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Christopher S. Graffeo, Kathryn M. Van Abel, Jonathan M. Morris, Matthew L. Carlson, Jamie J. Van Gompel, Eric J. Moore, Daniel L. Price, Jan L. Kasperbauer, Jeffrey R. Janus, Kerry D. Olsen and Michael J. Link

OBJECTIVE

Vagus nerve and sympathetic chain cervical schwannomas (VNCSs and SCCSs) are benign nerve sheath tumors that arise in the head and neck. Despite similar presentations that make accurate preoperative diagnosis more difficult, the potential for morbidity following resection is significantly higher for patients with VNCS. Therefore, the authors analyzed a retrospective case series and performed a comparative analysis of the literature to establish diagnostic criteria to facilitate more accurate preoperative diagnoses.

METHODS

The authors conducted a blinded review of imaging studies from retrospectively collected, operatively confirmed cases of VNCS and SCCS. They also performed a systematic review of published series that reported patient-specific preoperative imaging findings in VNCS or SCCS.

RESULTS

Nine patients with VNCS and 11 with SCCS were identified. In the study cohort, splaying of the internal carotid artery (ICA) and internal jugular vein (IJV) did not significantly predict the nerve of origin (p = 0.06); however, medial and lateral ICA displacement were significantly associated with VNCS and SCCS, respectively (p = 0.01 and p = 0.003, respectively). Multivariate analysis demonstrated that ICA and IJV splaying with medial ICA displacement carried an 86% probability of VNCS (p = 0.001), while the absence of splaying with lateral ICA displacement carried a 91% probability of SCCS (p = 0.006). The presence of vocal cord symptoms or peripheral enhancement significantly augmented the predictive probability of VNCS, as did Horner's syndrome or homogeneous enhancement for SCCS.

A review of the literature produced 25 publications that incorporated a total of 106 patients, including the present series. Splaying of the ICA and IJV was significantly, but not uniquely, associated with VNCS (p < 0.0001); multivariate analysis demonstrated that ICA and IJV splaying with medial ICA displacement carries a 75% probability of VNCS (p < 0.0001), while the absence of such splaying with lateral ICA displacement carries an 87% probability of SCCS (p = 0.0003).

CONCLUSIONS

ICA and IJV splaying frequently predicts VNCS; however, this finding is also commonly observed in SCCS and, among the 9 cases in the present study, was observed more often than previously reported. When congruent with splaying, medial or lateral ICA displacement significantly enhances the reliability of preoperative predictions, empowering more accurate prognostication.

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Yasunori Nagahama, Christopher K. Kovach, Michael Ciliberto, Charuta Joshi, Ariane E. Rhone, Adam Vesole, Phillip E. Gander, Kirill V. Nourski, Hiroyuki Oya, Matthew A. Howard III, Hiroto Kawasaki and Brian J. Dlouhy

Musicogenic epilepsy (ME) is an extremely rare form of the disorder that is provoked by listening to or playing music, and it has been localized to the temporal lobe. The number of reported cases of ME in which intracranial electroencephalography (iEEG) has been used for seizure focus localization is extremely small, especially with coverage of the superior temporal plane (STP) and specifically, Heschl’s gyrus (HG). The authors describe the case of a 17-year-old boy with a history of medically intractable ME who underwent iEEG monitoring that involved significant frontotemporal coverage as well as coverage of the STP with an HG depth electrode anteriorly and a planum temporale depth electrode posteriorly. Five seizures occurred during the monitoring period, and a seizure onset zone was localized to HG and the STP. The patient subsequently underwent right temporal neocortical resection, involving the STP and including HG, with preservation of the mesial temporal structures. The patient remains seizure free 1 year postoperatively. To the authors’ knowledge, this is the first reported case of ME in which the seizure focus has been localized to HG and the STP with iEEG monitoring. The authors review the literature on iEEG findings in ME, explain their approach to HG depth electrode placement, and discuss the utility of STP depth electrodes in temporal lobe epilepsy.

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Aaron J. Clark, Jessica A. Tang, Jeremi M. Leasure, Michael E. Ivan, Dimitriy Kondrashov, Jenni M. Buckley, Vedat Deviren and Christopher P. Ames

Object

Reconstruction after total sacrectomy is a critical component of malignant sacral tumor resection, permitting early mobilization and maintenance of spinal pelvic alignment. However, implant loosening, graft migration, and instrumentation breakage remain major problems. Traditional techniques have used interiliac femoral allograft, but more modern methods have used fibular or cage struts from the ilium to the L-5 endplate or sacral body replacement with transiliac bars anchored to cages to the L-5 endplate. This study compares the biomechanical stability under gait-simulating fatigue loading of the 3 current methods.

Methods

Total sacrectomy was performed and reconstruction was completed using 3 different constructs in conjunction with posterior spinal screw rod instrumentation from L-3 to pelvis: interiliac femur strut allograft (FSA); L5–iliac cage struts (CSs); and S-1 body replacement expandable cage (EC). Intact lumbar specimens (L3–sacrum) were tested for flexion-extension range of motion (FE-ROM), axial rotation ROM (AX-ROM), and lateral bending ROM (LB-ROM). Each instrumented specimen was compared with its matched intact specimen to generate an ROM ratio. Fatigue testing in compression and flexion was performed using a custom-designed long fusion gait model.

Results

Compared with intact specimen, the FSA FE-ROM ratio was 1.22 ± 0.60, the CS FE-ROM ratio was significantly lower (0.37 ± 0.12, p < 0.001), and EC was lower still (0.29 ± 0.14, p < 0.001; values are expressed as the mean ± SD). The difference between CS and EC in FE-ROM ratio was not significant (p = 0.83). There were no differences in AX-ROM or LB-ROM ratios (p = 0.77 and 0.44, respectively). No failures were noted on fatigue testing of any EC construct (250,000 cycles). This was significantly improved compared with FSA (856 cycles, p < 0.001) and CS (794 cycles, p < 0.001).

Conclusions

The CS and EC appear to be significantly more stable constructs compared with FSA with FE-ROM. The 3 constructs appear to be equal with AX-ROM and LB-ROM. Most importantly, EC appears to be significantly more resistant to fatigue compared with FSA and CS. Reconstruction of the load transfer mechanism to the pelvis via the L-5 endplate appears to be important in maintenance of alignment after total sacrectomy reconstruction.

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Steven W. Hetts, Parham Moftakhar, Joey D. English, Christopher F. Dowd, Randall T. Higashida, Michael T. Lawton, Vanja C. Douglas and Van V. Halbach

Object

Spinal dural arteriovenous fistulas (SDAVFs) cause myelopathy through arterialization of the perimedullary venous plexus and venous congestion of the spinal cord. The authors hypothesized that the craniocaudal extent of engorgement of intrathecal draining veins between the fistula site and the point of drainage out of the thecal sac correlates with the degree of myelopathy.

Methods

A retrospective review of the authors' institution's radiology databases identified 31 patients with SDAVFs who had undergone digital subtraction angiography (DSA) and MRI examinations of the spine. The authors counted the number of vertebral body levels of spinal cord enhancement and intrathecal vessel enhancement on T1-weighted postcontrast MRI studies. They also counted the number of levels of cord hyperintensity and intrathecal flow voids on T2-weighted MRI studies. On DSA, the authors identified the number of vertebral body levels of dilated intrathecal draining veins and outflow points from intrathecal veins to epidural veins. Functional status of the patients at the time of diagnosis was assessed using the Aminoff-Logue scale (ALS).

Results

Enlargement of the intrathecal draining veins averaged 10 ± 7.7 spinal levels on DSA. Patients with enlarged draining veins extending 10 or more spinal levels on DSA had worse ALS scores (mean gait 3.4, mean micturition 1.5) than patients with draining veins extending fewer than 10 levels (mean gait 1.8, mean micturition 0.6; p = 0.009 and 0.02, respectively). The number of vertebral body levels of enlarged draining veins correlated with the ALS score (gait r = 0.42, p = 0.009; and micturition r = 0.55, p = 0.0006). More extensive enlarged draining veins were associated with more spinal cord T2 hyperintensity, T2 intrathecal flow voids, and T1 vessel enhancement but not cord enhancement.

Conclusions

The craniocaudal extent of enlarged intrathecal veins draining SDAVF correlates with patient functional status, providing further insight into the pathophysiology of venous hypertensive myelopathy.

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Raqeeb M. Haque, Hani R. Malone, Martin W. Bauknight, Michael A. Kellner, Alfred T. Ogden, John H. Martin, Kurenai Tanji and Christopher J. Winfree

Object

Despite extensive study, no meaningful progress has been made in encouraging healing and recovery across the site of spinal cord injury (SCI) in humans. Spinal cord bypass surgery is an unconventional strategy in which intact peripheral nerves rostral to the level of injury are transferred into the spinal cord below the injury. This report details the feasibility of using spinal accessory nerves to bypass cervical SCI and intercostal nerves to bypass thoracolumbar SCI in human cadavers.

Methods

Twenty-three human cadavers underwent cervical and/or lumbar laminectomy and dural opening to expose the cervical cord and/or conus medullaris. Spinal accessory nerves were harvested from the Erb point to the origin of the nerve's first major branch into the trapezius. Intercostal nerves from the T6–12 levels were dissected from the lateral border of paraspinal muscles to the posterior axillary line. The distal ends of dissected nerves were then transferred medially and sequentially inserted 4 mm deep into the ipsilateral cervical cord (spinal accessory nerve) or conus medullaris (intercostals). The length of each transferred nerve was measured, and representative distal and proximal cross-sections were preserved for axonal counting.

Results

Spinal accessory nerves were consistently of sufficient length to be transferred to caudal cervical spinal cord levels (C4–8). Similarly, intercostal nerves (from T-7 to T-12) were of sufficient length to be transferred in a tension-free manner to the conus medullaris. Spinal accessory data revealed an average harvested nerve length of 15.85 cm with the average length needed to reach C4–8 of 4.7, 5.9, 6.5, 7.1, and 7.8 cm. The average length of available intercostal nerve from each thoracic level compared with the average length required to reach the conus medullaris in a tension-free manner was determined to be as follows (available, required in cm): T-7 (18.0, 14.5), T-8 (18.7, 11.7), T-9 (18.8, 9.0), T-10 (19.6, 7.0), T-11 (18.8, 4.6), and T-12 (15.8, 1.5). The number of myelinated axons present on cross-sectional analysis predictably decreased along both spinal accessory and intercostal nerves as they coursed distally.

Conclusions

Both spinal accessory and intercostal nerves, accessible from a posterior approach in the prone position, can be successfully harvested and transferred to their respective targets in the cervical spinal cord and conus medullaris. As expected, the number of axons available to grow into the spinal cord diminishes distally along each nerve. To maximize axon “bandwidth” in nerve bypass procedures, the most proximal section of the nerve that can be transferred in a tension-free manner to a spinal level caudal to the level of injury should be implanted. This study supports the feasibility of SAN and intercostal nerve transfer as a means of treating SCI and may assist in the preoperative selection of candidates for future human clinical trials of cervical and thoracolumbar SCI bypass surgery.

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Kristian Aquilina, Christopher Lim, Mahmoud Hamdy Kamel, Charles J. Marks, Michael G. O'Sullivan and Catherine Keohane

✓ Epithelioid hemangioendothelioma (EH) is a rare tumor of vascular origin. The authors describe two cases of spinal EH, one involving the T-10 vertebra and the second involving the upper cervical spine. In the first case the patient underwent resection of the tumor; this case represents the longest reported follow-up period for spinal EH. In the second case, extensive involvement of C-2, C-3, and C-4 as well as encasement of both vertebral arteries precluded safe tumor resection, and posterior occipitocervical stabilization was performed. The patient subsequently died of metastatic disease. The findings in these two cases underscore the difficulty in predicting the clinical behavior of spinal EH based solely on histological and clinical features as well as the uncertainty of the roles of surgery, chemotherapy, and radiotherapy in the oncological management of a spinal tumor for which clinical data are very limited.

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Jeffrey D. Coe, Alexander R. Vaccaro, Andrew T. Dailey, Rick C. Sasso, Steven C. Ludwig, James S. Harrop, Joseph R. Dettori, Christopher I. Shaffrey, Sanford E. Emery and Michael G. Fehlings

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Ananth K. Vellimana, Yasha Kadkhodayan, Keith M. Rich, DeWitte T. Cross III, Christopher J. Moran, Allyson R. Zazulia, Jin-Moo Lee, Michael R. Chicoine, Ralph G. Dacey Jr., Colin P. Derdeyn and Gregory J. Zipfel

Object

The aim of this study was to define the optimal treatment for patients with symptomatic intraluminal carotid artery thrombus (ICAT).

Methods

The authors performed a retrospective chart review of patients who had presented with symptomatic ICAT at their institution between 2001 and 2011.

Results

Twenty-four patients (16 males and 8 females) with ICAT presented with ischemic stroke (18 patients) or transient ischemic attack ([TIA], 6 patients). All were initially treated using anticoagulation with or without antiplatelet drugs. Eight of these patients had no or only mild carotid artery stenosis on initial angiography and were treated with medical management alone. The remaining 16 patients had moderate or severe carotid stenosis on initial angiography; of these, 10 underwent delayed revascularization (8 patients, carotid endarterectomy [CEA]; 2 patients, angioplasty and stenting), 2 refused revascularization, and 4 were treated with medical therapy alone. One patient had multiple TIAs despite medical therapy and eventually underwent CEA; the remaining 23 patients had no TIAs after treatment. No patient suffered ischemic or hemorrhagic stroke while on anticoagulation therapy, either during the perioperative period or in the long-term follow-up; 1 patient died of an unrelated condition. The mean follow-up was 16.4 months.

Conclusions

Results of this study suggest that initial anticoagulation for symptomatic ICAT leads to a low rate of recurrent ischemic events and that carotid revascularization, if indicated, can be safely performed in a delayed manner.

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Chad W. Washington, Gregory J. Zipfel, Michael R. Chicoine, Colin P. Derdeyn, Keith M. Rich, Christopher J. Moran, DeWitte T. Cross and Ralph G. Dacey Jr.

Object

The purpose of aneurysm surgery is complete aneurysm obliteration while sparing associated arteries. Indocyanine green (ICG) videoangiography is a new technique that allows for real-time evaluation of blood flow in the aneurysm and vessels. The authors performed a retrospective study to compare the accuracy of ICG videoangiography with intraoperative angiography (IA), and determine if ICG videoangiography can be used without follow-up IA.

Methods

From June 2007 through September 2009, 155 patients underwent craniotomies for clipping of aneurysms. Operative summaries, angiograms, and operative and ICG videoangiography videos were reviewed. The number, size, and location of aneurysms, the ICG videoangiography and IA findings, and the need for clip adjustment after ICG videoangiography and IA were recorded. Discordance between ICG videoangiography and IA was defined as ICG videoangiography demonstrating aneurysm obliteration and normal vessel flow, but post-IA showing either an aneurysmal remnant and/or vessel occlusion requiring clip adjustment.

Results

Thirty-two percent of patients (49 of 155) underwent both ICG videoangiography and IA. The post-ICG videoangiography clip adjustment rate was 4.1% (2 of 49). The overall rate of ICG videoangiography–IA agreement was 75.5% (37 of 49) and the ICG videoangiography–IA discordance rate requiring post-IA clip adjustment was 14.3% (7 of 49). Adjustments were due to 3 aneurysmal remnants and 4 vessel occlusions. These adjustments were attributed to obscuration of the residual aneurysm or the affected vessel from the field of view and the presence of dye in the affected vessel via collateral flow. Although not statistically significant, there was a trend for ICG videoangiography–IA discordance requiring clip adjustment to occur in cases involving the anterior communicating artery complex, with an odds ratio of 3.3 for ICG videoangiography–IA discordance in these cases.

Conclusions

These results suggest that care should be taken when considering ICG videoangiography as the sole means for intraoperative evaluation of aneurysm clip application. The authors further conclude that IA should remain the gold standard for evaluation during aneurysm surgery. However, a combination of ICG videoangiography and IA may ultimately prove to be the most effective strategy for maximizing the safety and efficacy of aneurysm surgery.