Fraser C. Henderson

Stretch-associated injury in cervical spondylotic myelopathy: new concept and review.

THE SIMPLE PATHOANATOMIC concept that a narrowed spinal canal causes compression of the enclosed cord, leading to local tissue ischemia, injury, and neurological impairment, fails to explain the entire spectrum of clinical findings observed in cervical spondylotic myelopathy. A growing body of evidence indicates that spondylotic narrowing of the spinal canal and abnormal or excessive motion of the cervical spine results in increased strain and shear forces that cause localized axonal injury within the spinal cord.During normal motion, significant axial strains occur in the cervical spinal cord. At the cervicothoracic junction, where flexion is greatest, the spinal cord stretches 24% of its length. This causes local spinal cord strain. In the presence of pathological displacement, strain can exceed the material properties of the spinal cord and cause transient or permanent neurological injury.Stretch-associated injury is now widely accepted as the principal etiological factor of myelopathy in experimental models of neural injury, tethered cord syndrome, and diffuse axonal injury. Axonal injury reproducibly occurs at sites of maximal tensile loading in a well-defined sequence of intracellular events: myelin stretch injury, altered axolemmal permeability, calcium entry, cytoskeletal collapse, compaction of neurofilaments and microtubules, disruption of anterograde axonal transport, accumulation of organelles, axon retraction bulb formation, and secondary axotomy. Stretch and shear forces generated within the spinal cord seem to be important factors in the pathogenesis of cervical spondylotic myelopathy.

Treatment of chordomas with CyberKnife: georgetown university experience and treatment recommendations.

OBJECTIVETo determine the efficacy and safety of chordoma treatment with CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (CK/SRS). METHODSEighteen patients with chordoma were treated with CK/SRS as a primary adjuvant (17 patients) or the only treatment (1 patient). The series included 24 lesions (28 treatments). The median age of the patients was 60 years (range, 24–85 years). Forty-four percent of the tumors were located in the mobile spine, 39% inside the cranium, and 17% in the sacral region. The male-to-female ratio was 1:1. The mean tumor volume was 128.0 mL (range, 12.0–457.3 mL), and the median dose of 35 Gy (range, 24.0–40.0 Gy) was delivered in 5 sessions. The median follow-up period was 46 months (range, 7–65 months). RESULTSThere were 3 significant complications in patients with previous irradiation, including infection in the surgical/radiation site (2 patients) and decreased vision (1 patient). Improvement in pain and quality of life did not reach statistical significance (α = 0.05). Seven patients experienced recurrence at a median of 10 months (range, 5–38 months), and 4 patients with disseminated disease died 7 to 48 months after therapy. Two patients had a partial response, whereas 9 others had stable disease. The local control rate at 65 months was 59.1%, with an overall survival of 74.3% and disease-specific survival of 88.9%. We estimated an α/β ratio of 2.45 for chordomas, which supports hypofractionation. CONCLUSIONThe CK/SRS safety and efficacy profile compares favorably with those of other treatment delivery systems. CK/SRS appears to reduce tumor volume, given an adequate dose. The authors recommend treatment with 40 Gy in 5 sessions to the clinical treatment volume, which includes the gross tumor volume and at least a 1-cm margin.OBJECTIVEnTo determine the efficacy and safety of chordoma treatment with CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (CK/SRS).nnnMETHODSnEighteen patients with chordoma were treated with CK/SRS as a primary adjuvant (17 patients) or the only treatment (1 patient). The series included 24 lesions (28 treatments). The median age of the patients was 60 years (range, 24-85 years). Forty-four percent of the tumors were located in the mobile spine, 39% inside the cranium, and 17% in the sacral region. The male-to-female ratio was 1:1. The mean tumor volume was 128.0 mL (range, 12.0-457.3 mL), and the median dose of 35 Gy (range, 24.0-40.0 Gy) was delivered in 5 sessions. The median follow-up period was 46 months (range, 7-65 months).nnnRESULTSnThere were 3 significant complications in patients with previous irradiation, including infection in the surgical/radiation site (2 patients) and decreased vision (1 patient). Improvement in pain and quality of life did not reach statistical significance (alpha = 0.05). Seven patients experienced recurrence at a median of 10 months (range, 5-38 months), and 4 patients with disseminated disease died 7 to 48 months after therapy. Two patients had a partial response, whereas 9 others had stable disease. The local control rate at 65 months was 59.1%, with an overall survival of 74.3% and disease-specific survival of 88.9%. We estimated an alpha/beta ratio of 2.45 for chordomas, which supports hypofractionation.nnnCONCLUSIONnThe CK/SRS safety and efficacy profile compares favorably with those of other treatment delivery systems. CK/SRS appears to reduce tumor volume, given an adequate dose. The authors recommend treatment with 40 Gy in 5 sessions to the clinical treatment volume, which includes the gross tumor volume and at least a 1-cm margin.

Occipitocervical fusion for rheumatoid arthritis using the inside-outside stabilization technique

Study Design. A retrospective study investigating the clinical outcome of the inside–outside cranial bolt technique for occipitocervical stabilization used to manage rheumatoid arthritis was conducted. Objective. To evaluate the safety and efficacy of the inside–outside technique for occipitocervical stabilization used to manage rheumatoid patients. Summary of Background Data. Achieving occipital cervical fusion for patients with rheumatoid arthritis is a complex and challenging problem. Complications related to placement of occipital screws have been reported. Methods. Occipitocervical stabilization was used for atlantoaxial subluxation or basilar invagination in 21 patients with rheumatoid arthritis. The patients were assessed for pre- and postoperative neurologic status (Ranawat classification), neck pain, fusion and alignment, hardware complications, and continued posterior cranial settling. All the patients underwent stabilization using inside–outside occipital screws. The technique involves bilateral fixation of cervical plates to the occiput using inside–outside screws, and to the cervical spine using pars screws at C2 or lateral mass screws at subaxial levels. Bone grafting was accomplished with autologous rib or iliac crest graft. Results. During the study, 14 women and 7 men with rheumatoid arthritis underwent occipitocervical stabilization and fusion. The average age of the patients was 65 years, and the mean follow-up period was 25.5 months. There were no surgical complications. Neck pain was reduced from an average Ranawat pain score of 2.40 to 0.4 (P < 0.0001). The Ranawat neurologic grade improved in 62% of the patients with preoperative neurologic deficit. Further cranial settling was not observed in any patient. There were no complications from implants and no incidence of instrumentation failure. Conclusions. The “inside–outside” technique is safe and effective for stabilizing the occipitocervical junction in rheumatoid patients. It is associated with significant reduction of neck pain, improved neurologic status, and maintenance of alignment and stability.

Molecular biology of cervical myelopathy and spinal cord injury: role of oligodendrocyte apoptosis.

BACKGROUND CONTEXTnRational design of treatment strategies for cervical myelopathy and spinal cord injury requires a working knowledge of the molecular biology underlying these pathological processes. The cellular process of apoptosis is an important component of tissue and organ development as well as the natural response to disease and injury. Recent studies have convincingly demonstrated that apoptosis also plays a pivotal role in numerous pathological processes, contributing to the adverse effects of various diseases and traumatic conditions. A growing body of evidence has implicated apoptosis as a key determinant of the extent of neurological damage and dysfunction after acute spinal cord injury and in chronic cervical myelopathy.nnnPURPOSEnTo provide clinicians and research investigators interested in spinal cord injury and myelopathy with a practical and up-to-date basic science review of cellular apoptosis in the context of spinal cord pathology.nnnSTUDY DESIGN/SETTINGnA review of recently published or presented data from molecular biological, animal model and human clinical studies.nnnMETHODSnA computer-based comprehensive review of the English-language scientific and medical literature was performed in order to identify relevant publications with emphasis given to more recent studies.nnnRESULTSnInvestigation into the role of apoptosis in spinal cord injury and myelopathy has drawn the interest of an increasing number of researchers and has yielded a substantial amount of new information.nnnCONCLUSIONSnApoptosis is a fundamental biological process that contributes to preservation of health as well as development of disease. There is now strong evidence to support a significant role for apoptosis in secondary injury mechanisms after acute spinal cord injury as well in the progressive neurological deficits observed in such conditions as spondylotic cervical myelopathy.

Oligodendroglioma with neurocytic differentiation versus atypical extraventricular neurocytoma: a case report of unusual pathologic findings of a spinal cord tumor

Differentiating oligodendroglioma from extraventricular neurocytoma by conventional light microscopy alone can present a diagnostic challenge. We report pathologic findings of an unusual spinal cord tumor from a 33-year-old male patient which showed hybrid features of oligodendroglioma and extraventricular neurocytoma. Magnetic resonance imaging (MRI) showed an enhancing intramedullary mass in the cervicothoracic region (C7 through T6). Histologic examination revealed a clear cell neoplasm containing ganglion-like cells and calcifications, prompting the differential diagnosis of oligodendroglioma and extraventricular neurocytoma. The immunohistochemical analysis disclosed neural differentiation of the neoplastic cells with strong synaptophysin and neurofilament staining consistent with extraventricular neurocytoma, as well as strong S-100 and glial fibrillary acidic protein (GFAP) expression. Molecular studies with fluorescent in situ hybridization (FISH) revealed chromosome 1p/(partial) 19q deletions, a finding commonly observed in oligodendroglioma. The proliferation index (using antibody MIB1) of the tumor was ∼30%. The morphologic findings and these results strengthen the hypothesis that these tumors may share a common progenitor cell, which has also been observed by others. Because there are differences in patient management and long-term prognosis, it is important to attempt to distinguish between oligodendroglioma and neurocytoma. This unusual case and similar rare reported cases support the need to reclassify tumors showing pathologic features common to both neurocytoma and oligodendroglioma as a unique entity, while the effort continues to identify the cell of origin.

Use of the telescopic plate spacer in treatment of cervical and cervicothoracic spine tumors.

OBJECTIVE We investigated the mechanical and in vivo properties of a novel device, called the telescopic plate spacer (TPS), designed to promote restoration of height, alignment, and stability after cervical corpectomy for tumor. METHODS The device first underwent mechanical testing. Comparisons were made with a commercially available anterior cervical plate. A caprine study was then performed. Twelve goats underwent a cervical corpectomy and placement of either a TPS filled with autograft or a plate and autograft. The animals were killed at 28 weeks and assessed for fusion. A prospective human study was then conducted. Fifteen patients with cervical or cervicothoracic tumors underwent corpectomy and placement of allograft-filled TPS. End points included pain scores and radiographic assessment of vertebral height, alignment, and stability. RESULTS In the mechanical study, the TPS outperformed the anterior cervical plate in all modalities except for torsion stiffness and tension-bending failure load. The caprine study demonstrated fusion in six of six cases at 28 weeks in the TPS group, compared with four of six cases in the plate and autograft group. In the human study, patients (n = 15) were stabilized with the TPS after corpectomy (range, 1–3 levels; average, 1.7 levels). There were no failures of instrumentation or neurological deterioration. Stability was achieved in all patients, with an average follow-up of 9 months. Durable improvements in pain scores (P = 0.001), vertebral height (P = 0.002), and reduction of kyphosis (P = 0.046) were achieved. CONCLUSION The TPS can be used to restore height, alignment, and stability after corpectomy.

Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis

Background: Chiari malformation, functional cranial settling and subtle forms of basilar invagination result in biomechanical neuraxial stress, manifested by bulbar symptoms, myelopathy and headache or neck pain. Finite element analysis is a means of predicting stress due to load, deformity and strain. The authors postulate linkage between finite element analysis (FEA)-predicted biomechanical neuraxial stress and metrics of neurological function. Methods: A prospective, Internal Review Board (IRB)-approved study examined a cohort of 5 children with Chiari I malformation or basilar invagination. Standardized outcome metrics were used. Patients underwent suboccipital decompression where indicated, open reduction of the abnormal clivo-axial angle or basilar invagination to correct ventral brainstem deformity, and stabilization/ fusion. FEA predictions of neuraxial preoperative and postoperative stress were correlated with clinical metrics. Results: Mean follow-up was 32 months (range, 7-64). There were no operative complications. Paired t tests/ Wilcoxon signed-rank tests comparing preoperative and postoperative status were statistically significant for pain, bulbar symptoms, quality of life, function but not sensorimotor status. Clinical improvement paralleled reduction in predicted biomechanical neuraxial stress within the corticospinal tract, dorsal columns and nucleus solitarius. Conclusion: The results are concurrent with others, that normalization of the clivo-axial angle, fusion-stabilization is associated with clinical improvement. FEA computations are consistent with the notion that reduction of deformative stress results in clinical improvement. This pilot study supports further investigation in the relationship between biomechanical stress and central nervous system (CNS) function.

Utility of the clivo-axial angle in assessing brainstem deformity: pilot study and literature review

There is growing recognition of the kyphotic clivo-axial angle (CXA) as anxa0index of risk of brainstem deformity and craniocervical instability. This review ofxa0literature and prospective pilot study is the first to address the potential correlationxa0between correction of the pathological CXA and postoperative clinical outcome. Thexa0CXA is a useful sentinel to alert the radiologist and surgeon to the possibility ofxa0brainstem deformity or instability. Ten adult subjects with ventral brainstem compression, radiographicallyxa0manifest as a kyphotic CXA, underwent correction of deformity (normalization of thexa0CXA) prior to fusion and occipito-cervical stabilization. The subjects were assessedxa0preoperatively and at one, three, six, and twelvexa0months after surgery, usingxa0established clinical metrics: the visual analog pain scale (VAS), American Spinal InjuryAssociation Impairment Scale (ASIA), Oswestry Neck Disability Index, SF 36, andxa0Karnofsky Index. Parametric and non-parametric statistical tests were performed toxa0correlate clinical outcome with CXA. No major complications were observed. Two patients showed pedicle screwsxa0adjacent to but not deforming the vertebral artery on post-operative CT scan. All clinicalxa0metrics showed statistically significant improvement. Mean CXA was normalized from 135.8° to 163.7°. Correction of abnormal CXA correlated with statistically significant clinicalxa0improvement in this cohort of patients. The study supports the thesis that the CXA maybe an important metric for predicting the risk of brainstem and upper spinal cord deformation. Further study is feasible and warranted.

Intravascular Fasciitis Clinically Mimicking an Axillary Peripheral Nerve Sheath Tumor A Case Report and Review of the Literature

Intravascular fasciitis is one of the benign myofibroblastic pseudosarcomatous proliferations, among which nodular fasciitis is the prototype. These lesions are important as they may mimic a variety of sarcomas and other lesions on both clinical and pathologic grounds. This report describes the features of one such lesion that arose within the brachial artery and invested nerve trunks of the brachial plexus. The patient presented with symptoms of arm fatigue and hand numbness. There were no neurological or vascular findings on physical examination. The clinicopathologic differential diagnosis is discussed. Also, surgeons are cautioned to involve a vascular etiology in their differential diagnosis and seek the help of a vascular surgeon when the lesion juxtaposes the axillary artery or vein.

Acute Whiplash: Clinical and Finite Element Analysis

Study Design: A prospective 1-year study of whiplash patients presenting with either isolated neck pain (WADI/II), or neck pain with neurological signs/or symptoms (WADIII). Objective: We hypothesize that WADI/II and WADIII are distinct entities with significant differences in clinical presentation, pathoanatomy, and prognosis. Summary of Background Data: Whiplash associated disorders (WAD) are disparate and can range from mild neck pain (WADI/II), to insults associated with neurologic sequellae (WADIII), and even fracture/dislocations (WADIV). To date, literature considers post whiplash syndrome a single clinical and pathologic entity along a spectrum with escalating grades of severity (WADI-IV). However, a diverse pathogenesis may underlie the different grades of WAD, and these distinctive pathoanatomies may better portray the prognosis of these entities. Methods: Thirty one subjects were divided into a WADI/II control group and a WADIII study group. All subjects underwent H&P, radiographic evaluations, and clinical outcome measures (collected at 3, 6, and 12 months). A finite element analysis (FEA) technology (SCOSIA©) was used to predict stresses within the neuraxis. Statistical analysis was performed (Student T-test, Wilcoxon Signed-Rank test) with significance set at p=0.05. Results: At presentation, WADI/II group demonstrated better neurologic assessments, functional performances, and higher quality-of-life measurements in comparison to WADIII cohort. Yet VAS scores were comparable between the two groups. At final follow-up, both groups reported improvements in neurologic status and disability symptoms. However, functional recovery and quality-of-life measures significantly improved in WADIII, and conversely deteriorated in WADI/II. Additionally, WADI/II also portrayed notable worsening of pain symptoms. Litigation claims were comparable between the two groups. FEA predicted higher stress within the neuraxis of WADIII, most notably in subjects with preexisting stenosis and odontoid retroflexion. Conclusion: WADI/II and WADIII are distinct entities with different pathoanatomy and outcomes. Musculoskeletal injury precipitates WADI/II pain symptoms while neuronal stretching leads to WADIII neurologic injuries. Notably, most of the neurologic injuries in WADIII are recoverable.