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William T. Couldwell

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William T. Couldwell

A 49-year-old man presented with headache and cognitive difficulty. MRI demonstrated a meningioma in the falcotentorial region with compression of the internal cerebral veins, basal veins of Rosenthal, and vein of Galen. It was a removed via a left-sided occipital interhemispheric approach, performed with the patient in the lateral position. After tumor debulking and removal of its attachment to the tentorium and anterior falx, the tumor was resected. All venous structures were preserved. The video demonstrates the technical nuances and strategy for removal of tumors in a region with complicated venous anatomy that must be preserved.

The video can be found here: https://youtu.be/wKqAn3dYu4E.

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William T. Couldwell

This video demonstrates stereotactic-guided resection of a ruptured diffuse left temporal arteriovenous malformation (AVM) in an adolescent male who presented with headache and speech difficulties. The diffuse nidus of the AVM, 25 mm in size, was located in the posterior superior temporal gyrus, with drainage into the sylvian veins (Spetzler-Martin Grade II). The AVM was located stereotactically, and resection was performed through a small corticectomy. The clot cavity was evacuated. Feeding branches to the AVM were identified during careful dissection, and parent M1 and M2 branches were preserved. The patient recovered well, with no residual speech deficit. Postoperative angiogram demonstrated complete AVM removal.

The video can be found here: https://youtu.be/Sttc86H8jCw.

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William T. Couldwell

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William T. Couldwell

Background

Good cardiorespiratory fitness has been associated with reduced risk for clinical events of atherosclerotic vascular diseases, but whether it is related to slower progression of early atherosclerosis is unclear. Objective: To study the association between cardiorespiratory fitness and the progression of early carotid atherosclerosis. Design: 4-year follow-up study. Setting: Eastern Finland. Participants: Population-based sample of 854 men 42 to 60 years of age. Measurements: Maximal oxygen uptake (VO2max [L/kg per minute]) was measured directly by using respiratory gas exchange in a cycle ergometer exercise test. Carotid atherosclerosis was assessed by using B-mode ultrasonography. Results: After adjustments for age, technical covariates, and cigarette smoking, VO2max had strong, inverse, and graded associations with 4-year increases i maximal intima-media thickness (IMT) (standard regression coefficient β = 0.120; P = 0.002); plaque height (β = 0.140; P < 0.001), surface roughness, and mean IMT (β = 0.080; P = 0.035). These associations weakened but remained statistically significant after additional adjustment for systole blood pressure, serum levels of apolipoprotein B, diabetes, and plasma fibrinogen levels. The increases in maximal IMT, surface roughness, and mean 26.1 mL/kg per IMT (23%, 32% and 100%, respectively) were larger among men in the lowest quartile of VO2max (< minute) than among those in the highest quartile (> 36.2 ML/kg per minute). Conclusions: Good cardiorespiratory fitness is associated with slower progression of early atherosclerosis in middle-aged men. These findings are important because they emphasize that middle-aged men can be evaluated for cardiorespiratory fitness to estimate their future risk for atherosclerotic vascular disease. Additional research is warranted to investigate a possible causal relationship between cardiorespiratory fitness and atherosclerosis.

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William T. Couldwell

Background: The first-degree relatives of patients who have subarachnoid hemorrhage from ruptured intracranial aneurysms are themselves at risk for subarachnoid hemorrhage. We studied the benefits and risks of screening for aneurysms in the first-degree relatives of patients with sporadic subarachnoid hemorrhage. Methods: We screened 626 first-degree relatives (parents, siblings, or children) of 160 patients with sporadic subarachnoid hemorrhage, from a prospective series of 193 consecutive index patients. Magnetic resonance angiography was the screening tool, and conventional angiography was used as the reference test in subjects thought to have aneurysms. Six months after elective operation, outcome was assessed by means of the modified Rankin scale of neurologic function. This observational study design was combined with a decision-analysis model to estimate the effectiveness of screening. The efficiency of screening was defined by the number of relatives who needed to be screened in order to prevent one subarachnoid hemorrhage. Results: Aneurysms were found in 25 of 626 first-degree relatives (4.0 percent; 95 percent confidence interval, 2.6 to 5.8 percent). Eighteen underwent surgery, which resulted in a decrease in function in 11 (disabling in 1). Five had medium-sized aneurysms that were 5 to 11 mm in diameter, 11 had small aneurysms that were less than 5 mm, and 2 had both small and medium-sized aneurysms. On average, surgery increased estimated life expectancy by 2.5 years for these 18 subjects (or by 0.9 month per person screened), at the expense of 19 years of decreased function per person. The number of relatives who would need to be screened in order to prevent 1 subarachnoid hemorrhage on a lifetime basis was 149, and 298 would have to be screened in order to prevent 1 fatal subarachnoid hemorrhage. Conclusions: Implementation of a screening program for the first-degree relatives of patients with sporadic subarachnoid hemorrhage does not seem warranted at this time, since the resulting slight increase in life expectancy does not offset the risk of postoperative sequelae.

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William T. Couldwell

Knowledge or experience is voluntarily recalled from memory by reactivation of the neural representations in the cerebral association cortex. In inferior temporal cortex, which serves as the storehouse of visual long-term memory, activation of mnemonic engrams through electric stimulation results in imagery recall in humans, and neurons can be dynamically activated by the necessity for memory recall in monkeys. Neuropsychological studies and previous split-brain experiments predicted that prefrontal cortex exerts executive control upon inferior temporal cortex in memory retrieval; however, no neuronal correlate of this process has ever been detected. Here we show evidence of the top-down signal from prefrontal cortex. In the absence of bottom-up visual inputs, single inferior temporal neurons were activated by the top-down signal, which conveyed information on semantic categorization imposed by visual stimulus-stimulus association. Behavioural performance was severely impaired with loss of the top-down signal. Control experiments confirmed that the signal was transmitted not through a subcortical but through a fronto-temporal cortical pathway. Thus, feedback projections from prefrontal cortex to the posterior association cortex appear to serve the executive control of voluntary recall.

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William T. Couldwell

Symptomatic brain stem cavernous malformations often present the dilemma of choosing an approach for their resection. Superior midline midbrain lesions are in a particularly challenging location, as they are less accessible via traditional lateral or posterior approaches. The author presents a case of a young woman who presented with a symptomatic cavernous malformation with surface presentation to the floor of the third ventricle. The lesion was causing sensory symptoms from local mass effect and hydrocephalus from occlusion of the Aqueduct of Sylvius. An approach was chosen to both perform a third ventriculostomy and remove the cavernous malformation. Through a right frontal craniotomy, a transcallosal–transforaminal approach was used to perform a third ventriculostomy. Through the same callosal opening, a subchoroidal approach was performed to provide access the cavernous malformation. The details of the procedure and nuances of technique are described in the narration.

The video can be found here: http://youtu.be/zKKnehp7l2c.

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William T. Couldwell

The long-term consequences of adenovirus-mediated conditional cytotoxic gene therapy for gliomas remain uncharacterized. We report here detection of active brain inflammation 3 months after successful inhibition of syngeneic glioma growth. The inflammatory infiltrate consisted of activated macrophages/microglia and astrocytes, and T lymphocytes positive for leucosyalin, CD3 and CD8, and included secondary demyelination. We detected strong widespread herpes simplex virus 1 thymidine kinase immunoreactivity and vector genomes throughout large areas of the brain. Thus, patient evaluation and the design of clinical trials in ongoing and future gene therapy for brain glioblastoma must address not only tumor-killing efficiency, but also long-term active brain inflammation, loss of myelin fibers and persistent transgene expression.