Field of view comparison between two-dimensional and three-dimensional endoscopy

OBJECTIVES/HYPOTHESIS

Relative to microscopic transnasal surgery, endoscopic surgery provides improved visualization with an increased field of view. Advances such as high-definition (HD) and three-dimensional (3D) endoscopy have been introduced and clearly improve visualization. However, do both technologies maintain an increased field of view? We hypothesize that the field of view of 3D endoscopy is restricted relative to two-dimensional (2D) HD endoscopy.

STUDY DESIGN

Laboratory investigation, prospective case series.

METHODS

Standard measurements at 6-cm and 2-cm working distances where made to determine the comparative field of view utilizing Storz 0° 2D HD and Visionsense 3D endoscopes. Relative measurements were then made to determine field of view. Five clinical patients were then utilized to confirm laboratory studies and demonstrate the relative field of view change.

RESULTS

3D endoscopy demonstrates a 52% loss of field of view compared to 2D endoscopy in a controlled lab testing. This was confirmed in a small clinical patient series where a 55% ± 3% relative field of view reduction was observed.

CONCLUSIONS

When working with 3D endoscopy in a currently available commercial product, the operator should be aware that relative to HD 2D endoscopy, there is a field of view restriction of 52%.

LEVEL OF EVIDENCE

N/A.

Acoustic neuroma observation associated with an increase in symptomatic tinnitus: results of the 2007-2008 Acoustic Neuroma Association survey

OBJECT

Tinnitus is a known presenting symptom of acoustic neuromas, but little is known about the impact of observation or treatment on tinnitus. Most patients experience improvement with treatment, while others may worsen. Therefore, this study was designed to assess the overall impact of observation and treatment on tinnitus outcome in patients with acoustic tumors.

METHODS

Data from the 2007-2008 Acoustic Neuroma Association survey were used. Tinnitus severity was graded both at presentation and at last follow-up for all patients questioned. This data set was analyzed using the Student t-test and a linear regression model adjusted for possible confounders.

RESULTS

Overall there were more patients receiving intervention (n = 1138) for their acoustic neuromas than observation (n = 289). Presenting tumor size positively correlated with tinnitus severity score. Regardless of treatment (microsurgery or stereotactic radiosurgery), tinnitus improved at last follow-up and worsened in those who were observed (p = 0.02). When comparing microsurgical options, retrosigmoid and translabyrinthine resection improved tinnitus symptoms (both p < 0.01). Stereotactic radiosurgery had a treatment effect similar to microsurgery.

CONCLUSIONS

Presenting tinnitus severity correlates strongly with tumor size. Furthermore, regardless of treatment, there appears to be an overall reduction in tinnitus severity for all forms of microsurgery and stereotactic radiosurgery. Importantly, observation leads to a worsening in symptomatic tinnitus and therefore should be weighed in the treatment recommendation.

Use of anterior temporal lobectomy for epilepsy in a community-based population

OBJECTIVE

To assess the hypothesis that use of anterior temporal lobectomy (ATL) for temporal epilepsy has diminished over time.

DESIGN

Population-based cohort study.

SETTING

The Rochester Epidemiology Project based in Olmsted County, Minnesota.

PARTICIPANTS

Residents of Olmsted County.

MAIN OUTCOME MEASURES

Poisson regression was used to evaluate changes in ATL use over time by sex.

RESULTS

Over a 17-year period, from 1993 to 2009, 847ATLs were performed with the primary indication of epilepsy(average, 50 procedures/y). Of these, 26 occurred among Olmsted County residents. The use rates declinedsignificantly between 1993 and 2000 (8 years) and 2001 and 2009 (9 years) according to Poisson regression analysis, from 1.9 to 0.7 per 100 000 person-years(P=.01). The rate of ATL use among Olmsted County residents was 1.2 (95% CI, 0.9 to 2.4) per 100 000 person years of follow-up over this 17-year period. The sex specific rates were 1.6 (95% CI, 0.9 to 2.4) and 0.7 (95%CI, 0.2 to 1.3) per 100 000 person-years for females and males, respectively.

CONCLUSIONS

In this community-based cohort, the rate of ATL use was 1.2 per 100 000 person-years of followup.Use of this procedure has declined over time; the reasons for this are unknown but do not include referral pattern changes.

Brain carcinoid metastases: outcomes and prognostic factors

OBJECT

Carcinoid tumors are rare and have generally been regarded as indolent neoplasms. Systemic disease is often incurable; however, patients may live years with this disease. Furthermore, metastatic brain lesions are extremely uncommon. As such, few series have examined outcomes and prognostic factors in those with brain involvement.

METHODS

The authors performed a retrospective review of patients who underwent primary treatment at Mayo Clinic in Rochester, Minnesota, for metastatic carcinoid tumors to the brain between 1986 and 2011. Progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier statistics. Cox proportional hazards were used to determine predictors of survival.

RESULTS

Fifteen patients underwent primary treatment for metastatic carcinoid tumors to the brain between 1986 and 2011. Their mean age was 58 ± 12 years. Eighty percent (n = 12) of patients underwent surgery, whereas 2 received stereotactic radiosurgery and 1 had whole-brain radiation therapy (WBRT) as the primary treatment. The median follow-up duration was 19 months (maximum 124 months). Systemic disease progression occurred in 73% and was the leading cause of death in known cases, while intracranial disease recurred in 40%. The median PFS and OS were 21 and 19 months, respectively. The use of adjuvant WBRT correlated with improved PFS (HR 0.15, CI 0.0074-0.95, p = 0.044). Those who underwent surgery as primary modalities trended toward longer progression-free intervals (p = 0.095), although this did not reach significance.

CONCLUSIONS

Metastatic carcinoid disease to the brain appears to have a worse prognosis than that of other extracranial metastases. Although there was a trend toward a survival advantage in patients who underwent surgery and WBRT, further study is needed to establish definitive treatment recommendations.

Intravenous recording of intracranial, broadband EEG

The most direct evaluation of human brain activity has been obtained from intracranial electrodes placed either on the surface of the brain or inserted into the brain to record from deep brain structures. Currently, the placement of intracranial electrodes implies transcranial surgery, either through a burr hole or a craniotomy, but the high degree of invasiveness and potential for morbidity of such major surgical procedures limits the applicability of intracranial recording. The vascular system provides a natural avenue to reach many brain regions that currently are reached by transcranial approaches, along with deep brain structures that cannot be reached via a transcranial approach without significant risk. To determine the applicability of intravascular approaches to high-frequency intracranial monitoring, a catheter containing multiple macro- and micro-electrodes was placed into the superior sagittal sinus of anesthetized pigs in parallel with clinical, subdural electrode grids to record epileptiform activity induced by direct, cortical injection of penicillin and to record responses to electrical stimulation. Intravascular electrodes recorded epileptiform spikes with similar magnitudes and waveshapes to those obtained by surface electrodes, both for macroelectrodes and microelectrodes, including the spatiotemporal evolution of epileptiform activity, suggesting that intravascular electrodes might provide localizing information regarding seizure foci. Sinusoidal electrical stimulation showed that intravascular electrodes provide sufficient broadband fidelity to record high-frequency, physiological events that may also prove useful in localizing seizure onset zones. As intravascular techniques have transformed cardiology, so intravascular neurophysiology may transform intracranial monitoring, in general, and the treatment of epilepsy, in particular.

Medullary venous hypertension secondary to a petrous apex dural arteriovenous fistula: a case report

Background

Dural arteriovenous fistulae (dAVF) are common intracranial vascular lesions typically becoming symptomatic with cortical venous hypertension and possible hemorrhage. Here, we present a case illustration of a petrous apex dAVF with marked medullary venous hypertension and a unique clinical presentation.

Methods

Case report.

Results

A 72-year-old female, whose clinical progression was significant for altered mental status and progressive weakness, presented with diplopia, right leg paresis, and ataxia. Magnetic resonance imaging revealed edema involving the medulla. On digital subtraction cerebral angiogram, the patient was found to have a petrous apex dAVF, Cognard type IV. Following treatment with Onyx embolization, her symptoms rapidly improved, with complete resolution of diplopia and drastic improvement of her ataxia.

Conclusion

The importance of this case is in the presentation and deterioration of the clinical exam, resembling an acute ischemic event. Further, this case illustrates that dAVF may cause venous hypertension with rapid onset of focal neurologic symptoms not exclusive to cortical locations.

Wireless fast-scan cyclic voltammetry to monitor adenosine in patients with essential tremor during deep brain stimulation

Essential tremor is often markedly reduced during deep brain stimulation simply by implanting the stimulating electrode before activating neurostimulation. Referred to as the microthalamotomy effect, the mechanisms of this unexpected consequence are thought to be related to microlesioning targeted brain tissue, that is, a microscopic version of tissue ablation in thalamotomy. An alternate possibility is that implanting the electrode induces immediate neurochemical release. Herein, we report the experiment performing with real-time fast-scan cyclic voltammetry to quantify neurotransmitter concentrations in human subjects with essential tremor during deep brain stimulation. The results show that the microthalamotomy effect is accompanied by local neurochemical changes, including adenosine release.

Scalp and intracranial EEG in medically intractable extratemporal epilepsy with normal MRI

Purpose. To investigate EEG and SPECT in the surgical outcome of patients with normal MRI (nonlesional) and extratemporal lobe epilepsy. Methods. We retrospectively identified 41 consecutive patients with nonlesional extratemporal epilepsy who underwent epilepsy surgery between 1997 and 2007. The history, noninvasive diagnostic studies (scalp EEG, MRI, and SPECT) and intracranial EEG (iEEG) monitoring was reviewed. Scalp and iEEG ictal onset patterns were defined. The association of preoperative studies and postoperative seizure freedom was analyzed using Kaplan-Meier analysis, log-rank test, and Cox proportional hazard. Results. Thirty-six of 41 patients had adequate information with a minimum of 1-year followup. Favorable surgical outcome was identified in 49% of patients at 1 year, and 35% at 4-year. On scalp EEG, an ictal onset pattern consisting of focal beta-frequency discharge (>13–125 Hz) was associated with favorable surgical outcome (P = 0.02). Similarly, a focal fast-frequency oscillation (>13–125 Hz) on iEEG at ictal onset was associated with favorable outcome (P = 0.03). Discussion. A focal fast-frequency discharge at ictal onset identifies nonlesional MRI, extratemporal epilepsy patients likely to have a favorable outcome after resective epilepsy surgery.

Symptomatic Rathke cleft cysts: extent of resection and surgical complications

OBJECT

Rathke cleft cysts (RCCs) are benign masses arising from the embryological Rathke pouch, and are commonly treated by transsphenoidal surgery. The authors retrospectively compared RCC extent of resection-either gross-total resection (GTR) or decompression-to the primary outcome measure, which was recurrences resulting in repeat surgery, and the secondary outcome measure, which was complications.

METHODS

Seventy-four patients presenting to the neurosurgical department with RCC were analyzed retrospectively. Sixty-eight patients had a total of 78 surgical procedures, with the diagnosis of RCC confirmed by histological investigation; of these, 61 patients had adequate operative notes for the authors to evaluate extent of resection. Groups were separated into GTR (32 patients) or decompression (subtotal resection or fenestration into the sphenoid sinus; 29 patients) based on operative notes and postoperative imaging. The mean follow-up duration was 60.5 ± 72.1 months (the mean is expressed ± SD throughout).

RESULTS

The average age at the time of the initial surgery was 42.8 ± 17.4 years, and 70% of patients were female. The mean cyst diameter preoperatively was 16.9 ± 17.8 mm. Eight patients had repeat surgery, our primary outcome measure; 3 repeat operations occurred in the GTR group, and 5 in the decompression group. There was no significant difference in recurrence when comparing groups (GTR 9%, decompression 17%; p = 0.36). There were no major complications; however, analysis of postoperative minor complications revealed that 11 (34%) GTRs resulted in surgical complications, whereas the decompression cohort accounted for only 3 complications (10%) (p = 0.03), with diabetes insipidus (6) and CSF leaks (5) being the most common. Gross-total resection also resulted in an increase in postoperative hyperprolactinemia compared with decompression (p = 0.03).

CONCLUSIONS

It appears that RCCs require repeat surgery in 13% of cases, and attempted GTR does not appear to reduce the overall rate of recurrence. However, more aggressive resections are associated with more complications in this series.

Spontaneous intraventricular hemorrhage associated with prolonged diosmin therapy

BACKGROUND

The prevalent use of anticoagulation in a growing elderly population has led to an increasing incidence of intracerebral hemorrhage. Furthermore, the understanding of the interactions and adverse effects of oral anticoagulants when used with non-FDA approved drugs is limited. Diosmin is one such non-FDA approved drug which is a semisynthetic, phlebotropic supplement with multiple microcirculatory effects. We report a case of a patient on oral anticoagulation and diosmin, who presented with spontaneous intraventricular hemorrhage, and discuss the possible etiology behind this rare event.

METHODS

A retrospective chart review and a comprehensive search of the literature using the PubMed database were performed.

RESULTS

A 77-year old female with a 6 week history of warfarin therapy and a several year history of diosmin use presented with severe bitemporal headache. Computed tomography scan revealed an acute hemorrhage within the right ventricle without associated intraparenchymal hemorrhage. International normalized ratio measured 1.8 and was corrected using fresh frozen plasma and vitamin K. She was discharged without neurological deficits.

CONCLUSIONS

Diosmin inhibits platelet aggregation and prolongs the effect of norepinephrine on venous tone, leading to increased venoconstriction. The combined effect of chronic microcirculatory hypertension and inhibition of platelet aggregation due to diosmin may have predisposed to spontaneous hemorrhage in this anticoagulated patient. Individual cases such as this serve as a reminder that over-the-counter dietary supplements may be associated with serious adverse events. The practicing clinician should be aware of this possible adverse event when evaluating patients on oral anticoagulation and chronic diosmin treatment.

Swine model for translational research of invasive intracranial monitoring

Focal cortical epilepsy is currently studied most effectively in humans. However, improvement in cortical monitoring and investigational device development is limited by lack of an animal model that mimics human acute focal cortical epileptiform activity under epilepsy surgery conditions. Therefore, we assessed the swine model for translational epilepsy research. Swine were used due to their cost-effectiveness, convoluted cortex, and comparative anatomy. The anatomy has all the same brain structures as the human, and in similar locations. Focal subcortical injection of benzyl-penicillin produced clinical seizures correlating with epileptiform activity demonstrating temporal and spatial progression. Swine were evaluated under five different anesthesia regimens. Of the five regimens, conditions similar to human intraoperative anesthesia, including continuous fentanyl with low dose isoflorane, was the most effective for eliciting complex, epileptiform activity after benzyl-penicillin injection. The most complex epileptiform activity (spikes, and high frequency activity) was then repeated reliably in nine animals, utilizing 14 swine total. There were 20.1 ± 10.8 [95% confidence interval (CI) 11.8-28.4] epileptiform events with > 3.5 Hz activity occurring per animal. Average duration of each event was 46.3 ± 15.6 (95% CI 44.0-48.6) s, ranging from 20-100 s. In conclusion, the acute swine model of focal cortical epilepsy surgery provides an animal model that mimics human surgical conditions with a large brain and gyrated cortex, and is relatively inexpensive among animal models. Therefore, we feel this model provides a valuable, reliable, and novel platform for translational studies of implantable hardware for intracranial monitoring.

Expanded endonasal endoscopic resection of anterior fossa meningiomas: report of 13 cases and meta-analysis of the literature

Object

Transnasal endoscopic (TNE) approaches have been proposed for the resection of anterior cranial base meningiomas. The purpose of this article was to evaluate the results of endoscopic resection of anterior cranial fossa meningiomas by reviewing available published data in addition to the authors' experience with 13 cases.

Methods

The literature was searched via OVID to identify all available disaggregate data pertaining to anterior fossa meningiomas treated primarily by TNE. In addition, the authors reviewed the records of a personal series of 13 patients who underwent TNE removal of parasellar meningiomas through a pure TNE approach.

Results

Meta-analysis from studies included a total of 69 patients with adequate disaggregated data to summarize. Mean age (± SD) at surgery was 53.3 ± 13.0 years (range 27–80 years); 78% of the patients were women. Tumor size was skewed toward smaller lesions, with a mean volume of 24.4 ± 2.9 cm3. Intraoperative impressions were of gross-total resection in 76% of cases. The most common complication reported was CSF leakage, occurring in 32% of the cases (22 of 69). The rate of CSF leakage was not affected by size (p = 0.52), location of tumor (p = 0.9), or age (p = 0.56). There was 1 death overall. The mean duration of follow-up was 21 ± 18 months.

Conclusions

Transnasal endoscopic resection of anterior cranial base meningiomas is feasible in selected cases. Reported resection rates are adequate, although the follow-up in the reported series is too short (mean 21 months) to make definitive conclusions regarding the long-term effectiveness. Cerebrospinal fluid leakage is a common complication, although it appears not to be associated with additional morbidity except for the need for reoperation. Long-term results are necessary before considering TNE resection as a valid alternative, in selected cases, to the more established transcranial techniques.

Cystic deterioration of the C1-2 articulation: clinical implications and treatment outcomes

OBJECT

Synovial cysts of the cervical spine are rare. Further, synovial cysts of the C1-2 articulation, or retroodontoid cysts, are very rare, with fewer than 20 cases reported overall. The authors report on a single-institution series of 10 patients with C1-2 retroodontoid synovial cysts.

METHODS

The charts of 10 patients with pathologically confirmed synovial cysts following resection between January 1998 and June 2009 were reviewed. The clinical presentation, radiographic findings, surgical management, and pre- and postoperative functional levels (reported as a modified Rankin outcome) are reported.

RESULTS

All 10 patients underwent attempts at complete resection of the synovial cyst; none of the lesions were simply aspirated. All 4 patients with an initial recommendation of observation alone ultimately underwent surgery because of their swift neurological deterioration. The mean age at surgery was 75.4 ± 4.6 years (range 54-81 years). The mean presenting cyst volume was 4.6 ± 1.7 cm(3). Nine of 10 patients underwent transoral resection of the cyst with posterior fusion. Six of the 10 patients underwent additional posterior laminectomy for decompression. The hospital length of stay varied from 2 to 45 days, with a mean of 19 ± 7 days. All patients undergoing transoral decompression had varying degrees of difficulty with postoperative dysphagia, diagnosed using videofluoroscopy. All patients improved in their modified Rankin Scale score after surgical intervention with a mean follow-up of 42 months (95% CI 12-72 months).

CONCLUSIONS

Synovial cysts of the atlantoaxial joint are rare. They occur in older patients in whom clinical deterioration is likely to occur. In most cases, these cysts can be diagnosed preoperatively. Transoral decompression with posterior fusion is an effective treatment for C1-2 degenerative cysts and can be accomplished with few complications. However, the ideal treatment for these lesions remains unknown.

Cortical ependymoma: an unusual epileptogenic lesion

OBJECT

Supratentorial cortical ependymomas (CE) are rare, with 7 cases reported. The lesions, typically occurring in the superficial cortex in young adults and associated with a history of seizures, are not fully characterized. Furthermore, their relationship with the recently described angiocentric glioma (AG) is still being debated. This study was undertaken to summarize the authors' experience with CEs.

METHODS

Between 1997 and 2009, 202 cases of ependymoma were surgically treated at the Mayo Clinic, 49 of which were supratentorial. Among these, 9 CE cases were retrospectively identified. Clinical, imaging, and pathological features of each case were reviewed.

RESULTS

Tumors arose from the frontal (5 cases), parietal (3), and occipital (1) lobes. No tumor occurred in the temporal lobe, despite its reported association with seizures. The mean age at presentation was 27 ± 19 years (± SD) and age at resection was 36 ± 16 years. The mean size of the lesion was 16 ± 14 cm(3). Seizures were the presenting symptom in 78%. Cross-sectional imaging in 8 cases was characterized by a heterogeneous mass with multiple cystlike areas and enhancement of the soft-tissue component. Gross-total resection was achieved in 8 of 9 tumors. Pathologically, 6 were low-grade (WHO Grade II) and 3 were anaplastic (WHO Grade III) ependymomas. All tumors exhibited the focal presence of perivascular pseudorosettes, but only 1 (11%) exhibited the focal presence of a true rosette. A bipolar spindle cell component resembling AG was present in 3 (33%) and "Schwannian-like" nodules in 2 (22%). Subpial aggregation and peripheral infiltration were present in 4 cases (44%). With a mean postsurgery follow-up of 62 ± 38 months, only 2 lesions recurred locally after imaging-confirmed gross-total resection, both being Grade III. In 5 (71%) of 7 patients presenting with seizures an Engel Class I outcome was achieved.

CONCLUSIONS

Cortical ependymomas represent a rare type of ependymoma occurring superficially in the cortex. Morphologically, these tumors are protean, varying from classic to epithelioid, clear cell, and tanycytic. Some also exhibited features typical of AG. Most tumors were low grade and cured with resection. Anaplastic tumors occur and may recur locally despite provision of radiation therapy. Cortical ependymomas frequently, but not always, present with seizures, but despite their high association with epilepsy, none occurred in the temporal lobe in any of the authors' 9 patients. Overall, CEs appear to have a relatively favorable prognosis compared with other supratentorial ependymomas.

Patient-assessed satisfaction and outcome after microsurgical resection of cavernomas causing epilepsy

OBJECT

Microsurgical resection of supratentorial cavernomas associated with intractable epilepsy is performed frequently. Despite its common occurrence, little is known about patient perceptions of microsurgical resection for cavernomas. This survey study was performed to investigate patient perceived outcome after surgery for cavernomas associated with intractable epilepsy.

METHODS

The authors' surgical database was searched for cavernoma resection performed between 1971 and July of 2006. Of the initial 173 patients identified, 102 met criteria for medically intractable seizures. These 102 patients were then mailed a survey to determine follow-up and patient satisfaction. Thirty-nine surveys were returned as undeliverable, and 30 (48%) of the remaining 63 patients responded.

RESULTS

The average age at surgery for patients responding to this survey was 40 +/- 16 years compared with 35 +/- 15 years for all 102 patients. At prolonged follow-up, 87% of patients reported being seizure-free. Of those with seizures, 2 (7%) reported being nearly seizure-free (rare disabling seizures), 2 (7%) believed they had a worthwhile improvement in seizure frequency, and no patient (0%) in this series believed they did not have a worthwhile improvement in seizure frequency. Ninety percent of responders stated they definitely, and 10% probably, would have surgery again. No patient responded that they probably or definitely would not have epilepsy surgery. Mean clinical follow-up was 36 +/- 8 months and survey follow-up was 97 +/- 13 months for these 30 patients. Use of the mail-in survey increased follow-up length 2.7 times longer compared with clinical follow-up.

CONCLUSIONS

It is clear from this select group of survey responders that patients undergoing surgery for cavernomas associated with medically intractable epilepsy are happy they underwent surgery (100%) and had excellent surgical outcomes (87% seizure-free) at prolonged follow-up of 97 +/- 13 months. These survey results support that microsurgical resection for cavernomas is highly effective and significantly improves these patients' quality of life.

Vascular Malformations, Rare Causes of Sciatic Neuropathy: A Case Series

BACKGROUND:

Sciatica is typically a clear-cut symptom complex commonly related to an impingement at the spinal nerve level. Etiologies of sciatic neuropathy outside the neural foramina are uncommon.

OBJECTIVE:

To describe 4 patients presenting with radiating leg pain due to sciatic nerve involvement, all with a vascular etiology.

METHODS:

Four patients presenting with neuropathic pain were retrospectively reviewed. Preoperative 3 Tesla magnetic resonance imaging was used to identify these lesions, which most commonly showed diffuse T2 changes with nerve enhancement upon administration of contrast.

RESULTS:

Exploration revealed vascular lesions. All patients went on to external and limited internal neurolysis of the involved sciatic nerve segment. Intraoperative histological study confirmed the presence of a venous angioma, an arteriovenous malformation, a venous malformation associated with Klippel-Trenaunay syndrome, and a capillary hemangioma. Follow-up demonstrated stable neurological examinations with reduction in pain at 1 year or greater.

CONCLUSION:

In patients with sciatic distribution symptoms and signs, after initial negative spine imaging, high-resolution imaging of the sciatic nerve itself should be undertaken to address rarer causes such as vascular abnormalities. In these cases, exploration and fascicular biopsy provided a diagnosis; external and limited internal neurolysis improved pain.

Surgically treated movement disorders associated with heterotopia: report of 2 cases

Heterotopic gray matter has been implicated in epilepsy; however, not much is known regarding heterotopia beyond epilepsy. Here, the authors describe 2 pediatric patients with deep heterotopias contiguous with basal ganglia structures. These heterotopias appear to have manifested as movement disorders. One patient presented with a left-sided myoclonus and choreiform movements associated with a right caudate heterotopia; she experienced vast improvement after resection of periventricular heterotopia. The other patient presented with progressive dystonia and a ballistic movement disorder. Initial bilateral globus pallidus internus stimulation resulted in successful treatment of the dystonia; however, her movement disorder worsened. After an extensive workup, including STATISCOM (statistical ictal SPECT coregistered to MR imaging), the patient underwent cortical stimulation with improvement in her movement disorder. To the best of our knowledge, these cases are the first reported instances of heterotopic gray matter associated with movement disorders. Both patients experienced significant improvements following resection of their heterotopias.

Preoperative embolization of the external carotid artery branches as an adjunct to superficial temporal artery-to-middle cerebral artery bypass

When technically feasible, the preferred revascularization procedure in patients with adult moyamoya disease is a superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass. The caliber of the STA has been reported as a prognostic factor for a successful bypass, with smaller-caliber STA being more likely to fail. We describe a novel approach to this circumstance in which preoperative embolization of external carotid artery (ECA) branches is used to augment blood flow through a small STA as a prelude to bypass surgery. We report 2 cases: a 42-year-old female presenting with symptomatic ischemic and radiographically progressive moyamoya disease and a 23-year-old female presenting with advanced moyamoya disease secondary to diabetes. Preoperative angiography demonstrated small-caliber STAs in each case, and primary revascularization was deemed difficult. Preoperative ECA embolization was undertaken to shunt blood toward the STA, thereby increasing its flow and caliber. In both cases, angiography after embolization demonstrated a 20%-45% increase in STA size, and doppler ultrasound indicated a 14%-50% increase in flow. Subsequently, both patients underwent successful STA-MCA bypass combined with encephalomyosynangiosis without complications. Of 167 STA-MCA bypasses performed by the senior author, embolization was performed in 7 unique patients on 9 sides. ECA embolization may be a beneficial adjunct when considering a direct bypass in the setting of a small STA. It can increase blood flow through the STA, making the operation technically easier and enhancing the patency of the bypass.

Development of intraoperative electrochemical detection: wireless instantaneous neurochemical concentration sensor for deep brain stimulation feedback

Deep brain stimulation (DBS) is effective when there appears to be a distortion in the complex neurochemical circuitry of the brain. Currently, the mechanism of DBS is incompletely understood; however, it has been hypothesized that DBS evokes release of neurochemicals. Well-established chemical detection systems such as microdialysis and mass spectrometry are impractical if one is assessing changes that are happening on a second-to-second time scale or for chronically used implanted recordings, as would be required for DBS feedback. Electrochemical detection techniques such as fast-scan cyclic voltammetry (FSCV) and amperometry have until recently remained in the realm of basic science; however, it is enticing to apply these powerful recording technologies to clinical and translational applications. The Wireless Instantaneous Neurochemical Concentration Sensor (WINCS) currently is a research device designed for human use capable of in vivo FSCV and amperometry, sampling at subsecond time resolution. In this paper, the authors review recent advances in this electrochemical application to DBS technologies. The WINCS can detect dopamine, adenosine, and serotonin by FSCV. For example, FSCV is capable of detecting dopamine in the caudate evoked by stimulation of the subthalamic nucleus/substantia nigra in pig and rat models of DBS. It is further capable of detecting dopamine by amperometry and, when used with enzyme linked sensors, both glutamate and adenosine. In conclusion, WINCS is a highly versatile instrument that allows near real-time (millisecond) detection of neurochemicals important to DBS research. In the future, the neurochemical changes detected using WINCS may be important as surrogate markers for proper DBS placement as well as the sensor component for a "smart" DBS system with electrochemical feedback that allows automatic modulation of stimulation parameters. Current work is under way to establish WINCS use in humans.

Magnetic resonance imaging-graded hypothalamic compression in surgically treated adult craniopharyngiomas determining postoperative obesity

OBJECT

Obesity as a consequence of management of pediatric craniopharyngioma is a well-described phenomenon related to the degree of hypothalamic involvement. However, weight change and obesity have not been analyzed in adult patients. Therefore, the purpose of this study was 1) to evaluate the pattern of postoperative weight gain related to preoperative body mass index (BMI), 2) determine if postoperative weight gain is an issue in adult patients, and 3) develop an objective MR imaging grading system to predict risk of postoperative weight gain and obesity in adults treated for craniopharyngioma.

METHODS

The authors retrospectively screened 296 patients with known craniopharyngioma for the following inclusion criteria: pathologically confirmed craniopharyngioma, index surgery at the authors' institution, and operative weight and height recorded with at least 3 months of follow-up including body weight measurement. Patients aged 18 years or younger were excluded, yielding 28 cases for analysis. Cases of craniopharyngiomas were compared with age- and sex-matched controls (pituitary adenoma patients) to evaluate the pattern and significance of perioperative weight changes.

RESULTS

Mean age was 46 +/- 17 years at surgery, and 64% of the patients were male. Complete resection was achieved in 71% of cases. There was no correlation of preoperative BMI and postoperative weight gain testing in a linear model. Sixty-one percent and 46% of patients had postoperative weight gains greater than 4 and 9%, respectively. Comparing craniopharyngioma patients (cases) to age- and sex-matched controls, the preoperative BMIs were similar (p = 0.93) between cases (mean 28.9 [95% CI 30.9-26.9]) and controls (mean 29.3 [95% CI 31.9-26.7]). However, there was a trend to a greater mean postoperative weight change (percentage) in cases (10.1%) than in controls (5.6%) (p = 0.24). Hypothalamic T2 signal change and irregular contrast enhancement correlated and predicted higher-grade hypothalamic involvement. Furthermore, they can be used to objectively grade hypothalamic involvement as the authors propose. Progressive hypothalamic involvement correlated with larger postoperative weight gains (p = 0.022); however, hypothalamic involvement did not correlate with preoperative BMI (p = 0.5).

CONCLUSIONS

Postoperative weight gain in adult patients undergoing surgery for craniopharyngioma is a significant problem and correlates with hypothalamic involvement, as it does in pediatric patients. Finally, objective MR imaging criteria can be used to predict risk of postoperative weight gain and aid in grading of hypothalamic involvement.

Stereotactic electroencephalography with temporal grid and mesial temporal depth electrode coverage: does technique of depth electrode placement affect outcome?

OBJECT

Intracranial monitoring for temporal lobe seizure localization to differentiate neocortical from mesial temporal onset seizures requires both neocortical subdural grids and hippocampal depth electrode implantation. There are 2 basic techniques for hippocampal depth electrode implantation. This first technique uses a stereotactically guided 8-contact depth electrode directed along the long axis of the hippocampus to the amygdala via an occipital bur hole. The second technique involves direct placement of 2 or 3 4-contact depth electrodes perpendicular to the temporal lobe through the middle temporal gyrus and overlying subdural grid. The purpose of this study was to determine whether one technique was superior to the other by examining monitoring success and complications.

METHODS

Between 1997 and 2005, 41 patients underwent invasive seizure monitoring with both temporal subdural grids and depth electrodes placed in 2 ways. Patients in Group A underwent the first technique, and patients in Group B underwent the second technique.

RESULTS

Group A consisted of 26 patients and Group B 15 patients. There were no statistically significant differences between Groups A and B regarding demographics, monitoring duration, seizure localization, or outcome (Engel classification). There was a statistically significant difference at the point in time at which these techniques were used: Group A represented more patients earlier in the series than Group B (p < 0.05). The complication rate attributable to the grids and depth electrodes was 0% in each group. It was more likely that the depth electrodes were placed through the grid if there was a prior resection and the patient was undergoing a new evaluation (p < 0.05). Furthermore, Group A procedures took significantly longer than Group B procedures.

CONCLUSIONS

In this patient series, there was no difference in efficacy of monitoring, complications, or outcome between hippocampal depth electrodes placed laterally through temporal grids or using an occipital bur hole stereotactic approach. Placement of the depth electrodes perpendicularly through the grids and middle temporal gyrus is technically more practical because multiple head positions and redraping are unnecessary, resulting in shorter operative times with comparable results.

Electrocorticography-guided resection of temporal cavernoma: is electrocorticography warranted and does it alter the surgical approach?

OBJECT

Cavernous hemangiomas associated with epilepsy present an interesting surgical dilemma in terms of whether one should perform a pure lesionectomy or tailored resection, especially in the temporal lobe given the potential for cognitive damage. This decision is often guided by electrocorticography (ECoG), despite the lack of data regarding its value in cavernoma surgery. The purpose of the present study was several-fold: first, to determine the epilepsy outcome following resection of cavernomas in all brain regions; second, to evaluate the usefulness of ECoG in guiding surgical decision making; and third, to determine the optimum surgical approach for temporal lobe cavernomas.

METHODS

The authors identified from their surgical database 173 patients who had undergone resection of cavernomas. One hundred two of these patients presented with epilepsy, and 61 harbored temporal lobe cavernomas. Preoperatively, all patients were initially evaluated by an epileptologist. The mean follow-up was 37 months.

RESULTS

Regardless of the cavernoma location, surgery resulted in an excellent seizure control rate: Engel Class I outcome in 88% of patients at 2 years postoperatively. Of 61 patients with temporal lobe cavernomas, the mesial structures were involved in 35. Among the patients with temporal lobe cavernomas, those who underwent ECoG typically had a more extensive parenchymal resection rather than a lesionectomy (p < 0.0001). The use of ECoG in cases of temporal lobe cavernomas resulted in a superior seizure-free outcome: 79% (29 patients) versus 91% (23 patients) of patients at 6 months postresection, 77% (22 patients) versus 90% (20 patients) at 1 year, and 79% (14 patients) versus 83% (18 patients) at 2 years without ECoG versus with ECoG, respectively.

CONCLUSIONS

The surgical removal of cavernomas most often leads to an excellent epilepsy outcome. In cases of temporal lobe cavernomas, the more extensive the ECoG-guided resection, the better the seizure outcome. In addition to upholding the concept of kindling, the data in this study support the use of ECoG in temporal lobe cavernoma surgery in patients presenting with epilepsy.

Rhabdomyolysis after transnasal repair of anterior basal encephalocele

BACKGROUND

Postoperative Rhabdomyolysis (RM) is rare after neurosurgical procedures. Furthermore, it has not been observed after transnasal approaches. The authors report a case of idiopathic RM occurring after transnasal resection of a sincipital encephalocele.

CASE DESCRIPTION

A 32-year-old woman underwent a transnasal resection of a sincipital encephalocele after 6 years of intermittent clear nasal drainage. Postoperatively, she experienced severe back pain, peripheral neuropathy, associated with a markedly elevated creatinine kinase, and severe RM. The patient was treated with hydration and forced urine alkalization and treated symptomatically for her pain and neuropathy. She ultimately made a full recovery without complication.

CONCLUSION

Rhabdomyolysis is a rare but known complication of neurosurgical procedures. We report the first known case report of RM after a transnasal procedure. Furthermore, a review of documented postneurosurgical cases of RM is presented and reveals that the causes and risk factors for this complication after neurosurgery are similar to those in other surgical subspecialties.