Masayuki Sasoh

Effects of EC-IC bypass surgery on cognitive impairment in patients with hemodynamic cerebral ischemia

BACKGROUND Chronic ischemia because of internal carotid artery (ICA) occlusive disease may result in dementia. The goal of this study was to assess cognitive impairment in symptomatic patients with hemodynamic cerebral ischemia and determine the efficacy of extracranial-intracranial (EC-IC) bypass in restoring neuropsychologic integrity. METHODS Twenty-five patients were defined by clinical and neuroradiological criteria as suffering from hemodynamic cerebral ischemia because of unilateral ICA or middle cerebral artery occlusion. Subjects underwent assessment of cerebral blood flow and metabolism using positron emission tomography (PET) before and after bypass surgery. To provide data regarding cognition, changes in the Japanese Wechsler Adult Intelligence Scale Revised (WAIS-R) were recorded. RESULTS Preoperative study of patients revealed significant impairment in cerebral blood flow and metabolism as well as reduced WAIS-R score. Among the factors considered, only elevated regional oxygen extraction fraction and reduced regional cerebral metabolic rates of oxygen were significantly associated with preoperative cognitive impairment (p = 0.0032 and p = 0.0255, respectively; logistic regression analysis). After bypass surgery, cerebral blood flow and metabolism improved significantly, and the WAIS-R score increased. CONCLUSIONS Symptomatic patients with hemodynamic cerebral ischemia displayed impaired cognition that was partially alleviated with EC-IC bypass surgery.

Exposure of the vertebrobasilar artery junction with traction of the dentate ligament for the treatment of large vertebral artery aneurysms

A technique for exposing the vertebrobasilar junction with traction of the dentate ligament is described for treatment of large vertebral artery (VA) aneurysms via the far lateral suboccipital approach with partial condylar resection. The most rostral attachment of the dentate ligament is divided above the site where the VA pierces the dura mater. A traction suture is placed into the dentate ligament and gently retracted using mosquito forceps. As a result, the medulla oblongata is lifted dorsally and slightly rotated by the divided and retracted dentate ligament, allowing an approach from a more superior or inferior direction. The present technique is useful for the treatment of large thrombosed VA aneurysms.