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✓ The boundaries of somatosensory cortex were localized noninvasively by means of a large-array biomagnetometer in six patients with mass lesions in or near eloquent cortex. The results were used by neurosurgeons and neurologists in preoperative planning and for reference in the operating room. The magnetic source imaging (MSI) localizations from somatosensory evoked potentials were used to predict the pattern of phase reversals measurable intraoperatively on the cortical surface, providing a quantitative comparison between the two measures. The magnetic localizations were found to be predictive in all six cases, with the two sets of localizations falling within an 8-mm distance on average. Somatosensory localizations using MSI offer accuracy in localizing somatosensory cortex stereotactically and in depicting its relationship to lesions. Such data are valuable preoperatively in assessing the risks associated with a proposed surgical procedure and for optimizing subsequent minimum-risk surgical strategy.

✓ Thirteen patients with recurrent hemorrhages from angiographically occult vascular malformations are presented. Recurrent hemorrhages were indicated by the exacerbation of neurological deficits, the appearance of a new neurological deficit, or the onset of acute severe headache confirmed by evidence of recent hemorrhage on either computerized tomography or magnetic resonance imaging. Persistent neurological deficits correlated with an increased number of recurrent hemorrhages and their location. The median time from initial hemorrhage to the first recurrent hemorrhage was 12 months and the second rebleed generally occurred much earlier, with a median time of 2 months after the first. Eight patients underwent surgery with total excision and favorable results. One patient with a large pontine lesion underwent partial excision and has had a progressing neurological deficit from recurrent hemorrhages. Histopathological review confirmed the excised lesions to be cavernous angiomas. The authors conclude that angiographically occult vascular malformations are not the benign entity they were previously thought to be, and that they are prone to cause recurrent hemorrhages and persistent neurological deficits. Surgery can be effective and relatively safe in removing these lesions even in eloquent areas of the brain, but the necessity of occasional incomplete removal must be recognized in order to avoid creating an unacceptable neurological outcome.