Introduction

According to ataxia.org.uk, at least 10,000 adults and 500 children in the UK have a progressive form of ataxia.^{1, 2} Many types of ataxia can affect different people in different ways. In most cases, ataxia is permanent and is a lifelong condition that can affect your quality of life and worsen over time. Depending on the ataxia type, the condition can appear in early childhood or later in life and decrease your life expectancy. 

Overview of ataxias

Generally, ataxia is a broad term covering many disorders affecting muscle coordination, speech, and balance. People with ataxia will have many different symptoms as a result that will affect their quality of life. It can not only affect your ability to do tasks that require a lot of control such as writing or typing but could can also affect your eating as you may struggle to swallow. Ataxia can affect three parts of your nervous system which are the cerebellum, the sensory system, and the vestibular system.³ The cerebellum is a part of the brain that is primarily involved in regulating your movement and balance. The sensory system is responsible for your awareness of the surrounding environment and the vestibular system is responsible for helping you sense your position and create a sense of balance. 

It is important to note that ataxia itself isn’t exactly classified as a disease but is rather a symptom of disorders and other diseases that can be caused by 2 main ways.^{3, 4} In this article, we will talk about the two types of ataxias that are commonly known. These two types are:

• Hereditary ataxia
• Acquired ataxia

Knowing the difference between the two will help determine the cause which can help with diagnosis and treatment of the disorder.

Hereditary ataxias

This is where a faulty mutated gene is inherited that directly affects the nervous system in your body causing the ataxia. This itself has two main ways it can be inherited:

• Autosomal dominant
• Autosomal recessive

Autosomal dominant

A mutated gene has been inherited from either the mother or the father and the effect of this gene is expressed more dominantly than the other gene that has been inherited. So, if the father has the mutated gene “A” whilst the mother has the normally functional gene “B”, the mutated gene “A” could have the ability to overcome the normal gene “B”.⁴

Autosomal recessive

Both parents can pass down a faulty mutated gene to their children which means that a child can develop ataxia if both the genes they inherit are the mutated gene. If they inherit only one of the mutated genes and inherit a normal gene, then the normal gene will override the mutated gene and the child will be able to live normally. This means that they will only be classified as of the gene which could be passed down to their children if their partner also has the mutated gene. If you do happen to carry the faulty gene but the partner doesn’t, the effects of your faulty gene will not be able to take place in the children as it is not dominant.⁴

Examples of hereditary ataxias

• Friedreich’s ataxias
• Episodic ataxias
• Spinocerebellar ataxias
• Ataxia-telangiectasia

Friedreich’s ataxias

Friedreich’s ataxia is the most common form of hereditary ataxias where nerve cells in the spinal cord and peripheral nerves breakdown. As they break down over time, symptoms generally begin to show between ages 15 and 25 and worsen as the patient ages. This can significantly shorten their lifespan with most people dying in their 30s whilst some can live well into their 60s.^{4, 5}

Some of the signs and symptoms include:

• Slurred speech
• Diabetes
• Abnormal spine curvature
• Having trouble balancing and doing fine movements
• Loss of sensation
• Clumsiness

Episodic ataxias

A rare form of ataxia where the disorder occurs in episodes for brief periods. They generally affect the cerebellum causing problems in balance and coordination whilst also being very unpredictable. These usually don’t last very long but can slowly worsen over time or disappear without affecting life expectancy. Sometimes stress or strenuous physical activity can act as triggers.^{4, 6}

Some of the signs and symptoms during an episode include:

• Slurred speech
• Ringing in the ears (tinnitus)
• Loss of balance and coordination
• Double vision
• Muscle spasms
• Vertigo (feeling as if the room is spinning)

Spinocerebellar ataxias

A form of ataxia that begins during adulthood directly affects the hindbrain which is made up of the pons, cerebellum, medulla, and spinal cord. Within 10-12 years of diagnosis, spinocerebellar ataxias can cause the patient to be wheelchair-bound. This can be fatal for some whilst others can still live an average lifespan.^{4, 6,7}

Some of the signs and symptoms include:

• Increasingly slurred speech
• Slow eye movement
• Reduced bladder control
• Cognitive problems
• Increasing loss of balance and coordination

Ataxia-telangiectasia

This form of ataxia tends to develop during childhood before the age of 5. It mainly affects the spine and the immune system and increases the risk of cancer. They can also develop lymphoma and or leukemia. This does gradually worsen as they age but with earlier diagnosis and treatment, they can survive into their 50s.^{4, 8}

Some of the signs and symptoms include:

• Increasing loss of balance and coordination
• Increasingly slurred speech
• Red “spider” veins around the ears, cheeks, and eyes
• Diabetes
• Difficulty swallowing

Acquired ataxias

These are ataxias that are acquired from external environmental factors. Many factors can contribute to the development of ataxia other than inheritance. More often than not, factors that directly affect the hindbrain may cause some form of ataxia. These can be either reversible or irreversible depending on the damage caused. As you may have already guessed, this can happen at any age and is often very sudden. The signs and symptoms of ataxia are generally the same throughout.⁴

Causes of acquired ataxia

• Traumatic Brain Injury (TBI)

Effects of trauma on the cerebellum or spinal cord can cause degeneration of these tissues⁴

• Stroke

A stroke can cause blood flow to the cerebellum to be blocked which can cut off the oxygen supply to this part of the brain. According to Jeremy Schmahmann from the National Ataxia Foundation, about 24,000 cases of stroke occur in the cerebellum⁹

• Infections

Viral Infections: Examples e.g. chickenpox (varicella), HIV, and others.

Bacterial Infections: Lyme disease, syphilis, and others. These viral infections can directly damage the cerebellum and spinal cord⁴

• Toxic Exposure

Alcohol abuse, drug toxicity, mercury, and other heavy metals can trigger ataxia⁴ 

• Paraneoplastic Syndromes

This group of syndromes can cause cerebellar degeneration which develops further over time¹⁰

• Vitamin deficiencies

According to the NHS, a deficiency in vitamin B12 can cause damage to parts of the nervous system causing ataxia.¹¹ A deficiency in vitamin E can also cause ataxia as vitamin E is a major source in protecting cells from free radicals.¹²

Conclusion

Ataxias are a group of disorders that affect your ability to balance, coordinate movement, and speak. Ataxia can be either inherited or acquired during your lifetime and both generally have the same symptoms with some symptoms being unique to each type. Inheriting ataxia will cause a lifelong condition that requires tailored and specific treatment. However, it can't be treated. The earlier the diagnosis the better the outcome of the treatment will be. Acquiring ataxia is usually preventable but other acquired diseases such as multiple sclerosis can increase your chances of attaining the disorder. 

In most cases of acquired ataxias, these can be prevented and reduced with effective diet and exercise, but if you ever feel any symptoms and signs, immediately consult your doctor or call 999. More information can be found on ataxia.org.uk. There is also a helpline open from Monday to Thursday 10:30 am to 2:30 pm by calling 0800 995 6037 or by emailing help@ataxia.org.uk.