Download POSITIONING NYSTAGMUS

POSITIONING NYSTAGMUS
POSITIONING NYSTAGMUS
IF THE NYSTAGMUS OCCURS AS A RESULT
OF THE HEAD OR HEAD AND BODY MOTION –
THE NYSTAGMUS IS SAID TO BE POSITIONING.
BENIGN PAROXYSMAL POSITIONAL
VERTIGO /BPPV/
BPPV IS A COMMON INNER EAR DISORDER RESULTING FROM ABNORMAL STIMULATION OF
THE SCC, USUALLY THE POSTERIOR.
THE ABNORMAL STIMULATION IS DUE
TO THE PRESENCE OF OTOLITHS MOVING IN CANAL ENDOLYPH UNDER THE
INFLUENCE OF GRAVITY.
ETIOLOGY OF BPPV
BPPV IS NOT A DESEASE, BUT RATHER , A
SYNDROME THAT CAN BE THE SEQUELA OF
SEVERAL INNER EAR DISEASES.
IN 2/3 OF THE CASES NO ETIOLOGY
CAN BE FOUND.
THE FIRST DISCRIBTION OF THE BPPV
THE BASIC FEATURES OF THE BPPV
AND THE ASSOCIATED POSITIONING
NYSTAGMUS WERE FIRST DESCRIBED
IN A SINGLE PATIENT BY BARANY IN
1921. HE SPECULATED THAT THE
PAROXYSMAL POSITIONAL NYSTAGMUS
WAS CAUSED BY LESION OF THE
OTOLITH ORGANS AS IT WAS INDUCED
BY A CHANGE IN HEAD POSITION RELTIVE
TO GRAVITY.
IN THE 1952 DIX AND HALLPIKE DESCRIBED
THE PROVOCATIVE POSITIONING MANEUVER
AND CLEARLY DEFINED THE CLINICAL
FEATURES OF THE SYNDROME.
CLINICAL FEATURES
PATIENTS REPORT ABOUT SHORT EPISODES
/SECONDS/ OF STRONG VERTIGO WITH
TURNING IN BED, COMING UP AND LYING
DOWN, COMING UP AND LYING DOWN,
LOOKING UP “TOP SHELF VERTIGO”.
PATHOPHYSIOLOGY
THE MOST LIKELY EX-
PLANATION FOR BPPV
IS CANALITHASIS
INVOLVING THE PCC.
WITH THE PATIENT SITTING UPRIGHT, A CLOT
OF CALCIUM CARBONATE CRYSTALS FORMS
THE MOST DEPENDENT
PORTION OF THE PC
MOVEMENT OF THE HEAD
BACK AND TO THE SIDE
IN THE PLANE OF PCC
CAUSES THE CLOT TO
MOVE IN THE
AMPULLOFUGAL
DIRECTION, PRODUCING AMPULLOFUGAL
DISPLACEMENT OF
CUPULA, DUE TO THE
“PLUNGER” EFFECT OF
THE CLOT, MOVING
WITHIN THE NARROW
CANAL.
TYPICAL CHARACTERISTICS
FATIGABILITY WITH REPEATED POSITIONING IS EXPLAINED
BY DISPERSION OF THE PARTICLES FROM THE CLOT,
MAKING THE PLUNGER EFFECT LESS.
THE INDUCED VERTIGO AND NYSTAGMUS ARE BRIEF IN
DURATION, BECAUSE CUPULA RETURNES TO ITS PRIMARY POSITION.
THE LATENCY BEFORE ONESET OF NYSTAGMUS IS
EXPLAINED BY THE DELAY IN SETTING THE CLOT
INTO MOTION.
NYSTAGMUS
EACH SCC HAS A UNIQUE EYE MOVEMENT
SIGNATURE WHEN STIMULATED.
FOR PSCC THE BEAT OF THE NYSTAGMUS IS
PRODUCED BY IPSILATERAL SUPERIOR
OBLIQUE AND CONTRALATERAL INFERIOR
RECTUS.
NYSTAGMUS IS TORSION TO THE SIDE STIMULATED, HORIZONTAL, AWAY FROM THE
STIMULATED SIDE AND UP.
NYSTAGMUS
EACH SCC HAS A UNIQUE EYE MOVEMENT
SIGNATURE WHEN STIMULATED.
FOR PSCC THE BEAT OF THE NYSTAGMUS IS
PRODUCED BY IPSILATERAL SUPERIOR
OBLIQUE AND CONTRALATERAL INFERIOR
RECTUS.
NYSTAGMUS IS TORSION TO THE SIDE STIMULATED, HORIZONTAL, AWAY FROM THE
STIMULATED SIDE AND UP.
RECORDING FOR RIGHT POSTERIOR CANAL
BPPV DEMONSTRATES UP AND LEFT BEATING
NYSTAGMUS.
RT BPPV
BLUE – HORIZONTAL EYE POSITION,
RED – VERTICAL EYE POSITION
LT BPPV
RECORDING FOR LT POSTERIOR CANAL BPPV
DEMONSTRATES UP AND RT BEATING NYSTAGMUS.
LT BPPV
LT BPPV