Ataxia: what is it, causes, symptoms, treatment, prognosis

What is ataxia?

Ataxia comes from the Greek word ἀταξία, meaning irregularity or disorder, but when used medically, the term describes a condition characterized by poor coordination of movements. Ataxia can cause involuntary eye movements (nystagmus), poor hand coordination, difficulty with fine motor skills (such as eating or writing), difficulty speaking, and unsteady walking. This can make the person appear "drunk."

Patients with ataxia cannot walk in a straight line and tend to collide with things. In advanced stages, they may need a walker or even a wheelchair. Patients may also have vision problems due to eye movement disorders. Damage or degeneration in the back of the brain, called the cerebellum, leads to ataxia. The disorder can also occur due to problems with the sensory system (abnormal perception of the position of a part of the body in space) and the vestibular system (abnormal balance). A neurologist usually distinguishes between two types of ataxia: motor and sensory ataxia.

Signs and symptoms

Symptoms of ataxia vary depending on the person and the type of disorder. The rate of progression also varies. Symptoms can get worse slowly over decades - or quickly over several months. Common symptoms of ataxia:

• lack of coordination;
• slurred speech;
• trouble eating and swallowing;
• deterioration in fine motor skills;
• difficulty walking;
• gait abnormalities;
• eye movement disorders;
• heart problems.

People with ataxia often require the use of wheelchairs and walkers to get around.

Causes and types

There are many causes of ataxia, but most of them can be categorized as sporadic (no specific cause), genetic (also called hereditary or familial) or secondary to medical conditions, certain drugs, or brain damage.

Congenital ataxias occur in children and are most often caused by structural abnormalities in the brain that occur before or during childbirth. These include cerebral palsy (often associated with brain damage at birth due to lack of oxygen or blood supply), hydrocephalus (high blood pressure caused by blockage or buildup of cerebrospinal fluid), brain tumors, and other brain damage.

Ataxia can occur suddenly (acute), over several weeks (subacute), or progress slowly over months or years (chronic). In acute cases, the most common cause is stroke or hemorrhage in or around the cerebellum. Patients usually have headache, vomiting, a stiff neck, or loss of consciousness. In children, bacterial or viral infections can cause acute ataxia, which usually resolves over time. They develop fever, trouble walking, and slurred speech over several hours or days, and recover within a few weeks. Subacute onset of ataxia is usually seen with paraneoplastic degeneration of the cerebellum. This is a condition in which mammary cancer, lungs, ovarian cancer or other areas of the body produces antibodies that affect the cerebellum and cause the disorder.

Hereditary or genetic ataxias occur due to gene mutations that result in abnormal proteins that cause neurons to function abnormally. You may inherit this from a parent and be affected (autosomal dominant inheritance, 50% chance of passing on to children) or from both parents (autosomal recessive inheritance, 25% chance of transmission to children if both parents carry a gene mutation and do not have symptoms). Sometimes there is no clear family history.

- Autosomal dominant ataxia.

Autosomal dominant disorders include spinocerebellar ataxias and episodic ataxias. Spinocerebellar ataxia (eng. abbreviation SCA) is the most common form of chronic progressive ataxia in adults. They are the result of degeneration of the pathways between the spinal cord and cerebellum. There are many types (SCA 1 to 37 have been recognized) and the number continues to grow based on new research. All patients with these disorders should undergo genetic counseling. SCA-2 is most common in the United States, while SCA-3 is most common in Japan, Germany, Portugal, and France. The typical age of onset of these syndromes is 4-60 years, with an average of 40 years. Patients can become disabled for five years, bedridden for ten years, and death occurs somewhere between 10-20 years after the onset of the disease. Common clinical problems with SCA are gait ataxia, eye movement abnormalities (nystagmus or twitching and double vision) and dysarthria (difficulty speaking). Some of the SCAs (SCA1, 2, 3, 4, 7, and 8) also cause peripheral neuropathy (damage to peripheral nerves that causes the patient to feel numb or tingling in the hands and feet). Some SCAs can lead to blindness, causing damage to the retina and macula in the eye (type 7 SCA).

Episodic ataxia (EA) is a disorder with recurrent attacks of ataxia with full recovery between episodes. Types 1 and 2 are well characterized. They are caused by genetic mutations in the voltage-gated potassium channel gene (KCNA1 on chromosome 12) and the gene for the calcium channel of the cerebral type P / Q (CACNL1A4 on chromosome 19) respectively. Patients have bouts of difficulty walking, dysarthria (difficulty speaking), and nystagmus (abnormal eye movements), with complete recovery between episodes. They can be triggered by stress, fright, or sudden movement. Type 1 EA includes short episodes of seconds or minutes. Type 2 EA episodes are longer, from minutes to hours. EA types 3 to 7 are also recognized. Genetic episodic ataxias are treatable. Taking medications multiple sclerosis and other causes can also in some cases lead to episodic ataxia.

- Autosomal recessive ataxia.

Friedreich's ataxia is an example of an autosomal recessive disorder. This disorder is caused by excessive repetitions of GAA nucleotides in DNA. Patients present with ataxia along with spasticity, speech problems, nystagmus, weakness of the lower limbs, and sensory problems. Patients with Friedreich's ataxia may also develop scoliosis(rachiocampsis), cardiomyopathy (heart enlargement), diabetes and bowel and bladder dysfunction. It is a slow progressive disorder, but most patients become wheelchair bound within 10 to 20 years after the onset of the disease. There is marked variability in the presentation and progression of the disease. Other recessively inherited ataxias include ataxia due to vitamin E deficiency (due to deficiency of the alpha-tocopherol transporter protein or abetalipoproteinemia), ataxia telangiectasia, ataxia with oculomotor apraxia of types I and II, as well as spinocerebellar ataxia of infantile origin and etc.

There are other inherited disorders that can cause ataxia, including dentator-rubro-pallidolusic atrophy. It is a rare neurodegenerative disorder that causes difficulty walking (ataxia), speech problems, dementia, chorea (an involuntary writhing type of movement), and muscle twitching (myoclonus). Some young patients have seizures (epilepsy).

Ataxia may be part of fragile X tremor / ataxia syndrome (CXXTA). It is a genetic disorder with a gene located on the X chromosome (female sex chromosome). CXXTA affects mainly males, but may occur in female carriers of the mutation. The clinical spectrum of SCXTA includes progressive ataxia, tremors, cognitive decline, and other features.

Other causes of chronic progressive ataxia include several disorders such as cerebellar degeneration due to alcohol, vitamin E deficiency, or copper deficiency. Deficit vitamin B12 causes sensory ataxia in addition to muscle weakness.

Diagnostics

The diagnosis of the disease is made after a thorough, detailed clinical examination by a neurologist. Once ataxia is confirmed, the cause is determined based on timing and other neurological features. Laboratory tests can help diagnose. MRI and cerebrospinal fluid analysis may also be helpful. In many cases, genetic testing is required.

Treatment

Of all movement disorders, ataxia is one of the most resistant to medical therapy. Clonazepam can help with tremors and balance problems. However, it has side effects such as sedation, fatigue or loss of libido and others. Other drugs have been studied, such as buspirone or 5-hydroxytryptophan, but have not been shown to be very beneficial. Phenytoin, an anticonvulsant drug, is useful for some episodic ataxias. Acetazolamide is also helpful in some rare forms of episodic ataxias.

Genetic ataxias have no definitive treatment. Some disorders have been reported to be slowed down by the intake of antioxidants such as vitamins A, E, B12, idebenone, and coenzyme Q10. Vitamin E is the treatment of choice for ataxia caused by vitamin E deficiency. Vitamin B12 or copper supplements are used to treat ataxia associated with vitamin B12 deficiency or copper deficiency, respectively. When associated with parkinsonism, for example, in multiple systemic cerebellar atrophy, levodopa may be helpful.

Weakness and spasticity exacerbate the difficulties a patient may experience with ataxia. Physical therapy is helpful to maximize strength and flexibility. General physical therapy and regular exercise are highly recommended. Early therapy can help patients avoid contracture development. Patients with ataxia may benefit from gait training early in the disease. Adaptive devices such as walking sticks, wheelchairs, and communications can help. Home adjustments can be discussed with a professional therapist. Some patients will need the help of a speech therapist.

Caring for patients in the later stages of progressive ataxia is very important. Taking care of your skin and inserting a feeding tube for patients with swallowing difficulties will help prevent lung infections such as pneumonia.

Forecast

The prognosis of the disease can vary greatly and depends greatly on the type of disorder. Some types may remain relatively stable or even improve over time, but most will gradually deteriorate over the years.

Life expectancy is generally shorter than usual for people with hereditary ataxia, although some people may live to be 50, 60, or older. In more severe cases, the condition can be fatal in childhood or early adulthood.

For acquired ataxia, the prognosis depends on the underlying cause. Some cases may improve or remain the same, while others may gradually worsen over time and shorten life expectancy.