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Paul L. Penar, Jung Kim, Douglas Chyatte, and James K. Sabshin

✓ Infection by Cryptococcus neoformans, a budding nonmycelial yeast, involves the central nervous system in 70% of patients at the time of diagnosis. Meningitis and meningoencephalitis are common manifestations of infection; solid granulomas occur but are unusual, and intraventricular granulomas are distinctly rare. Two cases of intraventricular cryptococcal granuloma are reported. The diagnosis and treatment of mass lesions due to cryptococcal infection are discussed, with special reference to intraventricular granulomas.

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Anand I. Rughani, Chih Lin, Travis M. Dumont, Paul L. Penar, Michael A. Horgan, and Bruce I. Tranmer

Object

The Subdural Evacuating Port System (SEPS) was recently introduced as a novel method of treating chronic subdural hematomas (SDHs). This system is a variation of the existing twist-drill craniostomy methods for treating chronic SDH. Compared with craniotomy or bur hole treatment of chronic SDH, this system offers the possibility of treatment at bedside without general anesthesia. In comparison with existing twist-drill methods, the system theoretically offers the advantage of a hermetically closed system that can evacuate a hematoma without an intracranial catheter.

Methods

The authors performed a case-control study of all chronic SDHs treated at a single institution over a 5-year period and compared the efficacy and safety of the SEPS to bur hole evacuation. Patients were matched for age, injury mechanism, medical comorbidities, use of anticoagulation, and radiographic appearance of the SDH. The primary outcome of interest was the recurrence rate in each group, which was evaluated by radiographic evidence as well as the number of patients requiring a second procedure. Secondary outcomes examined were mortality, infection, acute hematoma formation, seizure, length of hospital stay, length of intensive care unit stay, and discharge location.

Results

The authors found that there were no appreciable differences in symptoms on presentation, existing comorbidities, home medications, or laboratory values between the treatment groups. The average Hounsfield units of preoperative CT scanning was similar in both groups. Radiographic recurrence was statistically similar between the SEPS group (25.9%) and the bur hole group (18.5%; p = 0.37). Although there was a trend toward higher reoperation rates in the SEPS group, the need for a subsequent procedure was also statistically similar between the SEPS group (25.9%) and the bur hole group (14.8%; p = 0.25). The mortality rate was not significantly different between the SEPS group (9.5%) and the bur hole group (4.8%; p = 0.50). The SEPS procedure provided a mean reduction in SDH thickness of 27.3% compared with 37.9% with bur hole (p = 0.05) when comparing the preoperative CT scan with the first postoperative CT scan. The percentage of reduction in SDH thickness when comparing the preoperative CT scan with the most recent postoperative CT scan was 40.5% in the SEPS group and 45.4% in the bur hole group (p = 0.31).

Conclusions

The SEPS offers an alternative type of twist-drill craniostomy for the treatment of chronic SDH with a trend toward higher recurrence in our experience. The efficacy and safety of SEPS is similar to that of other twist-drill methods reported in the literature. In the authors' experience, the efficacy of this treatment as measured by radiographic worsening or the need for a subsequent procedure is statistically similar to that of bur hole treatment. There was no difference in mortality or other adverse outcomes associated with SEPS.

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Anand I. Rughani, Travis M. Dumont, Zhenyu Lu, Josh Bongard, Michael A. Horgan, Paul L. Penar, and Bruce I. Tranmer

Object

The authors describe the artificial neural network (ANN) as an innovative and powerful modeling tool that can be increasingly applied to develop predictive models in neurosurgery. They aimed to demonstrate the utility of an ANN in predicting survival following traumatic brain injury and compare its predictive ability with that of regression models and clinicians.

Methods

The authors designed an ANN to predict in-hospital survival following traumatic brain injury. The model was generated with 11 clinical inputs and a single output. Using a subset of the National Trauma Database, the authors “trained” the model to predict outcome by providing the model with patients for whom 11 clinical inputs were paired with known outcomes, which allowed the ANN to “learn” the relevant relationships that predict outcome. The model was tested against actual outcomes in a novel subset of 100 patients derived from the same database. For comparison with traditional forms of modeling, 2 regression models were developed using the same training set and were evaluated on the same testing set. Lastly, the authors used the same 100-patient testing set to evaluate 5 neurosurgery residents and 4 neurosurgery staff physicians on their ability to predict survival on the basis of the same 11 data points that were provided to the ANN. The ANN was compared with the clinicians and the regression models in terms of accuracy, sensitivity, specificity, and discrimination.

Results

Compared with regression models, the ANN was more accurate (p < 0.001), more sensitive (p < 0.001), as specific (p = 0.260), and more discriminating (p < 0.001). There was no difference between the neurosurgery residents and staff physicians, and all clinicians were pooled to compare with the 5 best neural networks. The ANNs were more accurate (p < 0.0001), more sensitive (p < 0.0001), as specific (p = 0.743), and more discriminating (p < 0.0001) than the clinicians.

Conclusions

When given the same limited clinical information, the ANN significantly outperformed regression models and clinicians on multiple performance measures. While this paradigm certainly does not adequately reflect a real clinical scenario, this form of modeling could ultimately serve as a useful clinical decision support tool. As the model evolves to include more complex clinical variables, the performance gap over clinicians and logistic regression models will persist or, ideally, further increase.

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Travis M. Dumont, Anand I. Rughani, Paul L. Penar, Michael A. Horgan, Bruce I. Tranmer, and Ryan P. Jewell

Object

The Accreditation Council for Graduate Medical Education instituted mandatory 80-hour work-week limitations in July 2003. The work-hour restriction was met with skepticism among the academic neurosurgery community and is thought to represent a barrier to teaching, ultimately compromising patient care. The authors hypothesize that the introduction of the mandatory resident work-hour restriction corresponds with an overall increase in morbidity rate.

Methods

This study compares the morbidity and mortality rates on an academic neurological surgery service before and after institution of the work-hour restriction. Complications are individually assessed at a monthly divisional conference by neurosurgical faculty and residents. A prospective database was commenced in July 2000 recording all complications, complications that were deemed to be potentially avoidable (“possibly preventable”), and complications that were deemed unavoidable. The incidence of morbidity and mortality from July 2000 to June 2003 is compared with the incidence from July 2003 to June 2006.

Results

The overall rate of morbidity and mortality increased from 103 to 114 per 1000 patients treated after institution of the work-hour restriction, although this increase was not statistically significant (χ2 1, N = 8546 = 2.6, p = 0.106). The morbidity rate increased from 70 to 89 per 1000 patients treated after institution of the work-hour restriction (χ2 1, N = 8546 = 10, p = 0.001). The overall mortality rate was diminished from 32 to 27 per 1000 patients treated after institution of the work-hour restriction (χ2 1, N = 8546 = 3.2, p = 0.075). Morbidities considered avoidable or possibly preventable were seen to increase from 56 to 66 per 1000 patients treated (χ2 1, N = 8546 = 5.7, p = 0.017). Avoidable or possibly preventable mortalities numbered 3 per 1000 patients treated, and this rate did not change after introduction of the work-hour restriction (χ2 1, N = 8546 = 0.08, p = 0.777).

Conclusions

The morbidity rate on a neurological surgery service is increased after implementation of the work-hour restriction. Mortality rates remain unchanged.

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Vijay Thadani, Paul L. Penar, Jonathan Partington, Robert Kalb, Robert Janssen, Lawrence B. Schonberger, Charles S. Rabkin, and James W. Prichard

✓ A case of Creutzfeldt-Jakob disease (CJD) is reported in a 28-year-old woman who had received a cadaveric dural graft 19 months earlier after resection of a cholesteatoma. The circumstances of the case point to the graft as the most likely source of the disease. Cadaveric dura should be added to the list of materials that may transmit CJD, and it must be very carefully screened if it is used at all for grafting. Autologous tissue should be considered whenever possible.

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Sami Khoshyomn, Steven P. Braff, Melissa A. McKenzie, Jeffrey E. Florman, William W. Pendlebury, and Paul L. Penar