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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

Force-frequency relationship curves. Each symbol represents one rat; Old (filled circle), Old radiation (open triangle), Young (open circle), Young radiation (filled triangle). (A) Whole nerve stimulation Old r2= .98, Old Radiation r2 = .96, Young r2 =.98, and Young radiation r2 = .98 and (B) Medial nerve stimulation Old r2 = .96, Old Radiation r2 = .96, Young r2 =.91, and Young radiation r2 =.95.
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Fig8: Force-frequency relationship curves. Each symbol represents one rat; Old (filled circle), Old radiation (open triangle), Young (open circle), Young radiation (filled triangle). (A) Whole nerve stimulation Old r2= .98, Old Radiation r2 = .96, Young r2 =.98, and Young radiation r2 = .98 and (B) Medial nerve stimulation Old r2 = .96, Old Radiation r2 = .96, Young r2 =.91, and Young radiation r2 =.95.

Mentions: As shown in Figure 8, curves for the old and radiation treatment groups were shifted to the left relative to the young adult controls during bilateral stimulation of the whole hypoglossal nerves. That is, a larger percentage of maximum force was achieved at lower stimulation frequencies and the total force range appeared constrained. There was a significant interaction effect between age and radiation treatment on force-frequency relationship (F[15, 171] = 5.56, p < .001; Figure 8A). Post hoc tests revealed that significant age effects (Young Adult vs. Old; Young Radiation vs. Old Radiation) and significant radiation treatment effects (Young Adult vs. Young Radiation; Old vs. Old Radiation) were found at 20 Hz and 40 Hz.Figure 8


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

Russell JA, Connor NP - Radiat Oncol (2014)

Force-frequency relationship curves. Each symbol represents one rat; Old (filled circle), Old radiation (open triangle), Young (open circle), Young radiation (filled triangle). (A) Whole nerve stimulation Old r2= .98, Old Radiation r2 = .96, Young r2 =.98, and Young radiation r2 = .98 and (B) Medial nerve stimulation Old r2 = .96, Old Radiation r2 = .96, Young r2 =.91, and Young radiation r2 =.95.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig8: Force-frequency relationship curves. Each symbol represents one rat; Old (filled circle), Old radiation (open triangle), Young (open circle), Young radiation (filled triangle). (A) Whole nerve stimulation Old r2= .98, Old Radiation r2 = .96, Young r2 =.98, and Young radiation r2 = .98 and (B) Medial nerve stimulation Old r2 = .96, Old Radiation r2 = .96, Young r2 =.91, and Young radiation r2 =.95.
Mentions: As shown in Figure 8, curves for the old and radiation treatment groups were shifted to the left relative to the young adult controls during bilateral stimulation of the whole hypoglossal nerves. That is, a larger percentage of maximum force was achieved at lower stimulation frequencies and the total force range appeared constrained. There was a significant interaction effect between age and radiation treatment on force-frequency relationship (F[15, 171] = 5.56, p < .001; Figure 8A). Post hoc tests revealed that significant age effects (Young Adult vs. Old; Young Radiation vs. Old Radiation) and significant radiation treatment effects (Young Adult vs. Young Radiation; Old vs. Old Radiation) were found at 20 Hz and 40 Hz.Figure 8

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