Page 81 - Clinical variability in Noonan syndrome with emphasison ear and eye

EXTERNAL EAR ANOMALIES AND HEARING IMPAIRMENT IN NOONAN SYNDROME
Figure 1. Audiological results of patients from Table 4 with non-congenital sensorineural hearing impairment.
percentages. In our total cohort of 97 patients, we found a HI in 34%. A few patients with SNHI in NS have been described before in literature: One patient, who had a normal hearing level in childhood, the SNHI started at the age of 27. This patient had the benefit of hearing amplification (15). This SNHI was possibly due to endolymphatic hydrops with central vestibular abnormalities. Another study performed hearing tests in 20 patients, 40 ears (7). Pure tone audiometric findings between 250 – 8000 Hz, showed HI in 20% of the ears in low frequency range (250-2000 Hz) and in 50% in the high frequency range (3000-8000 Hz).
In general, most Noonan patients with HI have a conductive type of HI that is due to otitis media with effusion. But also MHI and SNHI are found. Underlying anomalies causing HI are occasionally described. Miura et al. have discussed the results of histopathological examinations of the temporal bones in three patients with NS (16).
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