More information about text formats
We were very interested by the paper of Ceranic and Luxon 
which identified a progressive auditory neuropathy in two patients with
Leber’s hereditary optic neuropathy (LHON). The authors correctly
mentioned that we had reported auditory symptoms (bilateral tinnitus)
associated with prolongation of the I-III interpeak latency in a patient
with LHON harboring the T14484C mutation .
The patient did not
complain of hearing loss, but pure tone audiogram showed unilateral
hearing impairment (not mentioned in the case report because of space
limitations). This further suggests that the auditory dysfunction observed
in this patient was a subacute auditory neuropathy, not recognized as a
specific entity at this time.
However, Ceranic and Luxon gave an incorrect assessment of the
literature when stating that “the association of auditory neuropathy, or
any other auditory dysfunction, with LHON has not been recognized before”:
in 2002, we reported on another patient with LHON, which experienced
subacute bilateral hearing loss 12 years after the onset of the optic
neuropathy . This patient (patient 2 in ref. 3) harbored the
G14459A mtDNA mutation. Pure tone audiometry showed a bilateral loss of 40
dB on the right, 30 dB on the left. Poor waveform morphology on brainstem
auditory evoked potentials did not allow to measure interpeak intervals.
The association of this retrocochlear hearing loss with the visual
impairment due to LHON resulted in a severe handicap.
Our observations suggest that LHON may be complicated not only by
progressive but also by subacute auditory neuropathy. In our experience
however, this subacute auditory neuropathy was always associated with more
widespread abnormalities, such as symptoms of brainstem dysfunction and
Leigh-like lesions on brain magnetic resonance imaging.2-3 Whether
progressive auditory neuropathy can also be associated with clinical or
radiological signs of a more widespread mitochondrial disease remains to
(1). Ceranic B, Luxon LM. Progressive auditory neuropathy in patients
with Leber's hereditary optic neuropathy. J Neurol Neurosurg Psychiatry
(2). Funalot B, Ranoux D, Mas JL, et al. Brainstem involvement in
Leber's hereditary optic neuropathy: association with the 14484
mitochondrial DNA mutation. J Neurol Neurosurg Psychiatry 1996;61:533-534.
(3). Funalot B, Reynier P, Vighetto A, et al. Leigh-like encephalopathy
complicating Leber's hereditary optic neuropathy. Ann Neurol 2002;52:374-