Ataxia

Ataxia - What is Ataxia?

Ataxia is a form of movement disorder. There is loss of balance and physical co-ordination leading to difficulty in walking normally.

The Cerebellum of the brain is normally responsible for maintaining balance and co-ordination. Ataxia occurs when there is damage to the cerebellum. It may also result from damage to other parts of the nervous system.

Symptoms of ataxia

Ataxia leads to difficulty in balance, walking, speaking, vision, swallowing, performing tasks requiring high degree of motor control such as writing and eating etc.

The symptoms vary in intensity depending on the degree of damage to the parts of the brain regulating balance and co-ordination between motor movements.

What causes ataxia?

Ataxia is commonly caused by loss of function in the cerebellum. The cerebellum is located toward the back and lower part of the brain.

The central part of the cerebellum can control complex movements of walking, eye movements and stability of the head and trunk.

Other parts of the cerebellum help to coordinate smaller movements such as speech, eyes and swallowing.

Ataxia results when there is dysfunction in the pathways leading into and out of the cerebellum.

Types of ataxia

There are several types of ataxia which could be of over 100 types. Overall ataxia may be classified under three broad categories:-

  • Hereditary ataxia – one that runs in the families and is inherited genetically. The symptoms may develop slowly over many years
  • Acquired ataxia – the symptoms develop rapidly. This type of ataxia may occur due to injury to the brain or due to a stroke or other disease of the brain that affects movements and co-ordination.
  • Idiopathic late onset Cerebellar ataxia (ILOA) – in this type of ataxia the cerebellum is progressively damaged due to unexplained causes leading to ataxia.

Ataxia epidemiology

Of the three types of ataxia, acquired ataxia is the commonest type and is associated with brain infections or encephalitis, stroke and multiple sclerosis. All ages may be similarly affected.

Both hereditary and ILOA types of ataxia are relatively rare. The commonest type of hereditary ataxia is Friedreich’s ataxia that makes up for almost half the cases of hereditary ataxias. It affects an estimated 1 in every 50,000 people in England annually.

Hereditary ataxias may begin in childhood and progress as the child grows. ILOA on the other hand affects middle aged adults first.

Diagnosis and treatment of ataxia

Ataxia is diagnosed clinically. It is a symptom of an underlying cause rather than a disease in itself. Diagnosis is made using clinical examination as well as laboratory testing and imaging studies.

At present there is no cure for ataxia. If the underlying cause can be found, the disease may be treated using medications or approaches that ease the symptoms. For example, if ataxia is the result of a vitamin deficiency, the deficiency may be corrected to achieve symptom relief.

There are no specific treatments available for hereditary ataxia and ILOA and these tend to worsen over time. Treatment usually revolves around rehabilitation of these patients and making them as self sufficient or independent as possible for as long as possible.

Outcome or prognosis of ataxia

The cause determines the prognosis or outcome of ataxias. Those with hereditary ataxias, show a progressive deterioration. Individuals with Friedreich’s ataxia die in their thirties and more severe cases have a shorter survival.

Hereditary ataxia and ILOA generally progressively worsen whereas acquired ataxias may be sudden in onset and may resolve with time and treatment.

Ataxias after a stroke for example may become better as the brain areas related to motor coordination and movement heals.

Ataxia Types

Ataxia is the defect in normal movements like walking, speaking, eating swallowing etc. It is caused most commonly by damage to the brain stem or cerebellum that regulates movements.

Symptoms of ataxia

  • One of the earliest symptoms noticed in ataxia is loss of balance and co-ordination in the limbs. The limbs may feel numb or may lose strength altogether.
  • Walking becomes difficult as the sufferers may have to keep their feet apart to prevent falling over. A wheelchair may be required for transportation in most patients with ataxia sooner or later.
  • There is loss of co-ordination of fine motor activities such as writing, eating etc. the hands may shake when the person tries to use them.
  • As the condition progresses there is difficulty in speaking and the condition affects the mouth and the tongue. Speech starts to slur and becomes unclear. Slowly the capacity to swallow food becomes difficult with the person often choking on food.
  • There may be unusual and involuntary eye movements. The eyes roll upwards and below or sideways rapidly of their own accord. This is called oscillopsia.
  • Some ataxias also result in disturbance of bladder and bowel movements as well.
  • There may be cognitive or memory loss accompanied by depression and/or anxiety.

Three main types of ataxia

There are over 50 to 100 types of ataxia. Ataxias are classified under three broad headings:-

  • Hereditary ataxia – one that runs in the families and is inherited genetically. The symptoms may develop slowly over many years.
  • Idiopathic late onset Cerebellar ataxia (ILOA) – in this type of ataxia the cerebellum is progressively damaged due to unexplained causes leading to ataxia.
  • Acquired ataxia – the symptoms develop rapidly. This type of ataxia may occur due to injury to the brain or due to a stroke or other disease of the brain that affects movements and co-ordination.

Hereditary ataxias

Friedreich’s ataxia – this is the commonest type of hereditary ataxia and makes up for almost half of the cases of hereditary ataxias.

Symptoms usually first begin to appear in childhood between the ages of eight and 15 years. There is definitive deformity of the feet, such as high arches or abnormal curvature of the toes called hammer toes. In addition the spine may be curved to one side called scoliosis.

There is damage to the optic nerve resulting in blindness, and there may be hearing loss as well. Patients are often diabetic and may suffer from hypertrophic cardiomyopathy resulting in abnormal thickening of the muscles of the heart.

Ataxias due to vitamin A deficiency – this is a rare form of ataxia that begins in childhood. Lack of vitamin E leads to nerve damage. The symptoms are similar to Friedreich’s ataxia but the symptoms may be relieved by providing Vitamin E as supplements in the body.

Ataxia-telangiectasia – this is a rare type of hereditary ataxia and is seen in 1 in 100,000 babies. Symptoms usually begin in early childhood and progressively worsen with age.

The name of the condition is derived from the small, spider-like clusters of red blood vessels in the corner of their eyes and on their cheeks called telangiectases. This condition usually co-exists with a weak immune system making the children more vulnerable to infections.

By the age of 10 there is need for a wheelchair to move the child around. Many children with the condition also develop cancers like acute lymphoblastic leukaemia or lymphomas.

Spinocerebellar ataxias – are a variety of ataxias. These affect around one in every 100,000 persons. The symptoms usually manifest once the person reaches adulthood. The symptoms may be first seen when the person is in his or her 30’s or may begin when he or she is in their 70’s. Occasionally some types of spinocerebellar ataxias may begin in childhood as well.

The condition is manifested by muscle cramps and stiffness, lowered sensation of hands and feet, memory loss or difficulties in language, urinary incontinence, slow eye movements, restless legs syndrome, migraine, vertigo and progressive loss of vision.

Episodic ataxia – this is another rare type of hereditary ataxia. There are bouts or episodes of ataxia interspersed with normal periods with no ataxia. Bouts may last for minutes to hours.

Bouts come after specific triggers such as stress, exercise or excitement. The symptoms begin in adolescence and may disappear completely after the person reaches middle age.

Acquired ataxias

The symptoms are similar to hereditary ataxias but they are rapid in onset. In addition they may result after certain diseases or conditions such as strokes, multiple scleroses etc.

Idiopathic late onset cerebellar ataxia (ILOA)

These ataxias are rare and generally begin around the age of 50 and then progressively worsen with time. There are symptoms affecting walking, balance, disturbed sleep, double vision, cognitive changes, memory loss, and urinary incontinence. etc.

Ataxia Causes

Ataxia is mainly caused by damage to the part of the brain that deals with movement, coordination and balance. The condition is a symptom of an underlying disease rather than a disease in itself.

Normal brain functioning in movement and motion

The cerebellum is located towards the back and lower part of the brain.

The right side of the cerebellum controls movement and coordination in the right side while the left side controls the left side of the body.

The central part of the cerebellum can control complex movements of walking, eye movements and stability of the head and trunk.

Other parts of the cerebellum help to coordinate smaller movements such as speech, eyes and swallowing.

The signals from the limbs and other peripheral organs reach the brain and cerebellum via the nerves in the spinal cord.

It is the spinal cord that carries these signals away from the cerebellum to the limbs and instructs them to function adequately to result in normal co-ordinated movements.

Pathology of ataxias

Ataxias result when there is damage to the cerebellum or the connections in the spinal cord. This damage may be the result of an injury or illness like stroke as is seen in acquired ataxia or due to a degenerative condition affecting the cerebellum and spinal cord as is seen in hereditary ataxias.

In small number of cases no cause may be found. These are classified under idiopathic late onset Cerebellar ataxia (ILOA).

Causes of hereditary ataxia

These types of ataxias result from genetic mutations. Defective genes may be passed on from parents to their offspring.

Sometimes one or both of the parents might be a carrier of the defective gene with no apparent deformity or difficulty. The child inherits the defective gene and may manifest the condition.

It is estimated that around 1 person in every 75 is a carrier of the mutated gene that causes Friedreich’s ataxia and around 1 person in 100 carries the mutated gene that causes ataxia-telangiectasia.

If both parents are carriers of the autosomal dominant defective gene, there is a 25% chance that the baby will have either normal genes or a pair of mutated genes and go on to develop the ataxia.

There is a 50% chance that the baby will have a single abnormal gene and become a carrier without developing ataxia.

If both parents are carriers of the autosomal recessive gene, there is a 50% chance that the baby will receive one normal gene and one mutated gene and become a carrier and a 50% chance that the baby will receive a pair of mutated genes and go on to develop ataxia.

Causes of acquired ataxia

These ataxias usually result due to underlying causes unlike the other two types of ataxias – hereditary and ILOA. Some of the causes of acquired ataxias include:-

  • Injury to the brain due to severe head injury. This could damage the cerebellum or the spinal cord or the interconnecting links between them. A car crash or a fall may cause this type of damage.
  • Infection of the brain or encephalitis. After a bacterial infection that affects the brain or a viral infection like chickenpox or measles that can affect the brain, ataxias may result. Ataxias after viral infections are uncommon.
  • Cerebral palsy may distort a child’s brain growth and development and lead to ataxias.
  • Ataxias may be seen after a stroke. This may be caused when a vital part of the brain is deprived of blood (ischemic stroke) or a vital part of brain is flooded with blood after a blood vessel rupture (hemorrhagic stroke). After a transient ischemic attack (TIA) ataxia may be seen. This is also called a mini-stroke.
  • Multiple sclerosis – this condition damages the nerves and may lead to ataxia with time.
  • Some cancers and diseases of the thyroid gland (underactive thyroids) may also result in ataxia.
  • Defective immune system disorders like lupus may also cause ataxia.
  • In children epilepsy or seizures may cause ataxia. Usually an underlying brain development problem may be the cause of ataxia in these children.
  • Long term alcohol abuse or exposure to toxins and toxic chemicals and heavy metals like mercury, lead, solvents, pesticides etc. may also trigger ataxias.
  • Some medicines like benzodiazepines used as sleeping aids or tranquillizers may also lead to ataxia as a side effect.

Ataxia Treatment

Ataxia has no cure. There are no medications that can specifically treat and cure the symptoms of ataxias. However, medications may ease the symptoms by treating the underlying condition that causes the ataxia.

The aim of treatment of ataxia is to improve the quality of life though patient education and provision of aids and devices to maintain self sufficiency and independence for as long as possible.

Ataxias due to underlying causes may be treated by treating these underlying causes that include stroke, a low vitamin E level or exposure to a toxic drug or chemical.

Treatment also revolves around managing the co-existing conditions such as muscle cramps, stiffness, tremor, spasticity as well as depression, anxiety, sleep disorders etc.

Ataxia management team

Ataxia is managed by a team of specialists in different fields. This is called the multi-disciplinary team.

A usual team of specialists who treat ataxias include a neurologist (one who specializes in diseases of the brain and nervous system), an ophthalmologist or eye specialist, a urologist who treats problems like urinary incontinence in these patients, a cardiologist or heart specialist who deals with cardiomyopathy in ataxia patients, a physiotherapist, a speech and language therapist, a psychologist, an occupational therapist, a social worker, diet advisor and a specialist neurology nurse.

A geneticist or a genetic counsellor may be part of the team dealing with hereditary ataxias.

Treatment of ataxias

Symptomatic treatment - Some types of hereditary ataxias may be treated by easing the symptoms. This however does not cure the situation. For example in patients with episodic ataxia type 2, symptomatic relief may be obtained by treating with acetazolamide. Similarly ataxia with vitamin E deficiency may be treated with vitamin e supplements.

Physiotherapy - Physiotherapy helps prevent muscles from weakening or becoming stiff and spastic. This is achieved with a number of physical exercises that strengthen the muscles and maintain flexibility. Special braces may be prescribed to stretch the muscles.

Speech and language therapy - With progression of ataxia there may be slurring of speech and difficulty in communicating. A speech and language therapist may help in preventing these problems to a great extent.

In addition the therapist may also help with difficulties in swallowing. This may be achieved by performing several exercises that can stimulate the nerves used in the swallowing reflex and strengthen the muscles of swallowing.

Nutrition advice - A nutrition advisor may help develop a diet plan for these patients. With worsening swallowing reflexes, eating becomes difficult resulting in malnutrition. A diet plan that includes healthy and balanced options helps prevent malnutrition.

Occupational therapy - Occupational therapy helps the patient maintain as much self sufficiency and independence as possible for as long as possible. It helps patients adapt to their gradual loss of mobility and develop new skills to perform daily activities independently.

The occupational therapist helps patients adopt and use successfully wheelchair and walking aids (crutches), guiderails, stair lifts etc.

Medications for muscle stiffness, spasticity, cramps and pain - Patients with muscle spasms, cramps, pain and stiffness are treated with medications that are termed muscle relaxants. These agents include baclofen or tizanidine. Muscles can be loosened up by injections of botulinum toxin or botox as well. The effects of the injection normally last for up to three months.

Gabapentin

Involuntary eye movements of oscillopsia may be treated using medications such as gabapentin. Gabapentin helps control the eye movements. Double vision is corrected by using special lenses called prism lenses.

Sleeping aids

Tiredness and fatigue may be seen in ataxia patients. This could be due to disturbed sleep. Patients with multiple sclerosis may experience severe fatigue. This may be treated using sleeping aids like benzodiazepines and physiotherapy.

Antimuscarinics

Medications may also be prescribed for urinary incontinence and bladder difficulties seen in hereditary ataxias. These agents are antimuscarinic and help relax the bladder and reduce the urge to urinate frequently. The bladder may be catheterized (a small tube is inserted into the bladder via the urethra) in order to drain out the collected urine.

PDE-5 inhibitors

Erectile dysfunction may be seen in some patients with ataxia. This can be treated using medications known as phosphodiesterase-5 (PDE-5) inhibitors including Sildenafil.

Pain relievers

Nerve pain is seen as burning, aching or rapidly moving pain along with tingling and numbness in the affected areas. This can be treated with little efficacy using pain relievers like non steroidal anti-inflammatory drugs (NSAIDs) including ibuprofen, diclofenac, paracetamol etc. Agents that are more effective in treating nerve pain include amitriptyline, gabapentin or pregabalin.

Cardiomyopathy

Cardiomyopathy may result in certain ataxias. It is commonly seen in Friedreich’s ataxia resulting in abnormal thickening of the heart muscles. Left untreated it may result in heart failure and arrhythmias. Cardiomyopathy is difficult to treat and has no cure.

Antidepressants and cognitive behavioral therapy

Depression is seen with many of the long term conditions. It is commonly seen after stroke and in movement disorders like ataxia that severely limit activities of daily living and increase dependence on others for routine activities. Depression may be treated using antidepressant medications as well as cognitive behavioral therapy.

Occupational and physiotherapy

Idiopathic late onset cerebellar ataxia (ILOA) is treated similarly as hereditary ataxias using occupational and physiotherapy and providing symptom relief.

Treatment based on cause

The recommended treatment for acquired ataxia depends of the cause of the ataxia. Ataxias caused due to infections for example may be treated with antibiotics. In patients with ataxias after a stroke or a head injury the symptoms may persist until the brain has recovered from the injury. Recovery may be of varying degrees.