OBJECTIVE: To define auditory nerve and cochlear functions in two families with autosomal dominant axonal Charcot-Marie-Tooth (CMT). METHODS: Affected members in two families with different point mutations of NF-L gene were screened with auditory brainstem responses (ABRs). Those with abnormal ABRs were further investigated with clinical, neurophysiological and audiological procedures. The point mutations of NF-L gene involved were Glu397Lys in 8 affected members of the family with AN, and Pro22Ser in 9 affected members of the family without AN. RESULTS: ABRs and stapedial muscle reflexes were absent or abnormal in affected members of only one family consistent with auditory neuropathy (AN). In them, audiograms, otoacoustic emissions, and speech comprehension were normal. Absent or abnormal ABRs were consistent with slowing of conduction along auditory nerve and/or brainstem auditory pathway. Wave I when present was of normal latency. CONCLUSIONS: Auditory nerve involvement in the presence of normal cochlear outer hair cell activity is asymptomatic in one of two families with CMT disorder with different point mutations of the NF-L gene. The nerve disorder is consistent with altered synchrony and slowed conduction. SIGNIFICANCE: The absence of "deafness" may reflect the ability of central mechanisms to compensate for the slowly developing auditory nerve abnormalities.
OBJECTIVE: To define auditory nerve and cochlear functions in two families with autosomal dominant axonal Charcot-Marie-Tooth (CMT). METHODS: Affected members in two families with different point mutations of NF-L gene were screened with auditory brainstem responses (ABRs). Those with abnormal ABRs were further investigated with clinical, neurophysiological and audiological procedures. The point mutations of NF-L gene involved were Glu397Lys in 8 affected members of the family with AN, and Pro22Ser in 9 affected members of the family without AN. RESULTS: ABRs and stapedial muscle reflexes were absent or abnormal in affected members of only one family consistent with auditory neuropathy (AN). In them, audiograms, otoacoustic emissions, and speech comprehension were normal. Absent or abnormal ABRs were consistent with slowing of conduction along auditory nerve and/or brainstem auditory pathway. Wave I when present was of normal latency. CONCLUSIONS: Auditory nerve involvement in the presence of normal cochlear outer hair cell activity is asymptomatic in one of two families with CMT disorder with different point mutations of the NF-L gene. The nerve disorder is consistent with altered synchrony and slowed conduction. SIGNIFICANCE: The absence of "deafness" may reflect the ability of central mechanisms to compensate for the slowly developing auditory nerve abnormalities.
Authors: E Villalón; M R Jones; C Sibigtroth; S J Zino; J M Dale; D S Landayan; H Shen; D D W Cornelison; M L Garcia Journal: Genes Brain Behav Date: 2016-10-11 Impact factor: 3.449
Authors: Alejandro Horga; Matilde Laurà; Zane Jaunmuktane; Nivedita U Jerath; Michael A Gonzalez; James M Polke; Roy Poh; Julian C Blake; Yo-Tsen Liu; Sarah Wiethoff; Conceição Bettencourt; Michael Pt Lunn; Hadi Manji; Michael G Hanna; Henry Houlden; Sebastian Brandner; Stephan Züchner; Michael Shy; Mary M Reilly Journal: J Neurol Neurosurg Psychiatry Date: 2017-05-13 Impact factor: 10.154
Authors: Rosamaria Santarelli; Pietro Scimemi; Chiara La Morgia; Elona Cama; Ignacio Del Castillo; Valerio Carelli Journal: Audiol Res Date: 2021-11-26