Why might Lee Silverman Voice Therapy techniques improve articulation, facial expressions, and swallowing?

CSD 726: Assignment 7

Piper Doering

Spring, 2013

Why might Lee Silverman Voice Therapy techniques improve articulation, facial expressions, and swallowing?
Lee Silverman Voice Therapy (LSVT) techniques emphasize increasing loudness and effort through multiple, intense repetitions (Fox, Morrison, Ramig, & Sapir, 2002). In addition to increased loudness and effort, LSVT may also improve patients’ articulation, facial expressions, and swallowing functions. Following is an explanation of these findings, specific to patients with Idiopathic Parkinson Disease (IDP).
Articulation is the process of shaping sound into phonemes through the movement of oral and facial structures. Clients with IDP often have decreased amplitude and speed of orofacial movement, affecting articulation precision (Fox et al., 2002). LSVT has improved articulation function in this population. This improvement is demonstrated by changes in formant transition duration, increased orofacial muscle movement, and decreased vowel centralization (Fox et al., 2002). There are a couple of explanations for these changes. First, LSVT encourages increased neural activity to orofacial muscles as a result of the increased vocal effort (Fox et al., 2002). Second, increased loudness correlates with stable motor output, demonstrated by a decreased spatiotemporal index (Fox et al., 2002). In other words, a patient using LSVT indirectly decreases the variability in the space and time of his or her articulation movements by focusing on loudness and effort, thus making articulation more precise.
Facial expression is used when people show emotion through the movement of their oral and facial structures. This can increase in clients with IPD after LSVT. As in articulation, an increase in neural activity is a possible explanation for this change. Focusing on vocal loudness may also stimulate neural pathways that are associated with the regulation of emotion and vocal expression (Fox et al., 2002). As a whole, neural changes can be supported through positron emission tomography (PET) scans. PET scans conducted on clients using LSVT demonstrated increased paralimbic activity and the neural circuits connecting these areas of the brain (Fox et al., 2002). This data counters the explanation that successful therapy merely increases facial expression due to patient happiness. In addition, patients who participated in alternative treatments have not shown this similar increase in facial expression (Fox et al., 2002).
Swallowing involves the formation and movement of a bolus from the mouth to the esophagus. LSVT is associated with improved swallowing functions in patients with IPD who had oral-tongue and tongue-base disorders (Fox et al., 2002). In essence, the patients did not have the strength and coordination for a successful posterior bolus transfer. LSVT has been associated with improved tongue strength, thus improving swallowing function (Fox et al., 2002).
Articulation, facial expression, and swallowing are all secondary effects that may occur as a result of LSVT. While loudness and vocal effort are the main focuses of therapy, the changes that result in strength and speed of facial and oral musculature, in addition to the increased stimulation to neural pathways, causes secondary effects to occur. Changes in articulation, facial expressions, and swallowing have all been reported in literature.

How to counsel a patient with vocal tremor, who’s receiving a bilateral botulinum toxin injection to her thyroarytenoid muscles, about what to expect in the first 4 weeks post-injection
Essential tremor of the voice (ETV) occurs when muscle groups associated with the vocal tract periodically and unintentionally move in a rhythmic manner (Bové, Daamen, Rosen, Wang, Sulica, & Gartner-Schmidt, 2006). Bilateral botulinum toxin injections to the thyroarytenoid muscles are one option for ETV treatment. When a patient receives these injections, a clinician must counsel her about what to expect in the first four weeks post-injection. Steps to counseling are outlined below.
Starting from this point forward, the clinician should have a patient-friendly diagram of vocal tract musculature, for the patient to reference. First the clinician should describe botulinum toxin and the effects to the injected thyroarytenoid muscle. The aim of botulinum toxin is to denervate the thyroarytenoid muscle by blocking acetylcholine at the neuromuscular junction (Sapienza & Hoffman Ruddy, 2009). Thus, the patient should be aware that injections to the thyroaryteniod, the muscle that helps to relax and contract her vocal folds, will temporarily be inhibited of movement. This will be noticed immediately following injections, as the tremor resulting from uncontrollable movement of the thyroarytenoids will be diminished (Sapienza et al., 2009).
Secondly, the patient must be informed of the varying effects the botulinum toxin has on ETV as a result of the characteristics of this neurologically based voice disorder. Botulinum toxin injections are beneficial in 50% to 65% of treated patients (Bové et al., 2006). For patients that do benefit, voice quality improvements vary since muscles beyond the thyroarytenoid are often affected. Intrinsic laryngeal, extrinsic laryngeal, pharyngeal, and respiratory muscles may all be affected by ETV (Bové et al., 2006). Thus, bilateral injection to the thyroarytenoid muscles alone may have minimal effects to voice quality with the continual tremor of other muscles.
Specific improvements the patient will notice immediately post-injection should be described in consideration to the possible perceptual changes in her voice. Common voice characteristics associated with EVT include pitch changes, loudness variations, and voice breaks (Sapienza et al., 2009). These characteristics are expected to decrease following botulinum toxin injections, resulting in a less shaky, smoother voice quality.
While the aim of botulinum toxin injections is for the patient’s symptoms of voice tremor to decrease or be eliminated, the effects of the injections will be temporary. Over the four weeks post-injection the patient may notice her symptoms of tremor gradually returning (Sapienza et al., 2009). However, the timeline for when symptoms of tremor will return varies for every patient. The patient should be informed that tremor-relief is dependent on how fast her affected nerve endings recover from the injections, but that this period of time is typically three months (Sapienza et al., 2009). More injections can follow, with similar results.
Before receiving botulinum toxin injections to the thyroarytenoids, a patient must be counseled on what to expect four weeks post-injection. Information should be shared regarding a description of botulinum toxin, the effects on the thyroarytenoids, the persistence of tremor beyond the thyroarytenoid muscles, and the progressive return of EVT symptoms experienced pre-injections. Effective counseling aims to increase patient awareness and comfort.

References

Bové, M., Daamen, N., Rosen, C., Wang, C-C., Sulica, L., & Gartner-Schmidt, J. (2006). Development and validation of the vocal tremor scoring system. The Laryngoscope,116: 1662-1667.
Fox, C.M., Morrison, C.E., Ramig, L.O., & Sapir, S. (2002). Current perspectives on the Lee Silverman Voice Treatment (LSVT) for individuals with idiopathic Parkinson disease. American Journal of Speech-Language Pathology, 11, 111-123.
Sapienza, C.M. & Hoffman Ruddy, B. (2009). Voice disorders. San Diego, CA: Plural Publishing, Inc. – Chapter 6: Neurologically based voice disorders (pp. 267-313).