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Effects of age and radiation treatment on function of extrinsic tongue muscles.

Russell JA, Connor NP - Radiat Oncol (2014)

Bottom Line: Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction.Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction, and the reduction in the speed of tongue muscle contraction was exacerbated in the aged-rat tongue.This work provides a foundation for future investigations of treatments for concurrent effects of aging and radiation on muscles of the tongue and swallowing.

View Article: PubMed Central - PubMed

Affiliation: University of Wisconsin School of Medicine and Public Health, Otolaryngology Head and Neck Surgery, Madison, WI, 53706, USA. russell@surgery.wisc.edu.

ABSTRACT

Background: Radiation treatment for head and neck cancer often results in difficulty swallowing. Muscle weakness and fibrosis have been identified clinically as possible etiologies for swallowing problems following radiation. Aging may compound the effects of radiation on swallowing because radiation-induced damage to muscles and other tissues critical for the oropharyngeal swallow is overlaid on a declining sensorimotor system. However, there have been no investigations of the manner in which aging and radiation treatment effects combine to impact tongue muscles, which are critical effectors of the oropharyngeal swallow.

Methods: Thirty-seven male Fisher 344/Brown Norway rats were divided into four groups; young adults (9 month old), old (32 months old), young radiation (9 months), and old radiation (32 months old). Two fractions of 11 Gy on consecutive days was delivered by external beam radiation to the ventral side of the rat's body over the anterior portion (20 X 30 mm area) of the anterior digastric muscle. Two-way analysis of variance (ANOVA) was used to examine the effects of age and radiation and their interaction on muscle contractile properties. Post-hoc testing was completed using Fisher's least significant differences (LSD).

Results: Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction. However, radiation treatment did not lead to muscle atrophy and fibrosis formation in the GG muscle. Radiation treatment did not exacerbate atrophic changes observed with aging, or lead to additional fibrosis formation in the GG muscle from that observed in the other groups.

Conclusions: The purpose of this research was to determine the effect of radiation on muscles of the tongue and to determine whether aging altered the extent of radiation injury to tongue muscles. Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction, and the reduction in the speed of tongue muscle contraction was exacerbated in the aged-rat tongue. This work provides a foundation for future investigations of treatments for concurrent effects of aging and radiation on muscles of the tongue and swallowing.

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Related in: MedlinePlus

Standard deviation in muscle fiber cross sectional area (CSA). Box and whisker plot showing that radiation treatment caused a significant (p<.001) increase in the SD of muscle fiber CSA. Boxes depict the interquartile range (IQR), with a line at the median. Whiskers extend to the last observation within 1.5x the IQR. The closed circles are observations beyond 1.5x the IQR. Y = Young Adult Control; YR = Young Adult Radiated; O = Old Control, OR = Old Radiated.
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Fig11: Standard deviation in muscle fiber cross sectional area (CSA). Box and whisker plot showing that radiation treatment caused a significant (p<.001) increase in the SD of muscle fiber CSA. Boxes depict the interquartile range (IQR), with a line at the median. Whiskers extend to the last observation within 1.5x the IQR. The closed circles are observations beyond 1.5x the IQR. Y = Young Adult Control; YR = Young Adult Radiated; O = Old Control, OR = Old Radiated.

Mentions: Weight also had a significant effect on standard deviation in cross-sectional area therefore ANCOVA results are reported. There was not a significant interaction effect between age and radiation treatment on standard deviation of muscle fiber cross sectional area (F[1,32] = 1.759, p = .19). However, there were significant main effects for age (F[1,32] = 4.61, p = .04) and radiation treatment (F[1,32] = 14.31, p < .001) with larger standard deviations found in the old and radiated groups. Specifically, the old radiated group had a significantly larger standard deviation in muscle fiber CSA than the old control group (p = .003; Figure 11).Figure 11


Effects of age and radiation treatment on function of extrinsic tongue muscles.

Russell JA, Connor NP - Radiat Oncol (2014)

Standard deviation in muscle fiber cross sectional area (CSA). Box and whisker plot showing that radiation treatment caused a significant (p<.001) increase in the SD of muscle fiber CSA. Boxes depict the interquartile range (IQR), with a line at the median. Whiskers extend to the last observation within 1.5x the IQR. The closed circles are observations beyond 1.5x the IQR. Y = Young Adult Control; YR = Young Adult Radiated; O = Old Control, OR = Old Radiated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4269095&req=5

Fig11: Standard deviation in muscle fiber cross sectional area (CSA). Box and whisker plot showing that radiation treatment caused a significant (p<.001) increase in the SD of muscle fiber CSA. Boxes depict the interquartile range (IQR), with a line at the median. Whiskers extend to the last observation within 1.5x the IQR. The closed circles are observations beyond 1.5x the IQR. Y = Young Adult Control; YR = Young Adult Radiated; O = Old Control, OR = Old Radiated.
Mentions: Weight also had a significant effect on standard deviation in cross-sectional area therefore ANCOVA results are reported. There was not a significant interaction effect between age and radiation treatment on standard deviation of muscle fiber cross sectional area (F[1,32] = 1.759, p = .19). However, there were significant main effects for age (F[1,32] = 4.61, p = .04) and radiation treatment (F[1,32] = 14.31, p < .001) with larger standard deviations found in the old and radiated groups. Specifically, the old radiated group had a significantly larger standard deviation in muscle fiber CSA than the old control group (p = .003; Figure 11).Figure 11

Bottom Line: Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction.Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction, and the reduction in the speed of tongue muscle contraction was exacerbated in the aged-rat tongue.This work provides a foundation for future investigations of treatments for concurrent effects of aging and radiation on muscles of the tongue and swallowing.

View Article: PubMed Central - PubMed

Affiliation: University of Wisconsin School of Medicine and Public Health, Otolaryngology Head and Neck Surgery, Madison, WI, 53706, USA. russell@surgery.wisc.edu.

ABSTRACT

Background: Radiation treatment for head and neck cancer often results in difficulty swallowing. Muscle weakness and fibrosis have been identified clinically as possible etiologies for swallowing problems following radiation. Aging may compound the effects of radiation on swallowing because radiation-induced damage to muscles and other tissues critical for the oropharyngeal swallow is overlaid on a declining sensorimotor system. However, there have been no investigations of the manner in which aging and radiation treatment effects combine to impact tongue muscles, which are critical effectors of the oropharyngeal swallow.

Methods: Thirty-seven male Fisher 344/Brown Norway rats were divided into four groups; young adults (9 month old), old (32 months old), young radiation (9 months), and old radiation (32 months old). Two fractions of 11 Gy on consecutive days was delivered by external beam radiation to the ventral side of the rat's body over the anterior portion (20 X 30 mm area) of the anterior digastric muscle. Two-way analysis of variance (ANOVA) was used to examine the effects of age and radiation and their interaction on muscle contractile properties. Post-hoc testing was completed using Fisher's least significant differences (LSD).

Results: Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction. However, radiation treatment did not lead to muscle atrophy and fibrosis formation in the GG muscle. Radiation treatment did not exacerbate atrophic changes observed with aging, or lead to additional fibrosis formation in the GG muscle from that observed in the other groups.

Conclusions: The purpose of this research was to determine the effect of radiation on muscles of the tongue and to determine whether aging altered the extent of radiation injury to tongue muscles. Radiation was associated with a significant decrease in tongue force production and reduced speed of tongue muscle contraction, and the reduction in the speed of tongue muscle contraction was exacerbated in the aged-rat tongue. This work provides a foundation for future investigations of treatments for concurrent effects of aging and radiation on muscles of the tongue and swallowing.

Show MeSH
Related in: MedlinePlus