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Pyridoxine-dependent epilepsy: EEG investigations and long-term follow-up
M A Mikati1, E Trevathan, K S Krishnamoorthy
1Department of Neurology, Children's Hospital, Boston, MA 02115.
Insights
Pyridoxine (B6) therapy is crucial for diagnosing and treating B6-dependent epilepsy. EEG monitoring before, during, and after treatment provides vital diagnostic and prognostic information for seizure control and long-term outcomes.
Area of Science:
- Neurology
- Clinical Neuroscience
- Biochemistry
Background:
- Pyridoxine (Vitamin B6) deficiency can cause epilepsy, particularly in neonates.
- Electroencephalography (EEG) is essential for diagnosing and monitoring epilepsy.
- B6-dependent epilepsy presents unique diagnostic challenges.
Purpose of the Study:
- To investigate EEG features and clinical correlations in B6-dependent epilepsy.
- To evaluate the diagnostic and prognostic utility of EEG during pyridoxine therapy.
- To assess the long-term efficacy of pyridoxine monotherapy.
Main Methods:
- EEG monitoring before, immediately after, and long-term after pyridoxine initiation.
- Parenteral pyridoxine challenge test in patients with suspected B6-dependent epilepsy.
- Clinical seizure assessment and developmental evaluation.
Main Results:
- A unique neonatal EEG pattern of generalized bursts of 1-4 Hz sharp and slow activity was observed in B6-dependent epilepsy.
- Parenteral pyridoxine rapidly abolished clinical seizures and EEG paroxysmal discharges.
- Long-term pyridoxine monotherapy (10-100 mg/day) resulted in sustained seizure freedom in all 6 patients.
- EEG abnormalities correlated with developmental outcomes, with normal EEGs associated with normal development.
Conclusions:
- EEG is a critical tool for diagnosing and predicting outcomes in B6-dependent epilepsy.
- Pyridoxine therapy is highly effective for seizure control and long-term management.
- Sustained seizure control with pyridoxine is linked to normal neurodevelopmental outcomes.
Abstract:
The EEG features and clinical correlates were investigated before, directly after, and on long-term follow-up after initiation of pyridoxine therapy in 6 patients with B6-dependent epilepsy. At each phase, the EEG provided important diagnostic and prognostic information. Pre-B6 3 neonates manifested a unique EEG pattern of generalized bursts of 1-4 Hz sharp and slow activity. This pattern has not been previously described in neonates with B6 dependency and in this age group appears to be highly suggestive of the diagnosis. Five patients experienced an apparent initial response to traditional antiepileptics. The parenteral pyridoxine test, performed in all 5, and repeated in 3, proved to be a highly reliable and reproducible diagnostic test. After 50-100 mg of B6 there was cessation of clinical seizures within minutes and of paroxysmal discharges within hours. On long-term follow-up (3-28 years) all 6 patients were seizure free on B6 (10-100 mg/day) monotherapy. Recurrences of seizures and of specific sequential EEG changes (background slowing, photoparoxysmal response, spontaneous discharges, stimulus-induced myoclonus, generalized seizures) occurred upon B6 withdrawal. Long-term prognosis correlated with the EEG. Two patients had persistently abnormal EEG backgrounds and were moderately to severely retarded, while 4 had normal EEGs with normal or near normal development.