Infancy (first 2 years of life)

• Neonatal Prader - Willi syndrome - hypokinesia and limb dystonia - fluorescent in situ hybridization/multiplex ligation-dependent probe amplification for deletion paternally inherited chromosome 15

• Neonatal hyperekplexia/startle - GLRA1 and GlyT2 mutations
• Disorders of monoamine metabolism - temperature instability, oculogyric crises, lethargy and parkinsonism - plasma amino adds, CSF neurotransmitters pterins
• Although dopa-responsive dystonia usually presents later, this disorder should be considered in any infant with a pure dystonic disorder and oral levodopa trial initiated
• Glutaric acidura type 1 - usually after acute encephalopathy but not always; dystonia and choreoathetosis - urine organic acids
• Mitochondrial disorders - dystonias - MRI, lactates, enzyme activities, genes (e.g. pyruvate dehydrogenase, POLG1)
• Methaemoglobinaemia type 2 - microcephaly, dystonia, mild cyanosis -red cell methaemoglobin, gene NADH - cytochrome b 5 reductase
• Post-herpes encephalitis - ballismus - CSF, herpes simplex virus polymerase chain reaction though likely negative
• Lesch-Nyhan syndrome - choreoathetosis superimposed on gross motor delay (usually followed by self-mutilation) - urine uric acid, hypoxanthine phosphoribosyltransferase 1 assay red cells or cultured fibroblasts.
• Shuddering and benign infantile spasms - tremor-like spasms - video, video-EEG if in doubt
• Infantile masturbation - repeated dystonic adduction of the thighs - video
• Transient dystonia of infancy - episodes of dystonic posturing especially of upper limbs distally - home video

Older Children

Movement disorders in individuals with learning disability

Most of the abnormal movements in those with severe learning disability, in particular various kinds of stereotypy, do not help in clinical diagnosis and do not suggest particular neurological investigations. However, sound-startle induced falls that resemble cataplexy or hyperekplexia point to Coffm-Lowry syndrome (investigation: home or clinic video, possible gene analysis see Chapter 3.14), and status dystonicus in a boy with epileptic infantile spasms will prompt ARX mutation analysis (see Chapter 3.15).

In another ARX phenotype boys have focal dystonia with an X-linked inheritance. A prominent movement disorder in a boy with mild facial dysmorphism will prompt estimation of free T3 (triiodothyroxine) and, if elevated, mutation analysis of MCT8 (monocarboxylate transporter 8 gene).

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