Stephen P. Kalhorn

Vagus nerve stimulation in 436 consecutive patients with treatment-resistant epilepsy: Long-term outcomes and predictors of response

OBJECTIVE The goal of this study was to assess the efficacy and safety of vagus nerve stimulation in a consecutive series of adults and children with treatment-resistant epilepsy (TRE). METHODS In this retrospective review of a prospectively created database of 436 consecutive patients who underwent vagus nerve stimulator implantation for TRE between November 1997 and April 2008, there were 220 (50.5%) females and 216 (49.5%) males ranging in age from 1 to 76 years at the time of implantation (mean: 29.0 ± 16.5). Thirty-three patients (7.6%) in the primary implantation group had inadequate follow-up (<3 months from implantation) and three patients had early device removal because of infection and were excluded from seizure control outcome analyses. RESULTS Duration of vagus nerve stimulation treatment varied from 10 days to 11 years (mean: 4.94 years). Mean seizure frequency significantly improved following implantation (mean reduction: 55.8%, P<0.0001). Seizure control ≥ 90% was achieved in 90 patients (22.5%), ≥ 75% seizure control in 162 patients (40.5%), ≥ 50% improvement in 255 patients (63.75%), and <50% improvement in 145 patients (36.25%). Permanent injury to the vagus nerve occurred in 2.8% of patients. CONCLUSION Vagus nerve stimulation is a safe and effective palliative treatment option for focal and generalized TRE in adults and children. When used in conjunction with a multidisciplinary and multimodality treatment regimen including aggressive antiepileptic drug regimens and epilepsy surgery when appropriate, more than 60% of patients with TRE experienced at least a 50% reduction in seizure burden. Good results were seen in patients with non-U.S. Food and Drug Administration-approved indications. Prospective, randomized trials are needed for patients with generalized epilepsies and for younger children to potentially expand the number of patients who may benefit from this palliative treatment.

Decreased risk of wound infection after posterior cervical fusion with routine local application of vancomycin powder.

Study Design. A retrospective cohort study. Objective. To assess the ability of local vancomycin powder to prevent wound infection after posterior cervical fusion. Summary of Background Data. Wound infections are a significant source of morbidity and cost associated with spine surgery. Intraoperative application of vancomycin powder to the wound edges has been shown to lower the infection risk after posterior instrumented thoracolumbar fusion. There is little data on the efficacy and safety of local vancomycin powder in cervical spine surgery. Methods. All cases of posterior cervical fusion by a single surgeon were reviewed from 2007 to 2011. Routine application of 1 gram of vancomycin powder was started in August 2009. Baseline characteristics, operative details, and rates of wound infection and pseudarthrosis were compared between untreated patients and those who received vancomycin powder. Results. A total 171 patients underwent posterior cervical fusion between 2007 and 2011. Baseline and operative variables were similar between untreated patients (n = 92) and those who received vancomycin powder (n = 79). Patients were followed for a minimum of 1 year (range, 1.1–5.7 yr). The infection rate fell from 10.9% to 2.5% (P = 0.0384) following the introduction of vancomycin powder. The untreated and treated groups had similar rates of pseudarthrosis (5.4% vs. 5.1%). No complications attributable to vancomycin powder were identified. Conclusion. Routine local application of vancomycin powder is a low-cost effective strategy for preventing wound infection after posterior cervical fusion. Further studies are needed to optimize dosing, assess long-term safety, and evaluate use in other spinal operations. Level of Evidence: 2

Refractory epilepsy in tuberous sclerosis: Vagus nerve stimulation with or without subsequent resective surgery

OBJECTIVE The goal of the work described here was to assess the efficacy and safety of vagus nerve stimulation in a cohort of patients with tuberous sclerosis complex with refractory epilepsy. Furthermore, we examined the impact of vagus nerve stimulation failure on the ultimate outcome following subsequent intracranial epilepsy surgery. METHODS A retrospective review was performed on 19 patients with refractory epilepsy and TSC who underwent vagus nerve stimulator (VNS) implantation. There were 11 (58%) females and 8 (42%) males aged 2 to 44 years when the VNS was implanted (mean: 14.7+/-12 years). Twelve patients underwent primary VNS implantation after having failed a mean of 7.1 antiepileptic drugs. Two patients (17%) had generalized epilepsy, one had a single seizure focus, three (25%) had multifocal epilepsy, and six (50%) had multifocal and generalized epilepsy. Seven patients were referred for device removal and evaluation for intracranial procedures. One patient in the primary implantation group was lost to follow-up and excluded from outcome analysis. RESULTS All implantations and removals were performed without permanent complications. The duration of treatment for primary VNS implants varied from 8.5 months to 9.6 years (mean: 4.9 years). Mean seizure frequency significantly improved following VNS implantation (mean reduction: 72%, P<0.002). Two patients had Engel Class I (18%), one had Class II (9%), seven had Class III (64%), and one had Class IV (9%) outcome. Three patients with poor response to vagus nerve stimulation therapy at our center underwent resection of one or more seizure foci (Engel Class I, two patients; Engel Class III, one patient). Seven patients referred to our center for VNS removal and craniotomy underwent seizure focus resection (6) or corpus callosotomy (1) (Engel Class II: 2, Engel III: 2; Engel IV: 3). In total, 8 of 10 (80%) patients experienced improved seizure control following intracranial surgery (mean reduction: 65%, range: 0-100%, P<0.05). CONCLUSIONS VNS is a safe and effective treatment option for medically refractory epilepsy in patients with tuberous sclerosis complex. Nine of 11 patients (82%) experienced at least a 67% reduction in seizure burden. Lack of response to vagus nerve stimulation does not preclude subsequent improvement in seizure burden with intracranial epilepsy surgery.

Epilepsy surgery and tuberous sclerosis complex: special considerations

Epilepsy surgery for medically refractory seizures among patients with tuberous sclerosis complex (TSC) is a well-accepted treatment option. Many epilepsy centers around the world have published their experience over the past several years, supporting the idea that the best seizure control is obtained when a single tuber and associated epileptogenic zone is documented and targeted surgically. Recent advances in imaging and physiological techniques that reveal the epileptogenic zone have been used successfully in children with TSC who are being evaluated for surgery. As a result, a number of different surgical strategies have emerged, each reflecting the experience, strengths, and referral biases of the individual treating teams. Experience suggests that some patients with TSC who present with seizures that are difficult to localize and do not meet the classic selection criteria for epilepsy surgery may, nevertheless, benefit from surgery. Tuberectomy alone is often not sufficient for obtaining seizure control. Intracranial electrode recordings performed in a large number of children with TSC undergoing epilepsy surgery have raised new questions about the relationship of the cortical tuber to the epileptogenic zone in TSC. A careful assessment of the risks and benefits of any surgical strategy, compared with those associated with continued refractory epilepsy, should be considered by the treating team in conjunction with the patients family. Epilepsy surgery has not only benefited many children with TSC, but it also facilitates the understanding of epileptogenesis in TSC.

C2 nerve root sectioning in posterior C1-2 instrumented fusions.

OBJECTIVE To analyze qualitatively C2 nerve dysfunction after its transection in C1-2 posterolateral instrumented fusions. METHODS From 2002-2010, 20 consecutive patients underwent posterolateral instrumented fusions using C1 lateral mass and C2 pars or pedicle screws, mainly for type 2 dens fractures. Screws were placed under lateral fluoroscopic guidance using standard techniques. Bilateral C2 nerve roots were coagulated and transected in all patients. Mean follow-up was 30.7 months and consisted of clinical and radiographic examinations, telephone interviews, and mailed visual analogue scale (VAS) questionnaires assessing C2 nerve dysfunction. RESULTS One patient was lost to follow-up after the initial postoperative visit. Fusion was evident in all patients with 12 months of follow-up and two of three patients with <12 months of follow-up. There were no instances of unintended neurologic deficits, vascular injury, cerebrospinal fluid (CSF) leak, or hardware malfunction or malposition. By the 2-week or 6-week office visit, 4 of 20 patients complained of sensory disturbance, and 2 had paresthesias in the C2 distribution. After longer follow-up, one additional patient developed mild sensory symptoms. Quality of life was adversely affected in only one patient. No patient developed neuropathic pain at any time after C2 sectioning. CONCLUSIONS This study is the first series to describe C2 nerve function after posterior atlantoaxial instrumented fusion in adults of all ages. Sacrifice of the C2 nerve root increases fusion surface, allows for better preparation and decortication of the atlantoaxial joint, improves visualization for screw placement, and decreases blood loss and operative time without major clinical consequences.

Endovascular solutions to arterial injury due to posterior spine surgery

Iatrogenic arterial injury is an uncommon but recognized complication of posterior spinal surgery. The spectrum of injuries includes vessel perforation leading to hemorrhage, delayed pseudoaneurysm formation, and threatened perforation by screw impingement on arterial vessels. Repair of these injuries traditionally involved open direct vessel repair or graft placement, which can be associated with significant morbidity. We identified five patients with iatrogenic arterial injury during or after posterior spinal surgery between July 2004 and August 2009 and describe their endovascular treatment. Intraoperative arterial bleeding was encountered in two patients during posterior spinal surgery. The posterior wounds were packed, temporarily closed, and the patient was placed supine. In both patients, angiography demonstrated arterial injury necessitating repair. Covered stent grafts were deployed through femoral cutdowns to exclude the areas of injury. In three additional patients, postoperative computed tomography imaging demonstrated pedicle screws abutting/penetrating the thoracic or abdominal aorta. Angiography or intravascular ultrasound imaging, or both, confirmed indention/perforation of the aorta by the screw. Aortic stent graft cuffs were deployed through femoral cutdowns to cover the area of aortic contact before hardware removal. All five patients did well and were discharged home in good condition. Endovascular repair of arterial injuries occurring during posterior spinal procedures is feasible and can offer a safe and less invasive alternative to open repair.

Idiopathic bilateral stenosis of the foramina of Monro treated using endoscopic foraminoplasty and septostomy.

Hydrocephalus caused by stenosis of the foramen of Monro is rare. The authors describe a 28-year-old female patient with bilateral foraminal stenosis treated using endoscopic septostomy and unilateral foraminal balloon plasty (foraminoplasty). The patients hydrocephalus and symptoms resolved postoperatively. Endoscopic strategies may be employed as first-line therapy in this condition.

Metameric thoracic lesion: report of a rare case and a guide to management

Metameric lesions of the spine are rare. The authors present a case of patient with a complex metameric vascular lesion of the thoracic spine and describe a management strategy for this entity.

E-017 Cerebrovascular Decision Making: Professional and Personal Preferences

Introduction It is known that physicians sometimes recommend treatment that, in a similar clinical scenario, they might not choose for themselves. We sought to understand this dynamic across cerebrovascular practice and examine how neurosurgeons value the procedures they offer. Methods We conducted an online survey sent to a large cohort of neurosurgeons in May 2013. Respondents were randomised to answer either as the surgeon or as the patient. The questions involved patients presenting with 1) an epidural hematoma (control), 2) un-ruptured anterior communicating artery aneurysm, 3) incidentally found right temporal AVM, 4) spontaneous intracranial and intraventricular haemorrhage in deep structure. Data on practice parameters and experience levels was also collected. Results We obtained 534 survey responses, 279 responding as the “neurosurgeon”, and 255 as the “patient,” with a response rate of 19.7%. Demographics amongst the two groups of survey takers was similar. There was no difference in the management of an epidural hematoma, as expected. For the unruptured aneurysm, the rates of opting for treatment was similar amongst respondees. However within the treatment group there was a trend for survey takers to more often chose coiling for themselves and clipping for patients (p = 0.056). Surgeons, however, with a greater than 30% open-cerebrovascular practice had less of a tendency to do so. For arteriovenous malformation management, there was no statistical difference between choosing treatment or conservative management. However, amongst the respondees who chose treatment, more respondees chose resection/embolization for their patient but radiosurgery for self (p = 0.001). In a case of a large spontaneous intracranial and intraventricular haemorrhage neurosurgeons were more likely to place a ventricular drain in a patient than himself or herself. Neurosurgeons in practice more than 10 years since residency were more likely to recommend against interventions for aneurysms, AVMs or intracranial haemorrhage. Conclusions In the majority of cases altering the role of the surgeon did not change the decision to pursue treatment or conservative treatment. In certain clinical scenarios, however, neurosurgeons choose treatment options for themselves that are different than what they would choose for their patients. For the management of an arteriovenous malformations, intracranial aneurysms, and hypertensive haemorrhage, responses favored less invasive interventions when the surgeon was the patient. These findings are likely a result of cognitive biases, previous training, experience, areas of expertise, and personal values. Disclosures O. Tanweer: None. T. Wilson: None. S. Kalhorn: None. J. Golfinos: None. P. Huang: None. D. Kondziolka: None.

Pleural effusion accumulating in the epidural space: Recurrent cord compression in a patient with progressive lung adenocarcinoma

Pleural effusions are common in patients with advanced carcioma, particularly of the lung and breast. While the spinal column ies adjacent to the pleura, to our knowledge there is no reported ase of a pleural effusion causing cord compression. The epidural pace is normally isolated from the pleural space by the parietal leura, spinal column, ribs, and associated soft tissue. Here we describe a patient with lung carcinoma and a prior horacic laminectomy for epidural metastasis who presented with ecurrent cord compression. She was found to have a large epidural uid collection in the region of the prior laminectomy, as well as large pleural effusion which had developed simultaneously. The pidural collection was thin in consistency and under high pressure, onsistent with pleural fluid. The pleural effusion became smaller fter drainage of the epidural collection, suggesting the presence f a pleural–epidural fistula.