Hearing profile and MRI myelination of auditory pathway in Pelizaeus-Merzbacher disease.
CONCLUSIONS
This study showed that delayed auditory pathway myelination is common in Pelizaeus-Merzbacher disease (PMD), but this delay does not necessarily indicate poor hearing function.


OBJECTIVE
PMD is a rare recessively inherited X-linked leukodystrophy characterized by defective central nervous system myelination owing to a mutation in the proteolipid protein gene (PLP). The aims of this study were to evaluate the hearing function and auditory brain response (ABR) findings of patients with PMD and relate these findings to MRI-assessed myelination in the central auditory pathway.


METHODS
We retrospectively studied eight male pediatric patients with PMD. Serial auditory examinations included audiometry, behavior audiometry, distortion product otoacoustic emission (DPOAE), and ABR. MRI-assessed myelination in the auditory pathway was evaluated in the PMD patients and in 23 normal young children as a control group.


RESULTS
Audiometry showed normal to moderate hearing impairment and the hearing threshold improved with age and became almost normal over time. DPOAEs positivity and only ABR wave I or waves I and II were found in all the patients. MRI showed delayed myelination in all the patients and the auditory pathway was myelinated up to the inferior colliculus in four cases and up to the medial geniculate body in four cases. Serial MRIs showed no progression in myelination. No clear relation was found between hearing threshold and MRI-assessed myelination in the auditory pathway.
Kuan
Chen-Chieh
CC
Department of Otolaryngology, School of Medicine, University of Tokyo, Tokyo, Japan. volvo9837@yahoo.com
Sano
Masaki
M
Kaga
Kimitaka
K
Kodama
Mariko
M
Kodama
Kazuo
K
D001284:Atrophy; D001300:Audiometry, Evoked Response; D001301:Audiometry, Pure-Tone; D001306:Auditory Pathways / Q000473:pathology* / Q000503:physiopathology; D001309:Auditory Threshold / Q000502:physiology; D001933:Brain Stem / Q000473:pathology / Q000503:physiopathology; D002531:Cerebellum / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D017626:Cochlear Nucleus / Q000473:pathology / Q000503:physiopathology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005500:Follow-Up Studies; D005829:Geniculate Bodies / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007223:Infant; D007245:Inferior Colliculi / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology* / Q000502:physiology; D009847:Olivary Nucleus / Q000473:pathology / Q000503:physiopathology; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D020371:Pelizaeus-Merzbacher Disease / Q000151:congenital* / Q000175:diagnosis / Q000503:physiopathology; D013063:Speech Discrimination Tests