Fahr Syndrome

Very rare degenerative neurologic syndrome characterized by microcephaly, mental and growth retardation, seizures and dystonic movements, and athetosis with evidence of multiple intracranial calcifications in parts of the gray and dentate nuclei, particularly of smaller brain vessels.

Cerebral Nonarteriosclerotic Calcification; Idiopathic Basal Ganglia Calcification; Fahr Intracerebral Calcinosis; Fahr Disease; Morbus Fahr Ferrocalcinosis; Nonarteriosclerotic Cerebral Calcifications; Striopallidodentate (SPD) Calcinosis.

Presence of idiopathic intracranial calcifications has been recognized for many years. The initial report by Fahr was about an adult. The heterogeneous nature of the disease was later recognized and genetic conditions occurring in infants were included.

Autosomal recessive and autosomal dominant transmission have been reported. In some cases, the condition appears to be sporadic and may result from an unidentified infection during pregnancy affecting the developing fetus.

Pathogenesis is unclear, but a few hypotheses have been stated, such as the possible role of abnormal iron transport, fetal viral infection, and hypoparathyroidism.

Diagnosis of exclusion after ruling out common causes of microcephaly with intracranial calcifications, such as TORCH (toxoplasmosis, other agents, rubella, cytomegalovirus, herpes simplex) infection, varicella virus, and cytomegalovirus infections.

Children affected with the disease are normal at birth but then show poor psychomotor developmental progress. Seizures appear early in life and are of variable nature. Affected patients present with severe microcephaly, hypotonia, spasticity, and growth retardation. Some children also have thrombocytopenia and hepatosplenomegaly manifesting shortly after birth but lasting for only a few weeks and then resolving spontaneously. CT scan of the brain may show cerebral atrophy, dilated ventricles, calcifications, and a lower density of white matter consistent with dysmyelination. Hypoparathyroidism may be associated with this disorder. Clinical course and outcome are highly variable.

If the child needs surgery in the first few weeks of life, obtain a complete blood count (CBC) to rule out anemia and thrombocytopenia. Blood calcium should be checked to rule out hypocalcemia caused by hypoparathyroidism.

Locoregional anesthesia should be avoided in case of thrombopenia.

Presence of undetermined cause for hepatomegaly should limit the use of inhalational agent likely to affect the liver (e.g., halothane). Hepatic enzyme induction may occur in the presence of anticonvulsant, so the dose of some drugs, such as neuromuscular relaxants, may require adjustment. It is best to avoid succinylcholine if the patient has severe spastic paraplegia.