What is All of the following cranial nerves are involved in Acoustic neuroma, except ? and explain in detail?
Ans. is 'c' i.e., Oculomotor Clinical features of acoustic neuroma The clinical features depend on the extent of tumor and involved structure :? When tumor is still confined to the internal auditory canal Cochleovestibular symptoms are the earliest symptoms of acoustic neuroma when tumour is still confined to internal auditory canal. The commonest presenting symptoms are unilateral deafness or tinnitus, or a combination of both. Hearing loss is retrocochlear sensorineural type. There is marked difficulty in understanding speech, out of propoion to the pure tone hearing loss, a characteristic feature of acoustic neuroma. Vestibular symptoms are imbalance or unsteadiness. True veigo is very rare. When tumor extends beyond IAC and involves other structures Vhcranial nerve :- It is the earliest nerve to be involved. There is reduced corneal sensitivity and loss of corneal reflex which is the earliest sign of acoustic neuroma. Numbness or paraesthesia of face may occur. Involvement of Vth nerve indicates that tumor is roughly 2.5 cm in diameter and occupies the CP angle. VIP nerve :- Sensory fibres of facial nerve are involved. There is hypoesthesia of posterior meatal wall (Hitzelberg's sign), loss of taste, and loss of lacrimation on Schirmer's test. Motor fibres are more resistant. IXth and A' nerves :- Dysphagia and hoarseness due to palatal, pharyngeal and laryngeal paralysis. Brainstem :- Ataxia, weakness, numbness of arms & legs, exaggerated tendon reflexes. Cerebellum :- Ataxia, Dysdiadochokinesia, Nystagmus. Due to raised ICT :- Headache, neusea, vomiting, diplopia due to VI' nerve involvement, and papilloedema.