Transfacet and Transpedicular Posterior Approaches to Thoracic Disc Herniations: Consecutive Case Series of 24 Patients.

OBJECTIVE: Various approaches are advocated for symptomatic thoracic disc herniation (TDH). The aim of this series is to demonstrate the feasibility, safety, and results of posterior transfacet or transpedicular approaches for excision of all types of extradural TDH. We report a consecutive series of patients undergoing posterior approach surgery for TDH. METHODS: Twenty-four patients (17 women, 7 men) underwent surgery at 25 disc levels. Mean age was 56.3 years (range, 23-79 years). A posterior transfacet or transpedicular approach was used. Patients presented with myelopathy (n = 21, 88%), radiculopathy (n = 8, 33%), sphincter dysfunction (n = 16, 67%), and axial back pain (n = 10, 43%). Preoperative imaging revealed 7 (30%) central, 14 (61%) calcified, and 10 (43%) large disc herniations. The mean follow-up period was 6.0 months (range, 2-36 months). RESULTS: Eighteen patients underwent unilateral approach surgery (5 transfacet and 13 transfacet plus transpedicular), and 7 patients required bilateral approach laminectomy for unilateral (n = 4) or bilateral (n = 3) discectomy. One patient required unplanned reoperation for resection of residual disc. Average operative time was 95 minutes (range, 40-175 minutes). Mean hospital stay was 4.9 days (range, 2-35 days). There were no major complications. Postoperative Frankel scores were maintained or improved in all patients at last review. CONCLUSIONS: TDH including large central calcified discs can be safely removed through posterior transfacet or transpedicular approaches with reduced morbidity in comparison with more invasive anterior approaches. Careful microsurgical technique and use of specialized instruments are important for successful excision of TDH from a posterior approach.

Computed tomography parameters for atlantooccipital dislocation in adult patients: the occipital condyle-C1 interval.

OBJECT: Atlantooccipital dislocation (AOD) in adults cannot be diagnosed with adequate specificity and sensitivity using only CT or plain radiography, and the spine literature offers no guidelines. In children, the most sensitive and specific radiographic measurement for the diagnosis of AOD is the CT-based occipital condyle-C1 interval (CCI). The goal of the current study was to identify the normal CCI in healthy adults and compare it with the CCI in adults with AOD to establish a highly sensitive and specific cutoff value for the neuroimaging diagnosis of AOD. METHODS: A total of 81 patients, 59 without AOD and 22 with AOD, were included in this study. Measurements obtained from thin-slice CT scans of the craniovertebral joint to assess atlantooccipital dislocation included the CCI, condylar sum, the Wholey and Harris intervals, Powers and Sun ratios, Wackenheim line, and Lee X-lines. RESULTS: The group of patients without AOD included 30 men (50.8%) and 29 women (49.2%) with a mean age of 42.4 ± 16 years (range 19-87 years). The group of patients with AOD included 10 men (45.5%) and 12 women (54.5%) with a mean age of 38.2 ± 9.7 years (range 20-56 years). Interrater reliabilities within a 95% CI were all greater than 0.98 for CCI measurements. A total of 1296 measurements of the CCI were made in 81 patients. The mean CCI for non-AOD patients was 0.89 ± 0.12 mm, the single largest CCI measurement was 1.4 mm, and the largest mean for either right or left CCI was 1.2 mm. The mean condylar sum was 1.8 ± 0.2 mm, and the largest condylar sum value was 2.2 mm. Linear regression with age predicted an increase in CCI of 0.001 mm/year (p < 0.05). The mean CCI in AOD patients was 3.35 ± 0.18 mm (range 1.5 mm-6.4 mm). The shortest single CCI measurements in the AOD patients were 1.1 mm and 1.2 mm. The mean condylar sum for all 22 AOD patients was 6.7 ± 2.7 mm and the shortest condylar sums were 3.0 mm. Cutoff values for AOD were set at 1.5 mm for the CCI and 3.0 mm for the condylar sum, both with a sensitivity of 1 and false-negative rate of 0. Sensitivity for the Powers, Wholey, Harris, Sun, Wackenheim, and Lee criteria were determined to be 0.55, 0.46, 0.27, 0.23, 0.41, and 0.41, respectively. CONCLUSIONS: The CCI is shorter in adult patients as opposed to the pediatric population. The revised CCI (1.5 mm) and condylar sum (3.0 mm) cutoff values have the highest sensitivity and specificity for the diagnosis of AOD in the adult population.

Diagnostic and surgical implications of ventral vertebrobasilar displacement by posterior fossa neurenteric cysts.

OBJECTIVE: Neurenteric cysts (NECs) are uncommonly encountered lesions of the central nervous system with heterogeneous imaging characteristics. The object of this study was to review the preoperative imaging findings represented among a cohort of surgically treated posterior fossa NECs. These findings are considered in the context of surgical technique, and inform an understanding of aberrant neuroembryological development associated with NECs. METHODS: A single-institution, multisurgeon series of 7 consecutive patients (5 female and 2 male patients, mean age 36 years, range 19 to 57 years) treated surgically for histopathologically confirmed posterior fossa NECs was retrospectively reviewed. Lesion imaging and anatomic characteristics were noted on preoperative magnetic resonance imaging (MRI). Imaging comparisons were made against an additional cohort of 266 consecutive surgically treated posterior fossa masses to validate unique anatomic findings. RESULTS: T1 and T2 MRI signal characteristics were variable when compared across lesions. All NECs were found to be anteriorly located within the posterior fossa, but always situated between the brainstem pial surface and the vertebrobasilar system, causing ventral displacement of vertebrobasilar vessels. CONCLUSIONS: Posterior fossa NECs display variable patterns of MRI signal and are commonly considered as part of a broad differential of cystic posterior fossa masses. We identified tumor insinuation between the ventral brainstem and vertebrobasilar system as a highly sensitive and specific radiographic sign for NECs. This finding was not observed among a large cohort of posterior fossa masses representative of other multiple pathologies.

Intradural vertebral endarterectomy with nonautologous patch angioplasty for refractory vertebrobasilar ischemia: Case report and literature review.

BACKGROUND: The natural history of patients with symptomatic vertebrobasilar ischemic symptoms due to chronic bilateral vertebral artery occlusive disease is progressive, and poses significant challenges when refractory to medical therapy. Surgical treatment options depend largely on location and characteristics of the atheroma (s), and generally include percutaneous transluminal angioplasty (PTA) with or without stent placement, posterior circulation revascularization (bypass), extracranial vertebral artery reconstruction, or vertebral artery endarterectomy. CASE DESCRIPTION: We present the case of a 56-year-old male with progressive vertebrobasilar ischemia due to tandem lesions in the right vertebral artery at the origin and intracranially in the V4 segment. The contralateral vertebral artery was occluded to the level of posterior inferior cerebellar artery (PICA) and posterior communicating arteries were absent. Following PTA and stent placement at the right vertebral artery origin, the patient was successfully treated with intradural vertebral artery endarterectomy (V4EA) and patch angioplasty via the far lateral approach. Distal endovascular intervention at the V4 segment proved not technically feasible after multiple attempts. CONCLUSIONS: V4EA is an uncommonly performed procedure, but may be considered for carefully selected patients. The authors' techniques and indications are discussed. Historical outcomes, relevant anatomic considerations, and lessons learned are reviewed from the literature.

Comparative analysis of isocentric 3-dimensional C-arm fluoroscopy and biplanar fluoroscopy for anterior screw fixation in odontoid fractures.

STUDY DESIGN: Retrospective clinical study. OBJECTIVE: To compare long-term radiographic and clinical outcomes of patients undergoing anterior odontoid screw placement using traditional biplanar fluoroscopy or isocentric 3-dimensional C-arm (iso-C) fluoroscopy-assisted techniques. SUMMARY OF BACKGROUND DATA: Anterior screw fixation of odontoid fractures preserves motion at the C1-C2 joint, but accurate screw positioning is essential for successful outcomes. Biplanar fluoroscopy image guidance is most often used; however, iso-C imaging improves the ease and accuracy of screw placement with less radiation exposure. METHODS: Fifty-one patients underwent anterior odontoid screw fixation for type II (48 patients) and rostral type III fractures (3 patients). Procedures were guided by biplanar fluoroscopy in 25 (49%) patients, and with iso-C assistance in 26 (51%). Length of surgery, complications, and clinical outcomes based on the Smiley-Webster score were evaluated. Computed tomography confirmed adequate screw placement. Follow-up ranged from 3 to 9 months. RESULTS: At 3-month follow-up, screw position and fusion across the fracture were evident in 87% of the cases treated with biplanar fluoroscopy and in 100% treated by iso-C. The average outcome score in the iso-C group was superior to that of the biplanar group (1.08 vs. 1.33, respectively), although not statistically significant. At last follow-up, the rate of successful fusion was 88% in the biplanar group and 95% in the iso-C group. Length of surgery was significantly lower in the iso-C group compared with the biplanar group (P=0.05). The significantly longer preparation time in the iso-C group (P=0.04) accounted for no overall difference in total operating room occupancy time between the 2 groups. CONCLUSIONS: Iso-C significantly decreased surgical time. At last follow-up iso-C assistance was associated with improved rates of radiographic fusion with comparable outcome and complication profiles. This series represents the largest cohort of patients treated with intraoperative real-time navigation assistance for odontoid fractures.

Subaxial cervical juxtafacet cysts: single institution surgical experience and literature review.

OBJECTIVES: Juxtafacet cysts (JFCs) of the subaxial cervical spine are rare causes of neurological deficits. Their imaging characteristics, relationship to segmental instability, and potential for inducing acute symptomatic deterioration have only been described in a few case reports and small case series. The objective of the current study was to review the surgical experience at our center and across the literature to better define these variables. METHODS: A single-institution, multisurgeon series of 12 consecutive patients (mean age 63.4 years, range 52-83 years) harboring 14 JFCs treated across 9 years was retrospectively reviewed. Clinical history, neurological status, preoperative imaging, operative findings, pathology, and postoperative outcomes were obtained from medical records. The mean follow up was 9.2 ± 7.8 months. A literature review identified 35 studies with 89 previously reported cases of surgically treated subaxial cervical JFCs. RESULTS: Consistent with previously reported cases, most JFCs in our series involved the C7/T1 level. Nine patients reported axial neck pain, 12 patients had radicular symptoms, four patients had myelopathy, and one patient experienced rapid neurological decline attributable to cystic hemorrhage. Cyst expansion without hemorrhage caused subacute deterioration in one patient. All patients experienced sensory and/or motor improvement following surgical decompression. Preoperative axial neck pain improved in eight of nine patients (89 %). Seven out of 12 patients (58 %) underwent fusion either at the time of decompression (six patients) or at a delayed timepoint within the follow-up period (one patient). Prior history of cervical instrumentation, hypermobility on dynamic imaging, and other risk factors for segmental instability were more common in our series than in previous reports. CONCLUSIONS: Our findings lead us to advocate for early decompression rather than prolonged conservative treatment, for pre- and postoperative dynamic imaging, and for fusion in selected cases as an initial surgical consideration.

A simple and quantitative method to predict symptomatic vasospasm after subarachnoid hemorrhage based on computed tomography: beyond the Fisher scale.

BACKGROUND: Although the Fisher scale is commonly used to grade vasospasm risk in aneurysmal subarachnoid hemorrhage (aSAH) patients, it fails to account for increasing subarachnoid hemorrhage (SAH) thickness. OBJECTIVE: We developed a simple quantitative scale based on maximal SAH thickness and compared its reproducibility and ability to predict symptomatic vasospasm against the Fisher scale. METHODS: The incidence of radiographic and symptomatic vasospasm among 250 aSAH patients treated at our institution was investigated. Admission head computed tomography scans were graded according to the Fisher scale and the proposed scale, which assigns a score from 1 to 5 based on a single measurement of maximum SAH thickness. We calculated vasospasm risk per grade for the Fisher scale and the proposed scale, and compared inter- and intraobserver variability for both scales. RESULTS: Forty-five patients (20.6%) developed symptomatic vasospasm. On the proposed scale, grade 5 patients were at highest risk, with an odds ratio for symptomatic vasospasm of 11 (95% confidence interval [CI] 2.27-53.37). Odds ratios for proposed grades 4 and 3 were 4.63 (95% CI 1.10-19.59) and 3.04 (95% CI 0.85-10.90), respectively. The odds ratio for Fisher grade 3 was 3.3 (0.96-11.30). Mean inter- and intraobserver agreement was greater for the proposed scale in comparison with the Fisher scale (κ0.65 and κ0.81 vs κ0.51 and κ0.35, respectively). CONCLUSION: The new scale accounted for increasing SAH thickness and was superior to the Fisher scale in inter- and intraobserver agreement and in predicting symptomatic vasospasm, particularly among the highest-risk patients.

Multimodality treatment of conus medullaris arteriovenous malformations: 2 decades of experience with combined endovascular and microsurgical treatments.

BACKGROUND: Conus medullaris arteriovenous malformations (AVMs) are rare, challenging spinal vascular lesions that cause progressive debilitating myeloradiculopathy. Only sporadic reports of conus AVMs have been published. OBJECTIVE: To better define the presentation, prognosis, and optimal treatment of these lesions, we present the first case series of conus AVMs, reflecting over 2 decades of experience with a multimodality endovascular and surgical approach. METHODS: We retrospectively reviewed the charts of 16 patients with a conus AVM evaluated at our institution from 1989 to 2010. For each patient, the following clinical data were collected: age, sex, symptoms, angiographic findings, type of treatment, complications, degree of angiographic obliteration, recurrence at follow-up, and need for re-treatment. Ambulatory status, Frankel Grade, motor function, and bladder/bowel function were assessed before treatment, at discharge, and at last follow-up. RESULTS: All 16 patients were treated. Eight (50%) patients underwent embolization followed by microsurgical resection, and 8 (50%) underwent microsurgical resection only. The rate of complete angiographic obliteration was 88%. At last follow-up (mean, 70 months), 43% of patients neurologically improved, 43% were stable, and 14% worsened in comparison with before treatment. During follow-up, 3 recurrences were detected, including the only 2 instances of long-term neurological decline. In the absence of recurrence, all patients ambulatory before treatment remained ambulatory at follow-up, whereas 75% of the initially nonambulatory patients regained the ability to walk. CONCLUSION: Although conus AVMs are challenging to treat, excellent long-term outcomes are possible with a multimodality approach. Recurrence is associated with long-term neurological decline and calls for close follow-up.

Survival and functional outcome after surgical resection of intramedullary spinal cord metastases.

OBJECTIVE: Intramedullary spinal cord metastasis (ISCM) is a rare manifestation of systemic cancer and data about the optimal management of these lesions are lacking. To clarify the role of surgery, we investigated survival and neurological outcomes after surgical resection of ISCMs. METHODS: Between 2003 and 2010, we surgically treated 10 ISCMs in 9 patients. For each patient, we retrospectively collected the following data: demographic variables, history of prior cancer, site of primary cancer, extent of cancer on presentation, degree of resection, preoperative and postoperative spinal cord impairment (American Spinal Injury Association [ASIA] grade), and postoperative survival. We investigated the relationship between these variables, overall survival, and preservation of function. RESULTS: Eight ISCMs were treated with gross total resection and two were treated with subtotal resection. Overall postoperative survival was 6.4 ± 9.4 months (mean ± standard deviation), with one patient still alive at last follow-up. Patients with a diagnosis of melanoma had higher mean survival than those with nonmelanoma histology (20.5 ± 13.4 vs. 2.4 ± 1.7 months, P < 0.01). Degree of resection, number of organ systems affected, ambulatory status, and ASIA grade pre operatively or postoperatively, were not significantly associated with survival. Of the nine patients, seven (78%) demonstrated no change in ASIA grade postoperatively, one (11%) improved, and one patient (11%) deteriorated. All patients who were ambulatory preoperatively remained ambulatory postoperatively and at last follow-up. CONCLUSIONS: Although ISCM is associated with poor prognosis, survival appears to be greater in patients with melanoma. Surgical resection does not appear to significantly lengthen survival but may be indicated to preserve ambulatory status in symptomatic patients.

Supracerebellar infratentorial endoscopically controlled resection of pineal lesions: case series and operative technique.

OBJECT: The heterogeneous clinical manifestations and operative characteristics of pathological entities in the pineal region represent a significant challenge in terms of patient selection and surgical approach. Traditional surgical options have included endoscopic transventricular resection; open supratentorial microsurgical approaches through the midline, choroidal fissure, lateral ventricle, and tentorium; and supracerebellar infratentorial (SCIT) approaches through the posterior fossa. The object of the current study was to review the preoperative characteristics and outcomes for a cohort of patients treated purely via the novel endoscopically controlled SCIT approach. METHODS: A single-institution series of 9 consecutive patients (4 male and 5 female patients [10 total cases]; mean age 21 years, range 6-37 years) treated via the endoscopically controlled SCIT approach for a pathological entity in the pineal region was retrospectively reviewed. The mean follow-up time was 13.2 months. RESULTS: The endoscopically controlled SCIT approach was successfully used to approach a variety of pineal lesions, including pineal cysts (6 patients), epidermoid tumor, WHO Grade II astrocytoma (initial biopsy and recurrence), and malignant mixed germ cell tumor (1 patient each). Gross-total resection and/or adequate cyst fenestration was achieved in 8 cases. Biopsy with conservative debulking was performed for the single case of low-grade astrocytoma and again at the time of recurrence. The mean preoperative tumor and cyst volumes were 9.9 ± 4.4 and 3.7 ± 3.2 cm(3), respectively. The mean operating times were 212 ± 71 minutes for tumor cases and 177 ± 72 minutes for cysts. Estimated blood loss was less than 150 ml for all cases. A single case (pineal cyst) was converted to an open microsurgical approach to enhance visualization. There were no operative complications, as well as no documented CSF leaks, additional CSF diversion procedures, or air emboli. Seven patients underwent concomitant third ventriculostomy into the quadrigeminal cistern. At the time of the last follow-up evaluation, all patients had a stable or improved modified Rankin Scale score. CONCLUSIONS: The endoscopically controlled SCIT approach may be used for the biopsy and resection of appropriately selected solid tumors of the pineal region, in addition to the fenestration and/or resection of pineal cysts. Preoperative considerations include patient presentation, anticipated disease and vascularity, degree of local venous anatomical distortion, and selection of optimal paramedian trajectory.

Comparative use of turkey and chicken wing brachial artery models for microvascular anastomosis training.

OBJECT: The aim of this study was to describe a turkey wing model for microvascular anastomosis training and compare it to the previously outlined chicken wing model. METHODS: The authors compared diameter measurements in each of 5 turkey and 5 chicken brachial arteries at 3 equidistant points. Usable vessel length was measured (from joint to joint) in each of the specimens. A survey was created and distributed at a bypass training course to assess the attendees' impressions of various practice models used for bypass. RESULTS: The turkey wing brachial artery was consistently larger in diameter (p < 0.01) and longer (p < 0.01) than the chicken wing artery and showed less variability in the vessel diameter (1.47 ± 0.14 mm in the turkey vs 1.07 ± 0.25 mm in the chicken). In a survey of 15 bypass course participants, the live rat training model scored highest overall and was ranked as the best model for training; however, the turkey wing model was ranked second best and was consistently scored ahead of the chicken wing and silastic tube training models. CONCLUSIONS: The authors' institutional preference has shifted to the use of a turkey wing artery as the initial model for microanastomosis training. Advantages in terms of vessel size and tissue durability favor this model over the chicken wing as part of a graduated instruction process.

Orbitozygomatic resection for hypothalamic hamartoma and epilepsy: patient selection and outcome.

PURPOSE: This study aims to examine the outcomes of ten patients after orbitozygomatic (OZ) pterional surgery in cases of refractory epilepsy caused by hypothalamic hamartomas (HH). METHODS: Ten patients with HH and treatment-resistant epilepsy (mean age 18.3 years, range 0.7 to 42.7) underwent HH resection with an OZ approach (n = 8) or an OZ approach combined with a transventricular endoscopic approach (n = 2). Follow-up for the patients ranged from 0.5 to 6.2 years (mean 3.1). Outcomes were prospectively monitored with the use of a proprietary database. RESULTS: Four patients (40%) are seizure-free, and four (40%) have had greater than 50% reduction in seizures. One patient had no significant change in seizure frequency, and one patient died unexpectedly 2.8 years after surgery. Six patients had total or near-total HH resection (98-100% of HH lesion volume). Of these, four of six (66%) were seizure-free, and two had at least greater than 50% reduction in seizures. Residual complications include diabetes insipidus (n = 1), poikilothermia (n = 1), visual field deficit (n = 1), and hemiparesis (n = 1). Eight families (80%) reported improved quality of life. CONCLUSIONS: Patients with treatment-resistant epilepsy and tumors with an inferior or horizontal plane of attachment to the hypothalamus should continue to be approached from below. Those with both intrahypothalamic and parahypothalamic components may require approaches from above and below, either simultaneously or staged. For appropriately selected patients, the success of controlling seizures with an OZ is comparable to results utilizing transcallosal or transventricular approaches. The likelihood of controlling seizures appears to correlate with extent of resection.

Neuroblastoma-like schwannoma of lumbar spinal nerve root.

Neuroblastoma-like schwannoma is a rare nerve sheath tumor with histological features resembling a neuroblastoma. A comprehensive literature review identified only 10 previous case reports of this condition. The authors present the first reported case of a neuroblastoma-like schwannoma at a spinal nerve root. The patient, a 61-year-old woman, presented with severe pain in the right lower extremity that failed to resolve after conservative management. Magnetic resonance imaging revealed an intradural enhancing lesion extending out of the right neural foramen at L1-2. A right L1-2 hemilaminectomy and facetectomy with gross-total resection of the tumor was performed without complications. Neuroblastoma-like schwannoma was diagnosed based on histopathological examination of the biopsied tumor specimen. A postoperative course of serial examination and imaging was chosen based on a suspected benign postoperative course as in the case of a completely resected schwannoma. The authors present the novel case of neuroblastoma-like schwannoma at a lumbar spinal nerve root and describe the distinguishing pathological features of this rare lesion.

Motor neuron regeneration accuracy: balancing trophic influences between pathways and end-organs.

The key to recovery of function following peripheral nerve lesions is guiding axons back to their original target end-organs. The parent femoral nerve splits into two comparable terminal pathways: one to the muscle and the other to the skin. Normally, motor neurons only innervate the pathway to the muscle, but after the parent nerve is repaired regenerating motor neurons are often misrouted to the skin. When the muscle and skin pathways remain connected to their respective targets after the parent nerve is repaired, reinnervation favors the muscle pathway. If contact with the muscle is instead prevented, reinnervation favors the pathway to the skin. Here we examine whether shortening the skin pathway can alter motor reinnervation accuracy when the muscle pathway remains connected to the muscle. We demonstrate that reducing the influence of the skin pathway results in a more rapid and extensive reinnervation of the muscle pathway. These findings suggest that the relative balance of trophic influences from the pathways and their end-organs is an important determinant of motor neuron regeneration accuracy, and that the muscle pathway by itself is not the primary regulator for regeneration accuracy of motor neurons.

Primary spinal intramedullary adrenal cortical adenoma associated with spinal dysraphism: case report.

OBJECTIVE: The authors report a primary spinal intramedullary adrenal cortical adenoma in a patient with spinal dysraphism presenting with bilateral leg pain and urinary frequency. METHODS: Magnetic resonance imaging, L2 laminectomy with resection of mass, and pathological and immunohistochemical analysis of resected mass revealed the diagnosis. RESULTS: Microscopic and immunohistochemical findings confirmed the diagnosis as a primary intramedullary tumor of adrenal cortical origin. CONCLUSION: The occurrence of a primary adrenal tumor in the spinal cord is rare and difficult to explain based on our understanding of embryology. A review of the relevant literature and discussion of the pathophysiology and clinical implications is provided.