Amusia como distúrbio auditivo central na neurofibromatose tipo 1

Abstract

Introduction: Some cognitive disturbances, such as language disorder and learning difficulties are frequent in neurofibromatosis type 1 (NF1). It is postulated that this cognitive profile is related to alterations in the cortical white matter, characterizing it as a possible cerebral disconnection disorder. Some experts claim they have observed frequent musical difficulties in people with NF1, such as the difficulty to sing in tune or play any instrument. In light of the recent verification of Auditory Processing Disorder (APD) in the disease, it is considered as probable the existence of some damage in the musical perception of such individuals. This difficulty in noticing and executing music is described in literature as amusia, and in its congenital form is also considered as a result of a possible cerebral disconnection disorder. Objective: Investigate the occurrence of amusia in NF1; evaluate its characteristics and its connections to the subjects previous musical training; analyze their electrophysiological correlates and compare these findings with what has been previously described in the literature for congenital amusia. Methods: 18 volunteers with NF1 (cases) e 22 healthy ones (control), without auditory deficiency, paired by sex, age and schooling were evaluated through the application of the reduced version of the Montreal Battery Evaluation of Amusia (MBEA), after answering a questionnaire about their musical background. The integrity of the primary cortical areas of auditory processing was evaluated through the registry of evoked potential Mismatch Negativity (MMN). Results: Amusia was much more prevalent amongst the cases than amongst the controls (67% vs. 4.5%), and strong association with NF1 (P = 0,001 OR = 42 IC: 4.5-39.6). For their diagnosis it was defined as a cutoff in the MBEA the score value inferior to two standard deviations in the controls average. It was detected in individuals with NF1 the impairment in all of the subgroups of tasks in the test (melodic organization, temporal organization and memory), with significant damage in the temporal processing. The occurrence and latency of MNN were similar in both groups; however, amongst the people with NF1 it was observed a higher average value of latencies in those with worse performance in the MBEA. Discussion: Amusia showed more frequent in NF1, associated with an important impairment of the temporal processing. It was not observed a consistent connection between the musical background and its occurrence. Since most people with NF1 present APD it is likely that there is an association between this disorder and musical perception deficit. The occurrence of MNN showed itself preserved in these individuals, although with higher average value of the latencies amongst the non-musical. The alteration of these evoked potential and the important impairment of the temporal musical processing made evident in the present study are not characteristically present in congenital amusia, which suggests different neurophysiologic substrates for amusia in NF1. Conclusion: Amusia is a common disturbance in people with neurofibromatosis type 1. It presents itself in this disease with different characteristics than those in congenital amusia, related to an important dysfunction in the temporal processing and the alteration in the MMN.