Nystagmus is associated with all except:
(c) Cochlear disease(Ref. Cummings, 6th ed., page 2531)Nystagmus and vertigo per se are not the manifestations of cochlear diseases. Cochlear diseases lead to hearing loss. However additionally there may be tinnitus and deafness when there occurs involvement of cochlea.Important differentiating features between peripheral and central nystagmus include the followingCharacteristic of spontaneous nystagmusPeripheral vestibularCentral vestibularFormTorsional (i.e. rotatory movement of the eye globe about its anteroposterior axis) component superimposed on a horizontal (left or right movement) or vertical (downbeat or upbeat) nystagmusPure horizontal, pure vertical or purely torsional nystagmusDirectionDirection-fixed, i.e. unidirectional nystagmus. The nystagmus becomes more pronounced with gaze towards the side of the fast component.Direction changing, i.e. bidirectional. Here the direction of the fast component gets directed towards the side of gaze (e.g. left-beating in left gaze and right-beating in right gaze).On visual/optic fixationThe nystagmus disappears with visual fixation. On removing the visual fixation, the nystagmus reappears. If the nystagmus is very fine, i.e. difficult to be seen by naked eye, then Frenzel glasses, which are strong convex glasses, are used. These glasses allow the examiner to see the patient's eyes greatly magnified. These glasses at the same time remove visual fixation, by blurring the patient's vision, thereby making the nystagmus apparent.The nystagmus, does not disappear with visual fixation, indicating loss of inhibitionAssociated featuresUnilateral Tinnitus and deafness is often present, but without any other cranial nerve and cerebellar involvement.Besides tinnitus and deafness (indicating the involvement of 8th nerve), involvement and deficits of cranial nerves III to XII which are closely associated with the brainstem are often present. Also cerebellar manifestations (e.g. ataxia, dysarthria, etc.) may be seen.Common causesBPPV, Labyrinthitis, Vestibular neuronitis, Meniere's, Labyrinthine fistula and damage by ototoxic drugsVertebrobasilar insufficiency and other central vascular conditions, Demyelinating illnesses and Tumours.In Cerebellar disease the nystagmus is pendular.In Vestibular disease the nystagmus is jerky.In the Arnold-Chiari malformation a part of the brainstem and the cerebellum are herniated into the cervical vertebral canal. The Arnold-Chiari malformation is typically associated with vertical downbeat nystagmus.
Cerebellar disease
Vestibular disease
Cochlear disease
Arnold-Chiari malformation
Assessment of Vestibular Function