Cerebral blood flow in patients with normal pressure hydrocephalus

Mean cerebral blood flow (CBF) of the whole brain was measured in 48 patien ts who underwent cerebrospinal fluid shunt surgery for normal pressure hydr ocephalus (NPH) by performing first-pass radionuclide angiography using Tc- 99(m)-hexamethylpropylene amine oxime. Patients were divided according to o utcome into an 'excellent' improvement group, a 'good' improvement group, a 'fair' improvement group and a 'poor' improvement group. Patients with exc ellent and good improvement had a preoperative mean CBF of 40.4 +/- 3.9 ml. 100 g(-1).min(-1) and 37.1 +/- 5.5 ml.100 g(-1).min(-1), respectively, both of which were significantly (P < 0.005) higher than that in 11 patients wh o showed fair improvement (30.8 +/- 3.2 ml.100 g(-1)min(-1)) and six patien ts who showed poor improvement (31.8 +/- 2.5 ml.100 g(-1).min(-1)). Patient s with a clinical improvement after shunting had an increased postoperative mean CBF. We conclude that patients with a preoperative mean CBF of over 3 5 ml.100 g(-1).min(-1) can show favourable improvement after a shunting pro cedure, and that the preoperative mean CBF of 32 ml.100 g(-1).min(-1) can b e considered the critical level for treatment. ((C) 1999 Lippincott William s & Wilkins).