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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

LEFT: Representative images of genioglossus (GG) muscle CSA from old control (A) and old radiation (C) rats and, RIGHT: corresponding thresholded images used in measurement from these same samples (Old control = B; old radiation = D). The average muscle CSA for these examples was 657 μm2 and 766 μm2, respectively.
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Fig10: LEFT: Representative images of genioglossus (GG) muscle CSA from old control (A) and old radiation (C) rats and, RIGHT: corresponding thresholded images used in measurement from these same samples (Old control = B; old radiation = D). The average muscle CSA for these examples was 657 μm2 and 766 μm2, respectively.

Mentions: Weight had a significant effect on average muscle fiber cross-sectional area, and therefore ANCOVA results are reported. There was not a significant interaction effect between age and radiation treatment on the average muscle fiber CSA (F[1,32] = 2.97, p = .094). In addition, there was not significant main effect for age (F[1,32] = 2.34, p = .13). However, there was a significant main effect for radiation treatment (F[1,32] = 7.70, p = .001). The old radiated group had a significantly larger average muscle fiber CSA than the old control group (p = .003; Figure 9) Representative images of genioglossus muscle CSA of old and old radiation groups are shown in Figure 10.Figure 9


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

Russell JA, Connor NP - Radiat Oncol (2014)

LEFT: Representative images of genioglossus (GG) muscle CSA from old control (A) and old radiation (C) rats and, RIGHT: corresponding thresholded images used in measurement from these same samples (Old control = B; old radiation = D). The average muscle CSA for these examples was 657 μm2 and 766 μm2, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig10: LEFT: Representative images of genioglossus (GG) muscle CSA from old control (A) and old radiation (C) rats and, RIGHT: corresponding thresholded images used in measurement from these same samples (Old control = B; old radiation = D). The average muscle CSA for these examples was 657 μm2 and 766 μm2, respectively.
Mentions: Weight had a significant effect on average muscle fiber cross-sectional area, and therefore ANCOVA results are reported. There was not a significant interaction effect between age and radiation treatment on the average muscle fiber CSA (F[1,32] = 2.97, p = .094). In addition, there was not significant main effect for age (F[1,32] = 2.34, p = .13). However, there was a significant main effect for radiation treatment (F[1,32] = 7.70, p = .001). The old radiated group had a significantly larger average muscle fiber CSA than the old control group (p = .003; Figure 9) Representative images of genioglossus muscle CSA of old and old radiation groups are shown in Figure 10.Figure 9

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