MELODIC INTONATION THERAPY (MIT)
A) DESCRIPTION OF TREATMENT
Melodic Intonation Therapy is a hierarchically structured program that is divided into three levels. In the first two levels, multisyllabic words and short, high-probability phrases are musically intoned. The third level introduces longer or more phonologically complex sentences. These longer sentences first are intoned, then produced with exaggerated speech prosody, and finally spoken normally. On all intoned phrases the clinician taps the patient's left hand once for each syllable. Items are intoned very slowly, with continuous voicing, using simple high note-low note patterns based on the normal speech prosody of the phrase.
Stimulus items should be high probability words (of at least two syllables), phrases, and sentences. In selecting these items, phonological difficulty and number of syllables should be considered. For example, it is best to avoid consonant blends and to favor visualizable (e.g., bilabials) sounds in the first level. Similarly, the clinician should attend to syntactic complexity. Imperative sentences (e.g. "Sit down"; "Open the door") often are the easiest in the earlier stages. The communication needs of the individual patient also must be considered when choosing items. The use of family names, for example, may be helpful. If at all possible, each intoned item should be accompanied by pictures or environmental cues to increase saliency. Furthermore, it is important to have a wide selection of words, phrases, and sentences to be rotated through a series of treatment sessions.
Presentation of Items
Each word, phrase, or sentence should be intoned slowly, with constant voicing, using high/low tones and the stress and rhythm patterns associated with normal speech. It is best to determine the pitch, stress, and rhythm patterns before beginning the session. Sit directly across from the patient so that he/she can see your face/mouth, and note how the sounds are formed. Hold the patient's left hand with your hand and tap once for each intoned syllable; use your left hand to signal the patient when to listen and when to intone. At all times a staccato approach should be avoided, as it is the continuous voicing that facilitates verbal production.
Speech samples of:
"A (unintelligible) getting (unintelligible)...An the ink wrinning ower...um..giffle boy came (unintelligible)....boother...uh...sister (unintelligible)."
"The wady is doing her dishes. Link under over...uh. The window is open and co-son...a very funny day outside. Children ....a boy and a girl. The boy is up on a stoop and is stealing cookies and pass'em to ...his sister. I uh...I see nothing un-u-su-al about the picture."
B) INTENDED POPULATION
Etiology: unilateral, left-hemisphere stroke.
Lesion: confined to the left cerebral hemisphere and involving Broca's area, or undercutting Broca's area with inclusion of periventicular white matter deep to lower motor cortex for face.
Speech output: poorly articulated, nonfluent, or severely restricted verbal output that may be confined to a nonsense stereotype.
Auditory comprehension: at least moderately preserved, exceeding the 45th percentile of on the Boston Diagnostic Aphasia Examination (BDAE) Rating Scale.
Repetition: poor, even for single words
Articulation: poorly articulated speech, earning a rating of 3 or less on the BDAE Profile of
Psychological features: well motivated, emotionally stable, good attention span.
The ultimate goal of Melodic Intonation Therapy is to improve the verbal communication skills of patients with restricted speech output. The MIT program can only be judged successfully if it has a significantly positive effect on conversational speech skills.
C) EFFICACY OF RESEARCH
MIT is one of the stimulation techniques of aphasia therapy that was developed by Albert, Sparks and Helm in 1973. It is a recognized method for the rehabilitation of non-fluent aphasic patients with certain characteristics. The American Academy of Neurology reported the method as being promising, which denotes that more research would be welcomed.
Using PET scans, Belin et al. showed objectively the mechanism of recovery from non-fluent aphasia in patients rehabilitated with MIT. They believed that the reactivation of Broca's area was the possible mechanism for recovery from non-fluent aphasia after MIT. Concerning the number of treatment sessions, Helm-Estabrooks et al. suggested that the minimum number of treatment sessions for observing first improvements was 10-15 sessions and such improvements were taken as a sign that treatment should be continued.
In the preliminary report on Melodic Intonation Therapy in all 3 Persian patients, there were noticeable improvements in expository variables, such improvement being the ultimate goal of therapy. Researchers also observed positive changes in some auditory comprehension skills in both those who had more comprehension impairments. The observed results in Persian aphasics are in concordance with other reported studies from contributors.
Dr. Pascal Belin and his associates, working at the Service Hospitalier Frederic Joliot in Orsay and other institutions in France report that Melodic Intonation Therapy promotes recovery from aphasia. Belin et al. studied seven patients who had lengthy absence of spontaneous recovery. They also evaluated the effects of MIT on the brain by measuring relative cerebral blood flow (CBF) and PET (positron emission tomography) scanning during hearing and repetition of simple words and of "MIT-loaded" words. MIT produced recovery of speech capabilities. A critical regions of the brain was activated by "MIT-loaded" words but not regular words. The authors believe that the reactivation by MIT of Broca's area was critical to recovery of speech. These findings provide enormous promise for both the treatment of aphasia and understanding the role of music in normal and abnormal brain function.
The development of Melodic Intonation Therapy for aphasia (Albert et al. 1973) generated marked improvement in the expressive ability of patients by encoding linguistic phrases with simple melodic patterns. It may be that the use of intonation and pitch contours directly involves the non-dominant hemisphere in either the producing language or in enhancing its production by the damaged dominant hemisphere. Finally, the author speculate that normal language perception may involve the simultaneous analysis of the linguistic input in both hemispheres - with the analysis of the phonetic and semantic components of language conducted primarily in the left hemisphere and the analysis of intonational and perhaps other components of the speech signal conducted primarily in the right hemisphere.
In one PET study patients were scanned after successful Melodic Intonation Therapy (MIT) for nonfluent aphasia (Belin et al. 1996). Listening to words without MIT produced activation of right hemisphere homologues of language, whereas listening to words with MIT produced activation of Broca's area in the left hemisphere. The authors interpret this as showing that right hemisphere activation patterns are maladaptive and reflect persistence of aphasia, whereas MIT produced a normalization of language-related activation, with reactivation of Broca's area.
An fMRI study of lexical-semantic processing in recovered aphasics found that individual patients with predominantly right-hemisphere activity tended to be more poorly recovered than patients with bilateral activation (Cao et al. 1999). Therefore, reactivation of left hemisphere language areas was seen as crucial for full recovery to occur.
Similarly, a serial PET study of word repetition in aphasic patients found that well-recovered patients showed increased metabolic activity in left hemisphere language areas at follow-up, whereas poorly recovered patients were only able to activate the right hemisphere homologues (Heiss et al. 1997).
RELEVANCE TO SLP
SLP must have a knowledge of patient's neurological conditions. When faced with different kinds of communication disorders, the SLP would know where to find information about the disorder, the potential effect on communication, the appropriate treatment options for the patient and the prognosis for improved communication skills.
SLP examines and treats patients, develops and tests experimental strategies/treatment. Therefore, SLP's approach and knowledge of a treatment/strategy to clinical problem-solving, starting with language impaired patients and moving through a series of longitudinal studies to the development of an aphasia rehabilation method must be shaped to the needs of the individual patient.