Somatosensorisch evozierte Potenziale und biochemische Marker neuronaler Defizite während Endarterektomie der A. carotis in Regionalanästhesie

OBJECTIVE OF THE STUDY: Carotid endarterectomy (CEA) remains the standard procedure for primary and secondary prevention of stroke. Somato-sensory evoked potentials (SEP) are frequently used in carotid endarterectomy under general anaesthesia and recommended for monitoring cerebral functions. The aim of the study was to compare changes in SEP and serum levels of S-100 beta protein and neuron-specific enolase (NSE) with perioperative clinical neurological deficits in patients undergoing regional anaesthesia (RA). PATIENTS AND METHODS: After approval of the ethics committee of the Otto-von-Guericke-University, Magdeburg fifty patients undergoing elective CEA under RA were prospectively investigated. RA was performed by combined deep and superficial cervical plexus blockade. SEP was monitored continuously during the surgical procedure. A more of 50 % decrease of potentials (N 20 / P 25 amplitude) compared to potentials before clamping was considered to be significant. Arterial blood samples were collected preoperatively, before declamping and on the first postoperative day to determine serum levels of S-100 beta and NSE. RESULTS: 12 patients developed intraoperatively neurological deficits with carotid clamping. The symptoms were transient and regressed in one minute after shunting. One patient was discharged with persistent hemiparesis. In 8 of 12 patients (66 %) with neurological deficits a more of 50 % decrease of potentials was observed. In one patient with loss of consciousness and hemiparesis changes in SEP or decrease in N 20 / P 25 amplitude were absent. Decrease in amplitude was in patients with intraoperative neurological deficits with 78 % versus 34 % in patients without any deficits significantly reduced (p = 0.01). The sensitivity of monitoring was 67 % at a specifity of 74 %. Serum levels of S-100 beta increased before declamping between patients with and without any neurological deficits significantly (p = 0.02). On the first postoperative day, increased levels of S-100 beta correlated with decrease in amplitude (p = 0.001). CONCLUSION: Compared to SEP, CEA under regional anaesthesia is a safer method to detect patients with cerebral ischaemia before irreversible cellular brain damage occurs. Measuring blood levels of S-100 beta could help to evaluate patients with risk to develop cerebral ischaemia during clamping.