Hearing loss in beta-thalassaemia: An Italian multicentre case-control study.

BACKGROUND: Despite numerous studies, the true scenario of hearing loss in beta-thalassaemia remains rather nebulous. MATERIALS AND METHODS: Pure tone audiometry, chelation therapy, demographics and laboratory data of 376 patients (mean age 38.5 ± 16.6 years, 204 females, 66 non-transfusion-dependent) and 139 healthy controls (mean age 37.6 ± 17.7 years, 81 females) were collected. RESULTS: Patient and control groups did not differ for age (p = 0.59) or sex (p = 0.44). Hypoacusis rate was higher in patients (26.6% vs. 7.2%; p < 0.00001), correlated with male sex (32.6% in males vs. 21.8% in females; p = 0.01) and it was sensorineural in 79/100. Hypoacusis rate correlated with increasing age (p = 0.0006) but not with phenotype (13/66 non-transfusion-dependent vs. 87/310 transfusion-dependent patients; p = 0.16). Sensorineural-notch prevalence rate did not differ between patients (11.4%) and controls (12.2%); it correlated with age (p = 0.01) but not with patients' sex or phenotype. Among adult patients without chelation therapy, the sensorineural hypoacusis rate was non-significantly lower compared to chelation-treated patients while it was significantly higher compared to controls (p = 0.003). CONCLUSIONS: Sensorineural hypoacusis rate is high in beta-thalassaemia (about 21%) and it increases with age and in males while disease severity or chelation treatment seems to be less relevant. The meaning of sensorineural-notch in beta-thalassaemia appears questionable.

Auditory cortex hypoperfusion: a metabolic hallmark in Beta Thalassemia.

BACKGROUND: Sensorineural hearing loss in beta-thalassemia is common and it is generally associated with iron chelation therapy. However, data are scarce, especially on adult populations, and a possible involvement of the central auditory areas has not been investigated yet. We performed a multicenter cross-sectional audiological and single-center 3Tesla brain perfusion MRI study enrolling 77 transfusion-dependent/non transfusion-dependent adult patients and 56 healthy controls. Pure tone audiometry, demographics, clinical/laboratory and cognitive functioning data were recorded. RESULTS: Half of patients (52%) presented with high-frequency hearing deficit, with overt hypoacusia (Pure Tone Average (PTA) > 25 dB) in 35%, irrespective of iron chelation or clinical phenotype. Bilateral voxel clusters of significant relative hypoperfusion were found in the auditory cortex of beta-thalassemia patients, regardless of clinical phenotype. In controls and transfusion-dependent (but not in non-transfusion-dependent) patients, the relative auditory cortex perfusion values increased linearly with age (p < 0.04). Relative auditory cortex perfusion values showed a significant U-shaped correlation with PTA values among hearing loss patients, and a linear correlation with the full scale intelligence quotient (right side p = 0.01, left side p = 0.02) with its domain related to communication skills (right side p = 0.04, left side p = 0.07) in controls but not in beta-thalassemia patients. Audiometric test results did not correlate to cognitive test scores in any subgroup. CONCLUSIONS: In conclusion, primary auditory cortex perfusion changes are a metabolic hallmark of adult beta-thalassemia, thus suggesting complex remodeling of the hearing function, that occurs regardless of chelation therapy and before clinically manifest hearing loss. The cognitive impact of perfusion changes is intriguing but requires further investigations.