Topographical correlations of lateral medullary infarction with caloric- and vestibular-evoked myogenic potential results

This study investigated the correlation of caloric- and vestibular-evoked myogenic potential (VEMP) results with topographical lesions of lateral medullary infarction. Five patients with lateral medullary infarction were enrolled in this study. Each patient underwent a battery of tests, including audiometry, caloric test, VEMP test, and magnetic resonance imaging (MRI) study. Gaze nystagmus was observed in four patients (80%), while abnormal pursuit, saccade, and optokinetic nystagmus tests were noted in all patients (100%). MRI demonstrated infarction at the ponto-medullary junction in one patient and upper medulla in one patient. Both patients revealed caloric areflexia and normal VEMPs. In contrast, another three patients with infarction at the middle inferior olive level, all displayed abnormal (including absent or delayed) VEMPs, and one patient showed caloric areflexia. Topographical correlations of lateral medullary infarction with caloric and VEMP tests reveal that caloric areflexia is possibly linked with rostrally located infarction, while absent or delayed VEMPs relate to caudally located infarction.