Down-beat nystagmus is a central vestibular disorders -Pitch plane disorder.
It is a Jerk nystagmus with fast phase downwards.
Most prominent on looking down & out.
What is the site of lesion in downbeat nystagmus?
Site of lesion in down gaze nystagmus is disruption of posterior SCC projections secondary to Lesions
in the floor of fourth ventricle.
- Bilateral lesions of the flocculi
What are the causes of Downbeat nystagmus?
- Lesions of cervico-medullary
junction - ACM.
- Lesions of flocculus,
paraflocculus, nodule, uvula & medulla.
- Spinocerebellar ataxia.
- Metabolic causes.
Wernicke's encephalopathy.
Deficiency of magnesium, thiamine, Vit B12.
- Toxic.
Lithium, Phenytoin, CBZ, morphine, amiodarone.
Alcohol intoxication.
Reference Notes
What is See-Saw Nystagmus ?
What are the causes of Acquired Pendular nystagmus ?
What is Convergence-Retraction Nystagmus ?
Dissociated Jerk Nystagmus and causes
What is Rebound nystagmus and its causes?
What is Bruns's nystagmus?
What is Gaze evoked nystagmus?
Down-beat nystagmus and its causes
Upbeat nystagmus and its causes
What is the basic Pathophysiology of Nystagmus
Alexanders law in Nystagmus - A brief
