A patient suffers a small haemorrhage destroying the left inferior colliculus and lateral lemniscus. Which hearing finding is expected?
- A Complete deafness of the left ear
- B Bilateral reduction of hearing with diminished localisation, no complete unilateral deafness ✓
- C Complete deafness of the right ear
- D Normal pure tone thresholds with loss of speech comprehension only
Correct answer: B. Bilateral reduction of hearing with diminished localisation, no complete unilateral deafness
Explanation
Central auditory pathways are bilaterally represented because fibres cross at multiple levels through the trapezoid body, and each lateral lemniscus carries information from both ears. Therefore lesions rostral to the cochlear nucleus never cause complete unilateral deafness; they produce subtle bilateral hearing reduction and impaired sound localisation. Complete unilateral sensorineural deafness requires a lesion of the organ of Corti, cochlear nerve, or cochlear nucleus itself, which excludes options A and C.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.