POSTCAROTID ENDARTERECTOMY HYPERPERFUSION SYNDROME - PRELIMINARY-OBSERVATIONS FOR IDENTIFYING AT RISK PATIENTS BY TRANSCRANIAL DOPPLER SONOGRAPHY AND THE ACETAZOLAMIDE TEST

Patients at risk of hyperperfusion syndrome after carotid endarterectomy are often severely hypertensive and have a high grade internal carotid artery stenosis with disordered autoregulation due to a loss of reserve capacity (RC). Cerebral RC can be studied by sophisticated and expensive technical devices (SPECT, PET). Recently it has been demonstrated that the transcranial Doppler (TCD) and acetazolamide provocation test can be used to assess RC. From September 1991 to January 1992, 36 patients were studied by the TCD and acetazolamide test prior to carotid endarterectomy to identify patients at high risk of the hyperperfusion syndrome. Preoperatively, the patients were studied by TCD at rest and after vasolidation with acetazolamide 1 g intravenously (i.v.). Mean blood flow velocity on the middle cerebral artery (MCAv) was recorded for the following 20 min at 5 min intervals. MCAv at rest was 49 ± 17cm/s. After acetzaolamide infusion in 33 patients (92%), the mean MCAv was 62 ± 19 cm/s with an increase of 19 ± 13cm/s (normal RC). In three patients (8%), the mean MCAv was 43 ± 22cm/s with a decrease of -6 ± 3 cm/ s with respect to base values (reduction of RC). (t = 3.30; p = 0.0022). All these patients were hypertensive (BP >180/ 100 mmHg) and had a carotid artery stenosis >90%. Postoperatively, the three patients with reduction of RC complained of homolateral headache. TCD showed a mean MCAv of 67 ± 17cm/s, an increase compared to the preoperative rest values of 17 ± 8cm/s, the 33 patients with normal RC showed a mean change in MCAv -2 ± 12cm/s. The difference between the postoperative recorded mean MCAv in the two groups was statistically significant (t = 2,556, p = 0.0339). In this preliminary study, TCD associated with the acetazolamide test was demonstrated to be an inexpensive, easily performed and repeatable technique useful in assessing the patient at risk of hyperperfusion syndrome. © 1993 Grune & Stratton Ltd.