Auditory system dysfunction due to infantile thiamine deficiency: long-term auditory sequelae.

Eleven infants who were fed a thiamine-deficient formula for a mean of 3 months were evaluated for immediate and long-term auditory abnormalities. At presentation, 8 infants had auditory neuropathy spectrum disorder (ANSD), which resolved with supplementary thiamine in 5 children, was permanent in 2 children, and deteriorated in 1 patient who died at the age of 7 years. An additional patient had an auditory pattern corresponding to that of auditory neuropathy of brain stem origin. The 2 remaining patients had unilateral cochlear hearing loss. Six to 8 years later, all patients with transient ANSD had normal audiograms, 2 patients had unilateral cochlear hearing loss, and the rest had neural hearing loss. All survivors had a language developmental delay and impaired speech intelligibility of varying degrees, especially in the presence of background noise. Thiamine is crucial for normal auditory development and function, and its deficiency may be considered an acquired metabolic cause of ANSD in infants.

Epilepsy in children with infantile thiamine deficiency.

OBJECTIVE: To report the follow-up findings of 7 children with severe epilepsy as a result of thiamine deficiency in infancy caused by a defective soy-based formula. METHODS: The medical records of 7 children aged 5-6 years with thiamine deficiency in infancy who developed epilepsy were reviewed and their clinical data, EEG tracings, and neuroimaging results were recorded. The clinical course and present outcome of these children, now 5 years after exposure to thiamine deficiency, are described. RESULTS: All infants displayed seizures upon presentation, either tonic, myoclonic, or focal. Six infants had an EEG recording at this stage and all showed slow background. Five of them had no epileptic activity and only 1 displayed focal activity. Following a seizure-free period of 1-9 months, the seizures recurred, and all 7 children displayed either myoclonic or complex partial seizures. Multifocal or generalized spike wave complexes were recorded on the EEGs of all 7 patients, and the tracings of 3 children evolved into hypsarrhythmia. The seizures were refractory to most antiepileptic drugs, and 4 children remain with uncontrolled seizures. All children have mental retardation and motor disabilities as well as symptoms of brainstem dysfunction. CONCLUSIONS: Our findings indicate that severe infantile thiamine deficiency may result in epilepsy.