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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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H. Isaac Chen, Leif-Erik Bohman, Laurie A. Loevner and Timothy H. Lucas

Object

Resection of the hippocampus is the standard of care for medically intractable epilepsy in patients with mesial temporal sclerosis. Although temporal craniotomy in this setting is highly successful, the procedure carries certain immutable risks and may be associated with cognitive deficits related to cortical and white matter disruption. Alternative surgical approaches may reduce some of these risks by preserving the lateral temporal lobe. This study examined the feasibility of transorbital endoscopic amygdalohippocampectomy (TEA) as an alternative to open craniotomy in cadaveric specimens.

Methods

TEA dissections were performed in 4 hemispheres from 2 injected cadaveric specimens fixed in alcohol. Quantitative predictions of the limits of exposure based on predissection imaging were compared with intradissection measurements. The extent of resection and angles of exposure during the dissection and on postdissection imaging were recorded. These measurements were validated with MRI studies from 10 epilepsy patients undergoing standard surgical evaluations.

Results

The transorbital approach permitted direct access to the mesial temporal structures through the lateral orbital wall. Up to 97% of the hippocampal formation was resected with no brain retraction and minimal (mean 6.0 ± 1.4 mm) globe displacement. Lateral temporal lobe white matter tracts were preserved.

Conclusions

TEA permits hippocampectomy comparable to standard surgical approaches without disrupting the lateral temporal cortex or white matter. This novel approach is feasible in cadaveric specimens and warrants clinical investigation in carefully selected cases.

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Kalil G. Abdullah, Mark A. Attiah, Andrew S. Olsen, Andrew Richardson and Timothy H. Lucas

OBJECT

Although the use of topical vancomycin has been shown to be safe and effective for reducing postoperative infection rates in patients after spine surgery, its use in cranial wounds has not been studied systematically. The authors hypothesized that topical vancomycin, applied in powder form directly to the subgaleal space during closure, would reduce cranial wound infection rates.

METHODS

A cohort of 150 consecutive patients who underwent craniotomy was studied retrospectively. Seventy-five patients received 1 g of vancomycin powder applied in the subgaleal space at the time of closure. This group was compared with 75 matched-control patients who were accrued over the same time interval and did not receive vancomycin. The primary outcome measure was the presence of surgical site infection within 3 months. Secondary outcome measures included tissue pH from a subgaleal drain and vancomycin levels from the subgaleal space and serum.

RESULTS

Vancomycin was associated with significantly fewer surgical site infections (1 of 75) than was standard antibiotic prophylaxis alone (5 of 75; p < 0.05). Cultures were positive for typical skin flora species. As expected, local measured vancomycin concentrations peaked immediately after surgery (mean ± SD 499 ± 37 μg/ml) and gradually decreased over 12 hours. Vancomycin in the circulating serum remained undetectable. Subgaleal topical vancomycin was associated with a lower incidence of surgical site infections after craniotomy. The authors attribute this reduction in the infection rate to local vancomycin concentrations well above the minimum inhibitory concentration for antimicrobial efficacy.

CONCLUSIONS

Topical vancomycin is safe and effective for reducing surgical site infections after craniotomy. These data support the need for a prospective randomized examination of topical vancomycin in the setting of cranial surgery.

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Jared M. Pisapia, Nikhil R. Nayak, Ryan D. Salinas, Luke Macyszyn, John Y. K. Lee, Timothy H. Lucas, Neil R. Malhotra, H. Isaac Chen and James M. Schuster

OBJECTIVE

As odontoid process fractures become increasingly common in the aging population, a technical understanding of treatment approaches is critical. 3D image guidance can improve the safety of posterior cervical hardware placement, but few studies have explored its utility in anterior approaches. The authors present in a stepwise fashion the technique of odontoid screw placement using the Medtronic O-arm navigation system and describe their initial institutional experience with this surgical approach.

METHODS

The authors retrospectively reviewed all cases of anterior odontoid screw fixation for Type II fractures at an academic medical center between 2006 and 2015. Patients were identified from a prospectively collected institutional database of patients who had suffered spine trauma. A standardized protocol for navigated odontoid screw placement was generated from the collective experience at the authors' institution. Secondarily, the authors compared collected variables, including presenting symptoms, injury mechanism, surgical complications, blood loss, operative time, radiographically demonstrated nonunion rate, and clinical outcome at most recent follow-up, between navigated and nonnavigated cases.

RESULTS

Ten patients (three female; mean age 61) underwent odontoid screw placement. Most patients presented with neck pain without a neurological deficit after a fall. O-arm navigation was used in 8 patients. An acute neck hematoma and screw retraction, each requiring surgery, occurred in 2 patients in whom navigation was used. Partial vocal cord paralysis occurred after surgery in one patient in whom no navigation was used. There was no difference in blood loss or operative time with or without navigation. One patient from each group had radiographic nonunion. No patient reported a worsening of symptoms at follow-up (mean duration 9 months).

CONCLUSIONS

The authors provide a detailed step-by-step guide to the navigated placement of an odontoid screw. Their surgical experience suggests that O-arm–assisted odontoid screw fixation is a viable approach. Future studies will be needed to rigorously compare the accuracy and efficiency of navigated versus nonnavigated odontoid screw placement.

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Ian F. Caplan, Gregory Glauser, Stephen Goodrich, H. Isaac Chen, Timothy H. Lucas, John Y. K. Lee, Scott D. McClintock and Neil R. Malhotra

OBJECTIVE

Obstructive sleep apnea (OSA) is known to be associated with negative outcomes and is underdiagnosed. The STOP-Bang questionnaire is a screening tool for OSA that has been validated in both medical and surgical populations. Given that readmission after surgical intervention is an undesirable event, the authors sought to investigate, among patients not previously diagnosed with OSA, the capacity of the STOP-Bang questionnaire to predict 30-day readmissions following craniotomy for a supratentorial neoplasm.

METHODS

For patients undergoing craniotomy for treatment of a supratentorial neoplasm within a multiple-hospital academic medical center, data were captured in a prospective manner via the Neurosurgery Quality Improvement Initiative (NQII) EpiLog tool. Data were collected over a 1-year period for all supratentorial craniotomy cases. An additional criterion for study inclusion was that the patient was alive at 30 postoperative days. Statistical analysis consisted of simple logistic regression, which assessed the ability of the STOP-Bang questionnaire and additional variables to effectively predict outcomes such as 30-day readmission, 30-day emergency department (ED) visit, and 30-day reoperation. The C-statistic was used to represent the receiver operating characteristic (ROC) curve, which analyzes the discrimination of a variable or model.

RESULTS

Included in the sample were all admissions for supratentorial neoplasms treated with craniotomy (352 patients), 49.72% (n = 175) of which were female. The average STOP-Bang score was 1.91 ± 1.22 (range 0–7). A 1-unit higher STOP-Bang score accurately predicted 30-day readmissions (OR 1.31, p = 0.017) and 30-day ED visits (OR 1.36, p = 0.016) with fair accuracy as confirmed by the ROC curve (C-statistic 0.60–0.61). The STOP-Bang questionnaire did not correlate with 30-day reoperation (p = 0.805) or home discharge (p = 0.315).

CONCLUSIONS

The results of this study suggest that undiagnosed OSA, as assessed via the STOP-Bang questionnaire, is a significant predictor of patient health status and readmission risk in the brain tumor craniotomy population. Further investigations should be undertaken to apply this prediction tool in order to enhance postoperative patient care to reduce the need for unplanned readmissions.