Evaluation of infantile dystonia

Last reviewed: December 2018

Last updated: June 2018

Summary

Abnormal movement disorders are classified as parkinsonism, dystonia, tremor, chorea, myoclonus, tics, stereotypies, and complex movement disorder. Dystonia is described as contraction of both agonist and antagonist muscles simultaneously, causing twisting and repetitive movements or abnormal postures. [1] The earlier the age of onset, the more generalized and severe the condition tends to be.

Dystonic movements

Dystonic movements are patterned and sustained. They repeatedly involve the same muscle groups. The urge to perform the dystonic movements is absent, and there is no relief after the dystonic movements are executed. Dystonia usually gets worse with fatigue and emotional stress and it gets better with sleep and relaxation. [2] [3] Pictures and videotaping of affected infants are helpful in delineating the dystonic movements. Periodic follow-up is often a prerequisite to making an accurate diagnosis.

Types of infantile dystonia

The term infantile, in this case, refers to children <2 years of age. Of all dystonia cases, 45% are primary and 55% are secondary (35% related to specific syndromes; 20% other secondary causes). Syndromic types are mostly related to metabolic diseases.

Diagnosis involves recognizing the abnormal movements as dystonic, and then categorizing the type. Several conditions, although not actually dystonias in themselves, mimic dystonias (e.g., stereotypies), and these need to be considered in the differential diagnosis.

Several types of dystonia are more likely to develop the severe complication of status dystonicus (dystonic storm). This requires urgent therapy. In addition, it is important to correctly diagnose some of the conditions that mimic primary dystonia because they require specific urgent treatment.

Pitfalls in diagnosis include the fact that dopa-responsive dystonia (Segawa syndrome, dystonia-parkinsonism with diurnal fluctuation) is usually misdiagnosed as spastic diplegic or quadriplegic cerebral palsy, intractable epilepsy, or hereditary spastic paraplegia. [4] [5] This diagnosis needs to be considered in any child with paroxysmal progressive hypertonia of unknown origin. com.bmj.content.model.assessment.Caption@59ca027f [Figure caption and citation for the preceding image starts]: Benign paroxysmal torticollis of infancy From the collection of Dr Kenneth Silver; used with permission [Citation ends]. com.bmj.content.model.assessment.Caption@212470dc [Figure caption and citation for the preceding image starts]: Benign paroxysmal torticollis of infancy From the collection of Dr Kenneth Silver; used with permission [Citation ends].

Differentials

Common

Transient idiopathic dystonia of infancy
Benign paroxysmal torticollis of infancy
Congenital torticollis
Primary paroxysmal kinesigenic dyskinesia (PKD)
Drug-related dystonia
Dyskinetic cerebral palsy
Post-traumatic dystonia
Near drowning
Primary stereotypies
Secondary stereotypies
Secondary infantile torticollis (SIT)
Seizure

Full details

Uncommon

Primary paroxysmal nonkinesigenic dyskinesia (PNKD)
Alternating hemiplegia of childhood (AHC)
Primary torsion dystonia
Dopa-responsive dystonia (Segawa syndrome, dystonia-parkinsonism with diurnal fluctuation)
Paroxysmal exercise-induced dyskinesia GLUT1
Infantile parkinsonism-dystonia
Myoclonus-dystonia syndrome
Kernicterus
Glutaric aciduria type I (CGDH deficiency)
Methylmalonic acidemia
Lesch-Nyhan syndrome
Infantile GM2 gangliosidosis (Tay-Sachs and Sandhoff disease)
Mitochondrial encephalomyopathies
Secondary paroxysmal kinesigenic dyskinesia (PKD)
Secondary paroxysmal nonkinesigenic dyskinesia (PNKD)
Pantothenate kinase-associated neurodegeneration (PKAN)
Infantile epileptic-dyskinetic encephalopathy (ARX)
Aicardi-Goutieres syndrome (AGS)
Paroxysmal tonic upgaze of infancy