Safety Study of Cervical Sympathetic Block for Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage

Inclusion Criteria: 1. High grade spontaneous SAH (Fisher Grade III and IV) 2. Secured aneurysm (clipped/coiled) 3. Evidence of severe vasospasm - MCA mean flow velocity \>200 cm/sec and Lindegaard ratio \>6 OR Symptomatic vasospasm with either angiographic evidence (no angioplasty), or at least moderate severity according to TCD criteria (MCA mean flow velocity \>150 cm/sec and Lindegaard ratio \>3, or ACA vasospasm) 4. Age ≥18 Exclusion Criteria: 1. Allergy to local anesthetic or contrast 2. Coagulation disorders with PT \<70%, or INR \>1.4, or PTT \>1.5 times control and/or platelets \<70,000x106/L 3. Use of enoxaparin within 12 hours 4. Use of clopidogrel within 7 days 5. Use of coumadin within 5 days 6. Use of ticlopidine within 14 days 7. Use of intravenous thrombolytics within 10 days 8. Any use of hirudin derivatives during ICU stay