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Ataxia

Ataxia is defined as an inability to coordinate movements.
Ataxia produces, for example, clumsiness, balance problems, gait and speech disturbances as well as jerky movements.
The underlying pathology is often a dysfunction of the cerebellum and its connecting pathways, but ataxia may also be associated with a dysfunction of the posterior funiculus of the spinal cord or the sensory peripheral nervous system (sensory ataxia).
Ataxia may be a symptom of a variety of neurological disorders. In these cases the clinical picture will usually also include other neurological abnormalities. However, the most usual cause of ataxia is prolonged abuse of alcohol.
True ataxia is caused by the degeneration of the cerebellum or its connecting pathways of either hereditary or unknown (idiopathic) aetiology.

Cerebellar haemorrhage or infarction
Cerebellar injury
Poisoning by ethanol Alcohol Poisoning solvents or medicinal products Drugs Commonly Causing Poisonings
- Especially antiepileptics, lithium, benzodiazepines, hypnotics
Infection
- Cerebellitis (particularly in children), an abscess, encephalitis Encephalitis

Multiple sclerosis Multiple Sclerosis (Ms)
Tumour of the cerebellum or the posterior cranial fossa
Paraneoplastic or other autoimmune aetilogy
- Especially lung cancer Lung Cancer, ovarian cancer Benign Gynaecological Lesions and Tumours, breast cancer Breast Cancer and Hodgkin's disease Lymphomas
- Associated with GAD antibodies and glutamate receptor antibodies
Miller Fisher syndrome (a variant of Guillain-Barré syndrome; typical findings include paralysis of the eye muscles, ataxia, and absence of the tendon reflexes)
Prion disease (Creutzfeldt-Jakob disease) Uncommon Infections of the Central Nervous System
Hydrocephalus Increased Intracranial Pressure
Medications
- 5-fluorouracil, cytarabine, methotrexate, lithium

Alcoholism Neurological Disorders and Alcohol
Coeliac disease Coeliac Disease
Sporadic (idiopathic)
Multiple system atrophy, cerebellar type (MSA-C)
- Characterised by parkinsonism, autonomic dysfunction
Hereditary
- CANVAS (Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome)
  - Apparently one of the most common causes of ataxia; accounts for even 14-22% of ataxia cases in the European population.
  - The most common symptom is progressive uncertainty of balance which often stands out in the semidarkness or the darkness.
  - The syndrome is often associated with chronic cough and sensory disturbance (sensory polyneuropathy in electroneuromyography).
- Dominant
  - Spinocerebellar ataxias (SCA)
- Recessive
  - MIRAS (mitochondrial recessive ataxia syndrome), Friedreich's ataxia, neurometabolic disease, IOSCA (infantile onset spinocerebellar ataxia), ataxia-telangiectasia
- X-chromosomal inheritance
  - Fragile X-associated tremor/ataxia syndrome (FXTAS)
- Mitochondrial
Vitamin deficiencies
- B₁: in alcoholics Brain Death
- B₁₂: most commonly due to a malabsorption disorder Megaloblastic Anaemia
- E: may be hereditary or caused by a bowel disease
Long-term phenytoin use
Chronic exposure to solvents or heavy metals
Superficial siderosis
Arnold-Chiari malformation

Medicinal products or toxins, ataxia according to the fluctuation in their concentration
A TIA Transient Ischaemic Attack (Tia)
- In most cases accompanied by brain stem symptoms
Intermittent hydrocephalus
Hereditary (dominant)

The most common causes of ataxia with adult onset are long-term alcohol abuse, multiple sclerosis and CANVAS.
The combined prevalence of sporadic and hereditary ataxia is estimated to be about 10-15/100 000.

The examination should focus, in addition to ataxia, on the possible coexistence of other signs.
Ataxia associated with alcohol abuse is usually manifested by a wide gait and balance problems.
The symptoms of sporadic and hereditary adult ataxia generally progress very slowly over several years to decades.

Investigations are decided on according to the overall symptom picture, speed of symptom emergence and family history. Basically, a good history allows the selection of correct investigations.
The investigations most commonly indicated beyond a physical examination:
- An MRI scan of the head (a CT scan of the head is an alternative investigation for an acute situation)
- Cerebrospinal fluid (CSF) examination
- Spinal cord MRI and ENMG if considered appropriate
- The most important laboratory tests:
  - ESR, full blood count, electrolytes, calcium, liver and thyroid function tests, a coeliac screen, vitamin B₁, B₁₂ and E assays, CK and carbohydrate-deficient transferrin (CDT)
  - Genetic and other special investigations are carried out in specialist health care.

Treatment is dependent on the underlying cause. If a specific aetiology can be identified, e.g. multiple sclerosis, coeliac disease, vitamin deficiency or a tumour, the management is adapted to follow the treatment of these conditions.
In alcohol-induced ataxia the consumption of alcohol should be totally withdrawn. This may lead to symptom improvement in non-severe cases.
No symptomatic medicinal product effective specifically against ataxia is available.
- Benefit may sometimes be gained with amantadine, gabapentin riluzole, varenicline or buspirone.
Acetazolamide may be beneficial in hereditary episodic ataxia.
Physiotherapy, occupational therapy and speech therapy should be considered on a case by case basis.
Mobility equipment is often indicated as are adaptations to the patient's home.
A consultation with a geneticist should be considered for patients with genetic ataxia.

Ramirez-Zamora A, Zeigler W, Desai N et al. Treatable causes of cerebellar ataxia. Mov Disord 2015;30(5):614-23. [PubMed]
van de Warrenburg BP, van Gaalen J, Boesch S et al. EFNS/ENS Consensus on the diagnosis and management of chronic ataxias in adulthood. Eur J Neurol 2014;21(4):552-62. [PubMed]