Objective: To report the nature and extent of hearing loss and other otolaryngological problems in patients with mitochondrial disease, and to document the risk of neurodegeneration with infection.
Design: Medical chart review and telephone interview of 40 patients with documented mitochondrial disease.
Setting: An international referral center for the diagnosis and management of mitochondrial disorders.
Patients: We describe 40 patients with a definitive diagnosis of mitochondrial disease. Thirty-three (82%) were younger than 15 years.
Results: Hearing loss was the most common clinical finding associated with mitochondrial disease. Twenty-eight (80%) of the 35 patients undergoing testing had hearing loss or significant auditory dysfunction. In 20 (57%) of these, brainstem conduction abnormalities were identified. Eight (30%) of the 27 patients had an abnormal number of recurrent upper respiratory tract infections, and 4 (50%) of these had life-threatening or neurodegenerative sequelae. Mitochondrial disease followed an episodic course, with periods of stasis or slow developmental progress, punctuated by neurodegenerative events in 18 (60%) of 30 patients. Intercurrent infection was recognized as a precipitant of neurodegenerative events in 13 (72%) of 18 patients with a history of episodic degeneration.
Conclusions: Children and adults with mitochondrial disorders are at high risk for hearing loss and life-threatening complications of intercurrent infections. A constellation of audiologic abnormalities, multiorgan system involvement, and history of neuromuscular setbacks with infection strongly suggests mitochondrial disease. Knowledge of these features can lead to more rapid diagnosis and improved medical and surgical management for this special group of patients with fundamental defects in bioenergy metabolism.