Changes in muscle morphology in chronic trapezius myalgia

Area of Science:

• Muscle Physiology
• Pain Research
• Biochemistry

Background:

• Chronic trapezius myalgia is a prevalent condition causing significant pain and disability.
• Understanding the underlying muscle pathology is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the differences in muscle fiber characteristics and energy metabolism between women with chronic trapezius myalgia and healthy controls.
• To explore the potential link between muscle structural and biochemical alterations and the development of myalgia.

Main Methods:

• Enzyme histochemistry and immunohistochemistry were used to analyze muscle fiber types, size, and capillarization in trapezius muscle biopsies.
• Biochemical analysis assessed lactate concentration in mixed muscle samples and adenosine triphosphate (ATP) and phosphocreatine levels in single muscle fibers.

Main Results:

• Patients with chronic trapezius myalgia exhibited larger type I muscle fibers compared to healthy individuals.
• A reduced capillary-to-fiber area ratio was observed in both type I and type IIA fibers in patients.
• Lower levels of ATP and phosphocreatine were found in both type I and type II muscle fibers of patients.

Conclusions:

• The findings suggest an imbalance between capillary supply and muscle fiber cross-sectional area in patients with chronic trapezius myalgia.
• This imbalance may play a significant role in the development of muscular fatigue and pain associated with the condition.
• Further research is warranted to elucidate the precise mechanisms linking these physiological changes to chronic pain.