Acute proximal weakness after cochlear implant: Riboflavin transporter deficiency onset in child

Riboflavin transporter deficiencies (RTDs) are treatable progressive neurodegenerative disorders that present with symptoms including weakness, ataxia and neurosensory hearing loss. Once converted to the flavin cofactor, riboflavin plays a pivotal role in redox metabolic reactions. Similarly to classical mitochondrial diseases, stress may act as a trigger for disease progression. The subject is a 3-year-old girl with initially normal development who experienced language regression due to sensorineural deafness at 20 months old. One year later, the patient experienced an acute episode of asymmetric proximal weakness following cochlear implant surgery. All metabolic, immunological, and neuroimaging studies were normal. Serial electromyography studies revealed a rapidly progressive axonal sensory-motor neuropathy affecting the upper limbs. In search of treatable conditions, riboflavin was initiated, and later on, compound heterozygous pathogenic variants in SLC52A2 were identified. This report describes the clinical and electromyography findings of this patient during the four years following diagnosis.