SPONTANEOUS NYSTAGMUS

SPONTANEOUS NYSTAGMUS REFERS TO NYSTAGMUS THAT OCCURS WITH THE PATIENT SEATED, EYES IN THE PRIMARY POSITION AND WITHOUT VISUAL OR VESTI- BULAR STIMULATION. RECORDING IS PERFORMED 30 SECONDS WITH OPEN EYES AND GAZE FIXATION AND 30 SE- CONDS WITH CLOSED EYES /ENG/ OR IN COMPLETE DARKNESS /VNG/.

SPONTANEOUS NYSTAGMUS, RECORDED WITH OPEN EYES AND GAZE FIXATION IS ALWAYS PATHOLOGICAL. SPONTANEOUS NYSTAGMUS, RECORDED WITH CLOSED EYES OR IN DARKNESS IS PATHOLOGICAL IF SLOW PHASE VELOCITY /SPV/ IS = > 6 DEG/SEC.

SPONTANEOUS NYSTAGMUS CENTRAL ORIGIN PERIPHERAL ORIGIN

PERIPHERAL SPONTANEOUS NYSTAGMUS HORIZONTAL COMPONENT DOMINATES

------------------------------------------------------ RT LT ------------------------------------------------------ RT MED. RECT. LT MED. RECT. LT LAT. RECT . H RT LAT. RECT. ----------------------------------------------------------------- RT SUP. RECT. LT SUP. RECT. LT INF. OBLIQUE A RT INF. OBLIQUE ------------------------------------------------------------------------------- RT SUP. OBLIQUE P LT SUP. OBLIQUE LT INF. RECT. RT INF. RECT.

PERIPHERAL SPONTANEOUS NYSTAGMUS GAZE IN THE DIRECTION OF FAST COMPONENT INCREASES THE FREQUENCY AND AMPLITUDE OF THE NYSTAGMUS

PERIPHERAL SPONTANEOUS NYSTAGMUS THE SLOW PHASE IS LINEAR

PERIPHERAL SPONTANEOUS NYSTAGMUS NYSTAGMUS IS STRONGLY INHIBITED BY FIXATION

CENTRAL SPONTANEOUS NYSTAGMUS IS PROMINENT WITH AND WITHOUT FIXATION

SLOW COMPONENT SLOW PHASE OF SPONTANEOUS NYSTAGMUS MAY BE LINEAR, EXPONENTIALLY DECREASED OR EXPONENTIALLY INCREASED

Congenital nystagmus CONGENITAL NYSTAGMUS IS OF CENTRAL ORIGIN. IT IS USUALLY PURELY HORIZONTAL. THE WAVEFORM MAY BE PENDULAR TO SAWTOOTH. DIFFERENT WAVEFORMS OCCUR IN THE SAME PATIENT IN DIFFERENT EYE POSITIONS.