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Showing posts with label ocularmovements. Show all posts
Showing posts with label ocularmovements. Show all posts

Ocular bobbing and its clinical significance

Ocular bobbing is an eye movement disorder
It is defined as intermittent, often conjugate, brisk, bilateral downward movement of the eyes with slow return to midposition
It is usullay association with paralysis of spontaneous and reflex horizontal eye movements.
Types of ocular bobbing
Typical ocular bobbing 
 Associated with preserved horizontal eye movements
 Specific but not pathognomonic of acute pontine injury
Atypical ocular bobbing 
Associated with absent horizontal eye movements, non-localizing
Monocular bobbing (paretic bobbing)
May occur if there is a coexistent unilateral fascicular oculomotor nerve palsy
Causes of ocular bobbing
  • This is seen in patients with pontine dysfunction, secondary to infarction or haemorrhage 
  • Extra-axial posterior fossa masses 
  • Diffuse encephalitis 
  • Creutzfeldt-Jakob disease 
  • Toxic-metabolic encephalopathies (acute organophosphate poisoning)
Bobbing is also noticed in a patient with acute cerebellar hemorrhage without  intrapontine challenging the  myth that this sign is specific for intrapontine destruction
Clinical significance
Clinical significance of this sign bobbing is considered as a release phenomena and extremely poor prognostic sign for neurologic recovery.
Differential diagnosis
An initially fast upward deviation followed by a slow return to primary position is referred to as reverse ocular bobbing;
A slow initial upward drift followed by a fast return to primary position has been termed converse bobbing, or reverse ocular dipping. 
Ocular bobbing has valuable localizing value and prognostic information
But, inverse bobbing, reverse bobbing, and dipping are nonlocalizing and most often noted with hypoxic-ischemic encephalopathy.
Pretectal pseudobobbing 
It has been described with acute hydrocephalus.
This is an arrhythmic, repetitive downward and inward (V pattern) eye movements at a rate ranging from 1 per 3 seconds to 2 per second and an amplitude of 1/5 to 1/2 of the full voluntary range.
These movements may be mistaken for ocular bobbing, but their V pattern, their faster rate, and their pretectal rather than pontine-associated signs distinguished them from true pontine bobbing.
may have abnormal pupillary light reactions, intact horizontal eye movements, openand often retracted eyelids, a blink frequently preceding each eye movement, and a mute or stuporous rather than a comatose state.
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