S103. Description of short and middle latency somatosensory evoked potentials in adult patients with ischemic cerebrovascular accident

Abstract

Introduction In the United States, cerebrovascular accidents (CVAs) are the fourth most common cause of death with a general prevalence of 2.6%. Approximately 85% of all CVAs are of the ischemic type. Somatosensory evoked potentials (SSEPs) evoked through transcutaneous bipolar electrical stimulation applied to the selected nerve, this is one of the most informative neurophysiological techniques available, since it provides an evaluation of brain function. In turn, the middle latency somatosensory evoked potentials (MLSEP) between 35 and 100 ms after stimulation of the median nerve. SSEPs are abnormal in patients with lesions in the brainstem, diencephalon or cerebral hemispheres, when lemniscal pathways are involved, with similar patterns for brainstem, thalamic and thalamic-capsular lesions. The SSEPs have been studied in an attempt to prove their usefulness as a tool for clinical evaluation and prognosis in ischemic CVA. Methods Observational, cross-sectional, exploratory study enrolled 7 adult patients with corroborated ischemic stroke by imaging study (computed tomography CT or magnetic resonance imaging MRI) within the first 24 h of evolution. Short and middle latency somatosensory evoked potentials were performed at the American British Cowdray Medical Center, with Sierra Wave 4 channels electromyograph, recording and quantifying its latencies of N35, P45 and N60 ipsi and contralateral responses to the site of injury taking into account clinical and paraclinical variables. Results In this study 7 patients were recorded; the group had a median age of 61 years, with a minimum age of 25 years and maximum of 84 years. With their respective controls, the study showed the MLSEP in patients with CVA being of cardioembolic, atherothrombotic, prothrombotic and indeterminate etiology; in the short latency potentials peripheral response was found in all cases (N9), N60 was absent in patients with CVAs of different etiologies, the proportion of waves absent in lesion-ipsilateral MLSEP was greater than in contralateral MLSEP. Conclusion The clinical use of the middle latency responses has been limited by the incomplete knowledge of their generators, since the specific utility of this neurophysiological study is based on the evaluation of neurological pathways which can be interrupted in their journey by other pathologies such as ischemic stroke. The use of MLSEP shows that in patients with CVA they are present unilaterally, contralaterally and bilaterally, so the usefulness of performing them has future implications to determine the frequency of each of them related to the type of etiology, treatment and prognostic outcome.