Pyridoxine‐dependent seizures responding to extremely low‐dose pyridoxine

Abstract

We report on a male infant with pyridoxine dependency and seizures from birth, controlled with pharmacological doses of pyridoxine at 4 months of age. Seizures stopped between 30 and 80 days of age when very‐low doses of pyridoxine were given in a multivitamin supplement. Daily dose was 0.5 mg that corresponded to 0.08 to 0.16 mg/kg/day when weight gain is considered. In previous reports doses have ranged from 0.2 to 30 mg/kg/day. Another distinctive feature was that this infant went into a coma and developed hypotonia and irregular breathing when pyridoxine was given by enteral tube which has usually been reported when the vitamin is given intravenously. Use of low doses of pyridoxine in multivitamin supplements could be a confounding factor for early diagnosis and appropriate treatment of pyridoxine‐dependent seizures.

Pyridoxine‐dependent and pyridoxine‐responsive seizures

“…However, in others small doses of pyridoxine (1 mg or so) can be enough to control seizures, so the administration of vitamin supplements can confuse the diagnosis. 14 It seems advisable that pyridoxine should be a third-line drug in the management both of acute status and of chronic intractable seizure disorders of any type in young children.…”

Pyridoxine-dependent epilepsy initially responsive to phenobarbital

“…Atypical cases, however, have been reported such as late-onset PDE starting after 19 months of life, seizures that initially respond to very small doses of pyridoxine but then later require pharmacological doses 8 and epileptic conditions that initially respond to anticonvulsants but after a certain period of time respond only to pyridoxine, challenging its diagnosis 9 .…”

“…The only way to confi rm its diagnosis is through a formal trial of withdrawal. The other certainty in this disorder is that pyridoxine has to be continued for life [1][2][3][4][5]8,9 .…”

“…No toxicity or side effects were noticed with this dosage [1][2][3][4][5]8,9 . It is also recommended that pregnant women who previously gave birth to a child with PDE should receive 50-100 mg/ day of pyridoxine during the fi nal half of gestation 3 .…”

“…This rarity limits the development of clinical trials that would facilitate its diagnosis or determine its optimal treatment regimen 7 . Atypical presentations include lateonset PDE (after 19 months of life), seizures that initially respond to very small doses of pyridoxine but then require higher doses 8 and epileptic conditions that initially respond to anticonvulsants but then respond only to pyridoxine, challenging the diagnosis 7 .…”