Intrinsic laryngeal muscle investigations, especially those of the interarytenoid (IA) muscle, have been primarily teleologically based. We determined IA muscle anatomy and histochemical and immunohistochemical classification of extrafusal and intrafusal (muscle spindle) fibers in 5 patients. Extrafusal fibers were oxidative type I and glycolytic types IIA and IIX. Intrafusal fibers of muscle spindles were identified by the presence of tonic and neonatal myosin. The results demonstrate that the IA muscle has a phenotype similar to that of limb skeletal muscle. Myosin coexpression, the absence of intrafusal fibers, and fiber type grouping were unusual features found previously in the thyroarytenoid and posterior cricoarytenoid muscles, but they were not present in the IA muscle. These findings lead to the conclusion that the IA muscle has functional significance beyond its assumed importance in maintaining vocal fold position during phonation. The presence of spindles demonstrates differences in motor control as compared to the thyroarytenoid and posterior cricoarytenoid muscles. Further, extrafusal fiber characteristics implicate IA muscle involvement in muscle tension dysphonia and adductor spasmodic dysphonia. Given the unique physiologic characteristics of the human IA muscle, further research into the role of the IA muscle in voice disorders is warranted.

Functional near-infrared spectroscopy for speech protocols: characterization of motion artifacts and guidelines for improving data analysis,"

As the caseload of ethnically and culturally diverse students who stutter increases, speech-language pathologists will need to become more culturally sensitive. Many speech-language pathologists, however, indicate that they are not comfortable treating clients from diverse backgrounds who stutter. Busy school schedules may prevent speech-language pathologists from obtaining information about multicultural aspects of stuttering. The purpose of this article, therefore, is to provide speech-language pathologists with information that addresses multicultural perceptions about stuttering and suggestions for the assessment and treatment of stuttering in ethnically and culturally diverse groups.

Objectives/Hypothesis Visible light spectroscopy (VLS) is the technology behind the Food and Drug Administration–approved TSTAT device that is used to monitor tissue oxygen (StO2) and relative total hemoglobin (rtHb) levels by measuring reflected visible light. The purpose of this novel, pilot study was to determine if VLS is a reliable and valid method of measuring StO2 and rtHb levels in the human thyroarytenoid/lateral cricoarytenoid (TA-LCA) muscle complex, thus providing information about vocal fold muscle physiology. Study Design Pre-test/post-test with mulitple baselines and two conditions. Methods VLS measurements were taken at baseline, during exercise, and following recovery on six subjects using both noncontact channel-port endoscope (endo-probe) and laryngeal electromyography (LEMG) needle-guided techniques. Results The average baseline StO2 was 69% (standard deviation [SD] = 3.6%) for the LEMG-guided probe and was 71.5% (SD = 2.8%) for the endo-probe. During phonation, the StO2 for the LEMG-guided probe dropped to 59% (SD = 7%; P = .04). Mean rtHb measured by the LEMG probe rose from a baseline of 144 µM (SD = 165 µM) to 214 µM (SD = 166 µM, P = .34) during phonation and back to 149 µM (SD = 139 µM, P = .85) after recovery. Mean rtHb as measured using the endo-probe at baseline and after recovery was 104 µM (SD = 30 µM, P = .76). Conclusions VLS can be used to measure changes in StO2 and rtHb levels pre- and postexercise in the human TA-LCA muscle complex.

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