Postinfectious acute cerebellar ataxia may occur 1 to 3 weeks following varicella, infectious mononucleosis, mild respiratory or gastrointestinal viral illnesses, or other infections. The pathogenesis is uncertain and may represent either a direct viral infection of the cerebellum or, more likely, an autoimmune response precipitated by the viral infection and directed at the cerebellar white matter. Symptoms begin abruptly, causing truncal ataxia, staggering, and frequent falling. Dysmetria of the arms, dysarthria, nystagmus, vomiting, irritability, and lethargy may be present. Symptoms, which may be severe enough to prevent standing or sitting, usually peak within 2 days, then stabilize and resolve over several weeks. Cerebrospinal fluid (CSF) examination sometimes shows a mild lymphocytic pleocytosis or mild elevation of protein content. Brain magnetic resonance imaging may reveal cerebellar enhancement. No specific therapy is available except to prevent injury during the ataxic phase.
Brain tumors are the second most common neoplasm in children. About 50% arise from within the posterior fossa. Tumors that arise in the posterior fossa or brainstem produce progressive ataxia with headache that may be acute or gradual in onset. There is a progressive worsening over days, weeks, or months, typically with associated signs and symptoms of elevated intracranial pressure. The ataxia and dysmetria may result from primary cerebellar invasion or from obstruction of the CSF pathways (aqueduct of Sylvius or fourth ventricle) with resultant hydrocephalus. The most common tumors in this region include medulloblastoma, ependymoma, cerebellar astrocytoma, and brainstem glioma.
Rarely, a neuroblastoma located in the adrenal medulla or anywhere along the paraspinal sympathetic chain in the thorax or abdomen is associated with degeneration of Purkinje cells and the development of severe ataxia, dysmetria, irritability, myoclonus, and opsoclonus. An immunologic reaction directed toward the tumor may be misdirected to attack Purkinje cells and other neuronal elements. The myoclonic movements are irregular, lightning-like movements of a limb or the head. Opsoclonus is a rapid, multidirectional, conjugate movement of the eyes, which suddenly dart in random directions. The presence of opsoclonus-myoclonus in a child should prompt a vigorous search for an occult neuroblastoma.
Several rare inborn errors of metabolism can present with intermittent episodes of ataxia and somnolence. These include Hartnup disorder, maple syrup urine disease, mitochondrial disorders, abetalipoproteinemia, and vitamin E deficiency.
Difficulty walking with a severe staggering gait is one manifestation of acute labrynthitis, but the diagnosis usually is clarified by the associated symptoms of a severe sense of spinning dizziness (vertigo), nausea and vomiting, and associated signs of pallor, sweating, and nystagmus.
Ataxia-telangiectasia, an autosomal recessive genetic disorder, is the most common of the degenerative ataxias. Affected patients present with ataxia around age 2 years, progressing to loss of ambulation by adolescence. In mid-childhood, telangiectasia is evident over the sclerae, nose, ears, and extremities. Abnormalities in immune function and greatly increased risk of lymphoreticular tumors result in early death.
Friedreich ataxia is a relentlessly progressive, autosomalrecessive disorder. Children present in the late elementary yearswith ataxia, dysmetria, dysarthria, diminished proprioceptionand vibration, absent deep tendon reflexes, and nystagmus,and many develop hypertrophic cardiomyopathy and skeletalabnormalities (high-arched feet, hammer toes, kyphoscoliosis).
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