TRANSCRANIAL DOPPLER MONITORING AND CAUSES OF STROKE FROM CAROTID ENDARTERECTOMY

Background and Purpose The value of carotid endarterectomy (CEA) depen ds on the safety of the operation. Transcranial Doppler ultrasound (TC D) was used to evaluate the possibilities of hypoperfusion, hyperperfu sion, and embolization as causes of stroke and to evaluate the signifi cance of Doppler microembolic signals (DIMES). Methods Five hundred CE As were monitored with TCD of the ipsilateral middle cerebral artery d uring various phases of CEA to determine hemodynamic changes and incid ence of DMES. Complications were graded according to their severity, a nd their probable cause was determined from TCD criteria and review of hospital charts. Results We observed 24 cerebrovascular complications (4.8%), including 9 with transient ischemic attacks and 15 (3%) with permanent deficits. Among all cerebrovascular complications, embolism was judged to be responsible in 13 (54%; P < .02 compared with hypoper fusion), hyperperfusion in 7 (29%; P < .14 compared with hypoperfusion ), and hypoperfusion in 4 (17%; P < .08 compared with embolism plus hy perperfusion). The surgeons responded to TCD information by several st rategies depending on the TCD information The incidence of permanent d eficits diminished from 7% in the first 100 operations to 2% in the la st 400 (P less than or equal to .01). Shunting was more strongly assoc iated with cerebrovascular complications than nonshunting, but this di fference was not significant (P = .24). Intraoperative prevalence of D MES was strongly associated with cerebrovascular complications (P = .0 2). Conclusions Embolism is the principal cause of cerebrovascular com plications from CEA; hyperperfusion and hypoperfusion are also importa nt causes. TCD provides information that allows prompt identification and treatment of these three major causes of stroke from this operatio n. The perioperative stroke rate can be reduced by appropriate measure s, taken by the surgeons, based on findings of TCD monitoring.