Double athetosis This is probably the most frequent of the congenital extrapyramidal disorders. Two types stand out—one that is caused by hyperbilirubinemia or Rh incompatibility (kernicterus; see below) and hypoxic-ischemic encephalopathy. With control of neonatal hyperbilirubinemia (by use of anti-Rh immune globulin, exchange transfusions, and phototherapy), kernicterus has almost disappeared, whereas the severe hypoxic-ischemic form regularly continues to be seen. Rarely, a congenital, nonhemolytic icterus or a glucose-6-phosphate dehydrogenase deficiency produces the same syndrome.
Like the spastic states, double athetosis may not be recognized at birth but only after several months or a year has elapsed. In some cases, the appearance of choreoathetosis is for unexplained reasons delayed for several years; it may seem to progress during adolescence and even early adult life. It must then be differentiated from some of the inherited metabolic and degenerative extrapyramidal diseases. Chorea and athetosis dominate the clinical picture, but bewildering combinations of involuntary movements—including dystonia, ataxic tremor, myoclonus, and even hemiballismus—may be found in a single case. At times, we have been unable to classify the movement disorder because of its complexity. It should be noted that practically all instances of double athetosis are also associated with a defect in voluntary movement.
Choreoathetosis in infants and children varies greatly in severity. In some, the abnormal movements are so mild as to be misinterpreted as restlessness or “the fidgets”; in others, every attempted voluntary act provokes violent involuntary spasms, leaving the patient nearly helpless. The clinical features of choreoathetosis and other involuntary movements are discussed in Chap. 4.
Early hypotonia, followed by delayed motor development, is the rule in these cases. Erect posture and walking may not occur until the age of 3 to 5 years and may never be attained in some patients. Tonic neck reflexes or fragments thereof tend to persist well beyond their usual time of disappearance. The plantar reflexes are usually flexor, although they may be difficult to interpret because of the continuous flexion and extension of the toes. Sensory abnormalities are not found. Because of the motor and speech impairment, patients are often erroneously thought to be cognitively impaired. In some, this conclusion is doubtless correct, but cognitive function may be unaffected in many others.
A variety of rehabilitative measures have been tried: physiotherapy, surgery, sensory integrative therapy, progressive patterned movement, and various undocumented forms of neuromuscular facilitation. We agree with Hur, who has critically reviewed this subject, that properly controlled studies provide no proof of the success of any of them. Surely, with growth and development, new postures and motor capacities are acquired. The less-severely affected patients make successful occupational adjustments. The more-severely affected children rarely achieve a degree of motor control that permits them to live independently. One sees some of these unfortunate persons bobbing and twisting laboriously as they make their way in public places.
Imaging studies are seldom of diagnostic value. Mild cerebral atrophy and loss of volume of the basal ganglia are seen in some cases, and cavitary lesions are present in some of the severe anoxic encephalopathies. The EEG is rarely helpful unless there are seizures.
The most frequent pathologic finding in the brain has been a whitish, marble-like appearance of the putamen, thalamus, and border zones of the cerebral cortex. These whitish strands represent foci of nerve cell loss and gliosis with condensation of bands of transversing myelinated fibers—so-called status marmoratus (état marbré). This lesion does not develop if the insult occurs after infancy, that is, after myelination has completed its early developmental cycle.