In acoustic neuroma cranial nerve which is involved, earliest is
Cranial nerve involvement* Vth nerve. This is the earliest nerve to be involved. There is reduced corneal sensitivity, numbness or paresthesia of face. Involvement of this nerve indicates that a tumor is roughly 2.5 cm in diameter and occupies the cerebellopontine angle.* VIIth nerve. Sensory fibers are affected early. There is hypoaesthesia of the posterior metal wall (Hitzelberger's sign), loss of taste (as tested by electrogustometry) and reduced lacrimation on Schirmer test. Motor fibers are more resistant and are affected late. Delayed blink reflex may be an early manifestation.* IXth and Xth nerves. There is dysphagia and hoarseness due to palatal, pharyngeal and laryngeal paralysis.* Other cranial nerves. XIth and XIIth, IIIrd, IVth, and VIth are affected when the tumor is very large.Ref: Dhingra; 6th edition; Chapter 18; Acoustic neuroma; Page no: 113
5
7
9
10
Ear