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Abdullah Bin Zahid, David Balser, Rebekah Thomas, Margaret Y. Mahan, Molly E. Hubbard, and Uzma Samadani

OBJECTIVE

Chronic subdural hematoma (cSDH) is a highly morbid condition associated with brain atrophy in the elderly. It has a reported 30% 1-year mortality rate. Approximately half of afflicted individuals report either no or relatively unremarkable trauma preceding their diagnosis, raising the possibility that cSDH is a manifestation of degenerative or inflammatory disease rather than trauma. The purpose of this study was to compare the rates of cerebral atrophy before and after cSDH to determine whether it is more likely that cSDH causes atrophy or that atrophy causes cSDH. The authors also compared atrophy rates in patients with cSDH to the rates in patients with and without dementia.

METHODS

The authors developed algorithmic segmentation analysis software to measure whole-brain, CSF, and intracranial space volumes. They then identified military veterans who had undergone at least 4 brain CT scans over a period of 10 years. Within this database, the authors identified 146 patients with 962 head CT scans who had received diagnoses of either cSDH, dementia, or no known dementia condition. Volumetric analyses of brains in 45 patients with dementia (dementia group) and 73 patients without dementia (nondementia group), in whom 262 and 519 head CT scans were obtained, respectively, were compared with 11 patients in whom 81 CT scans were obtained a mean of 4.21 years before a cSDH diagnosis and 17 patients in whom 100 scans were obtained a mean of 4.24 years after SDH. Longitudinal measures were then related to disease status and the time since first scan by using hierarchical models, and atrophy rates between the groups were compared.

RESULTS

Head CT scans from patients were obtained for an average time period of 4.21 years (SD 1.69) starting at a mean patient age of 74 years. Absolute brain volume loss for the 17 patients in the post-SDH group (13 were treated surgically) was significantly greater, at 16.32 ml/year, compared with 6.61 ml/year in patients with dementia, 5.33 ml/year in patients without dementia, and 3.57 ml/year in pre-SDH patients. The atrophy rate for these individuals prior to enrollment in the study was 2.32 ml/year (p = 0.001). In terms of brain volume normalized to cranial cavity size, the post-SDH group had an atrophy rate of 0.7801%/year, compared with 0.4467%/year in patients with dementia, 0.3474%/year in patients without dementia, and 0.2135%/year in the pre-SDH group.

CONCLUSIONS

Prior to development of a cSDH, the atrophy rates in patients who ultimately develop cSDH are similar to those of patients without dementia. After development of a cSDH, the atrophy rates increase to more than twice those of patients with dementia. Chronic subdural hematoma is thus associated with a significant increase in brain atrophy rate. These findings suggest the neurotoxic consequences of cSDH and may have implications for better understanding of the pathophysiology of cerebral atrophy and dementia.

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David Balser, Sameer Farooq, Talha Mehmood, Marleen Reyes, and Uzma Samadani

OBJECT

Chronic subdural hematomas (SDHs) are more common among veterans and elderly persons than among members of the general population; however, precise incidence rates are unknown. The purposes of this study were 1) to determine the current incidence of chronic SDH in a US Veterans Administration (VA) population and 2) to create a mathematical model for determining the current and future incidence of chronic SDH as a function of population age, sex, and comorbidity in the United States VA and civilian populations.

METHODS

To determine the actual number of veterans who received a radiographic diagnosis and surgical treatment for SDH during 2000–2012, the authors used the VISN03 VA database. On the basis of this result and data from outside the United States, they then created a mathematical model accounting for age, sex, and alcohol consumption to predict the incidence of SDH in the VA and civilian populations during 2012–2040.

RESULTS

Of 875,842 unique (different patient) visits to a VA hospital during the study period, 695 new SDHs were identified on CT images. Of these 695 SDHs, 203 (29%) required surgical drainage. The incidence rate was 79.4 SDHs per 100,000 persons, and the age-standardized rate was 39.1 ± 4.74 SDHs per 100,000 persons. The authors' model predicts that incidence rates of chronic SDH in aging United States VA and civilian populations will reach 121.4 and 17.4 cases per 100,000 persons, respectively, by 2030, at which time, approximately 60,000 cases of chronic SDH will occur each year in the United States.

CONCLUSIONS

The incidence of chronic SDH is rising; SDH is projected to become the most common cranial neurosurgical condition among adults by the year 2030.

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Gabrielle Lynch, Karina Nieto, Saumya Puthenveettil, Marleen Reyes, Michael Jureller, Jason H. Huang, M. Sean Grady, Odette A. Harris, Aruna Ganju, Isabelle M. Germano, Julie G. Pilitsis, Susan C. Pannullo, Deborah L. Benzil, Aviva Abosch, Sarah J. Fouke, and Uzma Samadani

OBJECT

The objective of this study is to determine neurosurgery residency attrition rates by sex of matched applicant and by type and rank of medical school attended.

METHODS

The study follows a cohort of 1361 individuals who matched into a neurosurgery residency program through the SF Match Fellowship and Residency Matching Service from 1990 to 1999. The main outcome measure was achievement of board certification as documented in the American Board of Neurological Surgery Directory of Diplomats. A secondary outcome measure was documentation of practicing medicine as verified by the American Medical Association DoctorFinder and National Provider Identifier websites. Overall, 10.7% (n = 146) of these individuals were women. Twenty percent (n = 266) graduated from a top 10 medical school (24% of women [35/146] and 19% of men [232/1215], p = 0.19). Forty-five percent (n = 618) were graduates of a public medical school, 50% (n = 680) of a private medical school, and 5% (n = 63) of an international medical school. At the end of the study, 0.2% of subjects (n = 3) were deceased and 0.3% (n = 4) were lost to follow-up.

RESULTS

The total residency completion rate was 86.0% (n = 1171) overall, with 76.0% (n = 111/146) of women and 87.2% (n = 1059/1215) of men completing residency. Board certification was obtained by 79.4% (n = 1081) of all individuals matching into residency between 1990 and 1999. Overall, 63.0% (92/146) of women and 81.3% (989/1215) of men were board certified. Women were found to be significantly more at risk (p < 0.005) of not completing residency or becoming board certified than men. Public medical school alumni had significantly higher board certification rates than private and international alumni (82.2% for public [508/618]; 77.1% for private [524/680]; 77.8% for international [49/63]; p < 0.05). There was no significant difference in attrition for graduates of top 10–ranked institutions versus other institutions. There was no difference in number of years to achieve neurosurgical board certification for men versus women.

CONCLUSIONS

Overall, neurosurgery training attrition rates are low. Women have had greater attrition than men during and after neurosurgery residency training. International and private medical school alumni had higher attrition than public medical school alumni.

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Veit Rohde and Uzma Samadani

Object

Currently no adequate surgical treatment exists for spontaneous intracerebral hemorrhage (ICH). Implantable polymers can be used effectively to deliver therapeutic agents to the local site of the pathological process, thus reducing adverse systemic effects. The authors report the use of stereotactically implanted polymers loaded with tissue plasminogen activator (tPA) to induce lysis of ICH in a rabbit model.

Methods

Ethylene vinyl acetate (EVAc) polymers were loaded with bovine serum albumin (BSA) only or with BSA plus tPA. In vitro pharmacokinetic (three polymers) and thrombolysis (12 polymers) studies were performed. For the in vivo study, 12 rabbits were fixed in a stereotactic frame, and 0.2 ml of clotted autologous blood was injected into the right frontal lobe parenchyma. After 20 minutes, control BSA polymers were stereotactically implanted at the hemorrhage site in six rabbits, and experimental BSA plus tPA polymers were implanted in six rabbits. Animals were killed at 3 days, and blood clot volume was assessed.

The pharmacokinetic study showed release of 146 ng of tPA over 3 days. The tPA activity correlated with in vitro thrombolysis. In the in vivo study, the six animals treated with tPA polymers had a mean (±standard error of the mean [SEM]) thrombus volume of 1.43 ±0.29 mm3 at 3 days, whereas the six animals treated with blank (BSA-only) polymers had a mean (±SEM) thrombus volume of 19.99 ±3.74 mm3 (p <0.001).

Conclusions

Ethylene vinyl acetate polymers release tPA over the course of 3 days. Stereotactic implantation of tPA-loaded EVAc polymers significantly reduced ICH volume. Polymers loaded with tPA may be useful clinically for lysis of ICH without the side effects of systemic administration of tPA.

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Uzma Samadani, Atsushi Umemura, Jurg L. Jaggi, Amy Colcher, Eric L. Zager, and Gordon H. Baltuch

✓ Thalamic deep brain stimulation (DBS) has been demonstrated to be effective for the treatment of parkinsonian or essential tremor. To date, however, few data exist to support the application of this method to treat midbrain tremor.

A 24-year-old right-handed man underwent radiosurgery and subsequent resection of a recurrently hemorrhaging cavernous angioma located in the left side of the midbrain. The surgery exacerbated severe choreoathetotic resting and action tremors of his right extremities and trunk. The patient underwent placement of a deep brain stimulator into the left ventral intermediate nucleus of the thalamus (Vim). Postoperatively, decreased truncal ataxia and right-sided choreoathetotic tremor were demonstrated, with a 57% increase in dexterity as measured by task testing.

The authors demonstrate that DBS can be an effective treatment modality for disabling tremor after resection of a midbrain cavernous angioma.