Question
In a patient with BPPV of posterior semicircular canal, produces?
| A. | Horizontal nystagmus |
| B. | Pure vertical nystagmus |
| C. |
Pendular nystagmus |
| D. |
Torsional vertical nystagmus |
|
Correct Answer � D Explanation |
 |
Ans: Ans. is d i.e. Torsional vertical nystagmus
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Torsional nystagmus with vertical or horizontal component: signifies peripheral cause of nystagmus.
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Remember: BPPV of posterior semicircular canal leads to combined vertical upbeat and torsional nystagmus.
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BPPV of superior semicircular canal lesion leads to torsional vertical downbeat nystagmus.
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Horizontal semicircular canal lesion leads to torsional horizontal nystagmus Only vertical or horizontal nystagmus without torsion or only torsional without vertical and horizontal nystagmus is seen in central causes of nystagmus.
Points to Remember:
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Pure vertical nystagmus is seen in medullary pons or cerebellar lesions or vertebrobasilar insufficiency.
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Purely downbeating vertical nystagmus is seen in cerebellar degenerative lesions and Arnold chiari malformation.
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Purely upbeating vertical is seen in lesions of pontomedullary junction, pons and midbrain.
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Purely rotatory seen in syringomyelia and pendular syringomyelia.
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Pure horizontal nystagmus is seen in cerebral lesions.