Condition · Central / brainstem

Multiple Sclerosis

Demyelinating brainstem disease — crossed reflexes affected, abnormal decay

Demyelination in the reflex pathway

MS plaques in the brainstem can interrupt the reflex pathway — particularly the crossed (contralateral) fibres that traverse the midline. This produces absent or elevated crossed reflexes, often with abnormal decay, in an ear whose hearing may be near-normal.

A central sign with normal hearing

Abnormal crossed reflexes with a normal or near-normal audiogram point away from the cochlea and middle ear and toward a central pathway lesion. In a young adult with other neurological symptoms, demyelination should be considered.

The reflex signature

Stim. Right
Stim. Left
Probe Right
Present
95 dB HL
Absent
Probe Left
Elevated
115 dB HL
Present
95 dB HL
The characteristic four-cell grid for this condition.

Crossed (contralateral) cells are absent or elevated with preserved ipsilateral cells — a diagonal-type pattern of central origin.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Negative (normal) decay — amplitude is well maintained across the 10-second hold. Abnormal reflex decay can occur where demyelination affects the pathway; the crossed/uncrossed dissociation is the more characteristic sign.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Hearing is often normal or near-normal; the reflex abnormality is disproportionate to the audiogram.

Frequencies plotted: 250, 500, 1k, 2k, 4k, 8k Hz.

References for this page

  1. Hannley M, Jerger JF, Rivera VM (1983). Relationships among auditory brainstem responses, masking level differences and the acoustic reflex in multiple sclerosis. Audiology, 22(1), 20–33.
  2. Jerger S, Jerger J (1977). Diagnostic value of crossed versus uncrossed acoustic reflexes: Eighth nerve and brainstem disorders. Archives of Otolaryngology, 103(8), 445–453.
  3. Musiek FE, Baran JA (2007). The Auditory System: Anatomy, Physiology and Clinical Correlates. Pearson, Allyn & Bacon, Boston.
  4. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
Want to contrast this with another condition? The comparison tool places any two reflex signatures side by side.