Ataxia is a neurological sign that manifests in a lack of coordination in the movement of different muscles in the body. It is a clinical finding and not a disease, which mainly presents abnormalities in gait, changes in speech such as scanning speech, and abnormal eye movements such as nystagmus. It results from dysfunction of the brain areas, responsible for the coordination of movements, and, most commonly, the cerebellum. The three types of ataxia, according to the location, are cerebellar, sensory, and vestibular.
Ataxia can also subdivide into sporadic (patients have no family history of ataxia and manifesting in adulthood), hereditary (caused by a defect in a gene and manifesting in childhood), and acquired (due to structural or demyelinating conditions, toxicity, paraneoplastic, inflammatory or infections, and autoimmune conditions). Friedreich ataxia is an autosomal recessive form of ataxia and the commonest amongst the hereditary forms.
Ataxia may occur due to abnormalities in the nervous system's different areas, including the brain, spinal cord, nerves, and nerve roots. The different types of ataxia often have similar or overlapping causes in the same patient.
The overall prevalence of ataxia is 26 cases per 100,000 in children. The overall prevalence rate of hereditary ataxias is 10 cases per 100,000 individuals. Dominant cerebellar ataxia is present in 2.7 cases per 100,000 individuals, and recessive hereditary cerebellar ataxia in 3.3 per 100,000 individuals. An increased prevalence occurs in countries where consanguinity is a common practice. The worldwide prevalence of spinocerebellar ataxias is 3 to 5.6 cases per 100,000 individuals. The most common spinocerebellar ataxia is spinocerebellar ataxia type 3.
Ataxia may be due to an interference in the sensory transmission to the cerebellum caused by a lesion. This condition can lead to sensory or spinal ataxia. An interruption in cortical signals from the cerebellum causes cerebellar ataxia. Spinocerebellar ataxias are a result of both of the above-mentioned pathologies. They are autosomal dominant and result from CAG repetition on chromosomes.
Friedreich's ataxia is the most common of the inherited ataxias. It has an autosomal recessive pattern of inheritance. It involves the frataxin gene. There is degeneration of peripheral nerve axons and loss of sensory cells. Patients present between the first and second decades of life. Multisystem abnormalities are present and include, gait ataxia, loss in proprioception, sensory loss, pes cavus, spastic extensor plantar responses, atrophy of extremities, cardiomyopathy. Patients may also have diabetes mellitus, vision loss, and hearing loss.
Depending on the location of the lesion, characteristic findings are as follows:
Adequate history and examination are crucial parts in evaluating, assessing the location of the lesion, and treating patients with ataxia. The medical history should include age, gender, neurological, drug, toxin, and occupational exposures. Family history is essential. Systems review should assess the presence of constitutional symptoms such as fever, weight loss, and night sweats. A past medical history of diabetes, hypertension, and neurological diseases is essential.
Clinicians should ask the patients if any of the symptoms and signs are present, the level of functional disability in activities of daily living, onset, and progression. Common signs and symptoms include abnormalities in gait, slurred speech, difficulty in walking, abnormal eye movements, difficulty swallowing, increased fatigue, incoordination in fine motor movements such as handwriting, buttoning shirts, typing, tremors, vertigo, and problems in cognition.
A general and neurological physical examination is an integral part of the evaluation. A complete neurological examination, including mental status, cranial nerves, and cerebellar examination, is critical. Grading and level of functional disability are assessable with the use of scoring systems such as the International Cooperative Ataxia Rating Scale, Brief Ataxia Rating Scale (BARS), and for patients with Friedrich's ataxia, the Friedreich's Ataxia Rating Scale.
The necessary tests are guided by clinical presentation and clinical suspicion. Blood tests for specific deficiencies, drugs, and toxins may be in order. Urinalysis can look for mercury level measurement.
Brain imaging includes a computed tomographic scan as an initial study, but a magnetic resonance imaging (MRI) is critical to visualize structural lesions, strokes, and congenital or acquired abnormalities. Imaging of the spinal cord with MRI is indicated if a spine lesion is suspected.
Genetic testing is the diagnostic course for inherited ataxias.
Currently, there is no curative treatment available for hereditary ataxia. Depending on the causes, if the ataxia results from a stroke, toxic substances, hypothyroidism, or any modifiable risk factors, treatment is targeted at the specific condition causing ataxia. Some treatable causes are reversible by medication such as vitamin E, coenzyme Q10 deficiencies, and episodic ataxia type two.
Patients may use devices to reduce functional disability, such as walking aids, canes, wheelchairs, and walkers. Patients can receive physical, speech therapy, and symptomatic treatment. Medications can reduce tremors, muscle stiffness, and sleeping disorders. There is evidence that physical and mental exercises can improve the lives of patients with ataxia.
The prognosis largely depends on the type and cause of ataxia. Patients with progressive ataxia may suffer from worsening symptoms over the years and require symptomatic treatment. Hereditary ataxia has a shorter life expectancy; however, some people live up to the fifth or sixth decade. Severe forms may lead to death in childhood or the early years.
If the cause is acquired, for example, alcohol or drug-induced ataxia, the underlying cause needs to be treated, and triggering factors removed to improve prognosis.
Complications of ataxia are related to the type of ataxia. Commonly, patients have rigidity, dyspnea, breathing difficulty, and choking, which may also lead to death in severe cases. Patients may require assistance in ventilation, feeding tubes, and airway management. Patients who are unable to walk or require wheelchair assistance may develop pressure ulcers, infections, and thrombosis.
Psychological and psychiatric illnesses, such as dementia and depression, are common and require therapy. Other complications include lightheadedness, spasticity, tremors, lethargy, generalized pain, blood pressure changes, bowel, bladder, and sexual dysfunction.
Patients with ataxia may have a functional disability, so it is essential to inform them about the symptoms that should receive medical attention and provide them with assistance.
Referrals should manage swallowing, speech, visual, and hearing difficulties to the respected departments, and patients should receive education on the prevention of common emergencies such as aspiration and falls.
For acquired etiologies that can be modified, such as alcohol or drug-induced ataxia, the underlying cause will require treatment.
Ataxia frequently leads to complex decision making due to the multiple causes and nonspecific signs and symptoms. History taking and examination are essential in finding the cause and determining the severity of the illness. Neurologists, nurses, pediatricians, internal medicine physicians, occupational therapists, physiotherapists, radiologists, and pharmacists form a vital team for patient care. Each of them has a set role in the treatment and management of patients with ataxia. The collaboration of the team with shared decision-making and communication improve patients outcome.
As there is no determined treatment for ataxia, patients must receive assistance in reducing their functional disability by providing medications for symptoms, counseling, support groups, and wheelchair assistance. Research is underway to improve treatment further and help improve the prognosis of patients.
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