Anatomo-sonographic identification of the longissimus capitis and splenius cervicis muscles: principles for possible application to ultrasound-guided botulinum toxin injections in cervical dystonia

Differences in cervical sagittal parameters and muscular function among subjects with different cervical spine alignments: a surface electromyography-based cross-sectional study

Background

We analyzed cervical sagittal parameters and muscular function in different cervical kyphosis types.

Methods

This cross-sectional study enrolled subjects with cervical spine lordosis (cervical curvature < -4°) or degenerative cervical kyphosis (cervical curvature > 4°), including C-, S-, and R-type kyphosis. We recorded patients' general information (gender, age, body mass index), visual analog scale (VAS) scores, and the Neck Disability Index (NDI). Cervical sagittal parameters including C2-C7 Cobb angle (Cobb), T1 slope (T1S), C2-C7 sagittal vertical axis (SVA), spino-cranial angle (SCA), range of motion (ROM), and muscular function (flexion-relaxation ratio (FRR) and co-contraction ratio (CCR) of neck/shoulder muscles on surface electromyography). Differences in cervical sagittal parameters and muscular function in subjects with different cervical spine alignments, and correlations between VAS scores, NDI, cervical sagittal parameters, and muscular function indices were statistically analyzed.

Results

The FRR of the splenius capitis (SPL), upper trapezius (UTr), and sternocleidomastoid (SCM) were higher in subjects with cervical lordosis than in subjects with cervical kyphosis. FRRSPL was higher in subjects with C-type kyphosis than in subjects with R- and S-type kyphosis (P < 0.05), and was correlated with VAS scores, Cobb angle, T1S, and SVA. FRRUTr was correlated with NDI, SCA, T1S, and SVA. FRRSCM was correlated with VAS scores and Cobb angle. CCR was correlated with SCA and SVA.

Conclusion

Cervical sagittal parameters differed among different cervical kyphosis types. FRRs and CCRs were significantly worse in R-type kyphosis than other kyphosis types. Cervical muscular functions were correlated with cervical sagittal parameters and morphological alignment.

Pictorial Essay on Ultrasound and Magnetic Resonance Imaging of Paraspinal Muscles for Myofascial Pain Syndrome

The paraspinal muscles of the cervical, thoracic, and lumbar spine are important pain generators because muscle strains or myofascial pain syndrome caused by trigger points are common during clinical practice. Ultrasonography is the most convenient imaging tool for evaluating these muscles due to its advantages, such as providing good delineation of soft tissues, easy accessibility, and zero radiation. Additionally, ultrasound can serve as a useful guiding tool for paraspinal muscle intervention to prevent inadvertent injuries to vital axial neurovascular structures. This pictorial essay presents ultrasound scanning protocols for the paraspinal and other associated muscles as well as a discussion of their clinical relevance. Axial magnetic resonance imaging has also been used to elucidate reciprocal anatomy. In conclusion, ultrasound imaging proves to be a valuable tool that facilitates the differentiation of individual paraspinal muscles. This capability significantly enhances the precision of interventions designed to address myofascial pain syndrome.

Morphological characteristics of the posterior neck muscles and anatomical landmarks for botulinum toxin injections

PURPOSE

Cervical dystonia is a common movement disorder for which botulinum toxin (BoNT) is the first choice treatment. Injecting the specific neck muscles can be challenging because of their thin morphology and deep locations. We, therefore, designed a study to investigate the locations of the posterior neck muscles to help the physician predict the locations of the targeted neck muscles and to protect the vertebral vessels from injury during deep injections.

METHODS

The posterior neck region was divided into four quadrants by imaginary lines passing vertically and transversely through the spinous process of C2 vertebra (C2_sp). The thicknesses and depth of the posterior neck muscles were measured in ten formaldehyde-fixed adult male cadavers. These muscles were located and a projection of them was drawn on the neck. Using the measurements, colored latex in place of BoNT was injected into them in one cadaver. The cadaver was dissected to investigate whether the muscles were colored.

RESULTS

2 cm above the C2_sp, trapezius, splenius capitis (SPC) and semispinalis capitis (SSC) were colored at depths of 10.70 mm, 11.88 mm and 15.91 mm, respectively. 2 cm below the C2_sp, the trapezius, SPC and SSC were colored at depths of 20.89 mm, 23.25 mm and 27.63 mm, respectively. The posterior neck muscles were had taken up their assigned colors when they were injected according to the results obtained in this study. The vertebral vessels were not colored.

CONCLUSIONS

Although BoNT injection into the posterior neck muscles is challenging, we think that it can be practically and safely applied using the measurements obtained in this study.