Neurophysiological and neuro-otological study of homozygous beta-thalassemia under long-term desferrioxamine (DFO) treatment

This report presents data on visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs), as well as neurologic, ophthalmologic and otologic assessments performed on 120 patients with beta-thalassemia major undergoing long-term DFO treatment. A total of 32 patients showed abnormal VEPs and 14 abnormal BAEPs; seven had both VEP and BAEP abnormalities; 12 had sensorineural hearing loss (SNHL); 18 had conductive hearing loss, while 14 showed a combination of SNHL and conductive hearing loss. After DFO administration was modified (taking in consideration the serum ferritin levels) patients with abnormal findings were retested. The values of 15 patients of 23 who underwent VEP examinations had been normalized. Eleven of 15 who repeated the BAEP test had also gained normal values. The audiogram had not returned to normal in any patient with SNHL. In a second repetition of the examinations, no change was observed. It is concluded that in a great percentage of thalassemics at least one of the above examinations shows abnormal values. These abnormalities are mostly reversible, and probably reflect a dysfunction of the visual or auditory system, due either to DFO neurotoxicity or to iron overload or both.