Nystagmus series – Part VI
(periodic alternating nystagmus, PAN)
“Nystagmus processor for EEG machines”
2) Definition
“horizontal nystagmus reverses direction every 2 minutes”
During transition period
-upbeating, downbeating, square-wave jerks can occur
- acquired form is rare, but it is the best understood and the first to have effective treatment
3) Pathophysiology
3) Pathophysiology
“lesion in cerebellum nodulus & uvula”
nodulus & uvula
- responsible for velocity-storage mechanism
- inhibitory control on vestibular rotation using GABA (baclofen-responsive)
vestibular system
- repair mechanism
- reverse direction of nystagmus
4) Fixation in central vestibular nystagmus “poorly suppressed by fixation of a visual target” - abnormal smooth-pursuit system
5) Associated symptoms Periodic alternating head turns - minimizing nystagmus by Alexander’s law - head turn in the direction of the quick-phase
6) Management
Acquire form
- baclofen
Congenital form
- horizontal recti resection
7) Obs
a) vestibular stimuli (head rotations) can transiently change nystagmus
b) periodic alternating gaze deviation, if brainstem is affected
c) persist during sleep remaining horizontal in vertical gaze
d) see for 4 minutes every central position horizontal nystagmus
8) Differ
a)acquired vs congenital: congenital has congenital features & irregular time
b)ping-pong gaze: ocular deviations reverse after seconds; bihemispheric lesion
c)alternating windmill nystagmus: horizontal&vertical planes
d)paroxysm mixed torsional-horizontal-vertical
9) Acquired periodic alternating nystagmus – features
i) horizontal nystagmus reverses direction every 2 minutes
ii) transition phase ⬆️⬇️🔲
iii) no suppress by visual fixation
10) Acquired periodic alternating nystagmus, PAN
11) Acquired periodic alternating nystagmus, PAN
12) Acquired periodic alternating nystagmus, PAN
13) Acquired periodic alternating nystagmus, PAN
14) Acquired periodic alternating nystagmus, PAN
15) Acquired periodic alternating nystagmus, PAN
16) Acquired periodic alternating nystagmus, PAN
17) Acquired periodic alternating nystagmus, PAN
18) Differ
acquired periodic alternating nystagmus vs ping-pong gaze ping-pong gaze - ocular deviations reverse after few seconds - large bihemispheric lesion - unconscious patients19) Differ
acquired periodic alternating nystagmus vs ping-pong gaze ping-pong gaze - ocular deviations reverse after few seconds - large bihemispheric lesion - unconscious patients20) Differ
acquired periodic alternating nystagmus vs alternating windmill nystagmus alternating windmill nystagmus - horizontal & vertical planes oscillations - blind patients (most freq)