Nicholas C. Bambakidis

Evolution of surgical approaches in the treatment of petroclival meningiomas: a retrospective review.

OBJECTIVE We examined the surgical approaches used at a single institution to treat petroclival meningioma and evaluated changes in method utilization over time. METHODS Craniotomies performed to treat petroclival meningioma between September of 1994 and July of 2005 were examined retrospectively. We reviewed 46 patients (mean follow-up, 3.6 yr). Techniques included combined petrosal or transcochlear approaches (15% of patients), retrosigmoid craniotomies with or without some degree of petrosectomy (59% of patients), orbitozygomatic craniotomies (7% of patients), and combined orbitozygomatic-retrosigmoid approaches (19% of patients). In 18 patients, the tumor extended supratentorially. Overall, the rate of gross total resection was 43%. Seven patients demonstrated progression over a mean of 5.9 years. No patients died. At 36 months, the progression-free survival rate for patients treated without petrosal approaches was 96%. Of 14 patients treated with stereotactic radiosurgery, none developed progression. CONCLUSION Over the study period, a diminishing proportion of patients with petroclival meningioma were treated using petrosal approaches. Utilization of the orbitozygomatic and retrosigmoid approaches alone or in combination provided a viable alternative to petrosal approaches for treatment of petroclival meningioma. Regardless of approach, progression-free survival rates were excellent over short-term follow-up period.

The frequency and clinical significance of congenital defects of the posterior and anterior arch of the atlas

OBJECT In this study the authors investigated the anatomical, clinical, and imaging features as well as incidence of congenital defects of the C-1 arch. METHODS The records of 1104 patients who presented with various medical problems during the time between January 2006 and December 2006 were reviewed retrospectively. The craniocervical computed tomography (CT) scans obtained in these patients were evaluated to define the incidence of congenital defects of the posterior arch of C-1. In addition, 166 dried C-1 specimens and 84 fresh human cadaveric cervical spine segments were evaluated for anomalies of the C-1 arch. RESULTS Altogether, 40 anomalies (2.95%) were found in 1354 evaluated cases. Of the 1104 patients in whom CT scans were acquired, 37 (3.35%) had congenital defects of the posterior arch of the atlas. The incidence of each anomaly was as follows: Type A, 29 (2.6%); Type B, six (0.54%); and Type E, two (0.18%). There were no Type C or D defects. One patient (0.09%) had an anterior arch cleft. None of the reviewed patients had neurological deficits or required surgical intervention for their anomalies. Three cases of Type A posterior arch anomalies were present in the cadaveric specimens. CONCLUSIONS Most congenital anomalies of the atlantal arch are found incidentally in asymptomatic patients. Congenital defects of the posterior arch are more common than defects of the anterior arch.

Biomechanical comparison of occipitoatlantal screw fixation techniques: Laboratory investigation

OBJECT The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. METHODS Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. RESULTS Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p < 0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. CONCLUSIONS Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.

Indications for surgical fusion of the cervical and lumbar motion segment.

Study Design. A literature review and the authors’ clinical experience for the indication of fusion in the degenerative lumbar and cervical spine is provided. Objective. To establish absolute and relative criteria for the indication for fusion in the degenerative cervical and lumbar spine. Summary of Background Data. Fusion in the cervical and lumbar degenerative spine is indicated under certain strict criteria. However, fusion in circumstances not meeting these criteria is controversial. Method. A review of the literature and the authors’ experience concerning indication and criteria of fusion in degenerative, lumbar, and cervical spine is provided. Results. Fusion for the unstable spine related to trauma, infection, and tumors is relatively accepted. However, indications for fusion for degenerative, cervical, and lumbar spine are more controversial. Conclusion. Lumbar and cervical fusion in the degenerative spine is frequently performed. Certain criteria have been established when a fusion should be considered. However, even these are not universally accepted. Strict prospective studies are needed to determine when a fusion of the degenerative, cervical, and lumbar spine is indicated. Patients with severe radicular pain may be considered for surgery after a comprehensive trial of conservative management. Fusion is usually necessary after a cervical discectomy, especially when spondylosis or osteophytic compression is present. Lumbar fusion is rarely indicated for routine discectomy. In patients with mechanical back or neck pain, surgery should only be considered after conservative measures have been exhausted and a radiographic abnormality is present at the symptomatic level, perhaps with pain concordant with discographic findings. Careful patient selection is the key to obtaining favorable surgical outcomes. In many cases, the goal may be a return to functionality rather than achieving a completely asymptomatic state.

Surgical technique and outcomes in the treatment of spinal cord ependymomas: part II: myxopapillary ependymoma.

BACKGROUND: Myxopapillary ependymomas usually occur in the filum terminale of the spinal cord. OBJECTIVE: This report summarizes our experience treating myxopapillary ependymomas. METHODS: The records of 34 patients (14 men, 20 women; mean age 45.5 years; age range, 14-88 years) who underwent resection of a myxopapillary ependymoma between 1983 and 2006 were reviewed for age, sex, tumor location, symptoms at diagnosis, duration of symptoms, treatment before presentation, extent of surgical resection, adjuvant therapy, length of follow-up, evidence of recurrence, and complications. Neurological examinations performed at presentation, immediately after surgery, and last follow-up were graded according to the McCormick grading scale. RESULTS: The average duration of symptoms before diagnosis was 22.2 months. The most common symptom was pain followed by weakness, bowel/bladder symptoms, and numbness. The rate of gross total resection was 80%. All patients with a subtotal resection (20%) underwent postoperative radiation therapy. Presentation and outcomes of patients who underwent subtotal resection followed by radiation therapy were compared with those who underwent gross total resection. There was no significant difference in neurological grade between the groups at presentation or final follow-up. The overall recurrence rate was 10% (3/34 patients). CONCLUSION: The goal of surgical treatment of myxopapillary ependymomas is resection to the greatest extent possible with preservation of function. In cases of subtotal resection, postoperative radiation therapy may improve outcome. If neurological function is maintained at treatment, these indolent lesions allow years of good function.

Transfacet screw placement for posterior fixation of C-7 : Technical note

OBJECT Lateral mass screws are traditionally used to fixate the subaxial cervical spine, while pedicle screws are used in the thoracic spine. Lateral mass fixation at C-7 is challenging due to thin facets, and placing pedicle screws is difficult due to the narrow pedicles. The authors describe their clinical experience with a novel technique for transfacet screw placement for fixation at C-7. METHODS A retrospective chart review was undertaken in all patients who underwent transfacet screw placement at C-7. The technique of screw insertion was the same for each patient. Polyaxial screws between 8- and 10-mm-long were used in each case and placed through the facet from a perpendicular orientation. Postoperative radiography and clinical follow-up were analyzed for aberrant screw placement or construct failure. RESULTS Ten patients underwent C-7 transfacet screw placement between June 2006 and March 2007. In all but 1 patient screws were placed bilaterally, and the construct lengths ranged from C-3 to T-5. One patient with a unilateral screw had a prior facet fracture that precluded bilateral screw placement. There were no intraoperative complications or screw failures in these patients. After an average of 6 months of follow-up there were no hardware failures, and all patients showed excellent alignment. CONCLUSIONS The authors present the first clinical demonstration of a novel technique of posterior transfacet screw placement at C-7. These results provide evidence that this technique is safe to perform and adds stability to cervicothoracic fixation.

Intraosseous spinal glomus tumors: case report.

OBJECTIVEGlomus tumors are rare lesions that can arise intraosseously along the entire spinal axis. Only four cases have been reported, usually manifesting with severe back pain and involving the midthoracic spine or sacrum. The current report describes the largest such lesion reported in the literature to date and summarizes the clinical and pathological characteristics of these rare tumors. METHODSA single, recent case arising from the lumbar vertebra of L3 is described, and the literature of intraosseous spinal glomus tumors is reviewed. RESULTSThe lesion described arose in a 44-year-old man with a 1-year history of neurological symptoms and a large dumbbell-shaped lesion involving the lumbar vertebra, which extended through the neural foramen at L3. The lesion was resected using a two-stage approach. Severe intraoperative hemorrhage necessitated emergent angiographic embolization. Histopathological examination confirmed the presence of a glomus tumor arising from the smooth muscle cells of the glomus body. CONCLUSIONThese rare lesions may extend into the epidural space and through the neural foramina and abdominal compartments; over time, they grow very large. Preoperative embolization may be indicated for large tumors suspected to be glomus tumors.

A Functional Magnetic Resonance Imaging Study of Factors Influencing Motor Function After Surgery for Gliomas in the Rolandic Region

BACKGROUND Pre- and postoperative fMRI was performed in patients with rolandic gliomas to evaluate factors influencing motor function after surgery. METHODS The study population consisted of 9 right-handed patients (mean age, 43.3 years; range, 25-67, 2 female/7 male) affected by high-grade gliomas growing within or adjacent to the rolandic cortex. Patients had a diverse onset and evolution of their disease. All patients underwent morphological imaging and fMRI on a 3-T scanner before and after surgery. Postprocessed imaging data were analyzed off-line using SPM. RESULTS Patterns of activation in real-time maps and SPM were similar when coregistered head motion artifacts did not exceed more than 50% voxel size of the echo-planar imaging sequence. Movements of the hand opposite the affected hemisphere showed activation of the cMI in all patients. Coactivation of the iMI occurred in 5 patients. The cMII was activated in 4 patients, all with excellent postoperative motor function. The iMII and SMA were activated in patients with a good functional outcome. When the unaffected hand was tested, this activation pattern was similar. Postoperative fMRIs were comparable with the preoperative scans. CONCLUSIONS Postoperative evaluation is feasible and may add confirmatory information to preoperative findings in selected patients. Bilateral activation of primary and secondary motor areas may be the correlate for compensatory recruitment of additional functional areas and a predictor for better functional outcome.