Figure 4.

(A) Brainstem auditory evoked response (BAER) tests of the left ear (A) and the right ear (b). Both recorded tracings exhibited a complete absence of waves III to V, suggesting a likely overall involvement of the brainstem structures, as indicated by the clinical evaluation. However, on the left side (a), there is probable involvement of the inner ear. This hearing impairment resulted in the disappearance of wave I (cranial nerve VIII) and subsequent waves in the recordings. (B) Left (c) and right (d) BAER tracks of a clinically healthy tawny owl (Strix aluco) used to compare the BAER tracks obtained from the patient. The presence of five physiological waves (I–V) is evident.