Faculty Bibliography

PURPOSE: Surgical resection of single, dominant, epileptogenic lesions in patients with tuberous sclerosis complex (TSC) is now accepted as an effective therapy. However, patients with symptomatic tubers in eloquent cortex are sometimes not offered surgery because of the concern for postoperative neurologic morbidity. In this study, we examine our results in children undergoing surgery for resection of tubers and associated seizure foci in rolandic and perirolandic cortex. METHODS: Between 1998 and 2008, 52 pediatric patients (mean age 4 years) with TSC underwent epilepsy surgery at the NYU Comprehensive Epilepsy Center. Fifteen of these patients underwent multistage surgery for invasive mapping of seizure foci and surrounding functional cortex followed by resection of tubers/seizure foci in or near rolandic cortex. Data were retrospectively collected and neurologic outcomes were tabulated. RESULTS: Postoperatively, four patients (27%) had either new hemiparesis or worsening of a preexisting hemiparesis. However, all patients were back to their neurologic baselines at 3-month follow-up, yielding no permanent postoperative deficits. The modified Engel outcome was class I in nine patients (60%), class II in three patients (20%), class III in two patients (13%), and class IV in one patient (7%) after 40 months mean follow-up. DISCUSSION: Surgical resection of tubers and associated epileptogenic foci in rolandic and perirolandic cortex in children with TSC is feasible, with low neurologic morbidity, and yields good seizure control. These results suggest that tubers and perituberal epileptogenic foci can be safely resected even in eloquent regions because of reorganization of functional cortex or because these lesions contain no neurologic function

BACKGROUND CONTEXT: Large cell neuroendocrine carcinoma of the lung is an aggressive tumor with unique histopathological features. It is not known to metastasize to the spine. PURPOSE: To report a metastatic case of this rare tumor to the cauda equina. STUDY DESIGN: Case report. METHODS: Retrospective case review and review of the literature. RESULTS: The authors report a rare case of a large cell neuroendocrine lung metastasis to the lumbar spine, causing right foot drop. Magnetic resonance imaging revealed a heterogeneously enhancing intradural extramedullary mass at L2/L3 level compressing the surrounding nerve roots. During surgery, the identified nerve roots were encased by the tumor, and the dissection was tedious. Postoperatively, the patient reported significantly improved back pain and he had severe foot weakness. The functional outcome was poor because the patient lost entirely his foot function; however, his back pain improved significantly after surgery. CONCLUSIONS: This is the first published study in which the authors described a metastasis of a rather uncommon lung cancer to the cauda equina. When a lesion of the cauda equina presents with a rapid progressive neurological deficit, leptomeningeal metastasis should be in the differential diagnosis.

OBJECT: The choice of surgical approach during resection of a thalamic juvenile pilocytic astrocytoma (JPA) is dictated by the location of the displaced normal thalamus and posterior limb of the internal capsule (PLIC). Diffusion tensor (DT) imaging and white matter tractography can identify the location of the PLIC in relation to the tumor and may be useful in planning the operative trajectory. METHODS: Diffusion tensor imaging was used to localize the PLIC on preoperative MR imaging in 6 children undergoing resection of thalamic JPAs. After review of the standard T2-weighted MR imaging sequences, the anticipated position of the PLIC was determined. This result was compared with the location of the PLIC determined by a blinded radiologist with the use of DT imaging. The utility of DT imaging in determining the surgical approach to a thalamic JPA, degree of resection, and neurological outcomes were all evaluated. RESULTS: Diffusion tensor imaging confirmed the expected location of the PLIC as approximated on conventional T2-weighted images in all 6 cases. In 1 patient in particular, unexpected medial deviation of the PLIC was identified, and this proved useful in tailoring the approach to a more lateral trajectory. Gross-total resection of all cystic and solid tumor components was confirmed on postoperative imaging in all cases. All patients experienced mild to moderate worsening of neurological status immediately following resection, but 4 of 6 patients were back to their preoperative baseline at 6-month follow-up. CONCLUSIONS: Diffusion tensor imaging and white matter tractography successfully identified the white matter fibers emanating from the precentral gyrus within the PLIC in children with thalamic JPAs prior to surgery. Diffusion tensor imaging served as a valuable tool for stereotactic planning of operative approaches to thalamic JPAs. Localizing the position of the PLIC helped minimize potential neurological morbidity and facilitated gross-total resection

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

OBJECTIVE: To describe the surgical techniques and postoperative clinical outcomes with the occipital transtentorial (OT) approach in patients harboring lesions arising from the precentral cerebellar fissure, posterior incisural space, and adjoining structures. METHODS: Twenty-two patients underwent microsurgical resection of intra-axial lesions arising within the precentral cerebellar fissure and posterior incisural space between 1997 and 2006. Patient demographics, presenting symptoms, pathology, and neurological outcomes were retrospectively reviewed. Pre- and postoperative magnetic resonance imaging scans were evaluated to determine the anatomic extensions of the lesion and the degree of surgical resection. Patients with lesions primarily confined to the pineal and posterior third ventricle approached by a supracerebellar infratentorial trajectory were excluded from this study. RESULTS: Of the 22 patients reported in this series, 17 (77%) had contrast-enhancing lesions, and 5 (23%) had nonenhancing lesions arising from the precentral cerebellar fissure and posterior incisural space. The lesions were oriented dorsomedial to the midbrain and diencephalon in 6 patients (27%), dorsolateral in 14 patients (64%), and lateral in 2 patients (9%). A lateral OT approach directed under the occipitotemporal junction was used in 16 patients (73%), and an interhemispheric OT approach was used in 6 patients (27%). Transient visual field loss occurred in 3 patients (14%); it resolved by the third follow-up month. Gross total resection or near-total resection of the imaging-defined lesion volume was achieved in 19 patients (86%). CONCLUSION: The OT approaches provide excellent exposure for lesions of the precentral cerebellar fissure, posterior incisural space, and adjacent structures. The lateral OT approach directed under the occipitotemporal junction provides an inline view for lesions situated posterolateral to the brainstem. It also provides an inferiorly directed view under the venous system into the precentral cerebellar fissure and fourth ventricular roof. Visual field deficits are minimized by directing the trajectory under the occipitotemporal junction instead of retracting along the interhemispheric corridor. The interhemispheric OT approach was primarily used for lesions extending superiorly, in the midline or near midline, above the tentorium and venous system into the splenium of corpus callosum, lateral ventricle, and posterior thalamus, where extensive lateral retraction was not required