Treatable Causes in Children

Impaired glucose transport across the blood-brain barrier results in Glut-1 deficiency syndrome, characterised by infantile seizures, developmental delay, acquired microcephaly, and hypoglycorrhachia^169,170. A wider phenotype is now recognized, including ataxia, spasticity and paroxysmal movement disorders which can be triggered by exertion or fasting. A ketogenic diet has been found to be effective treatment for epilepsy, but may not help gait problems^169,171 (For further information see www.ncbi.nlm.nih.gov/omim; OMIM number 606777; also contact CLIMB (www.climb.org.uk)

Hypobetalipoproteinaemia is a rare disorder characterized by low levels of fats, beta-lipoproteins and cholesterol¹⁷². Familial hypobetalipoproteinemia can be severe with early onset (abetalipoproteinemia/homozygous familial hypobetalipoproteinemia), or benign (benign familial hypobetalipoproteinemia). Severe early familial hypobetalipoproteinemia is often associated with growth delay, diarrhoea with steatorrhea, and fat malabsorption. Spastic ataxia, atypical retinitis pigmentosa, acanthocytosis, a low level of liposoluble vitamins (A, E, K), major cytolysis, and even cirrhosis can occur¹⁷³.

Recent guidelines on the diagnosis and management of this treatable disorder have been published¹⁷². (For further information see www.orpha.net ORPHA426; also contact CLIMB www.climb.org.uk.) Management of the moderate form includes reduction of the proportion of fat in the patient’s diet and vitamin E supplementation.

Intermittent ataxia, photosensitive rash, psychotic behaviour and intellectual disability are possible features of this condition.

Patients benefit from a high-protein diet, sunlight protection, and avoidance of photosensitizing drugs¹⁷⁴. Treatment includes nicotinamide supplements; some patients may respond to a tryptophan-rich diet¹⁷⁴.

(For further information see www.ncbi.nlm.nih.gov/omim; OMIM number 34500. Also contact CLIMB www.climb.org.uk)

This is a metabolic disorder characterised primarily by cutaneous and neurologic abnormalities. This condition should be treated with biotin^175,176.

(For further information see www.ncbi.nlm.nih.gov/omim; OMIM number 253260. Also contact CLIMB www.climb.org.uk)

This is a metabolic disorder which can cause ataxia in some affected males. Treatment is generally aimed at stimulating the PDH complex or providing an alternative energy source for the brain. It can respond to treatment with thiamine, carnitine, and lipoic acid. A ketogenic diet may be indicated especially for those presenting with a dystonic disorder. Dichloroacetate has been used, but significant side effects, such as peripheral neuropathy, may limit effectiveness¹⁷⁷.

(For further information see www.orpha.net ORPHA765 or contact CLIMB www.climb.org.uk)

If ataxia is caused by structural disorders these are usually surgically treatable. Brain tumours can cause ataxia but usually other symptoms such as headache, vomiting and personality change are present. Hydrocephalus can have similar symptoms and can be due to a wide variety of causes.

Arnold-Chiari malformation is a congenital malformation at the back of the brain. (For more information contact the Association for Spina Bifida www.spinabifidaassociation.org)

Intoxication, either from recreational or medically prescribed drugs, can cause acute or intermittent ataxia, but is not always immediately recognised.

For more information about metabolic encephalopathies, such as branched chain amino-acidurias, contact CLIMB (www.climb.org.uk).

Can rarely present as intermittent ataxia (combined with altered consciousness) but seen more commonly in the context of a known epilepsy syndrome¹⁷⁸.

For more information contact Epilepsy Action (www.epilepsy.org.uk).

Refsum syndrome and chronic inflammatory demyelinating neuropathy (CIDP) are conditions affecting the nerves. Refsum syndrome also involves the cerebellum and can sometimes result in ataxia.

For more information see the National Institute of Neurological Disorders and Stroke (www.ninds.nih.gov) and contact CLIMB (www.climb.org.uk)¹⁷⁹.