Vitamin B-6 Dependency Syndromes Follow-up

Updated: May 15, 2017
  • Author: Haritha Reddy Chelimilla, MD; Chief Editor: Jatinder Bhatia, MBBS, FAAP  more...
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Follow-up

Further Outpatient Care

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  • Continue to monitor seizure activity.

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Further Inpatient Care

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  • Monitor seizure activity in patients with vitamin B-6 dependency syndrome.

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Inpatient & Outpatient Medications

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  • Pyridoxine (see Medication)

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Complications

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  • 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.

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Prognosis

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  • 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, 8] However, early therapy may decrease the severity of intellectual impairment. [1, 2, 19, 18] 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. [8] Additionally, one study reports a specific deficit in expressive speech. [18]

  • 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.

  • Scharer et al.. [27] have described three different phenotypes in pyridoxine treated patients: 1) complete seizure control and normal developmental outcome; 2) complete seizure control and developmental delay or intellectual disability; and 3) incomplete seizure control and developmental delay or intellectual disability

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Patient Education

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  • 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 eMedicineHealth's Children's Health Center and Digestive Disorders Center. Also, see eMedicineHealth's patient education articles Seizures in Children and Anatomy of the Digestive System.

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