Evaluation of infantile dystonia

Last reviewed: April 2019

Last updated: May 2019

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] Photographs and video footage 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

In the classification of dystonias, the term infantile refers to onset from birth to 2 years of age. [4] Dystonias are described according to two complementary axes: [4]

Clinical characteristics (axis 1), which include age at onset, body distribution, temporal pattern, and associated features
Etiology (axis 2), which includes nervous system pathology and inheritance.

Information from the history and physical examination allows an initial classification and differential diagnosis to be made. The presence and absence of motor features and other signs and symptoms can narrow the differential diagnosis by indicating a particular dystonia syndrome and by directing the diagnostic evaluation toward groups of disorders associated with different clinical patterns, such as:

Isolated dystonia (dystonia alone or dystonia with tremor)
Combined dystonia (dystonia with other motor features)
Complex dystonia (dystonia with other symptoms).

The clinical evaluation may also indicate whether the condition is neurodegenerative or suggest an acquired or inherited etiology.

Further investigations may be required including neuroimaging, evaluation for associated neurodevelopmental or systemic abnormalities, therapeutic trial of levodopa, or biochemical (including diagnostic lumbar puncture) and genetic tests.

Several pseudodystonias need to be considered in the differential diagnosis; these conditions involve dystonia-mimicking abnormal movements, but their etiologies differ from those of dystonias.

The rapid identification of several conditions is important to prevent irreversible injury or death:

Drug-induced acquired dystonia
Pseudodystonia due to cervical instability
Status dystonicus
Multiple neurometabolic disorders, such as glutaric aciduria type I
Acute bilirubin encephalopathy.

Many metabolic disorders present in infancy, and are high on the list of likely differential diagnoses in the first year of life. [4] [5]

Dopa-responsive dystonia (Segawa syndrome, dystonia-parkinsonism with diurnal fluctuation) needs to be considered in any infant or child with unknown diagnosis and normal MRI. It is usually misdiagnosed as spastic diplegic or quadriplegic cerebral palsy, intractable epilepsy, or hereditary spastic paraplegia. [6] [7]

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
Nonfatal drowning
Primary stereotypies
Secondary stereotypies
Secondary infantile torticollis (SIT)
Seizure

Full details

Uncommon

Primary paroxysmal nonkinesigenic dyskinesia (PNKD)
Alternating hemiplegia of childhood (AHC)
DYT-TOR1A (primary torsion dystonia)
Dopa-responsive dystonia (Segawa syndrome, dystonia-parkinsonism with diurnal fluctuation)
Paroxysmal exercise-induced dyskinesia glucose transporter 1 (GLUT1)
Dopamine transporter deficiency syndrome (DYT/PARK-SLC6A3, infantile parkinsonism-dystonia)
DYT-SGCE (myoclonus-dystonia syndrome)
ADCY5-related dyskinesia (CHOR-DYT/ADCY5)
Kernicterus
Glutaric aciduria type I (glutaryl-CoA dehydrogenase [GCDH] deficiency)
Methylmalonic acidemia
Lesch-Nyhan syndrome
Infantile GM2 gangliosidosis (Tay-Sachs and Sandhoff disease)
Mitochondrial encephalomyopathies
Allan-Herndon-Dudley syndrome (X-linked monocarboxylate transporter 8 deficiency)
Biotin-thiamine-responsive basal ganglia disease (DYT-SLC19A3)
Dopamine-serotonin vesicular transport disease
Hypermanganesemia
Acquired paroxysmal kinesigenic dyskinesia (PKD)
Acquired paroxysmal nonkinesigenic dyskinesia (PNKD)
Neurodegeneration with brain iron accumulation (NBIA), including pantothenate kinase-associated neurodegeneration (PKAN)
ARX-related disorders including infantile epileptic-dyskinetic encephalopathy
Leukodystrophies/hypomyelinating disorders
Aicardi-Goutieres syndrome (AGS)
Other inherited neurodegenerative disorders with dystonia
Paroxysmal tonic upgaze of infancy