Dysmetria is lack of coordination of movement typified by under- or over-shooting the intended position with the hand, arm, leg or eye. Dysmetria of a hand can make writing and picking things up difficult or even impossible. Dysmetria that involves undershooting is called hypometria and overshooting is called hypermetria.
Dysmetria is a closely related condition to intention tremor, where the constant overshoot causes shaking when performing fine movements. Ocular dysmetria, where movements of the pupil of the eye constantly overshoot, can make it difficult to fix your gaze on an object. Nystagmus, shaking eyes, is a related condition to ocular dysmetria.
In Multiple Sclerosis, dysmetria is usually caused by lesions in the cerebellum, the region of the brain responsible for coordinating movement, though it can also be caused by lesions in sensory nervous pathways leading to the cerebellum or the motor pathways leading from it.
Dysmetria is a difficult condition to treat although Isoniazid and Clonazepam work for some.
Many people with MS have reported great results from small regular doses of cannabis. Cannabis spray trials in the UK in 2001 also indicate a potential role for the drug in the treatment of dysmetria and intention tremor though, at the time of writing (November, 2001), no specific studies on cannabis and dysmetria have been done. It should be noted that cannabis is and illegal drug in many countries even for medical purposes, though this position is slowly changing.
Multiple Sclerosis Glossary: D
A study of tremor in multiple sclerosis