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Children Muscle Movement Disorders

Ataxias:

Ataxia is said to be present when coordination of muscles are absent in performing a motor act. The ataxia may be due to the lesions in the peripheral nerves, the posterior column or spinocerebellar tracts of the spinal cord and the cerebellum. The causes of ataxia are;

i) Acute ataxia:

Post-infectious- Acute cerebellar ataxia
Drugs- DDT, led, alcohol, primidone, phenytoin, vincristine, antihistamines.
Cerebellar abscess

ii) Chronic ataxia:

Friedreich's ataxia
Metabolic-Wilson diseases, maple syrup urine disease, ataxia telangiectasia.
Ataxic cerebral palsy
Posterior fossa tumour

Congenital: Agenesis of cerebellar vermis, Dandy-Walker syndrome, the Chiari malformation, and encephaloceles.

Acute cerebellar ataxia occurs primarily in children 1-3 yr of age and is a diagnosis by exclusion. The condition often follows a viral illness, by 2-3 wk and is thought to represent an autoimmune response to the viral agent. The onset is sudden, and the truncal ataxia can be so severe that the child is unable to stand or sit. Fever and nuchal rigidity is absent. Horizontal nystagmus is evident (50%).

Hypotonia, diminished deep reflexes and other signs of cerebellar lesions may be elicited. The ocular fundi are normal. There may be tremor and noble of the head but there is no blurring of consciousness. CSF is typically normal at the onset. The ataxia begins to improve in a few weeks but may persist for as long as 2 months. Symptomatic measures are only possible. The prognosis for complete recovery is excellent.

Friedreich ataxia is inherited as an autosomal recessive or dominant trait. The onset of ataxia is usually prior to 10 year of age. There is evidence of damage to spinocerebellar , dorsal columns and pyramidal tracts. The Romberg test is positive; the deep tendon reflexes are absent, and the plantar response is extensor. Patients develop a characteristic explosive, dysarthric speech, and nystagmus is present in most children.

Typically, there is a marked loss of vibration and position sense owing to degeneration of the posterior columns. It is also characterized by skeletal abnormalities, including high-arched feet (pes cavus) and hammer toes as well as progressive kyphoscoliosis. Hypertrophic cardiomyopathy with progression to intractable CCF is the cause of death for most patients. There are also several forms of spinocerebellar ataxia are similar to Friedreich ataxia.

Choreoathetosis: The ward means "dance". The involuntary movements are rapid, irregular, repetitive jerking either generalized or affecting any part of the body. At rest the patient appears fidgety and unable to sit still. The movements often appear less obvious during voluntary movements. Athetosis refer to slow writhing movements of limbs. Chorea and athetosis collectively known as dyskinesia.

The causes are Sydenham chorea is the manifestation of rheumatic fever, huntington's chorea an inherited presenile dementia, and after certain drugs (phenothiazines). The three major features of Sydenham chorea include chorea, hypotonia, and emotional lability. The chorea is usually symmetric, increased by stress and disappear during sleep.

Several typical signs include the "milkmaid's grip" (relaxing and tightening hand shake), the choreic hand (spooning of the extended hand by flexion at the wrist and extension of the fingers), the darting tongue (the tongue cannot be protruded for longer then a few seconds) and the pronator sign (the arms and palms turn outward when held above the head). Sydenham chorea may persist for several months and as long as 1-2 years. A trial of diazepam followed by phenothiazines or haloperidol improves the condition. A regimen of daily penicillin prophylaxis should be instituted in case of Sydenham chorea as they are risk of developing carditis.

Dystonia:

This is a slow intermittent, twisting motion that produces exaggerated turning and posture of the extremities and trunk. The principal cause includes perinatal asphyxia, drugs, hepatolenticular degeneration (Wilson disease) and most are unknown.