Posterior Semi circular canal (SCC) BPPV:
Most common variety.
BPPV is the most common cause of vertigo constituting 20-40% of all patient with peripheral vestibular disease. Mean age of on set ranging between 4th and 5th decades. women outnumbering men by 2:1.
DIGNOSIS is always clinical.
History: Patient c/o severe vertigo associated with change in head position. Symptoms are always sudden in nature never lasting more than one minute.The patient may even volunteer provocating postures.
On examination: The classic eye movement associated with Dix Hallpike manoeuver is seen. Dix-Hallpike maneuver: The patient is positioned on the examination table in such a way that when he/she is placed supine, the head extend over the edge. The patient is lower with the head supported and turned 45 degrees to one or the other side. The eyes are carefully observed, if no normal eye movements are seen, the patient is returned to upright position.
This same manoeuver is repeated with the head in the opposite direction and the patient’s symptoms are noted. The pattern of response consist of the following:
Canalithiasis involving the posterior canal is the commonest cause of BPPV. Posterior canal BPPV may rarely be bilateral, but while testing the head must be positioned in the
Lateral canal BPPV:
Lateral canal has also been identified as the offender in 17 % of cases with BPPV. Lateral canal BPPV can be detected by a variation of Dix Hallpike maneuver. The patient’s head is first brought to the supine position resting on the examination table (not hyperextended). The head is then turned rapidly to the right so that the patient’s right ear rests on the table. The eye movements of the patient are monitored with Frenzel’s glasses for 30 seconds. The patient’s head is then turned to the supine position (eyes looking upward) and is then rapidly turned to the left so that the left ear rests on the table. Eye movements are monitored. The nystagmus with lateral canal BPPV is horizontal and may beat toward (geotropic) or away (ageotropic) from the downward ear. It begins with a short latency, increases in magnitude progressively, and is less susceptible to fatigue with repetetive testing than the vertical torsional nystagmus of posterior canal BPPV.
Cupulolithiasis, either alone or in combination with canalithiasis is more likely to be involved in the etiology of lateral canal BPPV than in the case of posterior canal BPPV. If the nystagmus is geotropic, the particles are likely to be in the long arm of the lateral canal relatively far from the ampulla, if the nystagmus is ageotropic, the particles could be in the long arm relatively close to the ampulla or on the opposite side of the cupula either floating within the endolymph or embedded in the cupula.
Superior canal BPPV:
Incidence of superior canal BPPV is very rare.
Standard electro-oculography or two dimensional video nystagmography devices does not record the movement of eye associated with BPPV. Thus clinical examination of the patient is very important to dignose.