31 Middle ear disease
Initial presentation may include: facial paralysis, Horners syndrome, pain on opening the mouth.
The middle ear lies beyond the tympanic membrane (ear drum), and consists of the mucosa-lined tympanic bulla, a bony ‘balloon’ lying on the ventrolateral surface of the temporal bone. It contains the three auditory ossicles which transmit sound waves from the external ear to the internal ear. The tiny muscles attached to either end of the ossicle chain contract in response to loud noise, limiting the transmission of sound to the inner ear as a protective mechanism. The auditory (eustachian) tube connects the middle ear to the nasopharynx. In cats, the large ventromedial and small dorsolateral compartments are separated by a very thin bony lamella. The facial nerve and sympathetic nerve supply to the eye are closely associated with the cavity of the middle ear.
The initial presentation may include:
2–3 months of left otitis externa. A week of depression and 2 days of a left head tilt, nystagmus, ataxia, being unable to jump and stumbling to the left.
The cat was alert, ambulatory, ataxic and had a left head tilt. When walking, the cat staggered or fell to the left. Hopping and proprioception were normal in all limbs. Spontaneous horizontal nystagmus with a fast phase to the right was seen.