Episodic Ataxia: A Rare Neurological Condition Causing Episodes Of Unsteadiness And Incoordination

Overview

Episodic ataxia is a rare hereditary neurological disorder characterized by recurrent episodes of unsteadiness and lack of coordination, collectively known as ataxia. This condition involves brief periods during which individuals experience significant difficulty with muscle control and balance. These episodes can last from seconds to hours and are interspersed with periods of mild or no symptoms.

 Episodic ataxia is caused by genetic mutations(changes in the genes) that disrupt the function of ion channels in nerve cells, which are crucial for normal electrical transmission in the brain. The condition is typically inherited in an autosomal dominant manner, meaning a single copy of the mutated gene from an affected parent is sufficient to cause the disorder. 

The most common types of episodic ataxia, namely EA1 and EA2, involve mutations in potassium and calcium channels, respectively. While EA1 episodes are usually brief, EA2 episodes can last much longer. This article will further explore the causes, types, symptoms, diagnosis, and treatment options for episodic ataxia, providing a comprehensive understanding of and insight into this rare neurological(nervous system) condition.

Understanding episodic ataxia

What is episodic ataxia?

Episodic ataxia is a rare and unusual hereditary neurological condition marked by recurring episodes of body instability and lack of coordination, also known as ataxia. Ataxia is a condition characterised by a lack of muscle coordination, while the term episodic ataxia refers to patients having episodes of ataxia, while most of the time having mild to no symptoms.¹ There are various types of episodic ataxia with different specific symptoms and durations, with episodes lasting anywhere from seconds to hours depending on the type. These different types will be further explored in this article. 

Cause and origin

Episodic ataxia is a genetic condition, meaning it runs in families and is inherited from parents. The cause of episodic ataxia is a gene mutation, which is responsible for the function of certain ion channels in your nerve cells. These ion channels are incredibly important for the normal transmission of electric signals in your brain. When these ion channels have their functions changed due to the inherited mutated gene, the electric signals may be disrupted, leading to episodes of impaired neuronal function.²

These genes are often inherited in an autosomal dominant manner, meaning if one parent has the mutated gene, the child will inherit and manifest the mutated gene.²

Types of episodic ataxia

Episodic ataxia type 1

Symptoms of episodic ataxia type 1 (EA1) often include incoordination and disturbed balance with involuntary movement or rippling of the muscles or muscle spasms. There may also be twitching or tremors in the face and hands. The attack duration is usually quite short and only lasts seconds to minutes, and it is associated with a mutation in the gene KCNA1, and a mutation in the potassium channels. The mutation in potassium channels leads to abnormal firing and excitation of the nerves, which can cause sudden disruptions in the control of voluntary muscles.³

Common Symptoms:³

• Vertigo(loss of balance)
• Difficulty speaking (dysarthria)
• Weakness
• Tremor
• Seizure

Episodic ataxia type 2

Episodic ataxia type 2 (EA2) is often associated with muscle weakness, instability in the torso(trunk), and possibly dizziness and fatigue.⁴ Involuntary jerky eye movement is common and may happen between episodes. The attack duration of EA2 is significantly longer than EA1, with episodic attacks lasting anywhere from 30 minutes to 6 hours.⁴ The gene mutation associated with EA2 is in the gene CACNA1A,³ and the associated mutant protein is the calcium channels, with an impaired calcium channel leading to defects in transmission within the nerves, especially in the cerebellum(a part of the brain). This is particularly important for coordination and balance.⁵

Common Symptoms:³

• Vertigo
• Difficulty speaking (dysarthria)
• Double vision (diplopia)
• Weakness
• Tonic upward gaze
• Headache
• Seizure
• Involuntary contraction of muscles (dystonia)
• Cognitive impairment

Less episodic ataxia common types

While EA1 and EA2 are the most commonly discussed forms of episodic ataxia, there exists many other types, from type 3 to type 8. These are however very rarely discussed as they are very rare, with type 3, 7, and 8 having only been found in one family each, and 4-6 being incredibly uncommon.⁴

Diagnosis and treatment

How can episodic ataxia be diagnosed?

To get a diagnosis, a thorough family history and medical history are needed along with a full neurological and physical exam. Alongside this, your healthcare provider may recommend:⁶

• Genetic testing: Since episodic ataxia is caused due to mutations in genes, the genes in your body is the most efficient way of determining what genes have mutations and if you are at risk of having episodic ataxia
• Lab ests: Blood tests and urine tests are beneficial as they can provide insight into possible metabolic or other systemic issues that may be worsening symptoms. Genetic testing also requires blood or saliva samples
• Othertests: Using diagnostic tests such as magnetic resonance imaging (MRI) scan, computed tomography (CT) scan, or an electromyogram, your healthcare provider can look at your brain and your nerves for a better diagnosis

Treatment options

Unfortunately, episodic ataxia is incurable however, there are medical treatments to improve symptoms and quality of life significantly.

Your healthcare provider may recommend medication that blocks nerve channels to aid in controlling or reducing ataxia episodes,⁷ as EA1 and EA2 have mutations in the potassium and calcium channels, respectively. Other possible medications could be medication for certain symptoms like seizures. Commonly prescribed medication is carbamazepine for EA1 and acetazolamide for EA2, both commonly prescribed for seizures or epilepsy.⁸

As episodic ataxia is an inherited genetic disease, there is nothing you can do to prevent getting it. However, there are many changes you can take in your lifestyle to improve symptoms and reduce the risk of episodes.

These modifications include:

• Caffeine and alcohol: Limit or avoid consumption as these can trigger episodes
• Stress management: Practice stress-reduction techniques such as meditation, yoga, and deep-breathing exercises to help prevent stress-induced episodes
• Avoid overexertion: Moderate physical activity to avoid excessive fatigue, which can trigger episodes

Introducing certain positive changes into your life can also help in reducing the number of episodes or the impact of the episodes on you.

Positive Lifestyle Changes:⁷

• Low-Impact Exercises: Engage in activities like walking, swimming, or cycling to improve overall fitness without overexerting
• Physical Therapy: Work with a physical therapist to develop a tailored exercise program that helps improve coordination and balance
• Routine Monitoring: Regular visits to your neurologist or healthcare provider to monitor the condition and adjust treatment as needed
• Consistent Sleep Schedule: Maintain a regular sleep routine to ensure adequate rest, as fatigue can trigger episodes

Summary

Episodic ataxia is a genetically inherited disorder marked by recurring episodes of impaired coordination and balance, caused by mutations in genes affecting ion channels in nerve cells. These episodes, which can range from seconds to hours, are interspersed with periods of relative normalcy. The primary types, EA1 and EA2, are linked to specific genetic mutations in potassium and calcium channels, leading to their distinct symptoms and durations. Although there is no cure for episodic ataxia, diagnosis can be effectively achieved through genetic testing, lab tests, and diagnostic imaging. Treatment focuses on managing symptoms and improving quality of life, often involving medications that help control episodes Lifestyle modifications, such as avoiding known triggers like stress, sudden movements, caffeine, and alcohol, can also significantly reduce the frequency and severity of episodes. Through understanding and appropriate management, individuals with episodic can lead more stable and symptom-controlled lives. 

Understanding episodic ataxia is incredibly important, as although it is considered a very rare condition with less than 1 in 1000,000 having it,³ it is believed that this number is underestimated due to unidentified causes, highlighting the importance of further research in this area.