Intravenous magnesium sulfate administration in a patient with refractory vasospasm following subarachnoid hemorrhage

OBJECTIVE: Magnesium sulfate is being investigated for the prevention or treatment of vasospasm following subarachnoid hemorrhage. PATIENT: A 45-year-old woman suffered subarachnoid hemorrhage and developed after 8 days symptomatic vasospasm in the left middle cerebral artery (MCA) while she was receiving nimodipine prophylactically. METHODS AND RESULTS: Transcranial Doppler monitoring was performed. Cerebral autoregulation was abolished in the left MCA. Despite this finding the administration of a bolus dose of MgSO(4), followed by a continuous infusion in order to achieve serum magnesium levels in the range of 4-4.5 mg/dl (1.65-1.85 mmol/l), resulted in a marked decrease (12.2%) of the left MCA mean blood flow velocity, without clinically relevant change in systemic blood pressure (3%). This effect was maintained for at least 4 h. It did not prevent the development of ischemic lesions.