Pyridoxine-dependent seizures (PDS) is an extremely rare cause of difficult to control (intractable) neonatal seizures. Less than 200 cases have been reported in medical literature. The primary characteristic of all persons with PDS is intractable seizures that are not controlled with anticonvulsants but which do respond both clinically and electrographically to large daily supplements of pyridoxine (vitamin B6).
These persons are not pyridoxine-deficient. They are metabolically dependent on the vitamin. In other words, without supplemental pyridoxine, persons with PDS will experience seizures. With supplemental pyridoxine the patient will not experience seizures.
Muggy has had seizures while taking pyridoxine, but only if he was sick and ran a fever of over 101°. It is believed that high fever lowers his seizure threshold (triggering a febrile seizure) , so if he gets a cold or flu bug and starts running a fever, we raise his dosage from 150 mg per day to 300 mg. In the last 2 years, I’ve seen him run a fever as high as 104° or 105° at the higher dosage and not have a seizure! I guess this means either he responds to the higher dose or else he is becoming less susceptible to the febrile seizures.
Intellectual disability, particularly with expressive language, is common in individuals with PDS. Pyridoxine therapy will be required for life. Muggy exhibits autistic behaviors and has been diagnosed as having an Autism Spectrum Disorder. He is not considered classically autistic or having Aspergers, but rather falls under the Pervasive Developmental Disorder—Not Otherwise Specified (PDD-NOS).
If you are interested in reading more about PDS, Dr. Sidney M Gospe Jr, MD, PhD is the leading authority.