Melodic Intonation Therapy
Melodic Intonation Therapy (MIT) is a therapeutic process used by music therapists and speech-language pathologists to help patients with communication disorders caused by damage to the left hemisphere of the brain. This method of therapy uses musical elements, including melody and rhythm, to improve expressive language by capitalizing on preserved singing abilities and possibly engaging language-capable regions in the undamaged right hemisphere. According to recent research, it may not be melodic intonation that is the crucial element in MIT, but the combined use of rhythmic pacing and conversational speech formulas.
Neurological researchers Sparks, Helm, and Albert developed Melodic Intonation Therapy in 1973 while working with adults in the Aphasia Research Unit at the Boston VA Hospital. MIT is based on the hypothesis of these researchers that “increased use of the right hemisphere dominance for the melodic aspect of speech increases the role of that hemisphere in inter-hemispheric control of language, possibly diminishing the language dominance of the damaged left hemisphere.” In order to do this, common words and phrases are turned into melodic phrases emulating typical speech intonation and rhythmic patterns.
One study using positron emission tomography (PET) scans found that areas controlling speech in the left hemisphere were "reactivated" by the end of Melodic Intonation Therapy in 7 patients. Further work suggests that MIT can result in significant changes in brain structure through the brain's own neuroplasticity. Right-hemisphere axon connections in 6 patients were found to be increased in volume after MIT. At least theoretically, this could allow for language processing in right homologous areas, suggesting that the right hemisphere may compensate for an impaired left hemisphere by taking up language processing responsibilities. Some evidence suggests that the positive effects of MIT can be enhanced with non-invasive brain stimulation. During MIT training sessions, the researchers applied anodal transcranial direct current stimulation (tDCS) over the equivalent of Broca's area in the right hemisphere of 6 stroke patients with non-fluent aphasia. Compared to sham stimulation, the anodal stimulation led to a significant improvement in fluency.
Recent research suggests that it may not be melodic intonation that facilitates speech production in patients with non-fluent aphasia and apraxia of speech, but rhythmic pacing and lyric type. The rates of correct syllable production were found to be similar when patients were singing or speaking rhythmically. Hence, these results did not reveal an effect of singing over rhythmic speech. Also, the results indicate that speech production in patients with left-hemisphere basal ganglia lesions may be particularly dependent on external rhythmic cues, such as a metronome. Patients with larger basal ganglia lesions produced more syllables correctly when they were singing or speaking with rhythmic accompaniment. Finally, the results confirmed that common, formulaic expressions (e.g., “How are you?”) may have a strong influence on speech production in persons with non-fluent aphasia and apraxia of speech. Formulaic expressions yielded higher rates of correctly produced syllables than non-formulaic utterances, whether they were sung or rhythmically spoken.
The critical role of rhythmic pacing and formulaic language in MIT was confirmed in subsequent research, suggesting that singing and rhythmic speech may be similarly effective in the treatment of non-fluent aphasia and apraxia of speech. These findings challenge the view that singing causes a transfer of language function from the left to the right hemisphere. Instead, patients made good progress in the production of formulaic expressions, known to be supported by areas of the intact right hemisphere. Therefore, the particular sensitivity of the right hemisphere to MIT may, to some degree, depend on the intensive use of formulaic expressions. Taken together, these results recommend the combined use of conventional speech-language therapy and the training of formulaic expressions, whether they are sung or rhythmically spoken. “Standard speech-language therapy may engage, in particular, left perilesional brain regions, while training of formulaic phrases may open new ways of tapping into right-hemisphere language resources – even without singing,” the authors of the study conclude.
Who Benefits from Melodic Intonation Therapy
The majority of research in Melodic Intonation Therapy has been conducted with aphasia patients. Aphasia is a deficit in language abilities resulting from damage to the brain. There are different types of aphasia depending on the location of the damage. Patients that would benefit from MIT typically suffer from non-fluent aphasia or Broca’s aphasia. Some individuals with apraxia of speech have also benefited from MIT. As the name suggests, the damage to the brain in this category is mostly in the Broca’s area and thus speech production is affected. Sparks and associates found that adult patients meeting the following criteria achieved positive results with MIT:
1. Good auditory comprehension
2. Facility for self correction
3. Markedly limited verbal output
4. Reasonably good attention span
5. Good emotional stability
In addition to these above five qualities, patients that would benefit from Melodic Intonation Therapy include those with moderately preserved auditory comprehension. Also, these patients may exhibit poor articulated, or non fluent, attempts at speech. Patients that are also capable of producing some intelligible words are also seen as benefiting from MIT. Lastly, patients would a good attention span and motivation will have the most success with MIT.
Later researchers have also noted that for MIT to be effective the patient must not exhibit any “bi-lateral brain damage.” Melodic Intonation Therapy is not appropriate for patients suffering from receptive aphasia or brain damage affecting the patient’s ability to read and comprehend language. The main goal is to help the patient speak in a comprehendible manner. MIT may also be an effective treatment for speech impairments caused by other disorders such as Down syndrome, but research on this topic is even more limited than general research in MIT.
How Melodic Intonation Therapy Works
The traditional Melodic Intonation Therapy process is divided into four progressive stages. However, modifications are often made to meet the specific needs of the patient. This is one reason why it is difficult to obtain definitive research results in MIT. In the early stages, MIT was used solely for adult patients, but eventually therapists began to use MIT with children. Therapists found that the traditional procedure did not work well with children, so a new three level structure was developed by Helfrich-Miller. The following sections will describe both the adult and child models of Melodic Intonation Therapy.
As stated above, this is a four level process. As the patient progresses through the stages the role of the therapist decreases. In the first stage the therapist hums “intoned phrases” and the patient taps the “rhythm and stress of each pattern” with his/her hands or feet. In the beginning of the second stage the patient joins the therapist in humming while continuing to beat the rhythms. As the patient progresses, the therapist begins to sing “intoned phrases” and the patient repeats them. The third stage is the same as the final level of stage two except that now the patient is required to wait for a designated period of time before repeating the phrase or sentence. This helps to increase the patients ability to “retrieve” words. In the fourth and final stage the sentence length is increased and “sprechgesang” is used to facilitate the transition to normal speech. “This technique involves keeping the same melodic line as the intoned sentence of the proceeding step, except that the constant pitch of the intoned words is replaced by the variable pitch of speech.” The ultimate goal is to remove the musical elements entirely so the patient presents normal speech.
Roper (2003) provides an in depth description of MIT with children. She notes that this model was created by researchers working with children suffering from apraxia of speech, due to similarities between children with this disorder and adults with aphasia. This model is divided into three stages each with five or six progressive levels. Stage one is the same as that in the adult model, but instead of tapping the patient signs, using Signed English. The therapist also signs while singing the intoned phrases. This is step one of the process, by step six the patient will respond to an “intoned question” by singing and signing the “last words” of the question. The second stage is similar to the third stage of the adult model. In this stage the patient is required to wait roughly “six seconds” before repeating the intoned question. As this stage progresses the role of the therapist decreases. The final stage is the same as that of the adult model. As the patient moves through the steps of this stage “signing is faded out and the last two stages involve questioning, using normal speech.”
Melodic Intonation Therapy is commonly used with patients suffering from non-fluent aphasia and apraxia of speech. To date, a randomized controlled trial has confirmed the effectiveness of MIT in the early, sub-acute stage after stroke where spontaneous recovery is frequently observed. However, evidence from randomized controlled trials on the effectiveness of MIT in individuals with chronic aphasia is not yet available. An ongoing discussion in aphasia research concerns the various therapeutic elements included in MIT, such as singing, rhythmic speech, grammatical utterances, formulaic expressions, and rhythmic hand tapping. It is unclear whether or not these different elements equally contribute to the effectiveness of MIT. Researchers are working to resolve this issue. For example, a recent therapy study compared the effectiveness of singing and rhythmic speech in patients with non-fluent aphasia and apraxia of speech. The results of the study did not suggest an advantage of singing over rhythmic speech. Moreover, the results highlight the importance of conventional speech-language therapy along with the training of formulaic expressions, whether sung or rhythmically spoken.
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