Condition · Retrocochlear

Cerebellopontine-angle Meningioma

A non-schwannoma CPA mass — afferent compression, often with decay

Not every CPA mass is a schwannoma

A CPA meningioma compresses the eighth nerve and may also distort the adjacent brainstem. The reflex shows a retrocochlear picture — elevated or absent responses for stimulation of the affected ear, often with positive decay — and the pattern may carry a central component if the brainstem is indented.

The reflex signature

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

A stimulus-ear pattern for the affected ear with positive decay — a retrocochlear picture indistinguishable from schwannoma on the reflex alone.

Reflex decay

0s2s4s6s8s10s0%50%100%50% criterion
Positive (abnormal) decay — amplitude reaches 50% at about 8.3 s. Abnormal reflex decay may be present where the eighth nerve is compressed; findings overlap with vestibular schwannoma.

Pure-tone audiogram

0204060801002505001k2k4k8kFrequency (Hz)Hearing level (dB HL)
○ Right ear✕ Left ear
Right ear: asymmetric high-frequency sensorineural loss — asymmetry is again the audiometric clue.

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

References for this page

  1. Anderson H, Barr B, Wedenberg E (1970). Early diagnosis of eighth-nerve tumours by acoustic reflex tests. Acta Oto-Laryngologica, Suppl. 263, 232–237.
  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. Katz J (Ed.) (2015). Handbook of Clinical Audiology (7th ed.). Wolters Kluwer, Philadelphia.
  4. Hall JW (2014). Introduction to Audiology Today. Pearson, Boston.
Want to contrast this with another condition? The comparison tool places any two reflex signatures side by side.