Pyridoxine responsive convulsions. Pyridoxine dependency. Glutamic acid decarboxylase (GAD) deficiency.
Incidence
It is autosomal recessive disease. It is a rare cause of convulsions in neonatal infants. There is an atypical presentation characterized by later onset of attacks up to the age of 15 months, which incidence is probably much higher than the typical one.
Clinical Characteristics
This condition generally called pyridoxine responsive convulsions, is a rare cause of convulsions in neonatal infants. Typically, this autosomal recessive disease satisfies the following criteria: onset of convulsions before or shortly after birth, rapid response to pyridoxine and refractoriness to other anticonvulsants and absence of pyridoxine deficiency. The main central nervous system symptoms are irritability, flaccidity, abnormal eye movements from the neonatal period. Also, microcephaly and spasticity in infancy and childhood. All types of seizures can be observed and there is pronounced irritability. Abnormal eye movements have often been reported. It is considered an epileptic syndrome. There is an atypical presentation characterized by later onset of attacks up to the age of 15 months, and prolonged seizure-free intervals without pyridoxine. The incidence of this atypical type is probably higher than that of the typical one. The diagnosis is based on the clinical response to pyridoxine. In the typical presentation, convulsions cease within a few minutes when pyridoxine is given parenterally and within a few hours when it is administered orally. Laboratory testing include CSF GABA which is decreased in neonates and infancy and glutamic acid elevation in spinal fluid.
Precipitants
no
Provocation Tests
Pyridoxine 10 mg/kg/day will confirm or refute rapidly the diagnosis of this condition.
Diagnostic Procedures
The diagnosis is based on the clinical response to pyridoxine. In the typical presentation, convulsions cease within a few minutes when pyridoxine is given parenterally and within a few hours when it is administered orally. Laboratory testing include CSF GABA which is decreased in neonates and infancy and glutamic acid elevation in spinal fluid.