.9 days per patient. There were no ferromagnetic accidents during perioperative iMRI scanning and no airway/hemodynamic incidents in patients encountered during interhospital transfer.

Conclusions: In our local context, the use of interhospital transfers for access to iMRI OT is a safe and feasible option in ensuring good patient outcomes for a select group of patients with pediatric brain tumors.
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http://dx.doi.org/10.1016/j.wneu.2019.10.083DOI Listing
March 2020

Infratentorial Supracerebellar Approach for Resection of Midbrain Cavernous Malformation: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2020 Feb;18(2):E44

Division of Neurosurgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom.

Cavernous malformations (cavernomas) of the brain stem with recurrent hemorrhage may be amenable to microsurgical resection if they are present close to the surface. The risks of surgery need to be balanced with the natural history of the lesion and the accumulation of neurological deficits and risk to life with multiple hemorrhages. In this 3D operative video, we illustrate the technique for the resection of a dorsally located midbrain cavernous malformation. Informed consent was obtained for this procedure. The cavernoma is accessed with the use of a supracerebellar infratentorial approach. The infratentorial craniotomy and coagulation of the superior vermian veins is shown. A description is provided of the use of hemosiderin staining and the intercollicular relative "safe zone"1 as landmarks for the neurotomy. The technique of cavernoma dissection from the surrounding gliotic plane is shown and described. In this case, the patient required prolonged rehabilitation but fully recovered without residual deficit 1 yr following surgery.
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http://dx.doi.org/10.1093/ons/opz114DOI Listing
February 2020

Giant Aneurysm Arising from Anomalous Branch of the Middle Cerebral Artery in a Pediatric Patient: Case Report and Review of the Literature.

World Neurosurg 2019 Aug 10;128:165-168. Epub 2019 May 10.

Neurosurgical Service, KK Women's and Children's Hospital, Singapore; Department of Neurosurgery, National Neuroscience Institute, Singapore; SingHealth Duke-NUS Neuroscience Academic Clinical Program, Singapore. Electronic address:

Background: Pediatric intracranial aneurysms are extremely rare. In this age group, cerebral vascular anomalies have been associated with the development of intracranial aneurysms.

Case Description: We present a case of a previously well 11-year-old boy who presented with seizures secondary to a giant, unruptured, and partially thrombosed right middle cerebral artery (MCA) aneurysm. Extensive workup for underlying infective and autoimmune etiology was negative. Of interest, this vascular lesion was found to originate from an anomalous M2 branch, which ran an aberrant parallel course within the Sylvian fissure to the main and distally bifurcating MCA. The patient underwent successful surgical clipping and excision of the giant aneurysm.

Conclusions: Because of the infrequency of the diagnosis, clinical presentation, and its unique neurovascular anatomy, the management of this case is discussed in corroboration with current literature. In addition, highlighting this unusual case in an individual adds to the growing body of literature for better disease understanding, especially in the pediatric population.
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http://dx.doi.org/10.1016/j.wneu.2019.05.012DOI Listing
August 2019

Ossification of the pterygoalar and pterygospinous ligaments: a computed tomography analysis of infratemporal fossa anatomical variants relevant to percutaneous trigeminal rhizotomy.

J Neurosurg 2019 May 10;132(6):1942-1951. Epub 2019 May 10.

5Division of Neuroimaging and Neurointervention, Department of Radiology, Stanford University School of Medicine, Stanford, California.

Objective: Ossification of pterygoalar and pterygospinous ligaments traversing the superior aspect of the infratemporal fossa results in formation of osseous bars that can obstruct percutaneous needle access to the trigeminal ganglion through the foramen ovale (FO), interfere with lateral mandibular nerve block, and impede transzygomatic surgical approaches. Presence of these ligaments has been studied on dry skulls, but description of their radiological anatomy is scarce, in particular on cross-sectional imaging. The aim of this study was to describe visualization of pterygoalar and pterygospinous bars on computed tomography (CT) and to review their prevalence and clinical significance.

Methods: The authors retrospectively reviewed 200 helical sinonasal CT scans by analyzing 0.75- to 1.0-mm axial images, maximum intensity projection (MIP) reconstructions, and volume rendered (VR) images, including views along the anticipated axis of the needle in percutaneous Hartel and submandibular approaches to the FO.

Results: Ossified pterygoalar and pterygospinous ligaments were readily identifiable on CT scans. An ossified pterygoalar ligament was demonstrated in 10 patients, including 1 individual with bilateral complete ossification (0.5%), 4 patients with unilateral complete ossification (2.0%), and 5 with incomplete unilateral ossification (2.5%). Nearly all patients with pterygoalar bars were male (90%, p < 0.01). An ossified pterygospinous ligament was seen in 35 patients, including 2 individuals with bilateral complete (1.0%), 8 with unilateral complete (4%), 8 with bilateral incomplete (4.0%), 12 with bilateral incomplete (6.0%) ossification, and 5 (2.5%) with mixed ossification (complete on one side and incomplete on the contralateral side). All pterygoalar bars interfered with a hypothetical needle access to the FO using the Hartel approach but not the submandibular approach. In contrast, 54% of complete and 24% of incomplete pterygospinous bars impeded the submandibular approach to the FO, without affecting the Hartel approach.

Conclusions: This study provides the first detailed description of cross-sectional radiological and applied surgical anatomy of pterygoalar and pterygospinous bars. Our data are clinically useful during skull base imaging to predict potential obstacles to percutaneous cannulation of the FO and assist in the choice of approach, as these two variants differentially impede the Hartel and submandibular access routes. Our results can also be useful in planning surgical approaches to the skull base through the infratemporal fossa.
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http://dx.doi.org/10.3171/2019.2.JNS182709DOI Listing
May 2019

Awake Craniotomy for Resection of Left Temporal Cavernoma: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2019 Sep;17(3):E102

Division of Neurosurgery, Cambridge University Hospital's NHS Foundation Trust, Cambridge, United Kingdom.

Cavernomas presenting with seizures refractory to medical treatment may require surgical excision for seizure control. If superficial, they can be surgically accessible but can pose additional risks when located in or near eloquent cortex. In this 3D operative video we illustrate the technique for the resection of a left temporal cavernoma located near eloquent cortex for speech with awake surgery and cortical mapping to avoid a speech deficit postoperatively. Informed consent was obtained for this procedure. Navigation is used to localize the cavernoma following which a large craniotomy is performed exposing the temporal lobe, frontal lobe, and sylvian vein. Bipolar stimulation is used to localize speech with the patient awake until speech arrest occurs. The cavernoma is situated immediately inferior to the sulcus over which speech arrest occurs. The sulcus immediately above the cavernoma is opened and adjacent arteries are carefully preserved. The glial plane around the cavernoma is used to dissect the cavernoma from the surrounding cortex. Care is taken to remove the haemosiderin as this can act as a precipitant for ongoing seizures. In this case the patient had no neurological deficits following surgery and was seizure free.
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http://dx.doi.org/10.1093/ons/opy381DOI Listing
September 2019

An integrated genomic analysis of anaplastic meningioma identifies prognostic molecular signatures.

Sci Rep 2018 09 10;8(1):13537. Epub 2018 Sep 10.

Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK.

Anaplastic meningioma is a rare and aggressive brain tumor characterised by intractable recurrences and dismal outcomes. Here, we present an integrated analysis of the whole genome, transcriptome and methylation profiles of primary and recurrent anaplastic meningioma. A key finding was the delineation of distinct molecular subgroups that were associated with diametrically opposed survival outcomes. Relative to lower grade meningiomas, anaplastic tumors harbored frequent driver mutations in SWI/SNF complex genes, which were confined to the poor prognosis subgroup. Aggressive disease was further characterised by transcriptional evidence of increased PRC2 activity, stemness and epithelial-to-mesenchymal transition. Our analyses discern biologically distinct variants of anaplastic meningioma with prognostic and therapeutic significance.
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http://dx.doi.org/10.1038/s41598-018-31659-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6131140PMC
September 2018

Results of Transcranial Resection of Olfactory Groove Meningiomas in Relation to Imaging-Based Case Selection Criteria for the Endoscopic Approach.

Oper Neurosurg (Hagerstown) 2019 05;16(5):539-548

Division of Neurosurgery, Addenbrookes Hospital, University of Cambridge, Cambridge, United Kingdom.

Background: Endoscopic endonasal surgery (EES) is increasingly used for olfactory groove meningiomas (OGMs). The role of EES for large (≥4 cm) or complex OGMs is debated. Specific imaging features have been reported to affect the degree of gross total resection (GTR) and complications following EES for OGMs. The influence of these factors on transcranial resection (TCR) is unknown.

Objective: To examine the impact of specific imaging features on outcome following TCR to provide a standard for large and endoscopically less favorable OGMs against which endoscopic outcomes can be compared.

Methods: Retrospective study of patients undergoing TCR for OGMs 2002 to 2016.

Results: Fifty patients (mean age 62.1 yr, mean maximum tumor diameter 5.04 cm and average tumor volume of 48.8 cm3) were studied. Simpson grade 1 and 2 resections were achieved in 80% and 12%, respectively. A favorable functional outcome (modified Rankin Scale [mRS] 0-2) was attained in 86%. The degree of resection, mRS, mortality (4%), recurrence (6%), infection (8%), and cerebrospinal fluid leak requiring intervention (12%) were not associated with tumor calcification, absence of cortical cuff, T2 hyperintensity, tumor configuration, tumor extension beyond midpoint of superior orbital roof, or extension to posterior wall of frontal sinus. There was no difference in resection rates but a trend towards greater complications between 3 arbitrarily divided groups of large meningiomas of increasing complexity based on extensive extension or vascular adherence.

Conclusion: Favorable outcomes can be achieved with TCR for large and complex OGMs Factors that may preclude endoscopic resection do not negatively affect outcome following TCR.
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http://dx.doi.org/10.1093/ons/opy191DOI Listing
May 2019

Predictors of early progression of surgically treated atypical meningiomas.

Acta Neurochir (Wien) 2018 09 30;160(9):1813-1822. Epub 2018 Jun 30.

Division of Neurosurgery, Cambridge Biomedical Campus, Addenbrooke's Hospital, University of Cambridge, Box 167, Cambridge, CB2 0QQ, UK.

Background: Clinical behaviour of atypical meningiomas is not uniform. While, as a group, they exhibit a high recurrence rate, some pursue a more benign course, whereas others progress early. We aim to investigate the imaging and pathological factors that predict risk of early tumour progression and to determine whether early progression is related to outcome.

Methods: Adult patients with WHO grade II meningioma treated in three regional referral centres between 2007 and 2014 were included. MRI and pathology characteristics were assessed. Gross total resection (GTR) was defined as Simpson 1-3. Recurrence was classified into early and late (≤ 24 vs. > 24 months).

Results: Among the 220 cases, 37 (16.8%) patients progressed within 24 months of operation. Independent predictors of early progression were subtotal resection (STR) (p = 0.005), parafalcine/parasagittal location (p = 0.015), peritumoural oedema (p = 0.027) and mitotic index (MI) > 7 (p = 0.007). Adjuvant radiotherapy was negatively associated with early recurrence (p = 0.046). Thirty-two per cent of patients with residual tumour and 26% after GTR received adjuvant radiotherapy. There was a significantly lower proportion of favourable outcomes at last follow-up (mRS 0-1) in patients with early recurrence (p = 0.001).

Conclusions: Atypical meningiomas are a heterogeneous group of tumours with 16.8% patients having recurrence within 24 months of surgery. Residual tumour, parafalcine/parasagittal location, peritumoural oedema and a MI > 7 were all independently associated with early recurrence. As administration of adjuvant radiotherapy was not protocolised in this cohort, any conclusions about benefits of irradiation of WHO grade II meningiomas should be viewed with caution. Patients with early recurrence had worse neurological outcome. While histological and imaging characteristics provide some prognostic value, further molecular characterisation of atypical meningiomas is warranted to aid clinical decision making.
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http://dx.doi.org/10.1007/s00701-018-3593-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105233PMC
September 2018

Anterolateral Approach for Central Thoracic Disc Prolapse-Surgical Strategies Used to Tackle Differing Operative Findings: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2019 Jan;16(1):E5-E6

Department of Neurosurgery, Cambridge University Hospital's NHS Foundation Trust, Cambridge, UK.

Thoracic disc prolapses causing cord compression can be challenging. For compressive central disc protrusions, a posterior approach is not suitable due to an unacceptable level of cord manipulation. An anterolateral transthoracic approach provides direct access to the disc prolapse allowing for decompression without disturbing the spinal cord. In this video, we describe 2 cases of thoracic myelopathy from a compressive central thoracic disc prolapse. In both cases, informed consent was obtained. Despite similar radiological appearances of heavy calcification, intraoperatively significant differences can be encountered. We demonstrate different surgical strategies depending on the consistency of the disc and the adherence to the thecal sac. With adequate exposure and detachment from adjacent vertebral bodies, soft discs can be, in most instances, separated from the theca with minimal cord manipulation. On the other hand, largely calcified discs often present a significantly greater challenge and require thinning the disc capsule before removal. In cases with significant adherence to dura, in order to prevent cord injury or cerebrospinal fluid leak a thinned shell can be left, providing total detachment from adjacent vertebrae can be achieved. Postoperatively, the first patient, with a significantly calcified disc, developed a transient left leg weakness which recovered by 3-month follow-up. This video outlines the anatomical considerations and operative steps for a transthoracic approach to a central disc prolapse, whilst demonstrating that computed tomography appearances are not always indicative of potential operative difficulties.
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http://dx.doi.org/10.1093/ons/opy063DOI Listing
January 2019

Type I Spinal Dural Fistula Treated Using a Minimally Invasive Approach With a 20-mm Nonexpandable Tubular Retractor: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2018 Nov;15(5):E52

Division of Neurosurgery, Cambridge University Hospital's NHS Foundation Trust, Cambridge, United Kingdom.

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http://dx.doi.org/10.1093/ons/opy032DOI Listing
November 2018

Microsurgical Clipping of an Ophthalmic Artery Aneurysm With a Limited Intradural Anterior Clinoidectomy: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2018 Nov;15(5):604

Division of Neurosurgery, Cambridge University Hospital's NHS Foundation Trust, Cambridge, United Kingdom.

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http://dx.doi.org/10.1093/ons/opy021DOI Listing
November 2018

Radical, Staged Approach to Extensive Posterior Fossa Pediatric Ependymoma: 3-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2018 Jun;14(6):705

Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.

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http://dx.doi.org/10.1093/ons/opx206DOI Listing
June 2018

Intradural Spinal Arteriovenous Malformation of the Conus Medullaris-Management Strategies and Surgical Nuances: 3-Dimensional Video.

Oper Neurosurg (Hagerstown) 2018 May;14(5):592

Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.

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http://dx.doi.org/10.1093/ons/opx198DOI Listing
May 2018

Stereoscopic Three-Dimensional Neuroanatomy Lectures Enhance Neurosurgical Training: Prospective Comparison with Traditional Teaching.

World Neurosurg 2017 Dec 12;108:917-923.e5. Epub 2017 Sep 12.

Cambridge University Hospitals Foundation Trust, Cambridge, UK. Electronic address:

Objective: Stereoscopic three-dimensional (3D) imaging is increasingly used in the teaching of neuroanatomy and although this is mainly aimed at undergraduate medical students, it has enormous potential for enhancing the training of neurosurgeons. This study aims to assess whether 3D lecturing is an effective method of enhancing the knowledge and confidence of neurosurgeons and how it compares with traditional two-dimensional (2D) lecturing and cadaveric training.

Methods: Three separate teaching sessions for neurosurgical trainees were organized: 1) 2D course (2D lecture + cadaveric session), 2) 3D lecture alone, and 3) 3D course (3D lecture + cadaveric session). Before and after each session, delegates were asked to complete questionnaires containing questions relating to surgical experience, anatomic knowledge, confidence in performing procedures, and perceived value of 3D, 2D, and cadaveric teaching.

Results: Although both 2D and 3D lectures and courses were similarly effective at improving self-rated knowledge and understanding, the 3D lecture and course were associated with significantly greater gains in confidence reported by the delegates for performing a subfrontal approach and sylvian fissure dissection.

Conclusions: Stereoscopic 3D lectures provide neurosurgical trainees with greater confidence for performing standard operative approaches and enhances the benefit of subsequent practical experience in developing technical skills in cadaveric dissection.
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http://dx.doi.org/10.1016/j.wneu.2017.09.019DOI Listing
December 2017

Correlation of volumetric growth and histological grade in 50 meningiomas.

Acta Neurochir (Wien) 2017 11 9;159(11):2169-2177. Epub 2017 Aug 9.

Department of Neurosurgery, Cambridge University Hospitals NHS Foundation Trust, University of Cambridge, Cambridge, UK.

Introduction: Advances in radiological imaging techniques have enabled volumetric measurements of meningiomas to be easily monitored using serial imaging scans. There is limited literature on the relationship between tumour growth rates and the WHO classification of meningiomas despite tumour growth being a major determinant of type and timing of intervention. Volumetric growth has been successfully used to assess growth of low-grade glioma; however, there is limited information on the volumetric growth rate (VGR) of meningiomas. This study aimed to determine the reliability of VGR measurement in patients with meningioma, assess the relationship between VGR and 2016 WHO grading as well as clinical applicability of VGR in monitoring meningioma growth.

Methods: All histologically proven intracranial meningiomas that underwent resection in a single centre between April 2009 and April 2014 were reviewed and classified according to the 2016 edition of the Classification of the Tumours of the CNS. Only patients who had two pre-operative scans that were at least 3 months apart were included in the study. Two authors performed the volumetric measurements using the Slicer 3D software independently and the inter-rater reliability was assessed. Multiple regression analyses of factors affecting the VGR and VDE of meningiomas were performed using the R statistical software with p < 0.05 considered to be statistically significant.

Results: Of 548 patients who underwent resection of their meningiomas, 66 met the inclusion criteria. Sixteen cases met the exclusion criteria (NF2, spinal location, previous surgical or radiation treatment, significant intra-osseous component and poor quality imaging). Forty-two grade I and 8 grade II meningiomas were included in the analysis. The VGR was significantly higher for grade II meningiomas. Using receiver-operator characteristic (ROC) curve analysis, the optimal threshold that distinguishes between grade I and II meningiomas is 3 cm/year. Higher histological grade, high initial tumour volume, MRI T2-signal hyperintensity and presence of oedema were found to be significant predictors of higher VGR.

Conclusion: Reliable tools now exist to evaluate and monitor volumetric growth of meningiomas. Grade II meningiomas have significantly higher VGR compared with grade I meningiomas and growth of more than 3 cm/year is strongly suggestive of a higher grade meningioma. A larger, multi-centre prospective study to investigate the applicability of velocity of growth to predict the outcome of patients with meningioma is warranted.
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http://dx.doi.org/10.1007/s00701-017-3277-yDOI Listing
November 2017

Clinical Experience and Results of Microsurgical Resection of Arterioveonous Malformation in the Presence of Space-Occupying Intracerebral Hematoma.

Neurosurgery 2017 Jul;81(1):75-86

Department of Neurosurgery, Adden-brooke's Hospital, Cambridge, UK.

Background: Management of ruptured arteriovenous malformations (AVMs) with a mass-producing intracerebral hematoma (ICH) represents a surgical dilemma.

Objective: To evaluate the clinical outcome and obliteration rates of microsurgical resection of AVM when performed concomitantly with evacuation of an associated space-occupying ICH.

Methods: Data of patients with AVM were collected prospectively. Cases were identified in which an AVM was resected and an associated space-occupying ICH was evacuated at the same time, and divided into "group 1," in which the surgery was performed acutely within 48 h of presentation (secondary to elevated intracranial pressure); and "group 2," in which selected patients were operated upon in the presence of a liquefying ICH in the "subacute" stage. Clinical outcomes were assessed using the modified Rankin Scale, with a score of 0 to 2 considered a good outcome. Obliteration rates were assessed using postoperative angiography.

Results: From 2001 to 2015, 131 patients underwent microsurgical resection of an AVM, of which 65 cases were included. In "group 1" (n = 21; Spetzler-Ponce class A = 13, class B = 5, and class C = 3), 11 of 21 (52%) had a good outcome and in 18 of 19 (95%) of those who had a postoperative angiogram the AVMs were completely obliterated. In "group 2" (n = 44; Spetzler-Ponce class A = 33, class B = 9, and class C = 2), 31 of 44 (93%) had a good outcome and 42 of 44 (95%) were obliterated with a single procedure. For supratentorial AVMs, the ICH cavity was utilized to provide an operative trajectory to a deep AVM in 11 cases, and in 26 cases the ICH cavity was deep to the AVM and hence facilitated the deep dissection of the nidus.

Conclusion: In selected patients the presence of a liquefying ICH cavity may facilitate the resection of AVMs when performed in the subacute stage resulting in a good neurological outcome and high obliteration rate.
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http://dx.doi.org/10.1093/neuros/nyx003DOI Listing
July 2017

Body mass index and the risk of postoperative cerebrospinal fluid leak following transsphenoidal surgery in an Asian population.

Singapore Med J 2018 05 22;59(5):257-263. Epub 2016 Sep 22.

Division of Neurosurgery, Department of General Surgery, National University Hospital, Singapore.

Introduction: Postoperative cerebrospinal fluid (CSF) leak is a serious complication following transsphenoidal surgery for which elevated body mass index (BMI) has been implicated as a risk factor, albeit only in two recent North American studies. Given the paucity of evidence, we sought to determine if this association holds true in an Asian population, where the BMI criteria for obesity differ from the international standard.

Methods: A retrospective study of 119 patients who underwent 123 transsphenoidal procedures for sellar lesions between May 2000 and May 2012 was conducted. Univariate and multivariate logistic regression analyses were performed to investigate the impact of elevated BMI and other risk factors on postoperative CSF leak.

Results: 10 (8.1%) procedures in ten patients were complicated by postoperative CSF leak. The median BMI of patients with postoperative leak following transsphenoidal procedures was significantly higher than that of patients without postoperative CSF leak (27.0 kg/m vs. 24.6 kg/m; p = 0.018). Patients categorised as either moderate or high risk under the Asian BMI classification were more likely to suffer from a postoperative leak (p = 0.030). Repeat procedures were also found to be significantly associated with postoperative CSF leak (p = 0.041).

Conclusion: Elevated BMI is predictive of postoperative CSF leak following transsphenoidal procedures, even in an Asian population, where the definition of obesity differs from international standards. Thus, BMI should be considered in the clinical decision-making process prior to such procedures.
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http://dx.doi.org/10.11622/smedj.2016159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966635PMC
May 2018

The impact of major trauma centre implementation on the pathways and outcome of traumatic intracranial extradural haematoma in a regional centre.

Br J Neurosurg 2016 Oct 24;30(5):541-4. Epub 2016 May 24.

a Division of Neurosurgery, Department of Clinical Neurosciences , Addenbrooke's Hospital & University of Cambridge , Cambridge , UK.

Introduction: A new trauma care system with regional major trauma centres (MTC) was implemented on 1st April 2012 across England. We aimed to assess whether this has affected the referral pathways and mortality of patients undergoing emergency craniotomy for extradural haematoma (EDH), where clinical outcome is correlated with the time to intervention.

Materials And Methods: This was a retrospective cohort comparison study. All patients who had undergone evacuation of EDH from January 2011 to December 2013 were identified. Only those in whom a decision for emergency craniotomy had been made at the time of referral to the on-call neurosurgeon were included. The CRASH predicted risk of mortality was calculated for individual patients. Mortality was assessed at 14 days in order to compute standardised mortality ratios (SMR).

Results: Overall, 65 patients underwent EDH evacuation during the study period (21 pre-MTC and 44 post-MTC). Of those, 43 emergency procedures according to the aforementioned definition were included for further analysis (13 pre-MTC, 30 post-MTC). The mean CRASH predicted risk of mortality was 0.21 for the pre-MTC cohort (95% CI: 0.07-0.34) and 0.094 for the post-MTC cohort (95% CI: 0.039-0.15; p = 0.052). There was no significant difference in the rate of secondary transfers before and after MTC implementation (9/13 vs. 23/30, p = 0.71). The mean interval from referral to operation was 198 min for the pre-MTC cohort (95% CI: 123-273) and 201 min for the post-MTC cohort (95% CI: 141-262; p = 0.95). The SMR was 0.37 for the pre-MTC cohort (95% CI: 0.02-1.81; 1 death) and 0.71 for the post-MTC cohort (95% CI: 0.12-2.34; 2 deaths).

Conclusions: MTC implementation has not affected the time to operation or the mortality following EDH evacuation.
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http://dx.doi.org/10.1080/02688697.2016.1187252DOI Listing
October 2016

A quest towards personalised medicine for grade II meningiomas--will need to zoom in.

Acta Neurochir (Wien) 2016 05 28;158(5):931-2. Epub 2016 Mar 28.

Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Hills Road, Box 166, Cambridge, UK.

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http://dx.doi.org/10.1007/s00701-016-2774-8DOI Listing
May 2016

Bicoronal frontobasal approach with a limited, midline orbital bar osteotomy - a technical note.

Br J Neurosurg 2016 24;30(1):104-5. Epub 2015 Aug 24.

a Division of Neurosurgery, Addenbrookes Hospital & University of Cambridge , Cambridge , UK.

The frontobasal approach remains a workhorse for removing large olfactory groove meningiomas. Removal of the orbital bar in addition to standard bifrontal craniotomy allows for additional basal exposure, minimising brain retraction and allowing early and direct access to both the vascular supply and dural origin of this tumour. Here, we describe a simple yet effective modification to the standard orbital bar osteotomy. It has the benefit of being simpler and faster with improved cosmesis compared with an osteotomy of the entire orbital bar. It also has the advantage of not requiring manipulation of the supraorbital nerves or intraorbital or periorbital dissection.
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http://dx.doi.org/10.3109/02688697.2015.1071329DOI Listing
January 2017

Pharmacologic Management of Subarachnoid Hemorrhage.

World Neurosurg 2015 Jul 18;84(1):28-35. Epub 2015 Feb 18.

Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.

Subarachnoid hemorrhage (SAH) remains a condition with suboptimal functional outcomes, especially in the young population. Pharmacotherapy has an accepted role in several aspects of the disease and an emerging role in several others. No preventive pharmacologic interventions for SAH currently exist. Antiplatelet medications as well as anticoagulation have been used to prevent thromboembolic events after endovascular coiling. However, the main focus of pharmacologic treatment of SAH is the prevention of delayed cerebral ischemia (DCI). Currently the only evidence-based medical intervention is nimodipine. Other calcium channel blockers have been evaluated without convincing efficacy. Anti-inflammatory drugs such as statins have demonstrated early potential; however, they failed to provide significant evidence for the use in preventing DCI. Similar findings have been reported for magnesium, which showed potential in experimental studies and a phase 2 trial. Clazosentane, a potent endothelin receptor antagonist, did not translate to improve functional outcomes. Various other neuroprotective agents have been used to prevent DCI; however, the results have been, at best inconclusive. The prevention of DCI and improvement in functional outcome remain the goals of pharmacotherapy after the culprit lesion has been treated in aneurysmal SAH. Therefore, further research to elucidate the exact mechanisms by which DCI is propagated is clearly needed. In this article, we review the current pharmacologic approaches that have been evaluated in SAH and highlight the areas in which further research is needed.
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http://dx.doi.org/10.1016/j.wneu.2015.02.004DOI Listing
July 2015

Alternative cost-effective method to record 3D intra-operative images: a technical note.

Br J Neurosurg 2014 Dec 27;28(6):819-20. Epub 2014 Jun 27.

Department of Neurosurgery, The Walton Centre , Liverpool , UK.

The educational value of stereoscopic imaging in neurosurgical training has increasingly been appreciated and its use increased during the last decade. We describe a technique that we developed to acquire and reproduce intra-operative stereoscopic images.
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http://dx.doi.org/10.3109/02688697.2014.931348DOI Listing
December 2014

Recovery of oculomotor nerve palsy secondary to posterior communicating artery aneurysms.

Br J Neurosurg 2014 Aug 11;28(4):483-7. Epub 2013 Nov 11.

Department of Neurosurgery, Addenbrooke's Hospital , Cambridge , UK.

Background: Recent studies suggest more favourable recovery of oculomotor nerve palsy (ONP) caused by posterior communicating artery (PComA) aneurysms with microsurgical clipping compared to endovascular coiling. We describe a consecutive series of patients with ONP from PComA aneurysms treated by microsurgical clipping or endovascular coiling.

Methods: We retrospectively reviewed medical records of all patients from 2005 to 2009 with complete or partial ONP from PComA aneurysms.

Results: Twenty patients were identified, three with unruptured aneurysms. Two patients with ruptured aneurysms were unfit for treatment and therefore excluded. Of the 18 patients included (15 female), 9 underwent microsurgical clipping and 9 received endovascular coiling. Patients treated by surgical clipping were significantly younger compared to those treated by endovascular coiling (mean 52.3 vs. 67.9 years; p = 0.039). Five patients had incomplete ONP (3 clipped, 2 coiled) and thirteen had complete ONP. At 6 months, six of nine patients treated with clipping and five of nine patients treated with coiling had complete resolution of their ONP (p = 1.0); the remainder had partial improvement. There was no significant difference in duration of pre-treatment ONP, age, sex or status of aneurysm (ruptured or unruptured) between patients in the two groups or between those with full or partial recovery. However, all 5 patients with incomplete ONP at presentation recovered fully, compared with 6 of 13 patients who presented with complete ONP.

Conclusions: We found no significant difference between clipping and coiling in the recovery of ONP due to PComA aneurysms. Patient who present with incomplete ONP are more likely to have a full recovery of ONP following either treatment modality than those who present with complete ONP.
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http://dx.doi.org/10.3109/02688697.2013.857007DOI Listing
August 2014

No significant displacement of basal brain structures upon head movement: Kinematic MRI morphometry relevant to neuroendoscopy.

J Neurol Surg A Cent Eur Neurosurg 2014 Mar 24;75(2):98-103. Epub 2013 Jun 24.

Section of Neuroradiology, Addenbrooke's Hospital, Cambridge, United Kingdom.

Background: An appreciation of normal intracranial anatomy allows optimal planning of trajectories necessary for safe and effective neuroendoscopy. Little information exists on displacement of the caudal brain relative to the skull upon head movement; this could have important implications for planning and performance of neuroendoscopic procedures. We used kinematic magnetic resonance imaging (MRI) studies to examine the morphometric displacement and changing anatomical relationships between the clivus and basal brain structures, intracranial vessels, and subarachnoid spaces.

Patients: We retrospectively analyzed 15 patients undergoing sagittal T2 kinematic MRI of the head and neck in modest flexion and extension. The angle between a horizontal axial reference plane and a line between the opisthion and the hard palate defined the degree of flexion and extension. We then measured in flexion and extension (1) the cervicomedullary angle (CMA), (2) displacement of the ventral surface of the brainstem (i.e., depth of the prepontine and premedullary cisterns), (3) total sagittal area of the combined suprasellar and ventral brainstem cisterns, and (4) the basilar tip to tuber cinereum distance.

Results: Relative to neutral head position, a mean extension angle of -15.8 degrees was achieved in all 15 patients, and a mean flexion angle of +9.9 degrees was achieved in 6 patients. The mean CMA was 146 degrees in flexion and 158 degrees in extension. The mean reduction in prepontine and premedullary cistern depth was 0.7 mm and 0.5 mm, respectively, upon flexion from extension. The combined area of suprasellar and ventral brainstem cisterns was minimally reduced from 402 mm2 in flexion to 399 mm(2) in extension. The basilar tip did not move significantly from its position in flexion to extension, 5.3 mm to 5.2 mm respectively from the tuber cinereum.

Conclusion: Kinematic MRI shows minimal brainstem-to-clivus displacement even within minor physiological changes in head flexion. Importantly, these movements are small and there is no significant shift in the position of the basilar tip in modest flexion or extension. These results should be useful for presurgical planning of optimal patient positioning during neuroendoscopic procedures such as third ventriculostomy and the expanded endonasal transsphenoidal approach to the retroclival space.
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http://dx.doi.org/10.1055/s-0033-1342934DOI Listing
March 2014

Ophthalmological outcome after resection of tumors based on the pineal gland.

J Neurosurg 2013 Aug 10;119(2):420-6. Epub 2013 May 10.

Department of Neurosurgery, Addenbrooke’s Hospital, Cambridge, United Kingdom.

Object: Descriptions of visual dysfunction in pineal gland tumors tend to focus on upward gaze palsy alone. The authors aimed to characterize the nature, incidence, and functional significance of ophthalmological dysfunction after resection of tumors based on the pineal gland.

Methods: Review of a retrospective case series was performed and included consecutive patients who underwent surgery performed by a consultant neurosurgeon between 2002 and 2011. Only tumors specifically based on the pineal gland were included; tumors encroaching on the pineal gland from other regions were excluded. All patients with visual signs and/or symptoms were reviewed by a specialist consultant neuroophthalmologist to accurately characterize the nature of their deficits. Visual disturbance was defined as visual symptoms caused by a disturbance of ocular motility.

Results: A total of 20 patients underwent resection of pineal gland tumors. Complete resection was obtained in 85%, and there were no perioperative deaths. Visual disturbance was present in 35% at presentation; of those who had normal ocular motility preoperatively 82% had normal motility postoperatively. In total, 55% of patients had residual visual disturbance postoperatively. Although upward gaze tended to improve, significant functional deficits remained, particularly with regard to complex convergence and accommodation dysfunction. Prisms were used in 25% but were only ever partially effective. Visual outcome was only related to preoperative visual status and tumor volume (multivariate analysis).

Conclusions: Long-term visual morbidity after pineal gland tumor resection is common and leads to significant functional impairment. Improvement in deficits rarely occurs spontaneously, and prisms only have limited effectiveness, probably due to the dynamic nature of supranuclear ocular movement coordination.
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http://dx.doi.org/10.3171/2013.3.JNS122137DOI Listing
August 2013

The aqueduct of Sylvius: applied 3-T magnetic resonance imaging anatomy and morphometry with neuroendoscopic relevance.

Neurosurgery 2013 Dec;73(2 Suppl Operative):ons132-40; discussion ons140

*Section of Neuroradiology; and ‡Department of Neurosurgery, Addenbrooke's Hospital, Cambridge, United Kingdom; §Department of Radiology, University of Cambridge, Cambridge, United Kingdom.

Background: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv.

Objective: To study in detail hitherto unavailable normal magnetic resonance imaging morphometry and anatomic variants of the AqSylv.

Methods: We retrospectively studied normal midsagittal T1-weighted 3-T magnetic resonance images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, and pars posterior; its narrowest point; and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from the Talairach bicommissural line. We statistically determined age- and sex-related changes in AqSylv morphometry using the Pearson correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervicomedullary angle (a surrogate for head position).

Results: Patients were 13 to 83 years of age (45% male, 55% female). Mean morphometrics were as follows: pars anterior width, 1.1 mm; ampulla width, 1.2 mm; pars posterior width, 1.4 mm; length, 14.1 mm; narrowest point, 0.9 mm; and angulation in relation to the third and fourth ventricles, 26° and 18°, respectively. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum and the cervicomedullary angle.

Conclusion: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.
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http://dx.doi.org/10.1227/01.neu.0000430286.08552.caDOI Listing
December 2013

Tuber cinereum proximity to critical major arteries: a morphometric imaging analysis relevant to endoscopic third ventriculostomy.

Acta Neurochir (Wien) 2013 May 7;155(5):891-900. Epub 2013 Mar 7.

Section of Neuroradiology, Addenbrooke's Hospital, Cambridge, UK.

Background: Arterial bleeding in the interpeduncular fossa is a dreaded complication of endoscopic third ventriculostomy (ETV). When the "safe zone" of the tuber cinereum (TC) is fenestrated, the basilar artery tip (BT) or its branches may be encountered below the third ventriclular floor. Major arterial injuries might be avoided by careful preoperative planning. We aimed to establish previously unavailable normal magnetic resonance imaging (MRI) and MR angiographic (MRA) morphometry and configuration of the BT and posterior cerebral artery P1 segments relative to the TC.

Methods: We analyzed images of 82 patients with non-dilated ventricles (mean Evans' index 0.26), and lying in a neutral head position (mean cervico-medullary angle 141°). We cross-referenced axial MRAs with sagittal MRIs to measure distances of BT and P1 segments from the TC, and to classify the location of the BT in the interpeduncular and suprasellar cisterns. We correlated the sagittal areas of these cisterns and patients' ages with the TC-to-artery distances using regression analysis.

Results: The BT, right P1 and left P1 segments were a mean 4.9 mm, 5.5 mm, and 5.7 mm respectively from the TC. Seventy-four percent of BTs were anterior to the mammillary bodies. These distances and locations did not correlate with age (mean 53 years) or size of basal cisterns.

Conclusions: The normal BT and P1 segments are anatomically close to the TC and potentially at risk during ETV in adults of all ages. The new morphometric data presented, along with cross-referencing of preoperative multiplanar images, could help reduce vascular complications during ETV.
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http://dx.doi.org/10.1007/s00701-013-1661-9DOI Listing
May 2013

How I do it--pineal surgery: supracerebellar infratentorial versus occipital transtentorial.

Acta Neurochir (Wien) 2013 Mar 27;155(3):463-7. Epub 2012 Dec 27.

Department of Neurosurgery, Division of Neurosciences, Addenbrooke's Hospital, Box 166, Cambridge, CB2 0QQ, UK.

Background: Resection of a pineal tumour requires fastidious pre-operative planning to select the optimal surgical approach and maximise resection while minimising morbidity.

Method: To describe and compare the supracerebellar infratentorial and occipital transtentorial approaches.

Conclusions: Specific considerations include patient-specific anatomy, extent and relationships of the tumour, and the techniques likely to be employed during resection. The supracerebellar infratentorial approach provides a direct corridor to pineal tumours caudal to the deep veins; for tumours invaginating the tectal plate in a caudal direction the occipital transtentorial provides a better view.
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http://dx.doi.org/10.1007/s00701-012-1589-5DOI Listing
March 2013