Ataxia is incoordination caused by dysfunction to sensory nerve inputs, motor nerve outputs or the processing of them. It is not the result of muscular weakness. Ataxia is most often applied to unsteadiness in walking but it also refers to upper body incoordination and dysfunction in eye movements and speech.
Ataxia is common in multiple sclerosis but is also seen in several other conditions including diabetic polyneuropathy, acute transverse myelitis, vacuolar myelopathy, tumor or cord compression and hereditary forms of ataxia.
There are three types of ataxia, all of which are seen in MS:
This is caused by lesions in the cerebellum or in the parts of the brain that connect to it, such as the cerebellar peduncles, the pons or the red nucleus
In multiple sclerosis, vestibular ataxia is caused lesions to brainstem and the vestibular nuclei. In other conditions, it can also result from damage to the eighth cranial nerve leading from the balance organs in the inner ear.
Vestibular Ataxia can result in:
This results from dysfunction to position sensing (proprioceptive) nerve inputs. This means that the brain is confused as to the position of limbs.
Sensory Ataxia results in:
|Dysarthria||May be present||Absent||Absent|
|Vertigo||May be present||Present||Absent|
|Limb ataxia||Usually present||Absent||Present(only in the legs)|
|Stance||Unable to stand with feet together||May be able to stand with feet together||Able to stand with feet together and eyes open, but unable with eyes closed|
|Vibratory and position sense||Normal||Normal||Impaired|
|Ankle reflexes||Normal||Normal||Depressed or absent|
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