Hypophonia in Parkinson's disease: neural correlates of voice treatment revealed by PET.

OBJECTIVE: To investigate the neural correlates of hypophonia in individuals with idiopathic PD (IPD) before and after voice treatment with the Lee Silverman Voice Treatment method (VT) using (15)O-H(2)O PET. METHODS: Regional cerebral blood flow (rCBF) changes associated with overt speech-motor tasks relative to the resting state were measured in the IPD subjects before and after VT, and in a group of healthy control volunteers. RESULTS: Behavioral measures of voice loudness significantly improved following treatment. Before VT, patients had strong speech-related activations in motor and premotor cortex (M1-mouth, supplementary motor cortex [SMA], and inferior lateral premotor cortex [ILPm]), which were significantly reduced post-VT. Similar to the post-treatment session, premotor activations were absent (SMA) or below statistical threshold (M1-mouth) in the healthy control group. In addition, following VT treatment, significant right-sided activations were present in anterior insular cortex, caudate head, putamen, and dorsolateral prefrontal cortex (DLPFC). Finally, the VT-induced neural changes were not present with transient experimenter-cued increases of loudness in VT-untreated patients. CONCLUSIONS: Effective improvement of IPD hypophonia following voice treatment with VT was accompanied by a reduction of cortical motor-premotor activations, resembling the functional pattern observed in healthy volunteers and suggesting normalization, and additional recruitment of right anterior insula, caudate head, putamen, and DLPFC. This treatment-dependent functional reorganization suggests a shift from an abnormally effortful (premotor cortex) to a more automatic (basal ganglia, anterior insula) implementation of speech-motor actions.

Speech motor stability in IPD: effects of rate and loudness manipulations.

Increasing phonatory effort, an integral component of the Lee Silverman Voice Treatment, LSVT, has been identified as an effective management strategy for adults with hypokinetic dysarthria associated with Parkinsonism. The present study compares the effects of increased loudness on lower lip movements to those of changes in speaking rate, another approach to the treatment of hypokinetic dysarthria. Movements of the lower lip/jaw during speech were recorded from 8 adults with IPD, 8 healthy aged adults, and 8 young adults. The spatiotemporal index (STI), a measure of spatial and temporal variability, revealed that for all speaker groups slow rate was associated with the most variability. Compared to the other conditions, STI values from the loud condition were closest to those from habitual speech. Also, the normalized movement pattern for the loud condition resembled that of habitual speech. It is hypothesized that speaking loudly is associated with a spatial and temporal organization that closely resembles that used in habitual speech, which may contribute to the success of the LSVT.

Intensive voice treatment (LSVT) for patients with Parkinson's disease: a 2 year follow up.

OBJECTIVES: To assess long term (24 months) effects of the Lee Silverman voice treatment (LSVT), a method designed to improve vocal function in patients with Parkinson's disease. METHODS: Thirty three patients with idiopathic Parkinson's disease were stratified and randomly assigned to two treatment groups. One group received the LSVT, which emphasises high phonatory-respiratory effort. The other group received respiratory therapy (RET), which emphasises high respiratory effort alone. Patients in both treatment groups sustained vowel phonation, read a passage, and produced a monologue under identical conditions before, immediately after, and 24 months after speech treatment. Change in vocal function was measured by means of acoustic analyses of voice loudness (measured as sound pressure level, or SPL) and inflection in voice fundamental frequency (measured in terms of semitone standard deviation, or STSD). RESULTS: The LSVT was significantly more effective than the RET in improving (increasing) SPL and STSD immediately post-treatment and maintaining those improvements at 2 year follow up. CONCLUSIONS: The findings provide evidence for the efficacy of the LSVT as well as the long term maintenance of these effects in the treatment of voice and speech disorders in patients with idiopathic Parkinson's disease.

The aging voice: a review, treatment data and familial and genetic perspectives.

This paper will provide a review of aspects of vocal aging within the context of general body aging and describe two data sets related to the aging voice. Data will be presented which document pre- to posttreatment improvement in select voice characteristics (sound pressure level, subglottal air pressure, thyroarytenoid laryngeal muscle activity and voice quality) following application of an intensive voice treatment program (the LSVT) to 3 individuals with aged voice. Additionally, physiological data (forced expiratory volume, visual accommodation, bone density, taste discrimination, white blood count and resting heart rate) and select perceptual (perceived age) and acoustic measures (reflecting both cycle-to-cycle and longer-term intensity and frequency stability) from 67 subjects will be reviewed from the work of Gray and colleagues to document the differential impact of the global aging process across organ systems including the aging voice.

Review: occupational risks for voice problems.

The purpose of this paper is to provide a cohesive review of the literature regarding the functional consequences of voice problems and occupational risk factors for them. The salient points are as follows. According to conservative estimates, approximately 28,000,000 workers in the US experience daily voice problems. Many people who experience voice problems perceive them to have a negative impact on their work and their quality of life. Estimates based on empirical data suggest that, considering only lost work days and treatment expenses, the societal cost of voice problems in teachers alone may be of the order of about $2.5 billion annually in the US. In fact, across several countries, "teacher" consistently emerges as the common occupation most likely to seek otorhinolaryngological (ORL) evaluation for a voice problem. Other occupational categories likely to seek ORL examination for a voice problem are singer, counselor/social worker, lawyer, and clergy. Finally, US Census data indicate that keyboard operators may be at special risk for voice problems because of a near-epidemic growth of repetitive strain injury (RSI), which can adversely affect the voice especially when speech recognition software is implemented. This paper discusses frequency data, quality of life data, and treatment considerations for these voice-related occupational issues.

Control of vocal loudness in young and old adults.

This study examined the effect of aging on respiratory and laryngeal mechanisms involved in vocal loudness control. Simultaneous measures of subglottal pressure and electromyographic (EMG) activity from the thyroarytenoid (TA), lateral cricoarytenoid (LCA), and cricothyroid (CT) muscles were investigated in young and old individuals while they attempted to phonate at three loudness levels, "soft," "comfortable," and "loud." Voice sound pressure level (SPL) and fundamental frequency (F ) measures were also obtained. Across loudness conditions, subglottal pressure levels were similar for both age groups. Laryngeal EMG measures tended to be lower and more variable for old compared with young individuals. These differences were most apparent for the TA muscle. Finally, across the three loudness conditions, the old individuals generated SPLs that were lower overall than those produced by the young individuals but modulated loudness levels in a manner similar to that of the young subjects. These findings suggest that the laryngeal mechanism may be more affected than the respiratory system in these old individuals and that these changes may affect vocal loudness levels.

Changes in vocal loudness following intensive voice treatment (LSVT) in individuals with Parkinson's disease: a comparison with untreated patients and normal age-matched controls.

This study assessed the impact of the Lee Silverman Voice Treatment (LSVT) on vocal loudness [sound pressure level (SPL)] in a group of dysarthric individuals with idiopathic Parkinson's disease (IPD). Pre- to post-treatment changes in SPL in the treated group were compared with changes in voice SPL during the same time in two control groups: individuals with IPD not treated with the LSVT and in non-disordered individuals, age-matched to the patients. All subjects produced the same voice and speech tasks--sustaining vowel phonation, reading the "Rainbow Passage," producing a short monologue, and describing a picture. These tasks were recorded at three different occasions: just prior to treatment, just after treatment, and 6 months following treatment. The individuals treated with LSVT increased voice SPL from baseline to post-treatment by an average of 8 dB and from baseline to 6 months follow-up by an average of 6 dB. These changes were statistically significant and perceptibly audible. No significant changes in SPL were observed in the control groups during the time corresponding to the treatment and follow-up. Differences in SPL between the treated and untreated patients at post-treatment and follow-up were statistically significant for all voice and speech tasks. These findings, along with others, provide additional support for the efficacy of the LSVT.

Short-latency changes in voice F0 and neck surface EMG induced by mechanical perturbations of the larynx during sustained vowel phonation.

Nineteen healthy young adult males with normal voice and speech attempted to sustain the vowel /u/ at a constant pitch (target: 180 Hz) and a constant and comfortable loudness level while receiving a sudden mechanical perturbation to the larynx (thyroid prominence) via a servo-controlled probe. The probe moved toward or away from the larynx in a ramp-and-hold fashion (3.3-mm displacement, 0.7 N force, 20-ms rise time, 250-ms duration) as the subjects attempted to maintain a constant probe-larynx pressure. Eighty stimuli were applied in each direction, one stimulus per phonation. Pairs of surface electromyography (EMG) electrodes were attached to the skin of the anterior neck over laryngeal, infralaryngeal, and supralaryngeal areas. The rectified EMG signals, the voltage analog of the voice fundamental frequency (VAF0), and the voltage analog of the probe displacement were digitized and signal-averaged relative to the onset of the stimulus. Sudden perturbation of the larynx induced an instantaneous decrease or increase in VAF0, depending on the direction of the probe's movement, and a short-latency increase in the EMG (30-35 ms) and VAF0 (55-65 ms). We argue that the instantaneous VAF0 change was related to a mechanical effect, and the short-latency VAF0 and EMG changes to reflexogenic effects-the latter most likely associated with both intrinsic and extrinsic laryngeal sensorimotor mechanisms. Further physiological studies are needed to elucidate the sources of the VAF0 and EMG responses. Once elucidated, the present method may provide a powerful noninvasive tool for studying laryngeal neurophysiology. The theoretical and clinical implications of the present findings are addressed.

Messa di voce: an investigation of the symmetry of crescendo and decrescendo in a singing exercise.

A classical vocal exercise called "messa di voce" (Italian for "placing the voice") was used to study the symmetry of intensity increase and decrease in six trained singers. Ideally, the exercise is performed as a symmetric triangle, a linear increase in loudness, followed by a linear decrease. Given that some physiologic variables, like lung volume, undergo unidirectional change rather than a symmetric reversal, there is reason to believe that symmetries may not exist. It was found that highly trained singers who use large SPL ranges tend to abbreviate the decrescendo phase in comparison with the crescendo phase. In a few other cases, a plateau in SPL is reached, but an increase in loudness may still be perceived on the basis of a stronger vibrato or changes in timbre.

Discharge characteristics of laryngeal single motor units during phonation in young and older adults and in persons with parkinson disease.

Discharge characteristics of laryngeal single motor units during phonation in young and older adults, and in persons with Parkinson disease. The rate and variability of the firing of single motor units in the laryngeal muscles of young and older nondisordered humans and people with idiopathic Parkinson disease (IPD) were determined during steady phonation and other laryngeal behaviors. Typical firing rates during phonation were approximately 24 s/s. The highest rate observed, during a cough, was 50 s/s. Decreases in the rate and increases in the variability of motor unit firing were observed in the thyroarytenoid muscle of older and IPD male subjects but not female subjects. These gender-specific age-related changes may relate to differential effects of aging on the male and female voice characteristics. The range and typical firing rates of laryngeal motor units were similar to those reported for other human skeletal muscles, so we conclude that human laryngeal muscles are probably no faster, in terms of their contraction speed, than other human skeletal muscles. Interspike interval (ISI) variability during steady phonation was quite low, however, with average CV of approximately 10%, with a range of 5 to 30%. These values appear to be lower than typical values of the CV of firing reported in three studies of limb muscles of humans. We suggest therefore that low ISI variability is a special although not unique property of laryngeal muscles compared with other muscles of the body. This conceivably could be the result of less synaptic "noise" in the laryngeal motoneurons, perhaps as a result of suppression of local reflex inputs to these motoneurons during phonation.

Thyroarytenoid muscle activity associated with hypophonia in Parkinson disease and aging.

OBJECTIVE: To compare electromyographic (EMG) amplitudes of the thyroarytenoid (TA) muscle in young and older individuals and individuals with idiopathic PD (IPD) under conditions of known vocal loudness (sound pressure level). BACKGROUND: Voice disorders frequently accompany aging and IPD, but it is unclear how laryngeal muscle physiology is affected by these processes and how changes in laryngeal muscle activity result in characteristic changes of the voice. METHODS: Absolute and relative (to maximum) EMG amplitudes of the TA muscle were compared during speech and nonspeech tasks. Corresponding sound pressure level (SPL) measures were obtained for the speech tasks. RESULTS: Absolute TA amplitudes were consistently the highest in the young individuals, lowest in the individuals with IPD, and intermediate in the older individuals. Relative TA amplitudes were generally the highest for the young individuals, lowest for the older individuals, and intermediate for the individuals with IPD. SPL findings showed the older individuals and individuals with IPD produced most of the speech tasks with comparable SPLs, and these levels were consistently lower than those of the young individuals. CONCLUSIONS: Reduced levels of TA muscle activity may contribute to the characteristic hypophonic voice disorders that frequently accompany IPD and aging.

Intentional changes in sound pressure level and rate: their impact on measures of respiration, phonation, and articulation.

The purpose of the study was to compare the effects of changing sound pressure level (SPL) and rate on respiratory, phonatory, and articulatory behavior during sentence production. Ten subjects, 5 men and 5 women, repeated the sentence, "I sell a sapapple again," under 5 SPL and 5 rate conditions. From a multi-channel recording, measures were made of lung volume (LV), SPL, fundamental frequency (F0), semitone standard deviation (STSD), and upper and lower lip displacements and peak velocities. Loud speech led to increases in LV initiation, LV termination, F0, STSD, and articulatory displacements and peak velocities for both lips. Token-to-token variability in these articulatory measures generally decreased as SPL increased, whereas rate increases were associated with increased lip movement variability. LV excursion decreased as rate increased. F0 for the men and STSD for both genders increased with rate. Lower lip displacements became smaller for faster speech. The interspeaker differences in velocity change as a function of rate contrasted with the more consistent velocity performance across speakers for changes in SPL. Because SPL and rate change are targeted in therapy for dysarthria, the present data suggest directions for future research with disordered speakers.

The effect of lung volume on selected phonatory and articulatory variables.

The purpose of the study was to examine the effects of manipulating lung volume (LV) on phonatory and articulatory kinematic behavior during sentence production in healthy adults. Five men and five women repeated the sentence "I sell a sapapple again" under five LV conditions. These included (1) speaking normally, (2) speaking after exhaling most of the air from the lungs, (3) speaking at end expiratory level (EEL), (4) speaking after a maximal inhalation, and (5) speaking after a maximal inhalation while attempting to maintain as normal a mode of speech as possible. From a multichannel recording, measures were made of LV, sound pressure level (SPL), fundamental frequency (F0) and semitone standard deviation (STSD), and upper and lower lip displacements and peak velocities. When compared with the reference condition, the sentence was spoken significantly more quickly at the lowest LV. SPL increased significantly for the high LV condition, as did the women's F0 and STSD. Upper lip displacements and peak velocities generally decreased for LVs other than the reference condition. Lower lip movements showed inconsistent changes as a function of LV. Adjustments to the LV for speech led to SPL and F0 changes consistent with a coordinated control of the respiratory system and the larynx. However, less consistent effects were observed in the articulatory kinematic measures, possibly because of a less direct biomechanical and neural control linkage between respiratory and articulatory structures.

Treatment efficacy: voice disorders.

This article reviews the literature on the efficacy of treatment for voice disorders primarily using studies published in peer-reviewed journals. Voice disorders are defined, their frequency of occurrence across the life span is reported, and their impact on the lives of individuals with voice disorders is documented. The goal of voice treatment is to maximize vocal effectiveness given the existing disorder and to reduce the handicapping effect of the voice problem. Voice treatment may be (a) the preferred treatment to resolve the voice disorder when medical (surgical or pharmacological) treatments are not indicated; (b) the initial treatment in cases where medical treatment appears indicated; it may obviate the need for medical treatment; (c) completed before and after surgical treatment to maximize long-term post-surgical voice; and (d) a preventative treatment to preserve vocal health. Experimental and clinical data are reviewed that support these roles applied to various disorder types: (a) vocal misuse, hyperfunction and muscular imbalance (frequently resulting in edema, vocal nodules, polyps or contact ulcers); (b) medical or physical conditions (e.g., laryngeal nerve trauma, Parkinson disease); and (c) psychogenic disorders (e.g., conversion reactions, personality disorders). Directions for future research are suggested which maximize clinical outcomes and scientific rigor to enhance knowledge on the efficacy of voice treatment.

Preliminary voice and speech analysis following fetal dopamine transplants in 5 individuals with Parkinson disease.

A surgical procedure involving transplantation of fetal dopamine cells into the striatum of persons with advanced Parkinson disease (PD) has recently been performed in an attempt to alleviate Parkinsonian and drug-dose related symptoms (e.g., the "on-off" phenomena). Improvements in limb motor and neurological function, as well as less severe and shorter on-off episodes have been reported following fetal cell transplant (FCT) surgery. Acoustic, electroglottographic, and perceptual measures were analyzed pre- and post-surgery to determine if phonotory and articulatory function were affected by this relatively new form of treatment. In addition, speech and motor exam measures were compared to determine if similar directional changes across motor systems were apparent. Findings suggest that FCT surgery did not systematically influence voice and speech production. Also, it appears that FCT surgery may differentially affect phonatory, articulatory, and limb motor systems. Findings are discussed relative to these differential effects.

The Parkinson larynx: tremor and videostroboscopic findings.

Patients with Parkinson's disease have a high incidence of speech, voice, and laryngeal abnormalities. To characterize laryngeal abnormalities, visual-perceptual ratings of endoscopic and stroboscopic examinations of 22 patients diagnosed with idiopathic Parkinson's disease and 7 patients with Parkinson's-plus syndromes were carried out by for trained viewers. Incidence of tremor, tremor location, phase closure, phase symmetry, amplitude, and mucosal waveform were scored. Tremor was observed in one or more of these conditions-rest, normal pitch and loudness, or loud phonation-for most of the 29 patients. Fifty-five percent of the idiopathic Parkinson's disease patients had tremor, with the primary location being vertical laryngeal tremor. Sixty-four percent of the Parkinson's-plus patients had tremor, with the arytenoid cartilages being the primary location. Laryngeal tremor was observed early in the disease in these Parkinson's disease patients. The most striking stroboscopic findings for the idiopathic Parkinson's disease patients were abnormal phase closure and phase asymmetry. Amplitude and mucosal wave-form were essentially within normal limits in the majority of the idiopathic Parkinson patients.

Intensive speech treatment for patients with Parkinson's disease: short-and long-term comparison of two techniques.

The purpose of this study was to evaluate the long-term (12 months) effects of two forms of speech treatment on the speech and voice deficits that occur in Parkinson's disease. Thirty-five patients with idiopathic Parkinson's disease were assigned to one of two speech treatment groups: voice and respiration (The Lee Silverman Voice Treatment [LSVT]) or placebo (respiration) treatment. Vocal intensity data from before, immediately after, and at 6 and 12 months after speech treatment revealed statistically significant differences between the treatment groups. Only subjects in the LSVT group improved or maintained vocal intensity above pretreatment levels by 12 months after treatment. The placebo group had statistically significant deterioration of vocal intensity levels from before to 12 months after treatment during conversational monologue. The LSVT group did not deteriorate to levels below pretreatment in vocal intensity over the 12-month period. This study is the first to document the short-and long-term effects of intensive speech treatment (LSVT), which focuses on the voice, for patients with Parkinson's disease compared with a placebo speech treatment group.

Aerodynamic mechanisms underlying treatment-related changes in vocal intensity in patients with Parkinson disease.

The purpose of this study was to document changes in aerodynamic and glottographic aspects of vocal function in patients with Parkinson disease who received two forms of high effort treatment. Previous reports (Ramig, Countryman, Thompson, & Horii, 1995) have documented increased sound pressure level (SPL) following treatment that trained phonation and respiration (Lee Silverman Voice Treatment: LSVT), but not for treatment that trained respiration only (R). In order to examine the mechanisms underlying these differences, measures of maximum flow declination rate (MFDR) and estimated subglottal pressure (Psub) were made before and after treatment. A measure of relative vocal fold adduction (EGGW) was made from the electroglottographic signal during sustained vowel phonation. Sound pressure level data from syllable repetition, sustained vowel phonation, reading, and monologue tasks were also analyzed to allow a more detailed understanding of treatment-related change in several contexts. Consistent with increases in SPL, significant increases in MFDR, estimated Psub, and EGGW were measured posttreatment in patients who received the LSVT. Similar changes were not observed following R treatment. These findings suggest that the combination of increased vocal fold adduction and subglottal pressure is a key in generating posttreatment increases in vocal intensity in idiopathic Parkinson disease (IPD).

Intensive voice treatment in Parkinson disease: laryngostroboscopic findings.

As part of ongoing research to investigate and document the efficacy of intensive voice therapy to improve functional communication in patients with idiopathic Parkinson disease, 45 patients were enrolled in a controlled, randomized, prospective study. Pre- to posttreatment comparisons are presented here on 22 of those patients who underwent laryngeal imaging examination. Of the 22 patients, 13 patients received intensive therapy aimed at increasing vocal and respiratory effort (VR), whereas nine received intensive therapy aimed at increasing respiratory effort (R) only. All patients had a pretreatment evaluation that included two (but sometimes only one) voice recordings and an otolaryngologic examination with laryngostroboscopy. At the completion of 4 weeks of therapy (16 sessions), two voice recordings were made, and laryngostroboscopy was again performed. The pre- and posttherapy videolaryngostroboscopy tapes were then randomized and rated by four judges. Raters' findings were then compared with vocal intensity measured before and after therapy. The VR therapy group showed improvements on laryngostroboscopic variables: less glottal incompetence and no significant change in supraglottal hyperfunction after therapy. No differences were observed in the R-only group. The mean intensity increase in the VR therapy group was 12.5 dB, compared with a decrease of 1.9 dB in the R-only group. These findings suggest that in patients with Parkinson disease, intensive therapy focusing on phonatory effort improves adduction of the vocal folds as assessed by laryngostroboscopy. Differences in laryngeal function in these patients observed with fiberoptic laryngoscopy and rigid telescopic laryngoscopy are discussed.