title: Impaired sacculocollic reflex in lateral medullary infarction.
abstract: OBJECTIVE
  The aim of this study was to determine saccular dysfunction by measuring cervical vestibular-evoked myogenic potentials (cVEMP) and to correlate abnormality of cVEMP with results of other vestibular function tests in lateral medullary infarction (LMI).
  
  
  METHODS
  We recorded cVEMP in 21 patients with LMI documented on MRI. cVEMP was induced by a short tone burst and was recorded in contracting sternocleidomastoid muscle while patients turned their heads forcefully to the contralateral side against resistance. Patients also underwent video-oculographic recording of spontaneous, gaze-evoked and head shaking nystagmus (HSN), evaluation of ocular tilt reaction (OTR), measurement of the subjective visual vertical (SVV) tilt, bithermal caloric tests, and audiometry.
  
  
  RESULTS
  Nine patients (43%) showed abnormal cVEMP, unilateral in seven and bilateral in two. The cVEMP abnormalities included decreased p13-n23 amplitude in four, delayed p13/n23 responses in five, and both decreased and delayed responses in two. The abnormal cVEMP was ipsilesional in five, contralesional in two, and bilateral in two. The prevalence of OTR/SVV tilt, spontaneous nystagmus, and HSN did not differ between the patients with normal and abnormal cVEMP.
  
  
  CONCLUSIONS
  cVEMP was abnormal in approximately half of the patients with LMI. The abnormal cVEMP indicates damage to the descending sacculocollic reflex pathway or disruption of commissural modulation between the vestibular nuclei.
authors.affiliation: Department of Neurology, School of Medicine, Pusan National University Yangsan Hospital, Pusan National University Busan, South Korea.
authors.forename: Seonhye
authors.initials: S
authors.lastname: Kim
authors.forename: Hyo-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Kim