Abstracts

Seizures of different types are a common symptom during the course of metabolic diseases in infancy. Usually the seizures are accompanied by other obvious symptoms and signs of encephalopathy. Seizures not accompanied by other symptoms can be caused by a variety of disorders. However, rare metabolic disorders of infancy may present with seizures alone and require a specific and emergent approach. We recommend several tests that may provide the diagnosis in a timely manner and guide treatment.
Retrospective chart review of infants below age of three months that presented with seizures to a tertiary center from 2000 to present. When the diagnosis of a rare metabolic disorder was made, medical information and laboratory tests were reviewed.
Six infants meeting the inclusion criteria were encountered. Five of the children presented in the neonatal period, while one child presented at three months of age. In three infants seizures alone preceded all other symptoms. Three others presented with seizures and abnormal neurological examination at admission.
A diagnosis of isolated sulphite oxidase deficiency was suggested by positive sulphite stick reaction in urine in three patients, and confirmed. A novel mutation was found in one. All three presented during the second day of life with tonic, myoclonic and partial seizures that were intractable.
One infant presented at age of two weeks with decreased appetite and tonic episodes. Mapple Syrup Urine Disease was diagnosed based on blood amino acids analysis, without evidence of hypoglycemia or acidosis, and confirmed by genetics. Seizures subsided with dietary treatment.
One infant presented at age of three months with a generalized seizure preceded by two weeks of undiagnosed partial complex seizures. Neurological examination showed mild hypotonia. Abnormal blood gases, elevated serum and CSF lactate and bilateral symmetrical lesions of putamen ,caudate and thalami on CT were consistent with Leigh[rsquo]s syndrome confirmed by MRI, MRS. Anti epileptic medication and vitamins caused temporary seizure remission.
The sixth patient presented with multifocal asymmetric tonic seizures at two weeks of age and developed increased tone and cortical blindness by two months. Non Ketotic Hyperglycinemia was diagnosed based on urinary,blood and CSF glycine. Two siblings succumbed undiagnosed after similar clinical onset and course.
EEG background abnormalities and epileptiform activity was present in all patients but was not specific to the underlying disorder.
Afebrile seizures in infants below age of three months are the hallmark of many metabolic disorders. Obtaining blood gases, lactate, ammonia, serum amino acids, urine organic acids and sulfite stick may provide a rapid diagnosis. MRI and MRS can aid in ruling out anatomic causes and provide a non invasive measure of lactate and glycin. Metabolic disorders are a rare but potentially treatable cause of seizures in infancy.