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Kirsty E. Bortnik, Guy M. McKhann II and Marla J. Hamberger

Electrical stimulation mapping (ESM) is considered the gold standard for identification of essential language cortex and is especially important in patients for whom classic language landmarks are less useful because of reorganization in response to epileptogenic or neoplastic cortex. However, little is known regarding the reliability of the procedure, particularly over extended time intervals. The authors present the case of a young man with refractory left temporal lobe epilepsy in the setting of a low-grade left temporal tumor who had undergone intraoperative language mapping at age 14 years and repeat mapping at age 25. Results from both the initial ESM and the repeat ESM 11 years later revealed a positive auditory description naming site in the same location on the superior temporal gyrus, at the anterior aspect of the tumor. This case provides support for the reliability of ESM and underscores intraindividual reliability in the location of language cortex over a prolonged period.

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Andrew T. Dailey, Guy M. McKhann II and Mitchel S. Berger

✓ Mutism following posterior fossa tumor resection in pediatric patients has been previously recognized, although its pathophysiology remains unclear. A review of the available literature reveals 33 individuals with this condition, with only a few adults documented in the population. All of these patients had large midline posterior fossa tumors.

To better understand the incidence and anatomical substrate of this syndrome, the authors reviewed a 7-year series of 110 children who underwent a posterior fossa tumor resection. During that time, nine (8.2%) of the 110 children exhibited mutism postoperatively. They ranged from 2.5 to 20 years of age (mean 8.1 years) and became mute within 12 to 48 hours of surgery. The period of mutism lasted from 1.5 to 12 weeks after onset: all children had difficulty coordinating their oral pharyngeal musculature as manifested by postoperative drooling and inability to swallow. Further analysis of these cases revealed that all children had splitting of the entire inferior vermis at surgery, as confirmed on postoperative magnetic resonance studies. Lower cranial nerve function was intact in all nine patients.

Current concepts of cerebellar physiology emphasize the importance of the cerebellum in learning and language. The syndrome described resembles a loss of learned activities, or an apraxia, of the oral and pharyngeal musculature. To avoid the apraxia, therefore, the inferior vermis must be preserved. For large midline tumors that extend to the aqueduct, a combined approach through the fourth ventricle and a midvermis split may be used to avoid injuring the inferior vermis.

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Timothy H. Lucas II, Guy M. McKhann II and George A. Ojemann

Object. The aim of this investigation was to address three questions in bilingualism research: 1) are multiple languages functionally separated within the bilingual brain; 2) are these languages similarly organized; and 3) does language organization in bilinguals mirror that in monolinguals?

Methods. During awake dominant-hemisphere craniotomy in each of 25 bilingual patients, the authors mapped both languages by using identical object-naming stimuli. Essential sites for primary (L1) and secondary (L2) languages were compared. Sites were photographically recorded and plotted onto an anatomically referenced grid system. Language organization in bilinguals was then compared with that in 117 monolinguals and 11 monolingual children.

Conclusions. The authors found distinct language-specific sites as well as shared sites that support both languages. The L1 and L2 representations were similar in total cortical extent but significantly different in anatomical distribution. The L2-specific sites were located exclusively in the posterior temporal and parietal regions, whereas the L1 and shared sites could be found throughout the mapped regions. Bilinguals possessed seven perisylvian language zones, in which L2 sites were significantly underrepresented when compared with the distribution of language sites in monolinguals. These L2-restricted zones overlapped the primary language areas found in monolingual children, indicating that these zones become dedicated to L1 processing. These findings support three conclusions. First, it is necessary to map both languages in bilinguals because L1 and L2 sites are functionally distinct. Second, differences exist in the organization of L1 and L2 sites, with L2-specific sites located exclusively in the posterior temporal and parietal lobes. Third, language organization comparisons in bilingual and monolingual brains demonstrate the presence of L2-restricted zones, which are dedicated to L1.

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Robert A. McGovern, Kathleen M. Kelly, Andrew K. Chan, Nicholas J. Morrissey and Guy M. McKhann II

Object

Ventriculoatrial (VA) shunting is rarely used for patients with normal-pressure hydrocephalus (NPH), likely due to surgeon technical preference and case reports indicating cardiopulmonary complications. However, these complications have typically been limited to adults in whom VA shunts had been placed when they were children. Few studies have directly compared VA shunting to ventriculoperitoneal (VP) shunting in cases of NPH.

Methods

The authors retrospectively analyzed all NPH patients treated by a single surgeon at their center from January 2002 through December 2011. Thirty patients were treated with VA shunts (14 male) and 157 with VP shunts (86 male). The patients' mean age (± SD) at surgery was 73.7 ± 9.4 years for VA shunting and 76.0 ± 8.2 years for VP shunting; the median durations of follow-up were 42.0 months (IQR 19.2–63.6 months) and 34.2 months (IQR 15.8–67.5), respectively. Statistical analysis was performed using chi-square tests and Wilcoxon rank-sum tests.

Results

Perioperative and postoperative complications for VA and VP shunting cohorts, respectively, included distal revision (2.7% vs 6.6%, p = 0.45), proximal revision (2.7% vs 2.5%, p = 0.97), and postoperative seizure (2.7% vs 1.5%, p = 0.62). Shunt drainage–related subdural hematomas/hygromas developed in 8.1%/27.0% of VA shunt–treated patients versus 6.6%/26.4% of VP shunt–treated patients (p = 0.76/0.98) and were nearly always successfully managed with programmable-valve adjustment. Symptomatic intracerebral hemorrhage (1.5%) and shunt infection (2.0%) were only observed in those who underwent VP shunting. Of note, no cardiovascular complications were observed in any patient, and there were no cases of distal occlusion of the VA shunt.

Conclusions

The authors found no significant differences in complication rates between VA and VP shunting, and VA shunting was not associated with any cardiopulmonary complications. Thus, in the authors' experience, VA shunting is at least as safe as VP shunting for treating NPH.

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Lauren T. Brown, Charles B. Mikell, Brett E. Youngerman, Yuan Zhang, Guy M. McKhann II and Sameer A. Sheth

OBJECT

The object of this study was to perform a systematic review, according to Preferred Reporting Items of Systematic reviews and Meta-Analyses (PRISMA) and Agency for Healthcare Research and Quality (AHRQ) guidelines, of the clinical efficacy and adverse effect profile of dorsal anterior cingulotomy compared with anterior capsulotomy for the treatment of severe, refractory obsessive-compulsive disorder (OCD).

METHODS

The authors included studies comparing objective clinical measures before and after cingulotomy or capsulotomy (surgical and radiosurgical) in patients with OCD. Only papers reporting the most current follow-up data for each group of investigators were included. Studies reporting results on patients undergoing one or more procedures other than cingulotomy or capsulotomy were excluded. Case reports and studies with a mean follow-up shorter than 12 months were excluded. Clinical response was defined in terms of a change in the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score. The authors searched MEDLINE, PubMed, PsycINFO, Scopus, and Web of Knowledge through October 2013. English and non-English articles and abstracts were reviewed.

RESULTS

Ten studies involving 193 participants evaluated the length of follow-up, change in the Y-BOCS score, and postoperative adverse events (AEs) after cingulotomy (n = 2 studies, n = 81 participants) or capsulotomy (n = 8 studies, n = 112 participants). The average time to the last follow-up was 47 months for cingulotomy and 60 months for capsulotomy. The mean reduction in the Y-BOCS score at 12 months’ follow-up was 37% for cingulotomy and 55% for capsulotomy. At the last follow-up, the mean reduction in Y-BOCS score was 37% for cingulotomy and 57% for capsulotomy. The average full response rate to cingulotomy at the last follow-up was 41% (range 38%–47%, n = 2 studies, n = 51 participants), and to capsulotomy was 54% (range 37%–80%, n = 5 studies, n = 50 participants). The rate of transient AEs was 14.3% across cingulotomy studies (n = 116 procedures) and 56.2% across capsulotomy studies (n = 112 procedures). The rate of serious or permanent AEs was 5.2% across cingulotomy studies and 21.4% across capsulotomy studies.

CONCLUSIONS

This systematic review of the literature supports the efficacy of both dorsal anterior cingulotomy and anterior capsulotomy in this highly treatment-refractory population. The observational nature of available data limits the ability to directly compare these procedures. Controlled or head-to-head studies are necessary to identify differences in efficacy or AEs and may lead to the individualization of treatment recommendations.

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Toru Fukuhara, Guy M. McKhann II, Paul Santiago, Joseph M. Eskridge, John D. Loeser and H. Richard Winn

✓ The authors describe a patient with right-sided central pain resulting from a left parietal arteriovenous malformation (AVM). The AVM was treated with staged embolization and stereotactic radiosurgery, and its obliteration was documented on follow-up angiographic studies. Surprisingly, the patient noted complete resolution of her pain syndrome after embolization, which is an extremely rare result. Central pain and its proposed mechanisms are discussed.

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Guy M. McKhann II, Julie Schoenfeld-McNeill, Donald E. Born, Michael M. Haglund and George A. Ojemann

Object. Among the variety of surgical procedures that are performed for the treatment of medically refractory mesial temporal lobe epilepsy (TLE), no consensus exists as to how much of the hippocampus should be removed. Whether all patients require a maximal hippocampal resection has not yet been determined.

Methods. At the University of Washington, all TLE operations are performed in a tailored fashion, guided by electrocorticography (ECoG). The amount of hippocampal resection is determined intraoperatively by the extent of interictal epileptiform abnormalities on ECoG recorded from that structure, resulting in a hippocampal resection that is individualized for each patient. Using this approach, the authors prospectively observed 140 consecutive patients who underwent surgery for mesial TLE with pathological diagnoses of either mesial temporal sclerosis with neuronal loss (MTS group) or mild gliosis without neuronal loss (non-MTS group) to determine whether the extent of hippocampal resection correlates with outcome when a tailored approach is used. Additionally, the authors analyzed whether the presence of residual interictal epileptiform activity on ECoG following mesial temporal resection predicts poorer seizure control.

With at least 18 months of clinical follow up, 67% of the 140 patients were seizure free or had only a single postoperative seizure. There was no correlation between the size of the hippocampal resection and seizure control in the group as a whole or when stratified by pathological subtype. Using an intraoperatively tailored strategy, individuals with a larger hippocampal resection (> 2.5 cm) were not more likely to have seizure-free outcomes than patients with smaller resections (p = 0.9). Additionally, both MTS and non-MTS patients, in whom postoperative ECoG detected residual epileptiform hippocampal (but not cortical or parahippocampal) interictal activity following surgical resection, had significantly worse seizure outcomes (p = 0.01 in the MTS group; p = 0.002 in the non-MTS group).

Conclusions. Intraoperative hippocampal ECoG can predict how much hippocampus should be removed to maximize seizure-free outcome, allowing for sparing of possibly functionally important hippocampus.

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Robert A. McGovern, John P. Sheehy, Brad E. Zacharia, Andrew K. Chan, Blair Ford and Guy M. McKhann II

Object

Early work on deep brain stimulation (DBS) surgery, when procedures were mostly carried out in a small number of high-volume centers, demonstrated a relationship between surgical volume and procedural safety. However, over the past decade, DBS has become more widely available in the community rather than solely at academic medical centers. The authors examined the Nationwide Inpatient Sample (NIS) to study the safety of DBS surgery for Parkinson disease (PD) in association with this change in practice patterns.

Methods

The NIS is a stratified sample of 20% of all patient discharges from nonfederal hospitals in the United States. The authors identified patients with a primary diagnosis of PD (332.0) and a primary procedure code for implantation/replacement of intracranial neurostimulator leads (02.93) who underwent surgery between 2002 and 2009. They analyzed outcomes using univariate and hierarchical, logistic regression analyses.

Results

The total number of DBS cases remained stable from 2002 through 2009. Despite older and sicker patients undergoing DBS, procedural safety (rates of non-home discharges, complications) remained stable. Patients at low-volume hospitals were virtually indistinguishable from those at high-volume hospitals, except that patients at low-volume hospitals had slightly higher comorbidity scores (0.90 vs 0.75, p < 0.01). Complications, non-home discharges, length of hospital stay, and mortality rates did not significantly differ between low- and high-volume hospitals when accounting for hospital-related variables (caseload, teaching status, location).

Conclusions

Prior investigations have demonstrated a robust volume-outcome relationship for a variety of surgical procedures. However, the present study supports safety of DBS at smaller-volume centers. Prospective studies are required to determine whether low-volume centers and higher-volume centers have similar DBS efficacy, a critical factor in determining whether DBS is comparable between centers.

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Evan F. Joiner, Brett E. Youngerman, Taylor S. Hudson, Jingyan Yang, Mary R. Welch, Guy M. McKhann II, Alfred I. Neugut and Jeffrey N. Bruce

OBJECTIVE

The purpose of this meta-analysis was to evaluate the impact of perioperative antiepileptic drug (AED) prophylaxis on short- and long-term seizure incidence among patients undergoing brain tumor surgery. It is the first meta-analysis to focus exclusively on perioperative AED prophylaxis among patients undergoing brain tumor surgery.

METHODS

The authors searched PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials, clinicaltrials.gov, and the System for Information on Gray Literature in Europe for records related to perioperative AED prophylaxis for patients with brain tumors. Risk of bias in the included studies was assessed using the Cochrane risk of bias tool. Incidence rates for early seizures (within the first postoperative week) and total seizures were estimated based on data from randomized controlled trials. A Mantel-Haenszel random-effects model was used to analyze pooled relative risk (RR) of early seizures (within the first postoperative week) and total seizures associated with perioperative AED prophylaxis versus control.

RESULTS

Four RCTs involving 352 patients met the criteria of inclusion. The results demonstrated that perioperative AED prophylaxis for patients undergoing brain tumor surgery provides a statistically significant reduction in risk of early postoperative seizures compared with control (RR = 0.352, 95% confidence interval 0.130–0.949, p = 0.039). AED prophylaxis had no statistically significant effect on the total (combined short- and long-term) incidence of seizures.

CONCLUSIONS

This meta-analysis demonstrates for the first time that perioperative AED prophylaxis for brain tumor surgery provides a statistically significant reduction in early postoperative seizure risk.