Michael J. Harrison

BACKGROUND AND PURPOSE: Microemboli have been implicated in the etiology of neuropsychological deficits after cardiopulmonary bypass. This study examined the incidence of high-intensity transcranial signals (microemboli) and their relation to changes in neuropsychological performance after surgery. METHODS: Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood flow velocity and detect microemboli. The number of high-intensity transcranial signals was determined and related to a neurological examination and absolute changes in neuropsychological performance as well as the number of patients considered to exhibit a neuropsychological deficit. Data were available on 100 consenting patients undergoing routine cardiopulmonary bypass. Fifty of the patients were randomly assigned to a procedure that included a 40-microns arterial line filter, and 50 had the procedure without any arterial line filter. RESULTS: Significantly more patients were found to have neuropsychological deficits in the group without the arterial line filter at both 8 days (P < .05) and 8 weeks (P < .03) after surgery. In addition, more "soft" neurological signs were found in the nonfiltered group 24 hours after surgery (P < .05). More high-intensity transcranial signals were found in the nonfiltered group, and the number of high-intensity transcranial signals was found to be related to the likelihood of a patient having a neuropsychological deficit at 8 weeks. CONCLUSIONS: These data suggest that neuropsychological deficits after routine cardiopulmonary bypass are related to the number of microemboli delivered during surgery. Furthermore, the numbers of microemboli may be reduced by including a 40-microns filter on the arterial line.

BACKGROUND AND PURPOSE: Neuropsychological impairment may follow coronary artery bypass surgery as a result of peroperative cerebral microembolism. The hypothesis that remacemide, an NMDA receptor antagonist, would provide protection against such ischemic damage has been tested in a randomized trial. METHODS: One hundred seventy-one patients undergoing coronary artery bypass surgery by a single cardiothoracic surgical team were randomized to receive remacemide (up to 150 mg every 6 hours) or placebo from 4 days before to 5 days after their bypass procedure. Peroperative monitoring included an estimate of the number of microembolic events detected by transcranial Doppler ultrasonography of the middle cerebral artery. A battery of 9 neuropsychological tests was administered before and 8 weeks after surgery. RESULTS: The proportion of patients showing a decline in performance of 1 SD or more in 2 or more tests was reduced in the treated group (9% versus 12%), but this was not statistically significant. On the other hand, overall postoperative change (reflecting learning ability in addition to reduced deficits) was more favorable in the remacemide group, which demonstrated significantly greater improvement in a global z score (P=0.028) and changes in 3 individual tests (P<0.05). The 2 patient groups were well matched, including for the burden of microembolic events. CONCLUSIONS: This is the first study to show statistically significant drug-based neuroprotection during cardiac surgery. In addition to offering improvement in cerebral outcome for such at-risk patients, it supports the hypothesis that drugs acting on the excitotoxic mechanism of ischemic cerebral damage can be effective in humans.

Ten cases of symptomatic cavernous malformations affecting the spine and spinal cord were retrospectively reviewed. The cases display a spectrum of pathological findings involving the vertebral body, vertebral body with epidural extension, epidural space without bony involvement, intradural extramedullary space, and intramedullary lesions. Lesions at all locations are identical histologically, electron microscopically, and immunohistochemically. This perspective, in which cavernous malformations are envisioned as a single entity arising at numerous locations, runs contrary to the view found in the neurosurgical literature. In most discussions of cavernous malformations, vertebral body lesions are depicted as separate entities from intradural lesions. Cavernous malformations, also called cavernous hemangiomas, are developmental vascular hamartomas that, by definition, do not grow by mitotic activity. Yet, the expansion of these lesions is well documented both in the literature and among our cases. The therapeutic modalities used in our series included observation, embolization, radiation, and surgical resection alone or in combination. All modalities are effective but must be tailored to the specific needs and condition of the patient. The embryology, methods of treatment, and proposed mechanisms of growth, plus similarities and differences between cavernous malformations at each location, are reviewed. Analogies between spinal and intracranial lesions are presented. On the basis of this series and a review of the literature, we conclude that cavernous malformations represent a single entity regardless of location. Segregation based on location, as is prevalent throughout the neurosurgical literature, hinders an overall understanding of these lesions. Cavernous malformations are more appropriately viewed as a single pathological entity arising in a multitude of locations. The difficulties encountered when managing cavernous malformations at various locations are unique to the location and not the lesion.

A longitudinal study of cognitive function after coronary artery bypass surgery examined 107 participants using 11 tests, preoperatively and at 6 days, 8 weeks, and 5 years after surgery. The overall neuropsychological (NP) change score declined at 6 days, showed some recovery at 8 weeks, and declined again at 5 years. The number of microemboli recorded during surgery, postoperative short-term cognitive change, and degree of recovery at 8 weeks were identified as predictors of change in NP score to 5 years. This suggests that even over a 5-year period, operative damage is detectable. Patients' vulnerability to short-term deterioration and resilience or ability to recover over a few weeks from operative cerebral insult are important processes of unknown mechanisms.