Reviewed by B.Davies
Neck Muscles and CSM– An Update Part 1 of 2
This will be the first of a 2 part mini-series on the properties of muscles in the neck and how they impacts outcomes of surgery. We previously looked at this following an early piece of research from North America. This series will serve as an update on this research.
Why was this study conducted?
As outlined previously, the amount of fat found within muscles has been linked to the type of symptoms experienced by patients; including the amount of neck pain and walking ability. This new study was done on a separate cohort of patients than the previous study and included measures of neck strength and other quality of life scales not assessed previously which addresses some weaknesses of the previous study.
How was the study conducted?
This study used MRI imaging to measure the size and the amount of fat in muscles in the neck. Neck strength was measured by clinicians using a hand held force sensor. Several questionnaires were performed to assess function, pain, and quality of life. Importantly, this study used what is called a “cross-sectional’ design meaning it only looks at 1 time point.
What was discovered?
Larger muscles and larger amounts of lean muscle (i.e. muscle without fat) in the neck were associated with increased strength. (We already knew this in general, but it is good to ensure there isn’t something different about patients with cervical myelopathy). More fat in muscles of the neck was associated with more disability measured by the mJOA. Importantly, neither strength, muscle size, or muscle fat were associated with pain, duration of symptoms, neck disability index, or quality of life in this study.
Why is this important?
Between the previous study linked above and this study, it appears that muscle fat may be a biomarker of disability and function in patients with myelopathy. Currently there are no biomarkers for myelopathy, which makes it difficult to assess how severe it is or give an idea of how things will develop. More research will be needed to investigate the usefulness of muscle fat as a biomarker, but given that it can be quantified based on existing widely avaliable imaging techniques, it could enter routine clinical practice quickly.
Why could muscle fat relate to the severity of myelopathy?
One reason this is being investigated is that fat infiltrates muscle as a response to nerve injury and disuse. For example, if a nerve is injured the nerve doesn’t tell the muscle to contract as much and it allows more fat to become deposited within the muscle itself.
References
- Fortin M et al. Relationship Between Cervical Muscle Morphology Evaluated By MRI, Cervical Muscle Strength And Functional Outcomes In Patients With
Degenerative Cervical Myelopathy. Musculoskeletal Science and Practice. 38; epub 2018: 1-7
- Fortin M, et al. Association Between Paraspinal Muscle Morphology, Clinical Symptoms and Functional Status in Patients With Degenerative Cervical Myelopathy. Spine (PhilaPa 1976). 2016 May 23