Auditory evoked potentials in a patient with a unilateral lesion of the inferior colliculus and medial geniculate body

Catherine Fischer, Laszlo Bognar, Francis Turjman, Claude Lapras

Research output: Contribution to journalArticle

42 Citations (Scopus)


Brain-stem, middle latency and late auditory evoked potentials (BAEPs, MLAEPs and LAEPs, respectively) were recorded in a patient 2 months after removal of a tumor affecting the quadrigeminal plate. Simultaneously, MRI showed a left unilateral lesion involving the inferior colliculus, brachium colliculi and the medial geniculate body (MGB). On dichotic listening, there was complete extinction of the right ear input, without subjective auditory disturbance. BAEPs were abnormal after stimulation of the right ear alone. Wave V was delayed and reduced in amplitude, and the I-V interval was augmented. Above all, MLAEPs of both ears were very abnormal. The Pa and Na components over the left hemisphere were abolished (Pa) or very reduced in amplitude or abolished (Na) whereas both Pa and Na components over the right hemisphere were normal. LAEPs were asymmetrical, with reduced P1N1P2 complex over the left hemisphere and absence of polarity reversal over the mastoid. It has been demonstrated that a lesion affecting only the inferior colliculus and MGB unilaterally and not extending beyond the MGB can abolish Na and Pa ipsilaterally. Any discussion of Na and Pa sources should take into account the output of the MGB to the auditory radiations, the MGB, the brachium colliculi and the inferior colliculus.

Original languageEnglish
Pages (from-to)261-267
Number of pages7
JournalElectroencephalography and Clinical Neurophysiology/ Evoked Potentials
Issue number3
Publication statusPublished - May 1995


  • Auditory pathways
  • Brain-stem auditory evoked potentials (BAEPs)
  • Dichotic listening test
  • Inferior colliculus
  • Late auditory evoked potentials (LAEPs)
  • Medial geniculate body
  • Middle-latency auditory evoked potentials (MLAEPs)

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology

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