Dystonia is a hyperkinetic movement disorder described as contraction of both agonist and antagonist muscles simultaneously, causing twisting and repetitive movements or abnormal postures.[1] It can be confused with other abnormal movement disorders such as parkinsonism, tremor, chorea, myoclonus, tics, and stereotypies; mistaken for tonic seizures; or coexist with other features as part of a complex movement disorder. The earlier the age of onset, the more generalized and severe the condition tends to be.
The first priority in the evaluation of an infant with dystonia is to establish whether the patient has a condition needing urgent intervention. Several metabolic disorders fall into this category, so clinical biochemical tests may need to be done as part of the initial testing even if other genetic testing is being considered. See Urgent considerations .
Molecular genetic testing is important and clinically useful in infantile dystonia due to its high yield of genetic diagnoses and medically actionable information. Next-generation sequencing tests such as gene panels and exome sequencing reveal the diagnosis in up to 60% of patients with infantile-onset dystonias.[2] [3] However, thorough clinical evaluation beyond the dystonia itself is crucial to achieve this diagnostic rate. Phenotypic features from the history, family history, and physical exam help narrow the differential diagnosis, allow selection of the most appropriate genetic tests, and improve the interpretation of genetic testing results.
