Publications by authors named "Cynthia T Chin"

31 Publications

Cerebrospinal Fluid-Venous Fistulas: A Systematic Review and Examination of Individual Patient Data.

Neurosurgery 2021 04;88(5):931-941

Department of Neurological Surgery, University of California San Francisco, San Francisco, California.

Background: Spontaneous intracranial hypotension (SIH) is usually caused by a spinal cerebrospinal fluid (CSF) leak. CSF-venous fistula is an underdiagnosed cause of spinal CSF leak, as it is challenging to identify on myelography.

Objective: To review existing literature to summarize common presentations, diagnostic imaging modalities, and current treatment strategies for CSF-venous fistulas.

Methods: We conducted a systematic review using PubMed, Embase, Scopus, and Web of Science databases to identify studies discussing CSF-venous fistulas. Titles and abstracts were screened. Studies meeting prespecified inclusion criteria were reviewed in full.

Results: Of 180 articles identified, 16 articles met inclusion criteria. Individual patient data was acquired from 7 studies reporting on 18 patients. CSF-venous fistula most frequently presented as positional headache. Digital subtraction myelography provided greatest detection of CSF-venous fistula in the lateral decubitus position and detected CSF-venous fistula in all individual patient cases. Dynamic computed tomography (CT) myelogram enabled detection and differentiation of CSF-venous fistulas from low-flow epidural leaks. The majority of fistulas were in the thoracic spine and slightly more common on the right. Epidural blood patch (EBP) provided temporary or no relief in all individual patients. Resolution or improvement of clinical symptoms and radiologic normalization were observed in all surgically treated patients.

Conclusion: Although rare, CSF-venous fistula is an important cause of spinal CSF leak contributing to SIH. Dynamic CT myelogram and digital subtraction myelography, particularly in the lateral decubitus position, are the most accurate and effective diagnostic imaging modalities. EBPs often provide only transient relief, while surgical management is preferred.
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http://dx.doi.org/10.1093/neuros/nyaa558DOI Listing
April 2021

Diagnostic Challenges in Primary Sacral Tumors and the Yield of Computed Tomography-Guided Needle Biopsy in the Modern Era.

World Neurosurg 2020 06 25;138:e806-e818. Epub 2020 Mar 25.

Department of Neurological Surgery, University of California, San Francisco, California, USA. Electronic address:

Objective: Primary sacral tumors pose unique challenges because of their complex radiographic appearances, diverse pathologic entities, and dramatically different treatment paradigms based on tumor type. Magnetic resonance imaging and computed tomography (CT) can provide valuable information; however, sacral lesions can possess unique radiographic features and pose diagnostic dilemmas. CT-guided percutaneous needle biopsy is a critical component of the diagnostic workup. However, limited data are available on its efficacy for primary sacral tumors.

Methods: The data from patients with newly diagnosed primary sacral lesions during a 12-year period at our hospital were analyzed. The preoperative magnetic resonance imaging findings, biopsy results, and pathological data for patients who required surgery were analyzed. Unique cases in which the final pathologic result was unexpected from the preoperative imaging findings have been highlighted.

Results: Of 38 patients who underwent percutaneous needle biopsy, diagnostic tissue was obtained on the first attempt for 31 (82%). Five of the remaining 7 obtained diagnostic tissue on the second attempt, yielding 95% diagnosis, with only two requiring open biopsies. In 2 patients with diagnostic tissue on CT-guided biopsy, an open biopsy was still recommended because of the clinical scenario. In both patients, the open biopsy results matched those of the CT-guided biopsy. For the 18 patients who required surgery, we found 100% correlation between the percutaneous needle biopsy findings and the final pathological diagnosis. No biopsy-induced complications or extraspinal tumor seeding occurred.

Conclusions: CT-guided biopsy is a safe and effective technique. It represents a critical component of the diagnostic algorithm, given the diverse pathological findings of primary sacral lesions and dramatic differences in treatment.
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http://dx.doi.org/10.1016/j.wneu.2020.03.094DOI Listing
June 2020

Diagnostic Performance of CT-Guided Bone Biopsies in Patients with Suspected Osteomyelitis of the Appendicular and Axial Skeleton with a Focus on Clinical and Technical Factors Associated with Positive Microbiology Culture Results.

J Vasc Interv Radiol 2020 Mar 29;31(3):464-472. Epub 2020 Jan 29.

Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.

Purpose: To assess diagnostic performance of CT-guided percutaneous needle bone biopsy (CTNBB) in patients with suspected osteomyelitis and analyze whether certain clinical or technical factors were associated with positive microbiology results.

Materials And Methods: All CTNBBs performed in a single center for suspected osteomyelitis of the appendicular and axial skeleton during 2003-2018 were retrospectively reviewed. Specific inclusion criteria were clinical and radiologic suspicion of osteomyelitis. Standard of reference was defined using outcome of surgical histopathology and microbiology culture and clinical and imaging follow-up. Technical and clinical data (needle size, comorbidities, clinical factors, laboratory values, blood cultures) were collected. Logistic regression was performed to assess associations between technical and clinical data and microbiology biopsy outcome.

Results: A total of 142 CTNBBs were included (46.5% female patients; age ± SD 46.10 y ± 22.8), 72 (50.7%) from the appendicular skeleton and 70 (49.3%) from the axial skeleton. CTNBB showed a sensitivity of 42.5% (95% confidence interval [CI], 32.0%-53.6%) in isolating the causative pathogen. A higher rate of positive microbiology results was found in patients with intravenous drug use (odds ratio [OR] = 5.15; 95% CI, 1.2-21.0; P = .022) and elevated white blood cell count ≥ 10 × 10/L (OR = 3.9; 95% CI, 1.62-9.53; P = .002). Fever (≥ 38°C) was another clinical factor associated with positive microbiology results (OR = 3.6; 95% CI, 1.3-9.6; P = .011).

Conclusions: CTNBB had a low sensitivity of 42.5% for isolating the causative pathogen. Rate of positive microbiology samples was significantly higher in patients with IV drug use, elevated white blood cell count, and fever.
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http://dx.doi.org/10.1016/j.jvir.2019.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7036328PMC
March 2020

Schwannomatosis of the Spinal Accessory Nerve: A Case Report.

J Brachial Plex Peripher Nerve Inj 2019 Jan 26;14(1):e9-e13. Epub 2019 Apr 26.

Department of Neurological Surgery, University of California, San Francisco, California, United States.

Schwannomatosis is a distinct syndrome characterized by multiple peripheral nerve schwannomas that can be sporadic or familial in nature. Cases affecting the lower cranial nerves are infrequent. Here, the authors present a rare case of schwannomatosis affecting the left spinal accessory nerve. Upon genetic screening, an in-frame insertion at codon p.R177 of the Sox 10 gene was observed. There were no identifiable alterations in NF1, NF2, LZTR1, and SMARCB1. This case demonstrates a rare clinical presentation of schwannomatosis in addition to a genetic aberration that has not been previously reported in this disease context.
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http://dx.doi.org/10.1055/s-0039-1685457DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486389PMC
January 2019

Imaging-Based Approach to Extradural Infections of the Spine.

Semin Ultrasound CT MR 2018 12 26;39(6):570-586. Epub 2018 Sep 26.

Department of Radiology and Biomedical Imaging, University of California, San Francisco.

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http://dx.doi.org/10.1053/j.sult.2018.09.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291848PMC
December 2018

Clinical Utility of Diffusion-Weighted Imaging in Spinal Infections.

Clin Neuroradiol 2019 Sep 26;29(3):515-522. Epub 2018 Mar 26.

Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Avenue, Rm. L-358, 94143-0628, San Francisco, CA, USA.

Purpose: Both laboratory markers and radiographic findings in the setting of spinal infections can be nonspecific in determining the presence or absence of active infection, and can lag behind both clinical symptoms and antibiotic response. Magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) has been shown to be helpful in evaluating brain abscesses but has not been commonly used in evaluating spinal infections. We aimed to correlate findings on DWI of the spine to results of microbiological sampling in patients with suspected spinal infections.

Methods: Patients who underwent MRI with DWI for suspicion of spinal infections and microbiological sampling from 2002 to 2010 were identified and reviewed retrospectively in this institutional review board approved study. In addition to DWI, scans included sagittal and axial T1, fast-spin echo (FSE) T2, and post-gadolinium T1 with fat saturation. Regions of interest were drawn on apparent diffusion coefficient (ADC) maps in the area of suspected infections, and ADC values were correlated with microbiological sampling.

Results: Of 38 patients with suspected spinal infections, 29 (76%) had positive microbiological sampling, and 9 (24%) had negative results. The median ADC value was 740 × 10 mm/s for patients with positive microbiological sampling and 1980 × 10 mm/s for patients with negative microbiological sampling (p < 0.001). Using an ADC value of 1250 × 10 mm/s or less as the cut-off value for a positive result for spinal infection, sensitivity was 66%, specificity was 88%, positive predictive value was 95%, negative predictive value was 41% and accuracy was 70%.

Conclusion: In patients with suspected spine infection, ADC values on DWI are significantly reduced in those patients with positive microbiological sampling compared to patients with negative microbiological sampling. The DWI of the spine correlates well with the presence or absence of spinal infection and may complement conventional magnetic resonance imaging (MRI).
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http://dx.doi.org/10.1007/s00062-018-0681-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6158113PMC
September 2019

Large Cervical Vagus Nerve Tumor in a Patient with Neurofibromatosis Type 1 Treated with Gross Total Resection: Case Report and Review of the Literature.

J Brachial Plex Peripher Nerve Inj 2016 16;11(1):e48-e54. Epub 2016 Nov 16.

Department of Neurological Surgery, University of California, San Francisco, California, United States.

Neurofibromas are benign peripheral nerve sheath tumors that occur commonly in individuals with neurocutaneous disorders such as neurofibromatosis type 1. Vagal nerve neurofibromas, however, are a relatively rare occurrence. We present the case of a 22-year-old man with neurofibromatosis type 1 with a neurofibroma of the left cervical vagal nerve. The mass was resected through an anterior approach without major event. In the postoperative course, the patient developed left vocal cord paralysis treated with medialization with injectable gel. We then present a comprehensive review of the literature for surgical resection of vagal nerve neurofibromas.
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http://dx.doi.org/10.1055/s-0036-1594010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5152703PMC
November 2016

An Imaging-Based Approach to Spinal Cord Infection.

Semin Ultrasound CT MR 2016 Oct 2;37(5):411-30. Epub 2016 Jun 2.

Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA; Department of Radiology, San Francisco General Hospital, San Francisco, CA.

Infections of the spinal cord, nerve roots, and surrounding meninges are uncommon, but highly significant given their potential for severe morbidity and even mortality. Prompt diagnosis can be lifesaving, as many spinal infections are treatable. Advances in imaging technology have now firmly established magnetic resonance imaging (MRI) as the gold standard for spinal cord imaging evaluation, enabling the depiction of infectious myelopathies with exquisite detail and contrast. In this article, we aim to provide an overview of MRI findings for spinal cord infections with special focus on imaging patterns of infection that are primarily confined to the spinal cord, spinal meninges, and spinal nerve roots. In this context, we describe and organize this review around 5 distinct patterns of transverse spinal abnormality that may be detected with MRI as follows: (1) extramedullary, (2) centromedullary, (3) eccentric, (4) frontal horn, and (5) irregular. We seek to classify the most common presentations for a wide variety of infectious agents within this image-based framework while realizing that significant overlap and variation exists, including some infections that remain occult with conventional imaging techniques.
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http://dx.doi.org/10.1053/j.sult.2016.05.006DOI Listing
October 2016

Neurological outcomes and surgical complications in 221 spinal nerve sheath tumors.

J Neurosurg Spine 2017 Jan 29;26(1):103-111. Epub 2016 Jul 29.

Departments of 1 Neurological Surgery.

OBJECTIVE Among all primary spinal neoplasms, approximately two-thirds are intradural extramedullary lesions; nerve sheath tumors, mainly neurofibromas and schwannomas, comprise approximately half of them. Given the rarity of these lesions, reports of surgical complications are limited. The aim of this study was to identify the rates of new or worsening neurological deficits and surgical complications associated with the resection of spinal nerve sheath tumors and the potential factors related to these outcomes. METHODS Patients were identified through a search of an institutional neuropathology database and a separate review of current procedural terminology (CPT) codes. Age, sex, clinical presentation, presence of neurofibromatosis (NF), tumor type, tumor location, extent of resection characterized as gross total or subtotal, use of intraoperative neuromonitoring, surgical complications, presence of neurological deficit, and clinical follow-up were recorded. RESULTS Two hundred twenty-one tumors in 199 patients with a mean age of 45 years were identified. Fifty-three tumors were neurofibromas; 163, schwannomas; and 5, malignant peripheral nerve sheath tumors (MPNSTs). There were 70 complications in 221 cases, a rate of 32%, which included 34 new or worsening sensory symptoms (15%), 12 new or worsening motor deficits (5%), 10 CSF leaks or pseudomeningoceles (4%), 11 wound infections (5%), 5 cases of spinal deformity (2%), and 6 others (2 spinal epidural hematomas, 1 nonoperative cranial subdural hematoma, 1 deep venous thrombosis, 1 case of urinary retention, and 1 recurrent laryngeal nerve injury). Complications were more common in cervical (36%) and lumbosacral (38%) tumors than in thoracic (18%) lesions (p = 0.021). Intradural and dumbbell lesions were associated with higher rates of CSF leakage, pseudomeningocele, and wound infection. Complications were present in 18 neurofibromas (34%), 50 schwannomas (31%), and 2 MPNSTs (40%); the differences in frequency were not significant (p = 0.834). Higher complication rates were observed in patients with NF than in patients without (38% vs 30%, p = 0.189), although rates were higher in NF Type 2 than in Type 1 (64% vs 31%). There was no difference in the use of intraoperative neuromonitoring when comparing cases with surgical complications and those without (67% vs 69%, p = 0.797). However, the use of neuromonitoring was associated with a significantly higher rate of gross-total resection (79% vs 66%, p = 0.022). CONCLUSIONS Resection is a safe and effective treatment for spinal nerve sheath tumors. Approximately 30% of patients developed a postoperative complication, most commonly new or worsening sensory deficits. This rate probably represents an inevitable complication of nerve sheath tumor surgery given the intimacy of these lesions with functional neural elements.
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http://dx.doi.org/10.3171/2016.5.SPINE15974DOI Listing
January 2017

Magnetic resonance neurography in the diagnosis of neuropathies of the lumbosacral plexus: a pictorial review.

Clin Imaging 2016 Nov - Dec;40(6):1118-1130. Epub 2016 Jul 11.

Department of Neurology, University of California San Francisco, San Francisco, California, USA.

Magnetic resonance neurography (MRN) is an important tool to detect abnormalities of peripheral nerves. This pictorial review demonstrates the MRN features of a variety of neuropathies affecting the lumbosacral plexus (LSP) and lower extremity nerves, drawn from over 1200 MRNs from our institution and supplemented by the literature. Abnormalities can be due to spinal compression, extraspinal compression, malignancy, musculoskeletal disease, iatrogenesis, inflammation, infection, and idiopathic disorders. We discuss indications and limitations of MRN in diagnosing LSP neuropathies. As MRN becomes more widely used, physicians must become familiar with the differential diagnosis of abnormalities detectable with MRN of the LSP.
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http://dx.doi.org/10.1016/j.clinimag.2016.07.003DOI Listing
January 2017

Peripheral nerve imaging.

Handb Clin Neurol 2016 ;136:811-26

Department of Neurological Surgery, Northwestern Feinberg School of Medicine, Chicago, IL, USA. Electronic address:

Disorders of peripheral nerve have been traditionally diagnosed and monitored using clinical and electrodiagnostic approaches. The last two decades have seen rapid development of both magnetic resonance imaging (MRI) and ultrasound imaging of peripheral nerve, such that these imaging modalities are increasingly invaluable to the diagnosis of patients with peripheral nerve disorders. Peripheral nerve imaging provides information which is supplementary to clinical and electrodiagnostic diagnosis. Both MRI and ultrasound have particular benefits in specific clinical circumstances and can be considered as complementary techniques. These technologic developments in peripheral nerve imaging will usher in an era of multimodality assessment of peripheral nerve disorders, with clinical evaluations supported by anatomic information from imaging, and functional information from electrodiagnostic studies. Such a multimodality approach will improve the accuracy and efficiency of patient care.
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http://dx.doi.org/10.1016/B978-0-444-53486-6.00040-5DOI Listing
February 2017

Microsurgical Fenestration and Paraspinal Muscle Pedicle Flaps for the Treatment of Symptomatic Sacral Tarlov Cysts.

World Neurosurg 2016 Feb 28;86:233-42. Epub 2015 Sep 28.

Department of Neurological Surgery, University of California, San Francisco, San Francisco, California, USA. Electronic address:

Objective: Sacral Tarlov cysts are rare causes of sciatic and sacrococcygeal pain and neurologic deficits. Although several microsurgical treatments have been described, the optimal treatment has yet to be determined. We describe our initial experience with symptomatic lesions combining 1) cyst fenestration and imbrication and 2) filling the epidural space using vascularized paraspinous muscle flaps rotated into the cystic cavity.

Methods: We retrospectively reviewed all consecutive cases of symptomatic giant sacral Tarlov cysts treated with microsurgery at our institution between 2003 and 2011. The main outcome measure was self-reported symptom relief. Postoperative imaging, surgical complications, and subsequent treatments were also recorded.

Results: Thirty-five patients were treated. Mean age was 52 years. All patients presented with a chief complaint of sacral-perineal pain. The mean cyst size was 3.6 cm (largest diameter). Follow-up beyond the initial hospital stay was available in 86% (median 8 months). Ninety-three percent reported improvement in pain at some point during the postoperative course but 50% of those developed recurrent pain symptoms. Postoperative imaging was available in 69% of the patients in whom 92% showed complete obliteration (25%) or reduction in cyst size (67%).

Conclusions: The combination of microsurgical cyst fenestration and the use of vascularized muscle pedicle flaps to fill the cystic cavity and the epidural space results in obliteration or reduction in size of the majority of cysts and is associated with initial improvement in pain in most patients. However, delayed recurrence of pain was common with this technique.
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http://dx.doi.org/10.1016/j.wneu.2015.09.055DOI Listing
February 2016

Neurogenic thoracic outlet syndrome: current diagnostic criteria and advances in MRI diagnostics.

Neurosurg Focus 2015 Sep;39(3):E7

Departments of 1 Neurological Surgery and.

Neurogenic thoracic outlet syndrome (nTOS) is caused by compression of the brachial plexus as it traverses from the thoracic outlet to the axilla. Diagnosing nTOS can be difficult because of overlap with other complex pain and entrapment syndromes. An nTOS diagnosis is made based on patient history, physical exam, electrodiagnostic studies, and, more recently, interpretation of MR neurograms with tractography. Advances in high-resolution MRI and tractography can confirm an nTOS diagnosis and identify the location of nerve compression, allowing tailored surgical decompression. In this report, the authors review the current diagnostic criteria, present an update on advances in MRI, and provide case examples demonstrating how MR neurography (MRN) can aid in diagnosing nTOS. The authors conclude that improved high-resolution MRN and tractography are valuable tools for identifying the source of nerve compression in patients with nTOS and can augment current diagnostic modalities for this syndrome.
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http://dx.doi.org/10.3171/2015.6.FOCUS15219DOI Listing
September 2015

Visualization of nerve fibers and their relationship to peripheral nerve tumors by diffusion tensor imaging.

Neurosurg Focus 2015 Sep;39(3):E16

Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois.

OBJECT The majority of growing and/or symptomatic peripheral nerve tumors are schwannomas and neurofibromas. They are almost always benign and can usually be resected while minimizing motor and sensory deficits if approached with the proper expertise and techniques. Intraoperative electrophysiological stimulation and recording techniques allow the surgeon to map the surface of the tumor in an effort to identify and thus avoid damaging functioning nerve fibers. Recently, MR diffusion tensor imaging (DTI) techniques have permitted the visualization of axons, because of their anisotropic properties, in peripheral nerves. The object of this study was to compare the distribution of nerve fibers as revealed by direct electrical stimulation with that seen on preoperative MR DTI. METHODS The authors conducted a retrospective chart review of patients with a peripheral nerve or nerve root tumor between March 2012 and January 2014. Diffusion tensor imaging and intraoperative data had been prospectively collected for patients with peripheral nerve tumors that were resected. Preoperative identification of the nerve fiber location in relation to the nerve tumor surface as seen on DTI studies was compared with the nerve fiber's intraoperative localization using electrophysiological stimulation and recordings. RESULTS In 23 patients eligible for study there was good correlation between nerve fiber location on DTI and its anatomical location seen intraoperatively. Diffusion tensor imaging demonstrated the relationship of nerve fibers relative to the tumor with 95.7% sensitivity, 66.7% specificity, 75% positive predictive value, and 93.8% negative predictive value. CONCLUSIONS Preoperative DTI techniques are useful in helping the peripheral nerve surgeon to both determine the risks involved in resecting a nerve tumor and plan the safest surgical approach.
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http://dx.doi.org/10.3171/2015.6.FOCUS15235DOI Listing
September 2015

Magnetic resonance neurography evaluation of chronic extraspinal sciatica after remote proximal hamstring injury: a preliminary retrospective analysis.

J Neurosurg 2014 Aug 30;121(2):408-14. Epub 2014 May 30.

Department of Radiology and Biomedical Imaging, University of California, San Francisco, California.

Object: Extraspinal sciatica can present unique challenges in clinical diagnosis and management. In this study, the authors evaluated qualitative and quantitative patterns of sciatica-related pathology at the ischial tuberosity on MR neurography (MRN) studies performed for chronic extraspinal sciatica.

Methods: Lumbosacral MRN studies obtained in 14 patients at the University of California, San Francisco between 2007 and 2011 were retrospectively reviewed. The patients had been referred by neurosurgeons or neurologists for chronic unilateral sciatica (≥ 3 months), and the MRN reports described asymmetrical increased T2 signal within the sciatic nerve at the level of the ischial tuberosity. MRN studies were also performed prospectively in 6 healthy volunteers. Sciatic nerve T2 signal intensity (SI) and cross-sectional area at the ischial tuberosity were calculated and compared between the 2 sides in all 20 subjects. The same measurements were also performed at the sciatic notch as an internal reference. Adjacent musculoskeletal pathology was compared between the 2 sides in all subjects.

Results: Seven of the 9 patients for whom detailed histories were available had a specific history of injury or trauma near the proximal hamstring preceding the onset of sciatica. Eight of the 14 patients also demonstrated soft-tissue abnormalities adjacent to the proximal hamstring origin. The remaining 6 had normal muscles, tendons, and marrow in the region of the ischial tuberosity. There was a significant difference in sciatic nerve SI and size between the symptomatic and asymptomatic sides at the level of the ischial tuberosity, with a mean adjusted SI of 1.38 compared with 1.00 (p < 0.001) and a mean cross-sectional nerve area of 0.66 versus 0.54 cm(2) (p = 0.002). The control group demonstrated symmetrical adjusted SI and sciatic nerve size.

Conclusions: This study suggests that chronic sciatic neuropathy can be seen at the ischial tuberosity in the setting of prior proximal hamstring tendon injury or adjacent soft-tissue abnormalities. Because hamstring tendon injury as a cause of chronic sciatica remains a diagnosis of exclusion, this distinct category of patients has not been described in the radiographic literature and merits special attention from clinicians and radiologists in the management of extraspinal sciatica. Magnetic resonance neurography is useful for evaluating chronic sciatic neuropathy both qualitatively and quantitatively, particularly in patients for whom electromyography and traditional MRI studies are unrevealing.
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http://dx.doi.org/10.3171/2014.4.JNS13940DOI Listing
August 2014

Utility of MRI in spinal arteriovenous fistula.

Neurology 2012 Jul 16;79(1):25-30. Epub 2012 May 16.

Departments of Neurology, University of California San Francisco, CA, USA.

Objective And Background: Spinal arteriovenous fistula (SAVF) is a rare but treatable cause of myelopathy. The diagnostic accuracy of MRI for detecting SAVF is unknown. Our objective was to determine the sensitivity and specificity of MRI in the diagnosis SAVF and characterize its radiographic features.

Methods: We conducted a retrospective case-control study of all SAVF treated at our institution from 1995 to 2010, including patients who presented with myelopathy, had MRIs available for review, and underwent either spinal angiogram or had another diagnosis confirming test. Two blinded board-certified radiologists reviewed a series of MRIs and listed the most likely diagnoses, radiologic findings, and recommended follow-up. Sensitivities and specificities of MRI compared to spinal angiogram were calculated. We additionally conducted a literature review of cases describing MRI findings in spinal dural and perimedullary arteriovenous fistula.

Results: We identified 36 cases of SAVF (median age 56, 67% male) and 32 controls (median age 54, 44% male). MRI was sensitive in identifying SAVF as the primary diagnosis in 94% (radiologist A, 95% confidence interval [CI] 0.87-1.02) and 89% (radiologist B, 95% CI 0.79-0.99) of cases. The sensitivity of spinal cord T2 hyperintensity or flow voids was 100% and the specificity of T2 hyperintensity and flow voids was 97%.

Conclusions: Among patients with myelopathy, spinal angiography is mandatory in the presence of both T2 hyperintensity and flow voids but may be unnecessary if both of these findings are absent.
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http://dx.doi.org/10.1212/WNL.0b013e3182582f07DOI Listing
July 2012

Avoidance of wrong-level thoracic spine surgery: intraoperative localization with preoperative percutaneous fiducial screw placement.

J Neurosurg Spine 2012 Mar 4;16(3):280-4. Epub 2011 Nov 4.

Department of Neurological Surgery, University of California, San Francisco, California, USA.

Object: The accurate intraoperative localization of the correct thoracic spine level remains a challenging problem in both open and minimally invasive spine surgery. The authors describe a technique of using preoperatively placed percutaneous fiducial screws to localize the area of interest in the thoracic spine, and they assess the safety and efficacy of the technique.

Methods: To avoid wrong-level surgery in the thoracic spine, the authors preoperatively placed a percutaneous 5-mm fiducial screw at the level of intended surgery using CT guidance. Plain radiographs and CT images with reconstructed views can then be referenced in the operating room to verify the surgical level, and the fiducial screw is easily identified on intraoperative fluoroscopy. The authors compared a group of 26 patients who underwent preoperative (often outpatient) fiducial screw placement prior to open or minimally invasive thoracic spine surgery to a historical group of 26 patients who had intraoperative localization with fluoroscopy alone.

Results: In the treatment group of 26 patients, no complications related to fiducial screw placement occurred, and there was no incidence of wrong-level surgery. In comparison, there were no wrong-level surgeries in the historical cohort of 26 patients who underwent mini-open or open thoracic spine surgery without placement of a fiducial screw. However, the authors found that the intraoperative localization fluoroscopy time was greatly reduced when a fiducial screw localization technique was employed.

Conclusions: The aforementioned technique for intraoperative localization is safe, efficient, and accurate for identifying the target level in thoracic spine exposures. The fiducial marker screw can be placed using CT guidance on an outpatient basis. There is a reduction in the amount of intraoperative fluoroscopy time needed for localization in the fiducial screw group.
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http://dx.doi.org/10.3171/2011.3.SPINE10445DOI Listing
March 2012

Diagnosing ulnar neuropathy at the elbow using magnetic resonance neurography.

Skeletal Radiol 2012 Apr 16;41(4):401-7. Epub 2011 Aug 16.

Dept of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Avenue, Suite M392, Box 0628, San Francisco, CA 94143-0628, USA.

Introduction: Early diagnosis of ulnar neuropathy at the elbow is important. Magnetic resonance neurography (MRN) images peripheral nerves. We evaluated the usefulness of elbow MRN in diagnosing ulnar neuropathy at the elbow.

Methods: The MR neurograms of 21 patients with ulnar neuropathy were reviewed retrospectively. MRN was performed prospectively on 10 normal volunteers. The MR neurograms included axial T1 and axial T2 fat-saturated and/or axial STIR sequences. The sensitivity and specificity of MRN in detecting ulnar neuropathy were determined.

Results: The mean ulnar nerve size in the symptomatic and normal groups was 0.12 and 0.06 cm(2) (P < 0.001). The mean relative signal intensity in the symptomatic and normal groups was 2.7 and 1.4 (P < 0.01). When using a size of 0.08 cm(2), sensitivity was 95% and specificity was 80%.

Discussion: Ulnar nerve size and signal intensity were greater in patients with ulnar neuropathy. MRN is a useful test in evaluating ulnar neuropathy at the elbow.
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http://dx.doi.org/10.1007/s00256-011-1251-yDOI Listing
April 2012

CT-guided biopsy of bone and soft-tissue lesions: role of on-site immediate cytologic evaluation.

J Vasc Interv Radiol 2011 Jul 14;22(7):1024-30. Epub 2011 May 14.

Department of Radiology and Biomedical Imaging, University of California, San Francisco, 400 Parnassus Ave, A 367, Box 0628, San Francisco, CA 94143-0628, USA.

Purpose: To assess the impact of on-site immediate cytologic assessment (ICA) on the diagnostic success rate of computed tomography (CT)-guided percutaneous needle biopsy (PNB) of musculoskeletal lesions and the long-term outcome in inconclusive PNB findings.

Materials And Methods: A total of 299 CT-guided PNBs of musculoskeletal lesions performed between January 1997 and December 2009 were retrospectively reviewed. The lesions were categorized by their morphology, location, and size, and by biopsy type. The diagnostic success rates, impact of ICA, and outcome in inconclusive PNBs were studied, with final histopathologic findings and/or clinical follow-up as a reference.

Results: The overall diagnostic success rate of PNBs was 72.9% (218 of 299). The success rate increased with larger lesions (> 2 cm to 4 cm; P = .009). Biopsies performed with ICA had a higher success rate (77.0% vs 63.3%; P = .015). PNBs had inconclusive results in 109 of 299 cases (36.5%). In 66 of these, repeat open biopsy or clinical follow-up demonstrated 19 malignant/aggressive lesions (28.8%) and 47 benign/nonaggressive lesions (71.2%).

Conclusions: CT-guided PNB had a satisfactory success rate, which significantly increased when performed with ICA. Inconclusive results in PNB were most frequently associated with benign findings during further workup.
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http://dx.doi.org/10.1016/j.jvir.2011.03.019DOI Listing
July 2011

Heterogeneous patterns of tissue injury in NARP syndrome.

J Neurol 2011 Mar 16;258(3):440-8. Epub 2010 Oct 16.

Department of Neurology, University of California, San Francisco, CA 94143-0114, USA.

Point mutations at m.8993T>C and m.8993T>G of the mtDNA ATPase 6 gene cause the neurogenic weakness, ataxia and retinitis pigmentosa (NARP) syndrome, a mitochondrial disorder characterized by retinal, central and peripheral neurodegeneration. We performed detailed neurological, neuropsychological and ophthalmological phenotyping of a mother and four daughters with NARP syndrome from the mtDNA m.8993T>C ATPase 6 mutation, including 3-T brain MRI, spectral domain optical coherence tomography (SD-OCT), adaptive optics scanning laser ophthalmoscopy (AOSLO), electromyography and nerve conduction studies (EMG-NCS) and formal neuropsychological testing. The degree of mutant heteroplasmy for the m.8993T>C mutation was evaluated by real-time allele refractory mutation system quantitative PCR of mtDNA from hair bulbs (ectoderm) and blood leukocytes (mesoderm). There were marked phenotypic differences between family members, even between individuals with the greatest degrees of ectodermal and mesodermal heteroplasmy. 3-T MRI revealed cerebellar atrophy and cystic and cavitary T2 hyperintensities in the basal ganglia. SD-OCT demonstrated similarly heterogeneous areas of neuronal and axonal loss in inner and outer retinal layers. AOSLO showed increased cone spacing due to photoreceptor loss. EMG-NCS revealed varying degrees of length-dependent sensorimotor axonal polyneuropathy. On formal neuropsychological testing, there were varying deficits in processing speed, visual-spatial functioning and verbal fluency and high rates of severe depression. Many of these cognitive deficits likely localize to cerebellar and/or basal ganglia dysfunction. High-resolution retinal and brain imaging in NARP syndrome revealed analogous patterns of tissue injury characterized by heterogeneous areas of neuronal loss.
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http://dx.doi.org/10.1007/s00415-010-5775-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068520PMC
March 2011

Free-hand thoracic pedicle screws placed by neurosurgery residents: a CT analysis.

Eur Spine J 2010 May 5;19(5):821-7. Epub 2010 Feb 5.

Department of Neurological Surgery, University of California, 505 Parnassus Ave., Box 0112, San Francisco, CA 94143-0112, USA.

Free-hand thoracic pedicle screw placement is becoming more prevalent within neurosurgery residency training programs. This technique implements anatomic landmarks and tactile palpation without fluoroscopy or navigation to place thoracic pedicle screws. Because this technique is performed by surgeons in training, we wished to analyze the rate at which these screws were properly placed by residents by retrospectively reviewing the accuracy of resident-placed free-hand thoracic pedicle screws using computed tomography imaging. A total of 268 resident-placed thoracic pedicle screws was analyzed using axial computed tomography by an independent attending neuroradiologist. Eighty-five percent of the screws were completely within the pedicle and that 15% of the screws violated the pedicle cortex. The majority of the breaches were lateral breaches between 2 and 4 mm (46%). There was no clinical evidence of neurovascular injury or injury to the esophagus. There were no re-operations for screw replacement. We concluded that under appropriate supervision, neurosurgery residents can safely place free-hand thoracic pedicle screws with an acceptable breach rate.
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http://dx.doi.org/10.1007/s00586-010-1293-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899961PMC
May 2010

Magnetic resonance neurography for the evaluation of peripheral nerve, brachial plexus, and nerve root disorders.

J Neurosurg 2010 Feb;112(2):362-71

Department of Neurological Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachussetts 02115, USA.

Object: Treatment of spinal and peripheral nerve lesions relies on localization of the pathology by the use of neurological examination, spinal MR imaging and electromyography (EMG)/nerve conduction studies (NCSs). Magnetic resonance neurography (MRN) is a novel imaging technique recently developed for direct imaging of spinal and peripheral nerves. In this study, the authors analyzed the role of MRN in the evaluation of spinal and peripheral nerve lesions.

Methods: Imaging studies, medical records, and EMG/NCS results were analyzed retrospectively in a consecutive series of 191 patients who underwent MRN for spinal and peripheral nerve disorders at the University of California, San Francisco between March 1999 and February 2005. Ninety-one (47.6%) of these patients also underwent EMG/NCS studies.

Results: In those who underwent both MRN and EMG/NCS, MRN provided the same or additional diagnostic information 32 and 45% of patients, respectively. Magnetic resonance neurograms were obtained at a median of 12 months after the onset of symptoms. The utility of MRN correlated with the interval between the onset of symptoms to MRN. Twelve patients underwent repeated MRN for serial evaluation. The decrease in abnormal signal detected on subsequent MRN correlated with time from onset of symptoms and the time interval between MRN, but not with resolution of symptoms. Twenty-one patients underwent MRN postoperatively to assess persistent, recurrent, or new symptoms; of these 3 (14.3%) required a subsequent surgery.

Conclusions: Magnetic resonance neurography is a valuable adjunct to conventional MR imaging and EMG/NCS in the evaluation and localization of nerve root, brachial plexus, and peripheral nerve lesions. The authors found that MRN is indicated in patients: 1) in whom EMG and traditional MR imaging are inconclusive; 2) who present with brachial plexopathy who have previously received radiation therapy to the brachial plexus region; 3) who present with brachial plexopathy and have systemic tumors; and 4) in patients under consideration for surgery for peripheral nerve lesions or after trauma. Magnetic resonance neurography is limited by the size of the nerve trunk imaged and the timing of the study.
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http://dx.doi.org/10.3171/2009.7.JNS09414DOI Listing
February 2010

Intracranial hypotension caused by leakage of cerebrospinal fluid from the thecal sac after lumboperitoneal shunt placement. Case report.

J Neurosurg 2007 Jul;107(1):173-7

Department of Ophthalmology, University of California, San Francisco, California 94143-0730, USA.

The authors describe a newly recognized complication of lumboperitoneal (LP) shunt placement, namely, intracranial hypotension from leakage of cerebrospinal fluid (CSF) through a defect in the lumbar dura created by the shunt catheter. They report on a 47-year-old obese woman with idiopathic intracranial hypertension who underwent routine placement of an LP shunt. Following surgery, her headache became worse. Two radionuclide shunt studies showed no anterograde tracer flow, suggesting either obstruction or a leak. After shunt reservoir manometry indicated low pressure, spinal magnetic resonance (MR) imaging was performed. The MR images revealed a CSF leak from the lumbar thecal sac. A computed tomography (CT) myelogram, performed by injection into the shunt reservoir, confirmed the presence of a leak by showing extravasation of contrast agent into the epidural space. The patient was treated by application of a CT-guided blood patch at the leak site. Catheter-associated CSF leak is an unusual cause of intracranial hypotension that can occur following LP shunt placement. This case report outlines the clinical features of this condition, documents the neuroradiological findings, and demonstrates successful treatment with a blood patch.
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http://dx.doi.org/10.3171/JNS-07/07/0173DOI Listing
July 2007

Spontaneous regression of a discal cyst. Case report.

J Neurosurg Spine 2007 Jan;6(1):81-4

Department of Neurological Surgery, Division of Neuroradiology, University of California, San Francisco, California 94143-0112, USA.

The authors describe a case of a discal cyst that resolved almost completely without direct intervention. Discal cysts are rare, with the authors of only a few case reports describing this entity. These reports all identify at least some intervention performed for alleviation of the symptoms, including open surgery, minimally invasive surgery, or percutaneous puncture with aspiration. The authors report on a 35-year-old man with radiculopathy who presented with a discal cyst and was treated with a routine epidural injection and selective nerve root block. Within 5 months, the discal cyst showed dramatic regression on magnetic resonance imaging and the patient's symptoms improved. The natural history of this pathological entity is unknown, and to the authors' knowledge this is the first detailed report of the regression of a discal cyst without surgery or aspiration.
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http://dx.doi.org/10.3171/spi.2007.6.1.81DOI Listing
January 2007

Magnetic resonance neurography in extraspinal sciatica.

Arch Neurol 2006 Oct;63(10):1469-72

Department of Neurology, University of California, San Francisco, USA.

Background: Sciatica without evidence of lumbosacral root compression is often attributed to piriformis syndrome. However, specific diagnostic tools have not been available to demonstrate sciatic nerve entrapment by the piriformis muscle.

Objective: To evaluate the use of magnetic resonance (MR) neurography in identifying abnormalities of the sciatic nerve in patients with unexplained sciatica.

Design: Case series from a retrospective medical record review.

Patients: Fourteen patients with sciatic distribution pain and normal results on MR imaging for lumbosacral radiculopathy were referred for MR neurography of the lumbosacral plexus and sciatic nerves.

Results: In 12 patients, MR neurography demonstrated increased fluid-attenuated inversion recovery signal in the ipsilateral sciatic nerve. In most patients, this abnormal signal was seen at the sciatic notch, at or just inferior to the level of the piriformis muscle. To date, 4 patients have undergone surgical decompression, with excellent relief of symptoms in 3 of them.

Conclusion: Magnetic resonance neurography often identifies an abnormal increased signal in the proximal sciatic nerve in patients with extraspinal sciatica and allows more accurate diagnosis of sciatic nerve entrapment in suspected cases.
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http://dx.doi.org/10.1001/archneur.63.10.1469DOI Listing
October 2006

Frameless stereotactic image-guided C1-C2 transarticular screw fixation for atlantoaxial instability: review of 20 patients.

J Spinal Disord Tech 2005 Oct;18(5):385-91

Department of Neurological Surgery, University of California-San Francisco, San Francisco, CA 94143-0112, USA.

Objective: We retrospectively studied 20 adults who underwent C1-C2 transarticular screw (TAS) fixation utilizing frameless stereotaxy.

Methods: The study group comprised 13 men and 7 women, with a mean age of 63 years (range 12-87 years). All patients demonstrated clinical and radiographic evidence of C1-C2 instability. The cause of the instability was trauma in 11 patients, rheumatoid arthritis in 6 patients, failed prior surgery in 2 patients, and congenital malformation in 1 patient. All patients underwent stabilization with C1-C2 TASs using image-guided frameless stereotaxy.

Results: There were no new or worsening neurologic symptoms reported at 18-month follow-up. Motor weakness improved in seven of nine patients, myelopathy in seven of seven, and gait in three of six patients in whom these deficits were present preoperatively. Postoperative complications included one surgical site abscess, one cutaneous pressure ulcer, and one iliac crest donor site infection. Of 36 screws placed, 33 (92%) were well positioned. Normal C1-C2 alignment was achieved in 17 of 20 (85%) patients. In 4 of 20 cases, screw implant, which was thought to be anatomically difficult, if not impossible, on the basis of routine magnetic resonance or computed tomography imaging, was actually accomplished successfully using surgical navigation.

Conclusions: C1-C2 TAS placement is a safe and accurate surgical technique that may improve neurologic function. Use of intraoperative navigation can facilitate achieving difficult surgical trajectories that match the patient's anatomy, thus allowing TAS implant in patients who otherwise would not be candidates for this type of internal fixation.
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http://dx.doi.org/10.1097/01.bsd.0000169443.44202.67DOI Listing
October 2005

Acute pathological laughter.

Mov Disord 2005 Oct;20(10):1389-90

Division of Neurology, University of California at San Francisco, San Francisco, California 94117, USA.

Pseudobulbar affect is a condition characterized by uncontrollable episodes of inappropriate laughing or crying that are disproportionate and discordant to the situation at hand. We report on a 16-year-old woman presenting with acute pathological laughter in the context of CNS demyelinating disease. Brain MRI scans fortuitously obtained before and after the onset of this symptom demonstrated acute gadolinium-enhancing lesions in the cerebral peduncles. The etiology of this condition remains theoretical; however, the results here provide further insights into the pathways of emotional control.
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http://dx.doi.org/10.1002/mds.20607DOI Listing
October 2005

Diagnosis and management of adult pyogenic osteomyelitis of the cervical spine.

Neurosurg Focus 2004 Dec 15;17(6):E2. Epub 2004 Dec 15.

Department of Neurological Surgery, University of California, San Francisco, California 94143, USA.

Establishing the diagnosis of cervical osteomyelitis in a timely fashion is critical to prevent catastrophic neurological injury. In the modern imaging era, magnetic resonance imaging in particular has facilitated the diagnosis of cervical osteomyelitis, even before the onset of neurological signs or symptoms. Nevertheless, despite advancements in diagnosis, disagreement remains regarding appropriate surgical treatment. The role of instrumentation and type of graft material after cervical decompression remain controversial. The authors describe the epidemiological features, pathogenesis, and diagnostic evaluation, and the surgical and nonsurgical interventions that can be used to treat osteomyelitis of the cervical spine. They also review the current debate about the role of instrumentation in preventing spinal deformity after surgical decompression for cervical osteomyelitis. Based on this review, the authors conclude that nonsurgical therapy is appropriate if neurological signs or symptoms, instability, deformity, or spinal cord compression are absent. Surgical decompression, debridement, stabilization, and deformity correction are the goals once the decision to perform surgery has been made. The roles of autogenous graft, instrumentation, and allograft have not been clearly delineated with Class I data, but the authors believe that spinal stability and decompression override creating an environment that can be completely sterilized by antibiotic drugs.
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http://dx.doi.org/10.3171/foc.2004.17.6.2DOI Listing
December 2004

Percutaneous plasma decompression alters cytokine expression in injured porcine intervertebral discs.

Spine J 2004 Jan-Feb;4(1):88-98

Department of Radiology, University of California at San Francisco, San Francisco, CA 94143, USA.

Background Context: Discectomy is a surgical technique commonly used to treat bulging or herniated discs causing nerve root compression. Clinical data suggest discectomy may also help patients with contained discs and no clear neural compromise. However, the mechanisms of clinical efficacy are uncertain, and consequently bases for treatment optimization are limited.

Purpose: To determine the effect of percutaneous plasma decompression on the histologic, morphologic, biochemical and biomechanical features of degenerating intervertebral discs.

Study Design: An adult porcine model of disc degeneration was used to establish a degenerative baseline against which to evaluate discectomy efficacy.

Outcome Measures: Cytokines interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha were measured from tissue samples using enzyme-linked immunosorbent assay. Histology and morphology images were rated for degenerative findings (of cells and matrix) in both the nucleus and annulus. Proteoglycan content was determined, and intact specimen stiffness and flexibility were measured biomechanically. Magnetic resonance images were collected for biomechanical specimens.

Methods: Using a retroperitoneal surgical approach, stab incisions were made in four or five lumbar discs per spine in 12 minipigs. Animals were allocated into one of three groups: 6-week recovery, 12-week recovery and percutaneous plasma decompression using an electrosurgical device at 6 weeks with recovery for 6 additional weeks. Four additional animals served as controls.

Results: Discs treated with discectomy had a significant increase in IL-8 and a decrease in IL-1 as compared with the 12-week, nontreated discs. There were no significant differences in morphologic and biomechanical parameters or proteoglycan content between treated discs and time-matched, nontreated discs.

Conclusions: Our results demonstrate that percutaneous plasma discectomy alters the expression of inflammatory cytokines in degenerated discs, leading to a decrease in IL-1 and an increase in IL-8. Whereas both IL-1 and IL-8 have hyperalgesic properties, IL-1 is likely to be a more important pathophysiologic factor in painful disc disorders than IL-8. Therefore, the alteration in cytokine expression that we observed is consistent with this effect as a mechanism of pain relief after discectomy. In addition, given that IL-1 is catabolic in injured tissue and IL-8 is anabolic, our results suggest that a percutaneous plasma discectomy may be capable of initiating a repair response in the disc.
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http://dx.doi.org/10.1016/s1529-9430(03)00423-6DOI Listing
May 2004

Spine imaging.

Authors:
Cynthia T Chin

Semin Neurol 2002 Jun;22(2):205-20

Division of Neuroradiology, University of California San Francisco, 94143, USA.

Imaging of the vertebral column and spinal cord has evolved from plain film evaluation to computed tomography (CT), CT in conjunction with myelography, and most recently magnetic resonance imaging (MRI). Currently, MRI has essentially replaced other imaging modalities in evaluation of the spine because of its superiority in demonstrating anatomic detail and multiplanar capability. The following is a review of the various imaging modalities available and their application in the evaluation of common spinal disorders.
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http://dx.doi.org/10.1055/s-2002-36544DOI Listing
June 2002
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