Hereditary paroxysmal cerebral ataxia

Hereditary Paroxysmal Cerebral Ataxia (HPCA) is a neurological disorder characterized by episodes of ataxia, or lack of muscle coordination, that can affect various bodily movements including gait, balance, and speech. These episodes can vary in frequency and duration, often triggered by stress, sudden movements, or physical exertion. HPCA is inherited in an autosomal dominant manner, meaning a single copy of the altered gene in each cell is sufficient to cause the disorder.

Symptoms

The primary symptom of HPCA is the sudden onset of ataxia episodes, which can also be accompanied by other neurological symptoms such as:

• Vertigo or dizziness
• Nystagmus (rapid, uncontrolled eye movements)
• Dysarthria (difficulty in articulating words)
• Tinnitus (ringing in the ears)
• Migraine headaches

The severity and frequency of these episodes can vary widely among affected individuals. Some may experience daily episodes, while others may have them less frequently.

Causes

HPCA is caused by mutations in specific genes. The most well-known form, Episodic Ataxia Type 2 (EA2), is caused by mutations in the CACNA1A gene on chromosome 19p13. This gene provides instructions for making a protein that forms part of a calcium channel, which plays a key role in controlling muscle movements. Mutations in this gene disrupt the normal flow of calcium ions into cells, leading to the symptoms of ataxia.

Diagnosis

Diagnosis of HPCA involves a thorough clinical evaluation, detailed patient history, and the use of various neurological tests. Genetic testing can confirm the diagnosis by identifying a mutation in the relevant gene. Other tests, such as MRI scans, may be used to rule out other causes of ataxia.

Treatment

There is no cure for HPCA, but treatment focuses on managing symptoms and improving quality of life. Medications such as acetazolamide and 4-aminopyridine have been used to reduce the frequency and severity of ataxia episodes. Physical therapy can help improve coordination and balance. Lifestyle modifications, including avoiding triggers such as stress and physical exertion, can also be beneficial.

Prognosis

The prognosis for individuals with HPCA varies. While the disorder does not typically affect life expectancy, the severity of symptoms can impact an individual's ability to perform daily activities and maintain independence. Early diagnosis and treatment can help manage symptoms and improve quality of life.