Ataxia

Most often cerebellar ataxia is caused by loss of function in the cerebellum, which is the part of the brain that serves as the coordination center. The cerebellum is located toward the lower posterior part of the brain. The right side of the cerebellum controls coordination on the right side of the body while the left side controls coordination in the left part of the body. The central part of the cerebellum controls the very complex movements of gait or walking, head and trunk stability and eye movements. Other parts of the cerebellum help to coordinate eye movements, speech and swallowing.

Cerebellar ataxia may also be caused by dysfunction of the pathways leading into and out of the cerebellum. Information comes into the cerebellum from the spinal cord, and other parts of the brain and signals from the cerebellum go out to the spinal cord and to the brain. Although the cerebellum does not directly control strength, (motor function) or feeling, (sensory function) the motor sensory pathways must work properly to provide the correct input into the cerebellum. Thus, a person with impaired strength or sensation may notice clumsiness or poor coordination and may be diagnosed with cerebellar ataxia.

There are many causes that could affect the function of cerebellum. These causes could be classified into 10 categories: developmental (e.g. cerebellar hypoplasia); hereditary (e.g. Friedreich ataxia); vascular (e.g. cerebellar hemorrhage); toxin-associated (e.g. alcohol); medication-associated (e.g. anticonvulsants); neoplastic (e.g. cerebellar tumor); infectious (e.g. encephalitic bacterial infection); immune-associated (e.g. multiple sclerosis); metabolic and nutritional (e.g. deficiency in vitamin E). read more

The disease is characterized by progressively disabling clinical manifestations. Patients show symptoms of gait instability or dysarthria and may begin to fall without warning. Gradually they present progressive limitations in their activities, lose the ability to walk, become bedridden and fully dependent. Other clinical manifestations include astasia, impaired fine motor skills and intention tremor (cerebellar tremor). The cerebellar syndrome is often associated with other neurological signs such as pyramidal or extrapyramidal signs, ophthalmoplegia, and cognitive impairment.

Most people don’t know what cerebellar ataxia is and may overlook the early symptoms. Anyone with progressive gait disorder or imbalance should be evaluated by a neurologist. MRI is recommended in all cases. If a treatable cause is not discovered, a gene test should be done. In about 60 percent of the cases, the gene test will determine the type of ataxia.

Until now, conventional treatments are generally used to alleviate the symptoms, not the disease itself. The movement disorders can be managed using pharmacological, physical and occupational therapies to minimize the damage and to promote the mobility as long as possible but overall current treatment remains retardant.

Autosomal dominant and autosomal recessive ataxias are hereditary ataxias, and spinocerebellar ataxia (SCA) and Friedreich’s ataxia (FRDA) are the most common forms of hereditary ataxia. Autosomal dominant genes express themselves when present. Autosomal recessive genes will only express themselves when in the homozygous state — i.e., both genes in the gene pair are the recessive gene form. Thus, recessive genes can be “carried” by those whose phenotype does not exhibit the gene characteristic, while dominant genes cannot be “carried”. Therefore, generally autosomal dominant ataxias are easier to express and at a higher morbidity than autosomal recessive ataxias.

Purkinje cells are a type of neuron found in the cerebellar cortex, at the base of the brain. They are among the largest neurons and are responsible for most of the electrochemical signaling in the cerebellum. The Purkinje cells and the cerebellum are essential to the body’s motor function. Disorders involving the Purkinje cells usually negatively affect the patient’s movements.