Ataxia

Overview

Ataxia describes poor muscle control that causes clumsy voluntary movements. It’s usually a sign of a problem with an area of your brain, ears, or other parts of your nervous system. Ataxia is a condition that can impact various body parts and functions, including the fingers, hands, arms, legs, body, speech, and even eye movements.

Ataxia usually results from damage to the part of the brain that controls muscle coordination (cerebellum) or its connections. Many conditions can cause ataxia, including alcohol misuse, stroke, tumor, brain degeneration, multiple sclerosis, certain medications, and genetic disorders.

There are three primary types of ataxia, each with distinct underlying causes:

• Cerebellar Ataxia: This type occurs when there’s an issue in the cerebellum, the part of the brain responsible for coordinating movements and balance.
• Sensory Ataxia: Our brains have a special sense that helps us know where our body parts are, even without seeing them. Sensory ataxia disrupts this sense, making it difficult to understand where our body is in space.
• Vestibular Ataxia: This type is caused by a problem with the inner ears, affecting our sense of balance. When this happens, it becomes challenging to move smoothly and maintain stability.

Treatment for ataxia depends on the cause. Adaptive devices, such as walkers or canes, might help maintain independence. Physical therapy, occupational therapy, speech therapy, and regular aerobic exercise also might help.

Symptoms

Ataxia can appear suddenly or gradually over time. It is seen as a sign of several neurological conditions and may cause the following results:

• Impaired coordination
• Unsteady walking or walking with wide stance
• Poor balance
• Challenges with fine motor skills, such as eating, writing, or fastening buttons
• Altered speech pattern
• Nystagmus (involuntary eye movements)
• Difficulty in swallowing

Seek immediate medical attention if you experience symptoms like loss of balance, muscle coordination issues, difficulty walking, slurred speech, or trouble swallowing, as they may indicate ataxia.

Causes

Ataxia can arise from injury or dysfunction affecting the cerebellum, a vital brain region responsible for muscle coordination and its associated connections. Located at the base of the brain and attached to the brainstem, the cerebellum plays a crucial role in controlling balance, eye movements, swallowing, and speech.

There are three major groups of ataxia causes: acquired, degenerative disease and hereditary causes.

Acquired causes

Conditions that can develop or have an impact on people at different phases of their life are included among the acquired causes of ataxia. Some of these causes may be temporary or reversible, indicating that they can be resolved or overcome.

• Medications: Certain medications, particularly barbiturates like phenobarbital, sedatives such as benzodiazepines, antiepileptic drugs like phenytoin, and certain types of chemotherapy, have the potential to cause ataxia as a side effect.
• Alcohol:  Excessive and prolonged alcohol consumption can lead to persistent ataxia, but it may improve with complete alcohol avoidance.
• Heavy metal poisoning: Ataxia can also be caused by heavy metal poisoning, including exposure to lead or mercury, as well as by solvent poisoning, such as from substances like paint thinner.
• Stroke: A stroke may result in ataxia developing suddenly. This may be caused by either a blood artery obstruction or internal bleeding in the brain.
• Autoimmune diseases: Ataxia can be brought on by sarcoidosis, celiac disease, specific encephalomyelitis types, and other autoimmune disorders.
• Infections:  Ataxia can be a rare complication linked to childhood chickenpox and other viral infections, such as HIV and Lyme disease. It usually emerges during the recovery stage of the infection and may persist for a few days or weeks. Fortunately, ataxia signs and symptoms generally improve over time.
• Head trauma: Cerebellar ataxia can develop weeks to months after a severe brain injury, resulting in significant damage to the brain.
• Cerebral palsy: This term refers to a range of disorders caused by brain damage during early development – before, during, or shortly after birth – which impacts a child’s ability to coordinate body movements.
• Brain abnormality: Ataxia can be caused by the presence of an infected area (abscess) in the brain. Additionally, the presence of a brain tumor, whether malignant (cancerous) or benign (noncancerous), can lead to damage in the cerebellum and subsequent development of ataxia.
• Vitamins deficiency: Inadequate intake of essential vitamins such as vitamin E, vitamin B-1 (thiamine), vitamin B-12, or thiamine deficiency can contribute to the development of ataxia. Additionally, both deficiency and excess of vitamin B-6 can lead to ataxia. It is crucial to identify these causes as ataxia resulting from these deficiencies can often be reversible.
• Multiple sclerosis: Ataxia can be a potential manifestation of this neurological disorder.
  Thyroid disease: Ataxia can be caused by conditions such as hypothyroidism and hypoparathyroidism.
• COVID-19 infection: Severe cases of COVID-19 are most frequently associated with the development of ataxia.
• Paraneoplastic syndromes: These degenerative disorders are considered rare and initiated by an immune system response to a cancerous tumor (neoplasm), typically originating from lung, ovarian, breast cancer, or lymphoma. Prior for cancer diagnosis, ataxia may appear months or even years in advance.

Degenerative causes

• Multiple system atrophy: This condition commonly affects individuals in their early 50s. Apart from ataxia, it is also characterized by additional symptoms such as bladder incontinence, orthostatic hypotension (low blood pressure or fainting upon standing), and REM sleep behavior disorder (manifesting as yelling, kicking, or punching during sleep).

Hereditary causes

Some forms of ataxia and their causes are hereditary. If you have these conditions, it’s likely due to a gene mutation from birth that produces irregular proteins.

These abnormal proteins disrupt nerve cell function in the cerebellum and spinal cord, leading to their degeneration and worsening coordination problems over time.

Genetic ataxia can be inherited through either a dominant gene from one parent (autosomal dominant disorder) or a recessive gene from both parents (autosomal recessive disorder). In recessive cases, parents may not be affected, but affected siblings could be present.

Different gene mutations result in various types of ataxia, mostly progressive, each causing poor coordination with specific signs and symptoms.

• Autosomal dominant ataxia: Where a single copy of the gene from one parent can cause the disorder.
  • Spinocerebellar ataxias: Over 40 autosomal dominant ataxia genes have been identified by researchers, and the list continues to expand. All types of autosomal dominant ataxia share cerebellar ataxia and cerebellar degeneration, which are frequently accompanied by additional neurological signs and symptoms.
  • Episodic ataxia (EA): Episodic ataxia includes eight recognized types (EA1-EA7) and late-onset episodic ataxia. EA1 involves brief ataxic episodes triggered by stress or sudden movement, while EA2 features longer episodes triggered by stress. Symptoms may include muscle twitching, dizziness, fatigue, and muscle weakness. Episodic ataxia does not affect life span and can be managed with medication.
• Autosomal recessive ataxias: Where two copies of the gene (one from each parent) are required for the disorder to manifest. In the case of a recessive disorder, the parents themselves may not exhibit any symptoms, but there is a possibility of affected siblings being present.
  • Friedreich’s ataxia:  The most common hereditary ataxia is a condition that affects the cerebellum, spinal cord, and peripheral nerves. Symptoms often appear before age 25 and begin with difficulty walking, which then progresses to the arms and trunk. Deformities of the feet and spine curvature are common. Other possible signs include slurred speech, fatigue, involuntary eye movements, hearing loss, enlarged heart, and diabetes. Early treatment for heart problems can improve quality of life and survival. The cerebellum usually looks normal on brain scans.
  • RFC1 associated ataxia: Late-onset ataxia is commonly attributed to this particular cause. Ataxia symptoms frequently include dizziness, numbness, or tingling throughout the body, and on sometimes an unexplained cough.
  • Ataxia-telangiectasia.  This rare childhood disease causes degeneration in the brain and immune system, raising the risk of infections and tumors. Early signs include tiny red “spider” veins near the eyes, delayed motor skill development, poor balance, and slurred speech. Children may experience frequent sinus and respiratory infections. They are also at high risk of developing cancer, especially leukemia or lymphoma.
  • Congenital cerebellar ataxia:  This type of ataxia occurs due to congenital damage to the cerebellum.
  • Wilson’s disease: Copper builds up in the brain, liver, and other organs of those who have the condition. They might consequently experience ataxia and other neurological disorders.