Research Review By Dr. Ceara Higgins©

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Date Posted:

March 2017

Study Title:

A 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.

Author's Affiliations:

Departments of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Universidad Rey Juan Carlos, Madrid, Spain; Faculty of Nursery and Physical Therapy “Salus Infirmorum”, Universidad Pontifica de Salmanca, Madrid, Spain; Madrid Osteopathic School, Madrid, Spain; Department of Human Anatomy and Embriology, Complitense University of Madrid, Spain; Department of Physiotherapy, University of Sevilla, Spain.

Publication Information:

Spine 2017; 42(1): 49–54.

Background Information:

The pathophysiology of craniocervical pain is not well understood (1) and treatment of these disorders often targets the suboccipital region (2). 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 (4), pathophysiological (5), diagnostic (6), and therapeutic (3) 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.
myodural bridge

Pertinent Results:

26 studies were included: 20 observational studies, 2 case studies, 3 letters that contained original observational data and 1 summary of communication from a conference. Of these, the majority utilized dissection, primarily of embalmed cadavers. Five studies used plastination, 2 performed magnetic resonance imaging (MRI) of cadavers, 5 performed MRIs of live subjects, 1 utilized CAT scans, 6 performed histological analysis, and 1 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 (11), and others describing loose fatty connective tissue (10). EDITOR’S NOTE: 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 not incidental findings nor anatomic anomalies.

Clinical Application & Conclusions:

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 (UT), splenius capitis (SC), rhomboideus minor (RM), and serratus posterior superior (SPS) via the ligamentum nuchae (LN). Limited evidence supports a connection between the dura mater and the rectus capitis anterior (RCA) 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.

Study Methods:

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.

Inclusion Criteria:
  • Articles published in scientific journals in English, Spanish, Portuguese, or French.
  • Articles reporting on original data related to a continuity in non-post-surgical soft tissues between the cervical muscles and the dura mater.
Exclusion Criteria:
  • Articles where the continuity described between the cervical muscles and the dura mater was achieved through intermediate bony elements.
The authors retrieved the following information from each study: bibliographic references, participating sample, methodology and anatomical findings. Methodological quality of the articles was evaluated using the QUACS Scale (Quality Appraisal of Cadaveric Studies) (8), which scores the quality of the study as a percentage, with 81-100% indicating excellent quality, 61-80% substantial, 41-60% moderate, 21-40 fair, and 0-20% poor. Finally, the level of evidence for each proposed connection was evaluated via the Cochrane Collaboration Back Review Group (9) and rated as not existent (no studies available), conflicting (inconsistent findings among multiple studies), limited (one low-quality study), moderate (consistent findings among multiple low-quality studies or one high-quality study), or strong (consistent findings among multiple high-quality studies).

Study Strengths / Weaknesses:

Strengths;
  • The systematic review was performed according to the Preferred Reporting Item for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (7).
Weaknesses:
  • The QUACS Scale was designed for the assessment of observational cadaveric studies, however, five of these studies included living subjects. No other known scales exist for assessing the methodological quality of these types of studies, making the QUACS the best option available.
  • Some of the articles included were of low quality as the methodology used to obtain the anatomical data was not fully explained, the studies were very old, were from scientific letters, or included in the summary of a communication at a conference.

Additional References:

  1. Sheikh HU. Approach to chronic daily headache. Curr Neurol Neurosci Rep 2015; 15: 4.
  2. Antolinos-Campillo PJ, Oliva-Pascual-Vaca A, Rodriguez-Blanco C, et al. Short-term changes in median nerve neural tension after a suboccipital inhibition technique in subjects with cervical whiplash: a randomized controlled trial. Physiotherapy 2014; 100: 249-255.
  3. Hack GD, Hallgren RC. Chronic headache relief after section of suboccipital muscle dural connections: a case report. Headache 2004; 44: 84-89.
  4. Hack GD, Koritzer RT, Robinson WL, et al. Anatomic relation between the rectus capitis posterior minor muscle and the dura mater. Spine 1995; 20: 2484-2486.
  5. Pontell ME, Scali F, Enix DE, et al. Histological examination of the human obliquus capitis inferior myodural bridge, Ann Anat 2013; 195: 522-526.
  6. Scali F, Pontell ME, Welk AB, et al. Magnetic resonance imaging investigation of the atlanto-axial interspace. Clin Anat 2013; 26: 444-449.
  7. Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 2009; 6: e1000097.
  8. Wilke J, Krause D, Niederer T, et al. Appraising the methodological quality of cadaveric studies: validation of the QUACS Scale. J Anat 2015; 226: 440-446.
  9. Van Tulder M, Malmivaara A, Chou R, et al. 2015 Updated method guideline for systematic reviews in the Cochrane collaboration back and neck group. Spine 2015; 40: 1660-1673.
  10. Johnson GM, Zhang M, Jones DG. The fine connective tissue architecture of the human ligamentum nuchae. Spine 2000; 25: 5-9.
  11. Zhang M, Lee ASJ. The investing layer of the deep cervical facia does not exist between the sternocleidomastoid and trapezius muscles. Otolaringol Head Neck Surg 2002; 127: 452-457.