Identifying the Type of Vestibular Nystagmus

 

Types of vestibular nystagmus:

(1) peripheral vestibular

(2) central vestibular

(3) sustained positional

(4) central paroxysmal positional

(5) benign paroxysmal positional

 

Vestibular nystagmus present in upright position

Findings	Type
acute onset vertigo fixation decreases nystagmus (persists if blocked)	peripheral vestibular
fixation does not decrease nystagmus	central vestibular

 

Vestibular nystagmus absent in upright position

 

Positional vestibular nystagmus:

(1) not present in the sitting upright position

(2) induced by (1) lateral or supine positioning, or (2) rapid movements of the head and body into the head-hanging position

(3) may show fixed direction (direction same in right and left lateral position) or changing direction (direction changes when in right and left lateral position)

 

Findings	Type
present with static positioning	sustained positional
absent with static positioning; present with rapid positioning transient, intense upbeat, dissociated	benign paroxysmal
absent with static positioning; present with rapid positioning upbeat and downbeat, symmetric	central paroxysmal

 

Characteristics of the Different Types of Nystagmus

 

Peripheral vestibular:

(1) features: jerk nystagmus, mainly horizontal, small torsional and vertical components (rotary nystagmus)

(2) inhibited by fixation?: yes; blocking reveals

(3) findings: gaze in the direction of the fast component increases the nystagmus (amplitude X frequency); gaze in the direction of the slow component decreases the intensity (Alexander's law); nausea and vertigo with a sensation of rotation in the environment or of self-rotation in the direction of the fast component; may be accompanied by tinnitus, hearing loss and/or ear pain; nystagmus intensity is high during the first few days but then spontaneously decreases.

(4) associated findings: horizontal head-shaking for 10-15 seconds followed by fixation blocking induces a transient, horizontal jerk nystagmus with the fast component to the side opposite the damaged side (away from damaged side)

(5) localization: vestibular labyrinth, eight nerve

(6) destructive lesion (labyrinthitis, vestibular neuritis) decrease the innervation from the affected ear and produce jerk nystagmus with slow component towards the affected ear

(7) irritative disorders (Meniere's) increase the innervation from the affected ear and generate jerk nystagmus with the fast component towards the affected ear and the slow component toward the opposite ear

 

Central vestibular (fixation nystagmus):

(1) features: jerk nystagmus, pendular; may be purely horizontal, vertical, or torsional

(2) findings: horizontal head-shaking may induce a downbeat nystagmus or a horizontal nystagmus

(3) inhibited by fixation?: no

(4) localization: brainstem (vestibular nuclei), cerebellum, connection between the vestibulocerebellum (flocculonodular lobes) and the brainstem; jerk nystagmus in primary gaze that is predominantly torsional is associated with lesions of the vestibular nuclei on the side contralateral to the fast component.

 

Sustained positional:

(1) features: jerk nystagmus, horizontal with small torsional, direction fixed, direction changing

(2) findings: present in static positioning

(3) inhibited by fixation?: yes if peripheral, no if central

(4) localization: labyrinth, eighth nerve, brainstem, cerebellum

 

Central paroxysmal positional:

(1) features: jerk nystagmus, symmetric, upbeat and downbeat

(2) inhibited by fixation?: no

(3) localization: brainstem, cerebellum

 

Benign paroxysmal positional:

(1) features: jerk nystagmus, dissociated, upbeat

(2) findings: Nylen-Barany maneuver (rapid positioning of the head and body into the left or right head-hanging positions) induces vertical nystagmus after a delay of 1-2 seconds (latency), associated with vertigo; binocular asymmetry with nystagmus upbeat in higher eye (eye opposite the head-hanging position) but is oblique and torsional in the lower eye; rapid repetition of maneuver generates a less intense nystagmus (fatigue)

(3) inhibited by fixation?: no

(4) localization: posterior vertical canal