|Study title: Systematic Review of the Soft-Tissue Connections Between Neck Muscles and Dura Mater
Authors: Palomeque-del-Cerro L, Arráez-Aybar LA, Rodríguez-Blanco C et al.
Publication information: Spine 2017; 42(1): 49–54.
The pathophysiology of craniocervical pain is not well understood and treatment of these disorders often targets the suboccipital region. Recent anatomical research has described the existence of a myodural bridge – a connection between the dura mater and the upper cervical muscles via soft tissue. While some of these findings seem to contradict one another, this information has lead to the proposal of several physiological, pathophysiological, diagnostic, and therapeutic consequences of this connection. This review looked at these recent anatomical findings into a soft tissue connection between the cervical muscles and the dura matter in the upper cervical spine.
Study methods, results
A search of PubMed, Web of Knowledge, Cochrane Library, and PEDro was performed with no date limits. Cited articles were also reviewed for additional papers.
Twenty-six studies were included: 20 observational studies, two case studies, three letters that contained original observational data and one summary of communication from a conference. Of these, the majority utilized dissection, primarily of embalmed cadavers. Five studies used plastination, two performed magnetic resonance imaging (MRI) of cadavers, five performed MRIs of live subjects, one utilized CAT scans, six performed histological analysis, and one gathered data from a surgical procedure.
These studies provided strong evidence of a soft tissue continuity between the dura mater and three suboccipital muscles: rectus capitis posterior minor (RCPmi), rectus capitus posterior major (RCPma), and obliqus capitus inferior (OCI).
Conflicting evidence exists for a soft tissue connection between the dura mater and the ligamentum nuchae (LN). The LN is significant, as several muscles including the upper trapezius (UT), splenius capitis (SC), rhomboideus minor (RM), and serratus posterior superior (SPS) attach to it (or, perhaps more accurately, are continuous with it). Five studies, including 87 cases, confirm the connection, while four studies deny the connection. Those four studies only included roughly half as many total cases, however. The type of soft tissue connection is also controversial, with some studies describing the connection as a dense fibrous band, and others describing loose fatty connective tissue. (Perhaps this discrepancy may reflect the age/state of the body/cadaver under study in a particular paper?)
Finally, there is limited evidence to support the existence of a bridge between the dura mater and the rectus capitis anterior (RCA – which sits on the anterior craniocervical junction). Only one study confirmed this connection, however, the study looked at more than 30 cadaver dissections and histological analysis. More research is needed for confirmation.
In summary, the number of cases studied and the high number of instances where a connection was found or visualized implies these results are neither incidental findings nor anatomic anomalies.
Clinical applications, conclusion
Strong evidence supports the existence of a soft tissue bridge between the dura mater and the RCPmi, RCPma, and inferior oblique muscles. There is also moderate, yet conflicting, evidence of a soft tissue connection between the dura mater and the upper trapezius, splenius capitis, rhomboideus minor, and serratus posterior superior via the ligamentum nuchae. Limited evidence supports a connection between the dura mater and the rectus capitis anterior muscle.
These connections may play a physiological role in some forms of craniocervical pain. This connection may also help to explain some symptoms related to craniocervical disorders and the mechanical and neurophysiological effects seen with interventions such as massage, exercise, manipulation, or surgical interventions. More research is needed to confirm the significance of this bridge and any possible pathophysiological and therapeutic implications of these connections.
SHAWN THISTLE, BKIN (HONS), DC, CSCS, practises full time in Toronto. He is the founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners integrate current, relevant, scientific evidence into their practice (www.researchreviewservice.com).