Cochlear implantation in a patient with neurofibromatosis type 1 and profound hearing loss: evidence to support a cochlear site of lesion

Incidence of Hearing Loss in Patients With Neurofibromatosis Type 1 at a Tertiary Care Pediatric Hospital

BACKGROUND

Hearing loss has not been thoroughly investigated as a comorbidity in larger cohorts with neurofibromatosis type 1 (NF1).

METHODS

Available audiometric data were reviewed from patients with NF1 seen at a tertiary pediatric hospital to assess prevalence and risk factors for hearing loss.

RESULTS

Of 1172 patients with NF1 seen between 2010 and 2022, 90 had available audiometric data and 48 of 90 patients (53%) had one or more audiogram revealing hearing loss. Those not referred to audiology were presumed to have normal hearing, resulting in a conservative hearing loss estimate of 4% for children and young adults with NF1. Of 90 patients with audiograms, 29 (32%) had conductive loss (CHL), 15 (17%) had sensorineural loss (SNHL), and 3 (3%) had mixed hearing loss. Hearing loss type was undetermined for one patient. For children with CHL, six had permanent CHL secondary to plexiform neurofibroma, 19 CHL were transient due to active middle ear dysfunction, and four CHL cases were indeterminate in etiology. For three children with SNHL or mixed hearing loss, etiology included history of ototoxic chemotherapy and/or family history of SNHL. In the 16 patients with SNHL or mixed hearing loss with more than one audiogram over time, progressive hearing decline was noted in eight of 16, and 26 of 178 hearing thresholds (15%) progressed.

CONCLUSIONS

Our findings suggest that audiometric evaluations should be considered for at least a subset of children with NF1, given the higher-than-expected rate of hearing loss in patients with NF1 compared with the general population.

Presence of Auditory Pathway Abnormalities in Children With Neurofibromatosis Type 1 With Brainstem Focal Areas of Abnormal Signal Intensity: Diffusion Tensor Imaging Features

Background: To investigate whether there is a difference in mean diffusivity (MD) and fractional anisotropy (FA) values in the auditory pathways of neurofibromatosis type 1 patients with and without focal areas of abnormal signal intensity (FASI) compared to healthy controls by using diffusion tensor imaging (DTI). Methods: Patients were classified as group 1 with focal areas of abnormal signal intensity in the brainstem, group 2 without focal areas of abnormal signal intensity, and healthy control group 3 according to the MRI findings. Mean diffusivity and fractional anisotropy values of lateral lemniscus, inferior colliculus, corpus geniculatum mediale, Heschl gyrus, and brainstem were compared between groups. The correlation between mean diffusivity and fractional anisotropy values of auditory pathways and age was investigated. Results: There was a significant difference between group 1 and group 2 in terms of mean diffusivity and fractional anisotropy values at lateral lemniscus, inferior colliculus, corpus geniculatum mediale, and Heschl gyrus. Increased mean diffusivity and decreased fractional anisotropy values at brainstem were found in group 1. There was a significant difference between group 1 and group 3 in terms of mean diffusivity values at all auditory pathways. Fractional anisotropy values obtained from lateral lemniscus, inferior colliculus, and Heschl gyrus decreased in group 1 compared with group 3. There was a negative correlation between mean diffusivity values and positive correlation between fractional anisotropy values at lateral lemniscus, inferior colliculus, Heschl gyrus, and age. Conclusions: Our diffusion tensor imaging findings show that the neuronal integrity of the auditory pathways is affected in neurofibromatosis type 1 patients with brainstem focal areas of abnormal signal intensity. We think that the disappearance of brainstem focal areas of abnormal signal intensity associated with myelin repair and the regression of diffusion tensor imaging changes in the auditory pathways occur simultaneously with advancing age in patients with neurofibromatosis type 1.

Benefits of intervention in the Central Auditory Nervous System in individuals with Neurofibromatosis Type 1

OBJECTIVE

To verify the effectiveness of acoustically controlled auditory training in individuals with Neurofibromatosis Type 1.

METHODS

The sample consisted of individuals with Neurofibromatosis Type 1, randomly distributed into two groups, making up the intervention group: individuals undergoing formal auditory training; and the comparison group: individuals who were not submitted to the intervention. Behavioral assessment of central auditory processing and electrophysiological evaluation, composed by Brainstem Auditory Evoked Potential and Long Latency-P300 Auditory Evoked Potential, were evaluated in three moments of evaluations: initial evaluation, reevaluation and after four months of reevaluation and comparing the performance between the groups.

RESULTS

Better performances in central auditory processing were observed after the formal auditory training in the intervention group with significant differences between the evaluations and performance maintenance four months after the end of the training. Significant differences were observed between the groups in the evaluations after the intervention. The electrophysiological evaluation shows unsystematic variation in the short latency potentials and changes in the long latency potentials with the appearance of the P3 wave after the intervention. The behavioral and electrophysiological evaluation in group that was not submitted to the intervention demonstrated that there is no improvement without the intervention, with deterioration of performance. Significant differences were observed in the behavioral and electrophysiological evaluations, in favor of the group submitted to formal auditory training.

CONCLUSIONS

Formal auditory training is effective in rehabilitation in individuals with Neurofibromatosis Type 1.

DESCRIPTORS/KEYWORDS

Neurofibromatosis 1; Hearing Disorders; Auditory Perceptual Disorders; Acoustic Stimulation; Evoked Potentials, Auditory.

Successful cochlear implantation in two profoundly deafened patients with neurofibromatosis type 1: further evidence to support a cochlear site of lesion

OBJECTIVE

To investigate the usefulness of cochlear implantation and to examine the evidence for a cochlear or retrocochlear site of lesion for deafness in Neurofibromatosis Type 1 (NF1).

PATIENTS

Two profoundly deafened NF1 patients who underwent cochlear implantation.

INTERVENTIONS

Preoperative electrophysiologic and audiologic evaluation including pure-tone audiometry, auditory brainstem response, speech audiometry, otoacoustic emission, and promontory stimulation test. Intraoperative electrophysiologic tests were also performed.

MAIN OUTCOME MEASURES

Results of preoperative diagnostic workup. Cochlear implant performances were evaluated in the auditory-only condition in both closed-set and open-set formats.

RESULTS

Preoperative diagnostic assessment suggested cochlear impairment with preserved auditory pathway at the basis of the sensorineural hearing loss in both patients. Intraoperative electrically evoked auditory nerve and brainstem responses confirmed the integrity of the neural population all along the length of the cochlea. To date, with a follow-up of 2 and 10 years, both patients gained excellent open-set, auditory-only, speech understanding and were able to converse on the telephone without a code.

CONCLUSION

Cochlear impairment with preserved auditory pathways can be responsible for sensorineural hearing loss in NF1 patients. When their hearing deficit meets criteria for cochlear implantation, this type of auditory rehabilitation can restore social hearing in these patients while dramatically improving their quality of life.