Acetazolamide reactivity on cerebral blood flow in patients with subarachnoid haemorrhage.

Cerebral vasodilatory capacity was evaluated by acetazolamide-activated N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) single photon emission computed tomography (SPECT) in 42 patients with subarachnoid haemorrhage (SAH). A low perfusion area was present in the corresponding region of haematoma seen on the CT and continued to be noted throughout the time courses. Deteriorated acetazolamide reactivity affected by surgical intervention was seen in 100% of the patients who underwent aneurysm repair in the 1st postoperative week, 92% in the second week, 73% in the third week, and 47% in the fourth week. Three patients with acute diffuse brain swelling seen on CT showed intracranial non-filling of 123I-IMP on SPECTs performed on Day 6, and all three died by Day 10. Some low perfusion areas, due to probable vasospasm, were present in 77% of Hunt and Hess grades I and II patients and in 100% of grades III, IV, and V patients throughout their time courses. Overall, low perfusion areas, due to probable vasospasm, were seen in 10 patients (31%) of 32 who underwent SPECT between Day 4 and 8,23 (77%) of 30 between Day 9 and 14, 21 (72%) of 29 between Day 15 and 21, and 11 (48%) of 23 between Day 22 and 28. The results suggest acetazolamide-activated 123I-IMP study is of value in evaluating changes in vasodilatory capacity in SAH patients in the acute and subacute stages.