Differential changes in muscle composition exist in traumatic and nontraumatic neck pain

Area of Science:

• Biomedical Engineering
• Musculoskeletal Imaging
• Rehabilitation Science

Background:

• Previous MRI studies indicated increased neck muscle size and fat infiltration in chronic whiplash-associated disorders (WAD).
• These findings were not consistently observed in idiopathic neck pain or healthy individuals.

Purpose of the Study:

• To accurately assess viable muscle cross-sectional area (CSA) in cervical muscles.
• To differentiate true muscle hypertrophy from pseudohypertrophy in patients with WAD and idiopathic neck pain.

Main Methods:

• A cross-sectional study involving 136 females (79 WAD, 23 idiopathic neck pain, 34 controls).
• 14 cervical muscle regions were analyzed using magnetic resonance imaging (MRI).
• CSA measurements were performed with and without accounting for fat infiltration.

Main Results:

• Without fat correction, WAD patients showed larger CSA in 7/14 muscle regions.
• After fat removal, 8/14 muscle regions in WAD patients had similar CSA, and 5/14 were smaller compared to controls.
• Fat removal did not significantly alter CSA findings between idiopathic neck pain patients and controls.

Conclusions:

• Increased CSA in chronic WAD is attributed to pseudohypertrophy (fat infiltration), not true muscle growth.
• Muscle atrophy was identified in several cervical muscles of both WAD and idiopathic neck pain patients.
• Muscle conditioning should be integrated into the management of WAD and idiopathic neck pain.