Ataxia is a neurological disorder that affects the cerebellum, the part of the brain that controls muscle coordination. In patients with ataxia, damage and degeneration of cells in the cerebellum lead to a lack of control of voluntary movements, like walking, and can also affect speech, eye movement and swallowing.
Causes of Ataxia
Ataxia has a great many possible causes. In some cases, the disorder is genetic, while in others it results from a disease condition or injury.
In a disorder known as congenital cerebellar ataxia, the damage to the cerebellum is present at birth. An individual can inherit either a dominant gene from one parent (autosomal dominant) or a recessive gene from each parent (autosomal recessive). Patients who receive two recessive genes may do so when there has been silent mutation, meaning there is no evident family history of the disorder.
A number of disease conditions can damage the central nervous system, affecting movement and coordination. These include:
- Cerebral palsy
- Multiple sclerosis (MS)
- Chicken pox or other viral infections
- Paraneoplastic syndromes, responses to malignant tumors
The rare cases of ataxia triggered by viral infections are usually transitory, resolving within days or weeks after recovery from the illness. Paraneoplastic syndromes, the symptoms of which may appear well before the malignancy is diagnosed and may be ongoing, most commonly occur due to cancer of the lung, breast, ovaries, or lymphatic system.
Traumatic Injuries and Medical Events
Head trauma may be severe enough to damage the brain or spinal cord, resulting in acute cerebellar ataxia. Ataxia may also be triggered by a temporary decrease in blood supply to the brain as a result of a transient ischemic attack (TIA), in which case the ataxia is temporary, or by a stroke in which brain tissue deprived of oxygen and nutrients actually dies. In the latter case, ataxia may be a permanent condition.
Toxic reactions to certain medications, especially barbiturates and sedatives, can also cause ataxia. Patients may also develop ataxia as a result of alcohol or drug abuse, or from solvent poisoning. The accumulation of heavy metals, such as lead, mercury, or copper (Wilson disease) in the brain or liver may also result in the condition.
Individuals deficient in vitamin E or vitamin B-12, often due to an inability to absorb these substances, may also develop ataxia.
In some cases, the neurological disorder is referred to as sporadic degenerative ataxia, meaning it cannot be traced to any specific cause.
Symptoms of Ataxia
Ataxia may have a gradual or sudden onset. It is typically characterized by more than one of the following:
- Poor coordination
- Unsteady gait
- Tendency to stumble
- Slurred or otherwise impaired speech
- Nystagmus (rapid involuntary eye movements)
- Difficulty swallowing
Patients with ataxia may also have difficulty performing tasks that involve fine motor skills, such as writing, drawing, or buttoning.
Diagnosis of Ataxia
Ataxia is diagnosed by physical examination and observation, usually followed by imaging tests, such as CT and MRI scans and a lumbar puncture, also known as a spinal tap. In many cases, the doctor may advise the patient to have genetic testing as well in order to rule out or confirm hereditary ataxia. Genetic tests are not yet available for all forms of hereditary ataxia.
Treatment of Ataxia
Some cases of ataxia, particularly those caused by viral infections, resolve on their own, so no treatment is necessary. For most other types of ataxia, there is no treatment that will cure the condition. Nonetheless, there are treatments that may help patients navigate their lives, including adaptive devices, such as canes, walkers, adaptive eating utensils, and communication aids. Patients with ataxia may also benefit from physical, occupational, speech and swallowing therapy.