Infantile bilateral striatal necrosis (IBSN) comprises several syndromes of bilateral symmetric spongy degeneration of the caudate nucleaus, putamen and globus pallidus characterized by developmental regression, choreoathetosis and dystonia progressing to spastic quadriparesis. IBSN can be familial or sporadic (see these terms).
The prevalence of the sporadic form has been estimated at 1-9/1,000,000 and prevalence of the familial form has been estimated at less than 1/1,000,000.
The age of onset of familial IBSN varies between 7 months and 15 months, whereas sporadic IBSN can occur any time from the neonatal period through childhood and even in adolescence. Clinical features include choreoathetosis, dystonia, rigidity, spasticity, dysphagia, optic atrophy, intellectual deficit, developmental regression of motor and verbal skills, failure to thrive, myoclonus, quadriparesis, cerebellar ataxia and nystagmus. The familial form has an insidious onset and a slowly progressive downhill course, while the sporadic form is associated with abrupt neurologic dysfunction following an acute systemic febrile illness such as a mycoplasma, measles or streptococcus infection.
Autosomal recessive IBSN is caused by mutation in the NUP62 gene (19q13.33) and mitochondrial IBSN is caused by mutation in the ATP synthase-6 gene (MTATP6).
Diagnosis is based on clinical observation of choreoathetoid movements of the face, trunk and extremities and evidence of basal ganglia degeneration on CT and MRI images.
Differential diagnoses include Wilson's disease, acute disseminated encephalomyelitis, neurodegeneration with brain iron accumulation, Leigh disease, juvenile Huntington chorea, methylmalonic aciduria, guanidinoacetate methyltransferase deficiency, glutaric acidemia I (see these terms), carbon monoxide intoxication, small vessel arteritis and trauma.
Antenatal diagnosis and genetic counseling is offered to families of affected patients.
Familial IBSN can be inherited as an autosomal recessive or mitochondrial disorder.
There is no standard therapy for familial IBSN. Treatment with oral biotin has been observed to slow disease progress initially. Treatment for the sporadic form is based on treatment of the causal infection.
Prognosis for the familial form is usually poor with patients progressing to spastic quadriparesis followed by death, usually due to infection. For the sporadic form, prognosis is variable, with either gradual improvement in symptoms and complete recovery, observed after recovery from the infection, or severe neurological sequelae.
Last update: March 2010