eMedicine Specialties > Pediatrics: General Medicine > Nutrition
Vitamin B-6 Dependency Syndromes: Follow-up
Updated: Nov 19, 2008
Follow-up
Further Inpatient Care
- Monitor seizure activity in patients with vitamin B-6 dependency syndrome.
Further Outpatient Care
- Continue to monitor seizure activity.
Inpatient & Outpatient Medications
- Pyridoxine (see Medication)
Complications
- Patients who are taking long-term pyridoxine for pyridoxine-dependent seizure (PDS) must be assessed for signs of sensory peripheral neuropathy on follow-up; this should include monitoring of rombergism, ankle jerks, and joint position sense.1,2
- The toxic effects of pyridoxine administration are a major concern for patients with PDS. Prolonged depression of neurologic and respiratory function, bradycardia, hypotonia and apnea, and depression of cerebral electrical activity have all been reported in patients receiving oral or parenteral test doses of pyridoxine. A reversible sensory neuropathy has been described in some individuals who have taken high doses of pyridoxine on a long-term basis. In some patients, a chronic painful neuropathy has developed.1,2
- In adults, symptoms of adverse effects of megadoses of pyridoxine include unstable gait and feet numbness, followed by numbness and clumsiness of the hands, and then perioral numbness. Signs include gait ataxia, reduced or absent reflexes, decrease position, vibration, pain, and heightened temperature sensation.2
- Intercurrent illness can precipitate seizures in children whose states are usually well controlled on pyridoxine. Administration of an additional 100 mg of pyridoxine per day is recommended in these cases;2 however, this is not always effective.
Prognosis
- Untreated patients usually die with a severe seizure disorder, and most infants have mental retardation despite the initiation of therapy in utero or during the first hour of life.1,5 However, early therapy may decrease the severity of intellectual impairment.1,2,12,11 A meta-analysis of the most recent literature indicates no significant correlation between developmental outcome and the time of diagnosis and institution of pyridoxine therapy. Some studies suggest that the developmental outcome is dependent on the dose of pyridoxine used.1 Approximately 60% of patients with PDS have delayed developmental milestones for walking and talking.5 Additionally, one study reports a specific deficit in expressive speech.11
- Patients presenting older than 1 month have a better prognosis than those presenting younger than 1 month. Infants who have early seizures that are unresponsive to routine anticonvulsants usually have a poor prognosis.
Patient Education
- Instruct parents, caregivers, and other relevant parties (eg, relatives, teachers) on the administration of pyridoxine. Compliance in young children can be poor because liquid and tablet preparations of pyridoxine have an unpleasant taste, and breakthrough seizures can occur.2
- For excellent patient education resources, visit eMedicine's Children's Health Center and Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Seizures in Children and Anatomy of the Digestive System.
Miscellaneous
Medicolegal Pitfalls
- Failing to recognize pyridoxine dependency as a cause of intractable seizures is a pitfall.
- Litigation may result if pyridoxine-dependent seizures (PDS) remains undiagnosed in an infant in whom severe mental retardation develops.
Special Concerns
- One study suggests that treatment with intrauterine vitamin B-6 (100 mg/d) in pregnant women with a history of intrauterine convulsive movements (reported as a sustained hammering sensation) at 5 months' gestation or later may be successful in preventing PDS.
- Toxic effects of vitamin B-6 (>1 g/d) appear to be relatively low; however, several grams per day have produced sensory neuropathy, marked by changes in gait and peripheral sensation. No studies have reported the effect of vitamin B-6 toxicity on the fetus. Signs of vitamin B-6 toxicity seem to resemble vitamin B-6 deficiency.
- A highly significant correlation of the onset of seizures in affected siblings in the same family has been reported. Similarly, variable expression in the same family has also been found.1
The authors and editors of eMedicine gratefully acknowledge the contributions of previous author Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA, to the development and writing of this article.
More on Vitamin B-6 Dependency Syndromes |
| Overview: Vitamin B-6 Dependency Syndromes |
| Differential Diagnoses & Workup: Vitamin B-6 Dependency Syndromes |
| Treatment & Medication: Vitamin B-6 Dependency Syndromes |
 Follow-up: Vitamin B-6 Dependency Syndromes |
| References |
| « Previous Page |
References
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Hunt AD Jr, Stokes J Jr, McCrory WW, Stroud HH. Pyridoxine dependency: report of a case of intractable convulsions in an infant controlled by pyridoxine. Pediatrics. Feb 1954;13(2):140-5. [Medline].
Burd L, Stenehjem A, Franceschini LA, Kerbeshian J. A 15-year follow-up of a boy with pyridoxine (vitamin B6)-dependent seizures with autism, breath holding, and severe mental retardation. J Child Neurol. Nov 2000;15(11):763-5. [Medline].
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Kure S, Sakata Y, Miyabayashi S, et al. Mutation and polymorphic marker analyses of 65K- and 67K-glutamate decarboxylase genes in two families with pyridoxine-dependent epilepsy. J Hum Genet. 1998;43(2):128-31. [Medline].
Battaglioli G, Rosen DR, Gospe SM Jr, Martin DL. Glutamate decarboxylase is not genetically linked to pyridoxine-dependent seizures. Neurology. Jul 25 2000;55(2):309-11. [Medline].
Been JV, Bok LA, Andriessen P, Renier WO. Epidemiology of pyridoxine dependent seizures in the Netherlands. Arch Dis Child. Dec 2005;90(12):1293-6. [Medline].
Baxter P. Epidemiology of pyridoxine dependent and pyridoxine responsive seizures in the UK. Arch Dis Child. Nov 1999;81(5):431-3. [Medline].
Baxter P. Pyridoxine dependent epilepsy: a suggestive electroclinical pattern. Arch Dis Child Fetal Neonatal Ed. Sep 2000;83(2):F163. [Medline].
Plecko B, Paul K, Paschke E, et al. Biochemical and molecular characterization of 18 patients with pyridoxine-dependent epilepsy and mutations of the antiquitin (ALDH7A1) gene. Hum Mutat. Jan 2007;28(1):19-26. [Medline].
Kanno J, Kure S, Narisawa A, et al. Allelic and non-allelic heterogeneities in pyridoxine dependent seizures revealed by ALDH7A1 mutational analysis. Mol Genet Metab. Aug 2007;91(4):384-9. [Medline].
Ohtsuka Y, Ogino T, Asano T, et al. Long-term follow-up of vitamin B(6)-responsive West syndrome. Pediatr Neurol. Sep 2000;23(3):202-6. [Medline].
Hindley D, Huyton M. Pyridoxine dependent and pyridoxine responsive seizures. Arch Dis Child. Jan 2001;84(1):91-2. [Medline].
Further Reading
Keywords
pyridoxine-responsive convulsions, pyridoxine-dependent seizures, pyridoxine dependency–associated seizures, PDS, West syndrome, homocystinuria, myoclonic epilepsy, hemolytic-uremic syndromes, pyridoxal, pyridoxamine, pyridoxine deficiency, pyridoxine–deficient seizures, pyridoxine deficiency–associated seizures, vitamin B6, vitamin B6, vitamin B-6, nuts, meats, isoniazid, inborn disorder of metabolism, perinatal asphyxia , hypoxic-ischemia encephalopathy, tonic-clonic seizures, acute abdominal obstruction, respiratory distress, hydrocephalus
