From singing to speaking: facilitating recovery from nonfluent aphasia

Abstract

It has been reported for more than 100 years that patients with severe nonfluent aphasia are better at singing lyrics than they are at speaking the same words. This observation led to the development of melodic intonation therapy (MIT). However, the efficacy of this therapy has yet to be substantiated in a randomized controlled trial. Furthermore, its underlying neural mechanisms remain unclear. The two unique components of MIT are the intonation of words and simple phrases using a melodic contour that follows the prosody of speech and the rhythmic tapping of the left hand that accompanies the production of each syllable and serves as a catalyst for fluency. Research has shown that both components are capable of engaging fronto-temporal regions in the right hemisphere, thereby making MIT particularly well suited for patients with large left hemisphere lesions who also suffer from nonfluent aphasia. Recovery from aphasia can happen in two ways: either through the recruitment of perilesional brain regions in the affected hemisphere, with variable recruitment of righthemispheric regions if the lesion is small, or through the recruitment of homologous language and speech-motor regions in the unaffected hemisphere if the lesion of the affected hemisphere is extensive. Treatment-associated neural changes in patients undergoing MIT indicate that the unique engagement of right-hemispheric structures (e.g., the superior temporal lobe, primary sensorimotor, premotor and inferior frontal gyrus regions) and changes in the connections across these brain regions may be responsible for its therapeutic effect. Keywords aphasia; arcuate fasciculus; auditory-motor mapping; connectivity; intervention; melodic intonation therapy; neuroimaging; nonfluent aphasia; speech therapy Of the estimated 750,000-800,000 new stroke cases occurring in the USA each year, approximately 25-50% present with some form of aphasia, an estimation that is based on studies performed in countries other than the USA [1,2]. Approximately 40% of these acute patients were available for follow-up at 1 year (attrition was due to death or inability to participate in trial). Approximately two-thirds of this 40% of patients from the original cohort showed abnormal scores on aphasia testing, with approximately a quarter of them being in the nonfluent category [1][2][3][4]. In right-handed individuals, nonfluent aphasia generally results from lesions in the left frontal lobe, including the portion of the left frontal lobe known as Broca's region. The region is named after Paul Broca (1864), who first linked this area of the brain with nonfluent aphasia; this region is thought to consist of the posterior inferior frontal gyrus †

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Neurologic Music Therapy to Facilitate Recovery from Complications of Neurologic Diseases

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