Chronic neck pain appears to be associated with impaired respiratory function due to weakness of the respiratory muscles, study findings indicate.
"Cervical muscle dysfunction and psychological influences appear to be the factors that are mostly associated with this respiratory function," say Zacharias Dimitriadis (Technological Educational Institute of Lamia, Greece) and colleagues.
They believe that respiratory function should therefore be included in the assessment and treatment of patients with chronic neck pain.
"This can lead to changes in clinical reasoning with potentially more optimal therapeutic outcomes for these chronic pain sufferers," they write in Manual Therapy.
The researchers compared Maximal Inspiratory Pressure (MIP) and Maximal Expiratory Pressure (MEP) in 45 patients with neck pain and 45 healthy individuals of similar age, height, weight, body mass index, and levels of physical activity.
The intensity of neck pain in the patients was predominantly mild to moderate and they had mild disability. They had suffered with pain for an average of 69.6 months.
Compared with healthy individuals, neck pain sufferers had weak neck extensors and a trend for weak neck flexors. They had reduced mobility in all cervical movement planes and impaired deep neck flexors.
The study findings showed that patients with chronic neck pain had a significant 13.8% reduction in their MIP, compared with healthy individuals, and a significant 15.4% reduction in their MEP.
The ratio of MIP to MEP was not significantly affected, however, suggesting that the two respiratory indices were similarly reduced.
Neck muscle strength, kinesiophobia, and catastrophizing were significantly associated with both maximal mouth pressures, while MEP was also negatively correlated with neck pain and disability.
In prediction models, neck muscle strength was the only predictor that remained significant for MIP and MEP.
Dimitriadis and team suggest that this impaired muscle strength could be the result of a combination of the common function of sternocleidomastoid, scalene, and trapezius in neck movement and inspiration, changes in force-length curves and muscle imbalances, segmental instability of the cervical spine, and impairment of neck proprioceptors.
"These changes have been proposed to lead to adapted kinetic and kinematic patterns of rib cage, changing the force-length relationships of the associated respiratory muscles and consequentially leading to alteration of their contraction patterns, they say."
"These mechanical changes of respiratory muscles may influence their force production abilities and can lead to a permanent respiratory weakness due to plastic changes."
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