Dysmetria

Dysmetria is a neurological disorder marked by problems in movement. Read and get detailed information about the causes, symptoms, diagnosis and treatment.

What is Dysmetria?

The word “Dysmetria” means difficult to measure. It refers to a disease characterized by a lack of coordination of movement. This condition is also known as the inability to judge distance or scale. It is also marked by ataxia which is typified by undershoots or overshoots of intended position with the hand, arm, leg or eye.

The disease is not only marked by motor problems but also the inability to receive and process information and to produce a proper systematic fine-tuned response.

Dysmetria Symptoms

This disease is associated with lesions in the cerebella region.  It is characterized by overestimating or underestimating the range of motion needed to move the limbs correctly during voluntary movement. People suffering from Dysmetria are unable to move arms from a position of 90 degrees of flexion to a position over the head and then return to the 90 degrees position with eyes closed.

Types of Dysmetria

The commonly occurring types of the disorder include:

Ocular Dysmetria

It involves the continuous overshooting of the eyes while trying to focus gaze on something. It is a result of development of lesions in the cerebellum, the region of the brain which is responsible for coordinating movement. The experience of being in this condition is similar to the feeling of sea-sickness. This form of the disease is often a symptom of various neurological conditions, such as multiple sclerosis.

Appendicular Dysmetria

It is seen at the acute stage of Wallenberg syndrome. It is found in the ipsilateral upper extremity. Patents of this condition have peculiar types of eye movements, characterized by hypermetric saccades towards the side of the lesion and hypometric saccades to the side opposite to the hypermetric. This is accompanied by hypermetric arm and hand actions on the side of the lesion and hypometric on the opposite side. This form usually disappears with time. In some patients, however, it continues after six months after the ischemic damage.

Cognitive Dysmetria

Cognitive Dysmetria involves difficulty in prioritizing, responding to information and coordinating them. It is a poor mental condition defined by a fundamental cognitive deficit as seen in Schizophrenia. It is caused due to disruption in the circuit in the prefrontal regions of the brain, the cerebellum and the thalamic nuclei.

Causes of Dysmetria

This condition is closely related to intention tremor, in which the constant overshooting causes shaking of hands or legs while performing fine movements. This actually occurs due to the development of lesions in the cerebellum or in the proprioceptive nerve region which leads to the spot that controls visual, spatial and other sensory actions under motor control. Damage to the proproceptive nerves impacts the ability of the cerebellum to properly judge the location where the hand, arm, eye or leg must move. These lesions are often caused due to strokes, Amyotrophic Lateral Sclerosis, tumors or Multiple Sclerosis. According to researchers, motor control is a learning process which makes use of APPGs. APPGs malfunction when there is Ataxia and Dysmetria.

There are two types of cerebellar disorders which results in this disorder.

Midline Cerebellar Syndrome

It can cause Ocular Dysmetria. People suffering from this disorder find it difficult to focus their vision on one object. Here, the pupil of the eye overshoots constantly. This causes difficulties in fixing the gaze.

Hemispheric Cerebellar Syndrome

This syndrome causes Dysmetria in the typical motor sense.

Cerebellar Motor Syndrome

This common motor syndrome is marked by malfunctioning of gait or ataxia, improper eye movements, difficulty in swallowing, tremors and poor articulation. It is also known as Cerebellar Cognitive Syndrome.

Dysmetria Treatment

Since Dysmetria is a symptom, it is not possible to cure the condition completely in most cases. The condition can, however, be managed through drugs like Isoniazid and Clonazepam.

Experimental treatments, in the form of cannabis and chiropractic neurology, are also available. Sometimes, patients are also trained to practice specific eye movements before trying to go for physical movement. Deep brain stimulation can help multiple sclerosis patients to improve their motor skills. Patients do not experienced any relapse for six months after undergoing this treatment.

Researchers have found that visually guided stepping, which is parallel to visually guided arms movement, has been effective in some cases. Research has also been conducted on patients suffering from Multiple Sclerosis, many of whom have recovered due to implantation of electrodes. Some patients are found to have reported that their movement disorder have been corrected after surgery.

References:

http://en.wikipedia.org/wiki/Dysmetria

http://www.wisegeek.com/what-is-dysmetria.htm

http://www.mult-sclerosis.org/dysmetria.html

http://www.ncbi.nlm.nih.gov/pubmed/11061103

http://www.ncbi.nlm.nih.gov/pubmed/9613621

http://en.wikipedia.org/wiki/Ocular_dysmetria