Assessment: Botulinum neurotoxin for the treatment of movement disorders (an evidence-based review): report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.

OBJECTIVE: To perform an evidence-based review of the safety and efficacy of botulinum neurotoxin (BoNT) in the treatment of movement disorders. METHODS: A literature search was performed including MEDLINE and Current Contents for therapeutic articles relevant to BoNT and selected movement disorders. Authors reviewed, abstracted, and classified articles based on American Academy of Neurology criteria (Class I-IV). RESULTS: The highest quality literature available for the respective indications was as follows: blepharospasm (two Class II studies); hemifacial spasm (one Class II and one Class III study); cervical dystonia (seven Class I studies); focal upper extremity dystonia (one Class I and three Class II studies); focal lower extremity dystonia (one Class II study); laryngeal dystonia (one Class I study); motor tics (one Class II study); and upper extremity essential tremor (two Class II studies). RECOMMENDATIONS: Botulinum neurotoxin should be offered as a treatment option for the treatment of cervical dystonia (Level A), may be offered for blepharospasm, focal upper extremity dystonia, adductor laryngeal dystonia, and upper extremity essential tremor (Level B), and may be considered for hemifacial spasm, focal lower limb dystonia, and motor tics (Level C). While clinicians' practice may suggest stronger recommendations in some of these indications, evidence-based conclusions are limited by the availability of data.

Functional neuroanatomy of human vocalization: an H215O PET study.

Vocalization in lower animals is associated with a well-described visceromotor call system centered on the mesencephalic periacqueductal grey matter (PAG), which is itself regulated by paramedian cortical structures. To determine the role this phylogenetically older system plays in human phonation, we contrasted voiced and unvoiced speech using positron emission tomography and then evaluated functional connectivity of regions that significantly differentiated these conditions. Vocalization was associated with increased and highly correlated activity within the midline structures--PAG and paramedian cortices--described in lower mammalian species. Concurrent activation and connectivity of neocortical and subcortical motor regions--medial and lateral premotor structures and elements of basal ganglia thalamocortical circuitry--suggest a mechanism by which this system may have come under an increasing degree of voluntary control in humans. Additionally, areas in the temporal lobe and cerebellum were selectively activated during voiced but not unvoiced speech. These regions are functionally coupled to both visceromotor and neocortical motor areas during production of voiced speech, suggesting they may play a central role in self-monitoring and feedback regulation of human phonation.

Acoustic measures of symptoms in abductor spasmodic dysphonia.

Speech of patients with abductor spasmodic dysphonia (ABSD) was analyzed using acoustic analyses to determine: (1) which acoustic measures differed from controls and were independent factors representing patients' voice control difficulties, and (2) whether acoustic measures related to blinded perceptual counts of the symptom frequency in the same patients. Patients' voice onset time for voiceless consonants in speech were significantly longer than the controls (p = 0.015). A principle components analysis identified three factors that accounted for 95% of the variance: the first factor included sentence and word duration, frequency shifts, and aperiodic instances; the second was phonatory breaks; and the third was voice onset time. Significant relationships with perceptual counts of symptoms were found for the measures of acoustic disruptions in sentences and sentence duration. Finally, a multiple regression demonstrated that the acoustic measures related well with the perceptual counts (r2 = 0.84) with word duration most highly related and none of the other measures contributing once the effect of word duration was partialed out. The results indicate that some of the voice motor control deficits, namely aperiodicity, phonatory breaks, and frequency shifts, which occur in patients with ABSD, are similar to those previously found in adductor spasmodic dysphonia. Results also indicate that acoustic measures of intermittent disruptions in speech, voice onset time, and speech duration are closely related to the perception of symptom frequency in the disorder.

Assessment of posterior cricoarytenoid botulinum toxin injections in patients with abductor spasmodic dysphonia.

In this study, we compared 2 techniques for injection of botulinum toxin type A (Botox) into the posterior cricoarytenoid (PCA) muscle for the treatment of abductor spasmodic dysphonia (ABSD). Fifteen patients with ABSD were enrolled in a prospective randomized crossover treatment trial comparing the 2 injection techniques. The PCA muscle was injected with 5 units on each side, with the injections staged 2 weeks apart, via either a percutaneous posterior-lateral approach or a transnasal fiberoptic approach. Eleven patients reported some benefit with the injections; however, the patient-perceived benefits were not related to changes in symptoms on blinded counts by speech pathologists. No significant reductions in the numbers of breathy breaks occurred with either technique, and no differences were found between techniques. Although patients perceived a benefit, blinded symptom counts did not substantiate these benefits. Thus, PCA muscle injections of Botox provided limited benefits to patients with ABSD, demonstrating the need for a more effective therapy for these patients.

Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges.

UNLABELLED: Spasmodic dysphonia is a rare voice disorder that is most successfully treated by injection of botulinum toxin (i.e., BOTOX) into the affected laryngeal muscles. BOTOX is currently available for use by professionals outside of metropolitan voice centers who may be unfamiliar with this rare disorder. Patients may seek assessment and treatment locally from clinicians who are unfamiliar with the speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia. Although these disorders have been described in the literature, the symptoms have not been well defined and may appear similar to those of vocal tremor or muscle tension dysphonia (MTD). Thus, patients with spasmodic dysphonia might not be easily identified by local clinicians for treatment. The purpose of the current study was to determine whether voice clinicians with infrequent exposure to patients with spasmodic dysphonia could learn to identify speech symptoms for ADSD and ABSD comparable to voice clinicians with extensive experience with these disorders. The ratings of five nonexpert judges were compared to the ratings obtained from three expert judges. The results of this study demonstrated that nonexpert judges could be trained to identify the speech symptoms associated with ADSD, ABSD, and vocal tremor. While the nonexpert judges tended towards false positive judgements for the speech symptoms of interest, the overall speech symptom profiles for each type of voice disorder appeared comparable to those obtained from the expert judges. The symptom identificationscales used, therefore, have potential for use by clinicians unfamiliar with these disorders for correctly identifying persons with symptoms of ADSD and ABSD. EDUCATIONAL OBJECTIVES: Readers will be able to (1) define the predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor; and (2) describe the methods utilized in a new perceptual training protocol for teaching clinicians how to identify predominant speech symptoms associated with the voice disorder categories of ABSD, ADSD, and vocal tremor.

Adductor muscle activity abnormalities in abductor spasmodic dysphonia.

OBJECTIVE: To determine laryngeal muscle activation abnormalities associated with speech symptoms in abductor spasmodic dysphonia (ABSD). STUDY DESIGN: Bilateral laryngeal muscle recordings from the posterior cricoarytenoid, thyroarytenoid, and cricothyroid muscles were conducted in 12 ABSD patients. Patients' measures were compared during speech breaks and during speech without breaks and with 10 normal controls. RESULTS: Significant group differences were found in the thyroarytenoid muscle; the patients had significantly greater activity on the right side both during speech breaks and nonbreaks in comparison with the controls. Cricothyroid muscle levels were also increased on the right in the patients. CONCLUSION: An asymmetry in adductor muscle tone between the 2 sides in ABSD may account for difficulties with maintaining phonation and voice onset after voiceless consonants. SIGNIFICANCE: These abnormalities may indicate why PCA BOTOX injections have not been as effective in ABSD as thyroarytenoid injections have been in adductor spasmodic dysphonia.

Emerging clinical applications of electrical stimulation: opportunities for restoration of function.

Emerging clinical application of electrical stimulation in three systems is reviewed. In the bladder, stimulation of sacral posterior roots reduces reflex incontinence and significantly improves bladder capacity. With the combination of anterior and posterior root stimulation, bladder control can be achieved without the need for rhizotomy. Preliminary research demonstrates that bladder contractions may also be generated by stimulation of the urethral sensory branch of the pudendal nerve, even after acute spinal cord transection, while inhibition of the bladder and control of urge incontinence can be achieved by stimulation of the whole pudendal nerve. Spinal cord stimulation can modulate the activity of the intrinsic cardiac nervous system involved in the regulation of regional cardiac function and significantly reduce the pain associated with angina pectoris. Finally in the area of upper airway disorders, functional electrical stimulation has great potential for increasing life support as well as for quality of life in chronic ailments, particularly obstructive sleep apnea and dysphagia.

Effects of levodopa on laryngeal muscle activity for voice onset and offset in Parkinson disease.

The laryngeal pathophysiology underlying the speech disorder in idiopathic Parkinson disease (IPD) was addressed in this electromyographic study of laryngeal muscle activity. This muscle activity was examined during voice onset and offset gestures in 6 persons in the early stages of IPD who were not receiving medication. The purpose was to determine (a) if impaired voice onset and offset control for speech and vocal fold bowing were related to abnormalities in laryngeal muscle activity in the nonmedicated state and (b) if these attributes change with levodopa. Blinded listeners rated the IPD participants' voice onset and offset control before and after levodopa was administered. In the nonmedicated state, the IPD participants' vocal fold bowing was examined on nasoendoscopy, and laryngeal muscle activity levels were compared with normal research volunteers. The IPD participants were then administered a therapeutic dose of levodopa, and changes in laryngeal muscle activity for voice onset and offset gestures were measured during the same session. Significant differences were found between IPD participants in the nonmedicated state: those with higher levels of muscle activation had vocal fold bowing and greater impairment in voice onset and offset control for speech. Similarly, following levodopa administration, those with thyroarytenoid muscle activity reductions had greater improvements in voice onset and offset control for speech. In this study, voice onset and offset control difficulties and vocal fold bowing were associated with increased levels of laryngeal muscle activity in the absence of medication.

Effects of adductor muscle stimulation on speech in abductor spasmodic dysphonia.

OBJECTIVE: To determine whether adductor laryngeal muscle stimulation might be a beneficial treatment alternative for abductor spasmodic dysphonia (ABSD). STUDY DESIGN: Baseline comparisons were made on measures of voiceless consonant and syllable duration between patients with ABSD and normal control subjects, and speech and voice production with and without muscle stimulation were compared within 10 patients with ABSD. METHODS: Baseline group comparisons were conducted on measures of syllable and voiceless consonant duration between the patients and the control subjects. Neuromuscular stimulation was applied to the thyroarytenoid or lateral cricoarytenoid muscles in the patients during extended phonation, and measures were made of fundamental frequency and sound pressure level in the stimulated and nonstimulated conditions. Voiceless consonant duration was compared with and without adductor laryngeal muscle stimulation during syllable repetitions and sentences in the patients. RESULTS: Before stimulation, the patients had increased syllable durations in comparison with control subjects (P = .003). Repeated within-patient comparisons with and without stimulation demonstrated significant (P < .008) reductions in voiceless consonant durations during syllable repetition. The more severely affected patients had the greatest reductions in voiceless consonant duration during sentence production. CONCLUSIONS: Adductor muscle stimulation improved speech production in patients with ABSD, and the improvement was greatest in the most severely affected patients. Therefore adductor muscle stimulation has potential for benefiting patients with ABSD.