Abstract

OBJECTIVE: 3-methylglutaconic aciduria (MEG), dystonia-deafness (D), (hepatopathy (H)), encephalopathy (E), and Leigh-like-syndrome (L) (MEGD(H)EL) syndrome is a rare, severely disabling progressive mitochondrial disease associated with biallelic pathogenic variants in SERAC1. Knowledge about hearing loss (HL) and hearing rehabilitation is scarce but highly sought after for best possible care in the absence of causative treatment.

METHODS: Retrospective cross-sectional study.

RESULTS: This study analyzed the audiometric data of 36 MEGD(H)EL patients (14 unpublished). Bilateral HL was diagnosed in 31 individuals (86 %). Detailed audiometric data, available for 23 of 31 patients, did not allow for general statements on site and degree of HL. HL was mostly congenital (n = 14/31), pre-lingual in six and post-lingual in nine cases (median age 2 years, n = 15/31; age unknown in n = 2). In four of the five patients without HL, the severity of the other clinical-neurological symptoms was milder and less progressive, and their onset was significantly later than in the patients with HL. Five of 36 patients acquired spoken language, these were 4 of the 5 individuals without and one with HL. Twenty-two individuals received hearing rehabilitation with conventional hearing aids, followed by cochlear implant (CI) surgery in six. One of these six individuals acquired spoken language, which lessened in clarity as disease progressed.

CONCLUSIONS: Congenital HL represents a ubiquitous symptom in severe types of MEGD(H)EL syndrome, being absent in late onset milder forms. Regularly, severely affected MEGD(H)EL patients do not achieve spoken language, even with CI. Hence, hearing rehabilitation with CIs needs to be discussed very critically.