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Cervical instability describes a wide range of conditions from neck pain and deformation without any clear proof over little malformations too complete failure of intervertebral connection. White et al (1975) described cervical stability as the loss of ability of cervical spine under physiological loads to maintain relationships between vertebrae in such a way, that spinal cord or nerve roots are damaged or irritated and deformity or pain develops.
Clinically Relevant Anatomy
The cervical spine consist of 7 separate vertebrae. The first two vertebrae (referred as upper cervical spine) are highly specialized and differ from the other 5 cervical vertebrae (lower cervical) regarding anatomical structure and function.
The upper cervical spine is made of the atlas (C1) and the axis (C2). It comprises of two joint structures: one in between os occipital and atlas (atlanto-occipital joint), the other one between atlas and axis, which forms the atlanto-axial joint. The atlantoaxial joint is responsible for 50% of all cervical rotation; the atlanto-occipital joint is responsible for 50% of flexion and extension.
The craniocervical junction (atlanto-occipital joint), the lower atlanto-axial joint and other cervical segments are reinforced by internal as well as external ligaments. They secure the spinal stability of the cervical spine as a whole, together with surrounding postural muscles and allow cervical motion. They also provide proprioceptive information throughout the spinal nerve system to the brain.
The cervical spine has sacrificed stability for mobility and is therefore vunerable to injury.
The following risk factors are associated with the potential for bony or ligamentous compromise of the upper cervical spine:
- History of trauma (e.g. whiplash, rugby neck injury)
- Throat infection
- Congenital collagenous compromise (e.g. syndromes: Down’s, Ehlers-Danlos, Grisel, Morquio)
- Inflammatory arthritides (e.g. rheumatoid arthritis, ankylosing spondylitis)
- Recent neck/head/dental surgery.
Until this day there is no golden standard or acceptable measurement to diagnose cervical instability. Cervical instability is diagnosed as a combination of clinical findings and X-ray both dynamic and static. It is generally accepted that cervical instability is caused by trauma (one major trauma or repetitive microtrauma), rheumatoid arthritis or a tumor. Cervical instability leads to degenerative changes which effects the motion segment but may not be confused with severe incapacity or other signs of spinal cord compression.
A list of clinical findings composed by Magee et al:
- Complaints of locking/catching in the neck
- Weakness of the neck
- Altered ROM
- Neck pain and/or headaches provoked by sustained weightbearing postures and a relieve of those complaints in non-weighbearing positions
- Hypermobility and soft end-feeling in passive therapie
- Poor cervical muscle strength (multifidus, longus capitis, longus colli)
The findings in X-ray from Cervical Spine by Clark CL that combined with clinical findings can lead to a diagnosis of cervical instability.
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MRI images could be useful to screen the integrity of the vertebral ligaments. Taking images during an anterior shear test or a distraction test shows a greater intervertebral distance and an increase in direct length of the ligaments.
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Little is known about the diagnostic accuracy of upper cervical spine instability tests.
In the past few decades nonoperative maneuvers like traction, cast immobilization and long periods of bed rest had been replaced by the use of instrumentation to stabilize the spine after a trauma. This method can reduce the risk of negative sequelae of long term bed rest. The cervical stability can be received by using posterior fixation such as lateral mass plating, processus spinosus or facet wiring and cervical pedicle screws. The choice of which fixation is best, can be made by the surgeon after seeing a CT-scan or MRI. In a retrospective study of Fehlings, the cervical spine stabilization was successful in 93% off the cases. Obviously this fixation procedure also holds some risks. It is possible that the spinal cord, vertebral artery, spinal nerve and facet joints get injured. Levine et al. reported radicular symptoms in 6 of their 72 patients.
Physical Therapy Management
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Clinical Bottom Line
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Recent Related Research (from Pubmed)
- ↑ Hunningher A, Calder I, (2007), Cervical Spine Surgery ,Contin Educ Anaesth Crit Care Pain (3): 81-84.
- ↑ White AA et al (1975), Biomechanical analysis of cervical stability in the cervical spine Clin Orthop Relat Res; (109):85-96.
- ↑ Windsor, R. “Cervical Spine Anatomy.” Updated april 9, 2013 (http://emedicine.medscape.com/article/1948797-overview#a30)
- ↑ Cook C, Brismee JM, Fleming R, et al (2005). Identifiers suggestive of clinical cervical spine instability: a Delphi study of physical therapists. Physical Therapy 85(9):895-906.
- ↑ Magee DJ, Zachazewski JE, Quillen WS (2009) Cervical spine in Pathology an intervention in Musculoskeletal Rehabilitation p17-63 door Magee DJ, Zachazewski JE, Quillen WS, St-Louis, Saunders Elsevier
- ↑ Clark CL et al, Functional anatomy of joints ligaments and disks in Cervical Spine 4th ed.p 46-54 door Clark CL, Philadelphia, Lipincott Wlliams &amp;amp; Wilkins
- ↑ Osmotherly PG, Rivett DA, Rowe LJ. The anterior shear and distraction tests for craniocervical instability. An evaluation using magnetic resonance imaging. Man Ther. 2012 Oct;17(5):416-21. Level of evidence: 1B
- ↑ Hutting N, Scholten-Peeters GG, Vijverman V, Keesenberg MD, Verhagen AP. Diagnostic accuracy of upper cervical spine instability tests: a systematic review.Phys Ther. 2013 Dec;93(12):1686-95. doi: 10.2522/ptj.20130186. Epub 2013 Jul 25.
- ↑ 9.0 9.1 Kandziora F, Pflugmacher R, Scholz M, Schnake K, Putzier M? Khodadadyan-Klostermann C, Haas NP. Posterior stabilization of subaxial cervical spine trauma: indications and techniques. Injury 2005 Jul;36 Suppl 2:B36-43. (Level of Evidence IA) Review
- ↑ Ebraheim N. Posterior lateral mass screw fixation: anatomic and radiographic considerations. The University of Pennsylvania Orthopaedic Journal 12: 66-72, 1999. (Level of evidence Ia) Review