Mitochondrial neurogastrointestinal encephalomyopathy associated with progressive hearing loss.
OBJECTIVE
We report a rare case of mitochondrial neurogastrointestinal encephalomyopathy with hearing loss.


METHODS
A 46-year-old woman presented with a three-year history of progressive, bilateral hearing loss and tinnitus. She had been suffering from unexplained abdominal pain and diarrhoea for 20 years. When first seen, her otoscopic findings were normal, and pure tone audiometry showed mild and moderate hearing loss in her right and left ears, respectively. She also had: bilateral ophthalmoparesis, neck and limb muscle weakness, and hypoactive deep tendon reflexes on neurological examination; diffuse leukoencephalopathy on magnetic resonance imaging of the brain; and markedly reduced leukocyte thymidine phosphorylase activity. On the basis of these findings, the patient was diagnosed with mitochondrial neurogastrointestinal encephalomyopathy.


CONCLUSIONS
Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disease caused by mutation of the thymidine phosphorylase gene, and is characterised by ophthalmoparesis, peripheral neuropathy, leukoencephalopathy, gastrointestinal symptoms and abnormal mitochondria in muscle cells. Current advances in genetic research may reveal a higher prevalence of mitochondrial disorders than had previously been thought. Otolaryngologists should be aware of mitochondrial neurogastrointestinal encephalomyopathy and other rare genetic disorders when managing patients with progressive hearing loss.
Hiraki
N
N
Department of Otorhinolaryngology, Hamamatsu Rosai Hospital, Hamamatsu, Japan. hiraki@med.uoeh-u.ac.jp
Udaka
T
T
Yamamoto
H
H
Kadokawa
Y
Y
Ohkubo
J
J
Suzuki
H
H
D001301:Audiometry, Pure-Tone; D003937:Diagnosis, Differential; D018450:Disease Progression; D004576:Electromyography; D005260:Female; D006312:Hearing Loss, Bilateral / Q000175:diagnosis / Q000209:etiology; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007418:Intestinal Pseudo-Obstruction / Q000150:complications / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods; D008875:Middle Aged; D017237:Mitochondrial Encephalomyopathies / Q000150:complications / Q000175:diagnosis; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology; D039141:Muscular Dystrophy, Oculopharyngeal; D009886:Ophthalmoplegia / Q000151:congenital; D017354:Point Mutation / Q000235:genetics; D035583:Rare Diseases; D013939:Thymidine Phosphorylase / Q000235:genetics*; D014012:Tinnitus / Q000209:etiology; D028361:Mitochondrial Diseases
D013939:Thymidine Phosphorylase