Neurofibromatosis type 1 tied to severe auditory dysfunction in children, adults
Severe auditory dysfunction was a common neurobiological feature of neurofibromatosis type 1, according to results of a case-control study published in JAMA Network Open.
“Neurofibromatosis type 1 (NF1) is an autosomal dominant condition with a birth incidence of approximately 1 in 2,700 and is caused by loss-of-function alterations within the NF1 gene (OMIM 613113),” Gary Rance, PhD, of the department of audiology and speech pathology at the University of Melbourne in Australia, and colleagues wrote. “Although characterized by diverse cutaneous, skeletal and neoplastic manifestations, cognitive deficits and behavioral problems are also common. Intelligence typically falls within the low to average range, and as many as 80% of children with NF1 experience executive dysfunction, inattention and visuoperception deficits.”
According to the researchers, data are sparse regarding the hearing of patients with NF1. Studies have shown normal sound detection thresholds among most individuals with this diagnosis; however, there have been reports of abnormal results on auditory neural and temporal processing tests. Thus, central processing deficits may correlate with high rates of speech and/or communication delays among this patient population.
In the current study, Rance and colleagues analyzed data of children and adults with NF1 (n = 44; mean age, 16.9 years; 41% were female) and compared their outcomes with control participants (n = 44; mean age, 17.2 years; 41% were female) matched via age, sex and hearing level. They recruited patients through specialist neurofibromatosis and neurogenetic outpatient clinics between April 2019 and September 2019 and evaluated auditory neural activity, monaural/binaural processing and functional hearing. From a subset of 10 children with NF1 and 10 matched controls, the researchers collected diffusion-weighted MRI data. Auditory dysfunction type and severity, assessed via laboratory testing and questionnaire data, served as the main outcomes and measures.
Results showed 11 participants (25%) with NF1 exhibited evidence of auditory neural dysfunction, including absent, delayed or low amplitude electrophysiological responses from the auditory nerve and/or brainstem. One participant (2%) in the control group (OR = 13.03; 95% CI, 1.59-106.95) had similar dysfunction. A total of 14 (32%) participants with NF1 exhibited clinically abnormal speech perception in background noise vs. one participant (2%) in the control group (OR = 20.07; 95% CI, 2.5-160.89). Researchers noted significantly lower apparent fiber density within the ascending auditory brainstem pathways among those with NF1, according to analysis of diffusion-weighted MRI data. Identified regions correlated with neural dysfunction measured via electrophysiological assessment.
“The findings suggest that auditory evaluation should be part of the management regime for every patient with NF1. and that the test protocol should include electrophysiological and speech perception (in noise) assessment,” Rance and colleagues wrote. “Standard audiometry is inadequate for this group, as sound detection can be normal in individuals with severe functional hearing limitations.”