Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Per-operative use of S.E.P.s for vascular disease is based on: 1. The relationship between electrical cortical responses and cerebral blood flow. 2. The existence of a reversible threshold of cerebral ischemia. Intra-operative monitoring S.E.P.s were used during 30 procedures for aneurysms of the middle cerebral artery (M.C.A.). In 18 cases, a temporary occlusion of M.C.A. was necessary. Occlusion times ranged from 1 to 30 minutes. The central conduction time delay (C.C.T.), i.e. the delay N14-N20 and the cortical peak (N20) amplitude, elicited by median nerve stimulation was bilaterally monitored. A prolongation of the C.C.T. by 1 millisecond (compared with the baseline induction value) and a progressive decrease or a disappearance of the N20 peak were considered as "significant" changes. In response to these changes, immediate corrective actions (interruption of temporary M.C.A. occlusion (T.O.), repositioning of brain retractors, reapplication of aneurysm clips ...) were implemented. The reversibility of the S.E.P.s alterations during surgery was correlated with the post-operative outcome. Significant changes were found in 20 cases (including 13 T.O.). They were totally reversible in 11 cases: 5 of them developed a new but transient immediate post-operative deficit, none had a definitive deficit, and 6 patients had no new deficit. In 9 cases, the per-operative S.E.P.s alterations were not reversible: 3 cases (including 1 T.O.) had a transient deficit, 4 a permanent deficit, and 1 died (aneurysm rupture during craniotomy). An irreversible N20 peak disappearance predicted a permanent post-operative deficit in 4 of 4 patients (100%), whereas an isolated irreversible C.C.T. increase was only followed by a transitory deficit. Only 1 of 9 patients with no change in S.E.P.s (during a 15 min. T.O.), had a transient hemiparesis: this "false-negative" case will be discussed. This study confirms that S.E.P.s monitoring provides useful warning during aneurysm surgery. Median nerve S.E.P.s reflect the functional integrity of cortical M.C.A. territory; it is the pathway a risk during M.C.A. aneurysm surgery. S.E.P.s changes are not real-time information (an average of 500 responses need about 2 min), but these delays allow the surgeon to reverse the situation by immediate intra-operative adjustment, especially during temporary M.C.A. occlusion.
 ...
PMID:[Monitoring of somatosensory evoked potentials during surgery for aneurysms of the sylvian artery]. 130 88

Ninety-seven patients undergoing 103 carotid operations were studied intraoperatively using somatosensory evoked potentials after median nerve stimulation (SEP) and transcranial Doppler sonography (TCD). SEP were recorded from the scalp (C3'-Fz or C4'-Fz) and from the second cervical vertebra. The amplitude of the primary cortical response (N20P25) was measured peak-to-peak. Central conduction time (CCT) resulted from the difference between the first negative cortical (N20) and cervical (N14) response. TCD was performed using a pulsed 2-MHz-Doppler device to record the mean blood flow velocity of the middle cerebral artery (Vm-MCA) transtemporally. TCD and SEP variables were registered prior to and after carotid clamping, at short intervals during the clamping period, and after declamping. Critical SEP alterations (N20P25 less than 50% and/or CCT greater than 20% compared to the preceding values) were regarded as significant indicators of cerebral ischaemia, and selective intraluminal shunting was generally based on SEP criteria. The incidence of critical SEP changes was compared to Vm-MCA reductions greater than 60% using the Chi2-test. With SEP always recordable, additional TCD monitoring was possible in only 78 patients in our series for technical or anatomical reasons. Vm-MCA reductions greater than 60% were associated with critical SEP alterations in six cases. In five patients, Vm-MCA was reduced greater than 60% without relevant SEP changes, whereas one patient with critical SEP findings had only a minor Vm-MCA reduction (33%). In the remaining 66 cases, carotid clamping was tolerated without critical SEP changes associated with Vm-MCA reductions not exceeding 60%.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Transcranial Doppler sonography and somatosensory evoked potential monitoring in carotid surgery. 227 69