Overview 

Ataxia is a Greek word meaning "without order". It refers to a group of neurological disorders in which there is damage to an area of the brain responsible for balance called the cerebellum.¹ It is commonly characterised by:

• Clumsy walking 
• Uncoordinated hand movement affecting ordinary functions like writing. 
• Speech problems 
• Vision problems 
• Difficulty swallowing²

Ataxia can be categorised as hereditary, meaning they have a genetic cause, or acquired, meaning it is triggered by environmental factors or another condition. Diagnosis, treatment and prognosis depend on the cause and type of ataxia.

In this article, we are going to explore the different causes of ataxia. This is not designed to replace medical advice, please contact your GP if you are concerned about any of the symptoms. 

Hereditary ataxias

Hereditary ataxias are caused by genetic mutations. Genetic mutations may be inherited from parents or may develop spontaneously. Hereditary ataxia usually occurs in childhood.

There are different types of hereditary ataxias based on which gene is affected: Autosomal dominant ataxia.

In autosomal dominant inheritance, only one copy of the faulty gene is needed to cause the disease, meaning that it will be inherited if either parent carries the gene.¹

They include: Spinocerebellar ataxia (SCA)SCA is a large group of disorders caused by numerous gene mutations. In SCA, there is degeneration of the cerebellum and death of the cells of the brain stem, the part connecting the brain to the spinal cord. SCA is often a progressive disorder, meaning symptoms tend to worsen with time, but the rate of progress depends on the type of ataxia. It presents in early adulthood. 

Symptoms include: 

• Abnormal gait 
• Speaking difficulty 
• Disturbed vision 
• Tremor 
• Slow movement 
• Cognitive impairment³

Primary episodic ataxias 

Episodic ataxia usually presents in childhood or adolescence. It comes in the form of recurring brief bouts that resolve to then repeat again. The episodes are either triggered by stress or sudden movement.

Symptoms include:

• Unsteady gait 
• Dizziness 
• Nystagmus: abnormal eyeball movement⁴

Autosomal recessive ataxia 

In autosomal recessive inheritance, two copies of the faulty gene are needed from each parent to cause the disease.

Friedreich’s ataxia (FA) 

The most common form of ataxia, FA, manifests in early life (between 5 and 20 years old ) and progresses with age. In FA there is degeneration of the nerve cells of the central nervous system in the cerebellum and the spinal cord, but also in the peripheral nervous system in nerves affecting the arms and legs. The earliest and most common feature is unsteady gait, movement problems, and loss of sensation;⁴ however, FA may also present with:

• Heart enlargement and dysfunction: the leading cause of death 
• Scoliosis: abnormal curvature of the spine 
• High-arched arched foot: the foot doesn't flatten with pressure, leads to walking discomfort 
• Diabetes mellitus (DM)⁵ ​

Ataxia telangiectasia 

Ataxia telangiectasia is a rare disorder that occurs in early childhood. Children experience balance problems and tiny dilated spider-like blood vessels in the eyes and the skin. 

Children with ataxia-telangiectasia have weakened immunity and an increased likelihood of developing cancer.⁶ ​

X-linked cerebellar ataxia

It is associated with Fragile X syndrome, and symptoms include tremor and cognitive impairment. The mutation is also known to cause intellectual disability, autism spectrum disorder and primary ovarian insufficiency in people assigned female at birth.⁴

Mitochondrial cerebellar ataxia

The mutation is passed exclusively from the mother. It is often characterised by epileptic seizures, muscle weakness and twitches.⁴

Acquired ataxia

Ataxia disorders that develop over the lifespan and are not associated with genetic mutations are referred to as acquired ataxias. These can be broadly split into autoimmune, toxic, infectious and vitamin deficiency causes.⁷

Autoimmune causes

In autoimmune conditions, an individual’s immune system mistakenly attacks healthy cells, causing disease symptoms. In autoimmune ataxia, this autoimmune response affects the cerebellum and other areas of the brain responsible for balance, leading to degeneration. 

Several immune-mediated conditions result in ataxia, including: 

Gluten ataxia 

Gluten is a food constituent found in some grains like wheat. Some people develop sensitivity to glut, a condition known as Coeliac disease. Coeliac disease is an autoimmune condition, where immune cells damage the lining of the gut. It is characterised by digestion-related symptoms, such as stomach upset, diarrhoea and constipation after ingesting gluten products. It may cause gluten ataxia. This causes symptoms such as clumsiness, poor coordination and slurred speech. It is treated with a gluten-free diet.⁷

Paraneoplastic neurological syndromes (PNS) 

PNS are rare conditions that happen to people with cancerous tumours. The immune system mistakenly attacks healthy cells that are similar to the cancer cells, including those in the cerebellum, leading to paraneoplastic cerebellar ataxia. 

Symptoms include rapidly progressive and include double vision, unsteady gait and difficulties with hand movements. Early and prompt treatment of the tumour controls the symptoms of ataxia. Treatment often involves Immunosuppressive therapy such as corticosteroids.^​8

Multiple sclerosis (MS)

Multiple sclerosis is another autoimmune condition, where the immune cells attack the fatty sheath called myelin covering the nerves of the brain and the spinal cord. This leads to plaques, disrupting their function. This causes a wide range of symptoms, including loss of vision, difficulty chewing and swallowing, loss of bladder and bowel control, altered sensations and mental health problems.⁹

If this autoimmune response affects the cerebellum, it can cause ataxia, leading to shakiness, clumsiness, speech problems and impaired eye movements.¹⁰ ​

Toxic causes

Toxic substances can cause death or dysfunction in the cells of the central nervous system, including the cerebellum, causing ataxia. This includes: 

Alcohol 

The most common cause of acquired ataxia is chronic alcohol abuse. Chronic alcohol abuse can lead to thiamine (vitamin B1) deficiency, causing Wernicke–Korsakoff syndrome. This is characterised by alcoholic cerebellar degeneration (shrinkage of the cerebellum, known as atrophy), and ataxia. The early stage is called Wernicke’s encephalopathy, and is characterised by:

• Anxiety 
• Fatigue
• nausea/ vomiting
• Memory loss 
• Blurred vision

Later symptoms include: 

• Abnormal rhythmic eye movement or paralysis 
• Gait disturbance, leading to difficulty walking
• Speaking difficulty
• Confusion

The condition is best managed with alcohol cessation and vitamin B1 supplementation.^7,11

Medication

Both prescription medication and non-prescription drugs can cause ataxia. Onset occurs within days to weeks and can be reversible or irreversible. Medication may cause new symptoms of ataxia or worsen a preexisting cerebellar ataxia.

Medication that can cause ataxia includes:

• Anti-seizure medications: used to control epilepsy, such as phenytoin and sodium valproate 
• Amiodarone: for stabilising the heart’s electrical activity 
• Immunosuppressants: tacrolimus and cyclosporine
• Psychiatric drugs: for the treatment of bipolar disorder, such as lithium 
• Antibiotics: like metronidazole⁴ ​
• Non-prescription drugs: Cocaine, heroin and methadone.¹²

Treatment of ataxia involves discontinuation or dose adjustment of the medication. 

Chemical toxins

Chemical toxins such as benzene derivatives and heavy metals such as mercury, thallium and manganese can cause ataxia. 

Vitamin deficiencies

Vitamin deficiencies can cause ataxia, due to their integral role in neuronal function, activity and stability. 

The deficiency may be caused by inadequate nutritional intake or poor bodily absorption. Treatment typically involves supplementation of the deficient vitamin, which may reverse symptoms of ataxia if identified early.

Vitamin deficiencies that can cause ataxia include: 

Vitamine B1 (thiamine)

Thiamine deficiency may be caused by alcoholism, as described above, but may also be caused by malnutrition from eating disorders such as anorexia, gastric bypass surgery, treatment for kidney disease or chronic diarrhoea. The deficiency can cause ataxia as part of Wenicke-Korsakoff syndrome. Treatment involves thiamine replacement therapy.⁷

Vitamin B12 

Deficiency may be caused by poor diet or an autoimmune condition called pernicious anaemia. It may also develop as a result of medication such as metformin, which is used to treat diabetes. B12 deficiency can affect the cerebellum, leading to cerebellar ataxia. This is often characterised by sensory disturbances. Treatment involves early supplementation.

Vitamin E 

Vitamin E deficiency typically occurs in children aged 5 to 15 years old. Ataxia is progressive and characterised by clumsiness and changes to proprioception (awareness of bodily movements in space). It is most commonly a result of reduced vitamin absorption in the gut.^7,13

Infectious causes 

Ataxia may also be caused by an infection, which can trigger an inflammatory process such as acute cerebellitis. This is rare, but is more common in children. One of the symptoms includes instability while sitting, This may be caused by infections such as: 

• Chickenpox 
• Mumps
• Infectious mononucleosis: a viral infection also known as glandular fever⁷​
• Creutzfeld-Jakob disease⁴

Other causes

Other causes of ataxia may include age-related degenerative, brain malformations, trauma or hyperthermia^14,15. In some cases, the cause may be unknown.

FAQs

Can a person have more than one cause of ataxia? 

Yes, multiple causes can coexist in an individual. For instance, a person can have a genetic predisposition to develop ataxia with the right environmental or autoimmune trigger or may have a preexisting ataxic condition that is exacerbated by another. 

Summary 

Ataxia is a group of neurological conditions characterised by disordered muscle coordination, abnormal gait, visual and speech changes. Ataxia is often a sign of cerebellar damage, and may be caused by genetic, autoimmune and environmental factors. Diagnosis and treatment depend on the cause of symptoms, and early identification is essential. Ataxia may be reversible in some cases, but there is no curative treatment