Temporal bone pathology in patients without caloric response.

Pathologies of serial sections of 9 temporal bones from 6 patients without caloric response were studied. The patients died of epipharyngeal cancer, middle ear cancer, chronic renal failure with DIC, pancreatic cancer with DIC, multiple brain metastasis of pancreatic cancer, and leukemia. Under light microscopy, 8 ears showed pathologies in the vestibular end organs and the nerves. Possible causes of the lack of caloric responses in the 8 ears were endolymphatic hemorrhage, labyrinthitis, leukemic infiltration in the labyrinth, degeneration or disappearance of the vestibular sensory cells, reduction in the number of vestibular nerve fibers, and/or brainstem lesions. The remaining one ear did not show abnormal findings in the vestibular end organs or the nerves, but the patient had brainstem lesions. Four types of temporal bone pathologies were observed according to the lesion site responsible for the lack of caloric response; i) sensory type, ii) neural type, iii) mixed type and iv) central type.