COMMON CASES

Dr. Riyad Banayot

Nystagmus Remember to describe the nystagmus as

follow: Position: Primary position or gaze-related

(only in eccentric gaze) Type: Pendular (equal velocity in both

directions) or jerky (possessing a fast and slow phase). The direction of the nystagmus refers to the fast phase

Rate: Rapid or slow Plane: Horizontal, vertical or rotary Null zone: Nystagmus is minimal in this field

of gaze (this may be left or right or on convergence)

Binocular or monocular / dissociated

Nystagmus Cerebellar jerk nystagmus Congenital pendular nystagmus Down-beat nystagmus  See-saw nystagmus

Cerebellar jerk nystagmus The nystagmus is jerky with large amplitude and

low frequency. It may be present in the primary position. The nystagmus increases when the eyes look in

the direction of the fast phase.

Other additional examination: Examine for other cerebellar signs such as

scanning speech, intention tremor, past-pointing, disdianochokinesia and wide-based gaits

Test the hearing and corneal sensation for possible cerebello-pontine lesion

Examine the fundus for optic atrophy (as cerebellar signs and optic neuritis are common in multiple sclerosis)

Nystagmus with localizing signs See-saw nystagmus (lesion in chiasm and

third ventricle) Convergence-retraction (dorsal mid-brain) Upbeat nystagmus (ponto-medullary

junction, fourth ventricle and cerebellar vermis)

Dissociated nystagmus (as in internuclear ophthalmoplegia, lesion in the medial longitudinal fasciculus)

Down-beat nystagmus (cranio-cervical junction)

Congenital pendular nystagmus

There is pendular nystagmus in the primary position. This may be horizontal, vertical or rotary. The nystagmus decreases on convergence but increases on covering one eye. There may be abnormal eye posture in an attempt to keep the eyes in the null point.

Further examination:Anterior segment:

Congenital cataract Aphakia from previous cataract operation Albinism Aniridia Corneal abnormalities

Posterior segment: Optic nerve hypoplasia Dragged discs from retinopathy of prematurity

and foveal hypoplasia

How would you treat a child with congenital nystagmus ?

Establish and treat the underlying cause if possible (e.g. cataract)

Improve visual acuity by Conservative treatment such as placing the

child in front of the class or anywhere where he can maintain his null point and therefore maximize his vision

Refractive correction Prisms for null point and convergence Surgery such as liberal recession to reduce

the nystagmus

Down-beat nystagmus

There is nystagmus in the primary position with the fast phase beating downward. The nystagmus remains down-beating in different directions of gaze. Lateral gaze usually accentuates the nystagmus. The nystagmus is associated with cervico-medullary lesion such as Arnold-Chiari malformation (Examine the back of the neck for any surgical scar). 

What are the causes of a down-beat nystagmus ?

Arnold-Chiari malformation Spinocerebellar degeneration Brain stem stroke Multiple sclerosis Drugs such as alcohol or anticonvulsant

such as phenytoin

See-saw nystagmus

There is torsional nystagmus in the primary position. When one eye elevates and intorts the other depresses and extorts and vice-versa. This typical of lesion in chiasmal region. Examine the visual field for bitemporal hemianopia