Pyridoxine-dependent seizures have been recognised for 40 years, but the clinical and biochemical features are still not understood. It is a rare recessively inherited condition where classically a baby starts convulsing in utero and continues to do so after birth, until given pyridoxine. Many of these early onset cases also have an acute encephalopathy and other clinical features. Late onset cases are now recognised with a less severe form of the condition. Seizures can break through with intercurrent illness but otherwise remain controlled on pharmacologic doses of pyridoxine. The long-term outcome is affected by several factors including whether onset is early or late and how soon pyridoxine is given. Biochemical studies have been sparse, on very small numbers. There does not appear to be any defect in the uptake or metabolism of pyridoxine or pyridoxal phosphate (PLP). For a long time glutamic acid decarboxylase (GAD), a pyridoxal-dependent enzyme, has been suspected to be the abnormal gene product, but glutamate and gamma-aminobutyric acid (GABA) studies on the cerebrospinal fluid (CSF) have been contradictory and recent genetic studies have not found any linkage to the two brain isoforms. A recent report describes raised pipecolic acid levels in patients but how this ties in is unexplained.

Drug Overdose↗

PubMed2003

Idiopathic catastrophic epileptic encephalopathy presenting with acute onset intractable status.

PURPOSE: To delineate a catastrophic childhood epileptic syndrome of unknown cause presenting with persistent intractable multifocal status. METHODS: Case note review. RESULTS: Six children aged 5 months to 6 years presented with focal seizures that progressed within days to intractable multifocal seizures with or without secondary generalisation, which recurred every few minutes and persisted for weeks. One developed impaired consciousness shortly before seizures started. The two younger children showed mild developmental delay before onset but the others were normal. The seizures were unresponsive to all conventional anticonvulsants, steroids or pyridoxine and could only be controlled with doses of thiopentone sufficient to cause electrical suppression. MRI scans were initially normal but later showed focal cortical swelling followed by generalised atrophy. Two developed hepatomegaly, with a normal liver biopsy in one and steatosis in the other. No cause has been found even after neuropathological investigation. Three have died, two within 3 months of onset, while the three survivors have very severe neurological impairment and continued seizures. CONCLUSION: The similarity of the clinical features suggests that this is a consistent clinical syndrome.

Anesthetics, Intravenous↗

PubMed2002

Treating head injuries. Studies of efficacy of medical and surgical interventions are urgently needed.

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Child↗