RESUMEN
Metabolic syndromes associated with hearing loss are rare and are characterized by specific enzyme pathway deficiencies involving lysosomal storage, peroxisomes, fatty acid enzymes, organic acids and amino acids. The deficiency of biotinidase, an enzyme involved in the metabolism of biotin, is one such rare cause of congenital hearing loss estimated at 1:60,000 newborns. The parents of a 5-year-old girl presented to the clinic with complaints that she was hard of hearing with no speech development. At age 2 she had been diagnosed with organic aciduria and hydronephrourethrosis and was operated for renal calculi. Clinical examination showed periorificial scaly skin lesions and eczematous otitis externa. An audiological evaluation showed bilateral profound SNHL. Imaging and routine investigations were unremarkable, except for a mild low anion gap metabolic acidosis. General anaesthesia involved avoidance of neuromuscular agents due to the risk of inducing hypotonia. Surgery consisted of cortical mastoidectomy followed by the facial recess approach. A standard electrode array was inserted via the round window technique and complete atraumatic insertion was achieved. Intraoperative electrode impedance and NRT tracings were good. Hearing loss in biotinidase deficiency may be expected to be of progressive nature and regular evaluation of hearing and speech is required. Cochlear implantation is currently the best available solution for severe to profound hearing loss in this disorder although the enzymatic pathology affects the entire auditory pathway. Biotin supplementation is required lifelong for its management.
RESUMEN
BACKGROUND: While hearing aids for a contralateral routing of signals (CROS-HA) and bone conduction devices have been the traditional treatment for single-sided deafness (SSD) and asymmetric hearing loss (AHL), in recent years, cochlear implants (CIs) have increasingly become a viable treatment choice, particularly in countries where regulatory approval and reimbursement schemes are in place. Part of the reason for this shift is that the CI is the only device capable of restoring bilateral input to the auditory system and hence of possibly reinstating binaural hearing. Although several studies have independently shown that the CI is a safe and effective treatment for SSD and AHL, clinical outcome measures in those studies and across CI centers vary greatly. Only with a consistent use of defined and agreed-upon outcome measures across centers can high-level evidence be generated to assess the safety and efficacy of CIs and alternative treatments in recipients with SSD and AHL. METHODS: This paper presents a comparative study design and minimum outcome measures for the assessment of current treatment options in patients with SSD/AHL. The protocol was developed, discussed, and eventually agreed upon by expert panels that convened at the 2015 APSCI conference in Beijing, China, and at the CI 2016 conference in Toronto, Canada. RESULTS: A longitudinal study design comparing CROS-HA, BCD, and CI treatments is proposed. The recommended outcome measures include (1) speech in noise testing, using the same set of 3 spatial configurations to compare binaural benefits such as summation, squelch, and head shadow across devices; (2) localization testing, using stimuli that rove in both level and spectral content; (3) questionnaires to collect quality of life measures and the frequency of device use; and (4) questionnaires for assessing the impact of tinnitus before and after treatment, if applicable. CONCLUSION: A protocol for the assessment of treatment options and outcomes in recipients with SSD and AHL is presented. The proposed set of minimum outcome measures aims at harmonizing assessment methods across centers and thus at generating a growing body of high-level evidence for those treatment options.