title: [Anomalies in early somatosensory evoked potentials in brain stem lesions (study of 64 cases)].
abstract: Short latency somatosensory evoked potentials (SEPs) have been recorded in 64 patients with brainstem lesions documented by neuroimaging techniques. Patients were classified in four groups according to the lesion topography: cervico-medullary junction and medulla (16 cases), pons (19 cases), mesencephalon (8 cases), extensive (21 cases). SEPs were abnormal in 57.8% of cases either bilaterally (17.2%), or unilaterally (40.6%). The different components were affected as follows, P14: 34.4%; N20: 56.9%; P22 and N30: 54.7%, peripheral and spinal responses were always spared: N18 and P14 abnormalities were highly correlated. In cervico-medullary lesions P14 and N20 were constantly abnormal, P14 was normal in strictly mesencephalic lesions but could be abnormal in cases of subthalamic lesions with mesencephalic extension; in pontic lesions, P14 could be normal or not, and N20 was always very reduced. These results confirm that P14 has a supra-spinal origin and may have two generators. SEPs detected a subclinical dysfunction of the lemniscal pathways in 18% of patients with normal somatosensory performances and, as BAEPs (abnormal in 54% of the 54 recordings performed in this series) deserve to be recorded for the routine investigation of brainstem function.
authors.affiliation: Service de neurologie CHRU 15, Saint-Etienne, France.
authors.forename: P
authors.initials: P
authors.lastname: Convers
authors.forename: L
authors.initials: L
authors.lastname: Garcia-Larrea
authors.forename: C
authors.initials: C
authors.lastname: Fischer
authors.forename: D
authors.initials: D
authors.lastname: Michel
authors.forename: F
authors.initials: F
authors.lastname: Mauguière
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000503:physiopathology*; D001932:Brain Neoplasms / Q000503:physiopathology; D001933:Brain Stem / Q000503:physiopathology*; D002648:Child; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
vernacular_title: Les anomalies des potentiels évoqués somesthésiques précoces dans les lésions du tronc cérébral (étude de 64 observations).