Cervical Instability

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Definition/Description

Internet is a gigantic source of knowledge. Databases such as PubMed, Web of Science, PEDro or Google Scholar can be useful. Use keywords as ‘Cervical instability’, ‘Instability of the cervical spine’, etc. . For specific information you can add ‘AND’ followed by ‘physical therapy’, ‘characteristics’, ‘definition’, 'treatment', depending of the need.

Definition/Description

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)  and Panjabi (1992) 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 vulnerable to injury.
The total ROM of a spinal segment may be divided into two zones:
- Neutral zone: motion occurring in this zone is produced against a minimal passive resistance.
- Elastic zone: motion occurring in occurring near the end-range of spinal motion is produced against increased passive resistance.

There are many authors that identified common components of spinal stability. Panjabi on conceptualized the components into 3 functionally integrated subsystems of the spinal stabilizing system: ^{[10]Level of Evidence 4,[11]Level of Evidence 2C}

• The passive subsystem:

- Consists of vertebral bodies, facet joints and capsules, spinal ligaments (lig. longitudinale anterius and posterius, ligamentum interspinosum, lig. Interspinosus and lig. Flavum).^{[17]Level of Evidence 2A}
- Passive tension from spinal muscles and tendons.
- Provides significant stabilization of the elastic zone and limits the size of the neutral zone.
- Acts as a transducer and provides the neural control subsystem with information about vertebral position and motion

• The active subsystem:

- Consists of spinal muscles and tendons, such as: M. multifidus cervicis, M. Longus capitis and the M. Longus Colli.[18]Level of Evidence 5
- Generates forces required to stabilize the spine in response to changing loads.
- Controls the motion occurring within the neutral zone and contributes to maintain the size the size of the neutral zone.
- Acts also as a transducer by providing the neural control subsystem with information about the forces generated by each muscle.

• The neural control subsystem:

- Consists of peripheral nerves and the central nervous system.
- Receives information from the transducers of the passive and active subsystems about vertebral position, vertebral motion, and forces generated by spinal muscles. The subsystem determines the requirements for spinal stability and acts on the spinal muscles to produce the required forces.

Clinical instability of the spine occurs when the neutral zone increases relative to the total ROM, the stabilizing subsystems are unable to compensate for this increase, which causes a poor and uncontrolled quality of motion in the neutral zone. ^{[10] Level of Evidence 4, [3] Level of Evidence 2C,[17] Level of Evidence 2A.}

Risk Factors

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.

Characteristics/Clinical Presentation

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:

• Neckpain
• 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.

Differential Diagnosis

Certain Patients that might present acute neurologic symptoms that raise alarm for cervical compression or neck pain but without a specific origin should undergo a thorough physical examination and radiographic evaluation to determine the source.

More often than not are the findings nonspecific and can be representative of any number of related conditions, including the following:^{(9) level of evidence 5}
• Cervical strain
• Cervical trauma or fracture
• Occipital headaches
• Degenerative disease of the spine
• Previously undiagnosed syndrome
• Neurological involvement
• Progressive neck pain
• Resistant neck pain

Diagnostic Procedures

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.

Research shows us that abnormal MRI images in end-range flexion and extension of the cervical spine could be associated with cervical segmental instability. These abnormal radiographs refer to soft tissue damages (passive subsystem), for example from the intervertebral discus and the integrity of the vertebral ligaments (lig. longitudinale anterius), which thus results in an abnormally increased mobility in that region. 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. However, radiographs do not provide information about the quantity or quality of motion in the neutral zone (mid-range), which limits his value in the diagnosis of cervical spine clinical
instabilities. ^{[1] Level of Evidence 4, [2] Level of Evidence 2B}

A method to measure the quality and quantity of active motion would be beneficial in establishing a diagnosis of the clinical instability, but to this day there are no clinical or diagnostic tests that yield valid and reliable described in the literature to diagnose cervical instability.

Because a definitive diagnostic tool has not been developed yet, cervical clinical instability will continue to be diagnosed through clinical findings, including history, subjective complaints, visual analysis of the active quality, and manual examination methods. ^{[10] Level of Evidence 4, [12] Level of evidence 2C, [13] Level of Evidence 2B}

Outcome Measures

add links to outcome measures here (also see Outcome Measures Database)

Examination

Little is known about the diagnostic accuracy of upper cervical spine instability tests.

• Sharp-Purser Test 
• Transverse Ligament Stress Test
  

Medical Management

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

The goal of the physical treatment is to enhance the function of the spinal stabilizing subsystems and to decrease the stresses on the involved spinal segments.

• Posture education and spinal manipulation:

- Decreases stresses on the passive subsystem.
- Proper posture: reduces the loads placed on the spinal segments at end-ranges and returns the spine to a biomechanically efficient position.
- Spinal manipulation can be performed on hypomobile segments above and below the level of instability, what eventually will result in a distribution of the spinal movement across several segments. Also the mechanical stresses on the level of clinical instability are believed to be decreased. ^{[10] Level of Evidence 4}
- Video over joint mobilization: https://www.youtube.com/watch?v=Rn1Ed2SxTx0

• Strengthening exercises:

- Enhances the function of the active subsystem.
- The cervical multifidus may provide stability via segmental attachments to cervical vertebrae.
- The m. longus colli and capitus provide anterior stability.
- Strengthening the stabilizing muscles may enable those muscles to improve the quality and control of movement occurring within the neutral zone.^{[10] Level of Evidence 4, [13] Level of Evidence 2B}

• Exercise video: Neck strength and stability

In a more specific situation such as post-operative revalidation for example in the case of a cervical fusion, the treatment can differ as described hereunder.

• The patient is not required to wear a brace. After 6 weeks it is not encouraged to do any lifting more than 4kg as also overhead work. The rehabilitation begins at week 6, mostly a basic stability exercises program. No cervical strengthening or ranges of motion exercises are encouraged in the first 6 months.The exercises or mainly focused on the neutral postural alignment, were the patients are recommended to us there trunk, hips and chest to produce proper cervical alignment. For other types of operations the treatment-plan will be defined in function of the critical nature of the trauma.^{[19]Level of Evidence 5}
  
  

Key Research

- P.G. Osmotherly et Al., Knowledge and use of craniovertebral instability testing by Australian physiotherapists, Elsevier, 2011. ^{[13] Level of Evidence 2B}

Resources

- K.A. Olson, D. Joder, Diagnosis and treatment of Cervical Spine Clinical Instability, Journal of Orthopaedic & Sports Physical Therapy, April 2001. ^{[10] Level of Evidence 4}

Clinical Bottom Line

Clinical cervical spine instability (CCSI) is controversial and difficult to diagnose. Within the literature, no clinical or diagnostic tests that yield valid and reliable results have been described to differentially diagnose this condition. ^[10]
The screening by tests for upper cervical instability cannot be done accurately at the moment. ^{[11] level of Evidence 2B}

Recent Related Research (from Pubmed)

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References

1. Inamasu J, Nakatsukasa M, Hirose Y. Computed tomography evaluation of the brain and upper cervical spine in patients with traumatic cardiac arrest who achieved return of spontaneous circulation. Neurol Med Chir (Tokyo). 2013. 53 (9):585-9. ^{[1] Level of Evidence 4}
2. Hill BW, Song B, Morgan RA, Kang MM. The Role of Adjustable Scout Lines in Advanced Cervical Spinal Imaging. J Spinal Disord Tech. 2013 Nov 6. ^{[2] Level of Evidence 2B}
3. Choudhary AK, Ishak R, Zacharia TT, Dias MS. Imaging of spinal injury in abusive head trauma: a retrospective study. Pediatr Radiol. 2014 Sep. 44 (9):1130-40.^[3]
4. Qualls D, Leonard JR, Keller M, Pineda J, Leonard JC. Utility of magnetic resonance imaging in diagnosing cervical spine injury in children with severe traumatic brain injury. J Trauma Acute Care Surg. 2015 Jun. 78 (6):1122-8.^[4]
5. Hannon M, Mannix R, Dorney K, Mooney D, Hennelly K. Pediatric cervical spine injury evaluation after blunt trauma: a clinical decision analysis. Ann Emerg Med. 2015 Mar. 65 (3):239-47. ^[5]
6. James IA, Moukalled A, Yu E, Tulman DB, Bergese SD, Jones CD, et al. A systematic review of the need for MRI for the clearance of cervical spine injury in obtunded blunt trauma patients after normal cervical spine CT. J Emerg Trauma Shock. 2014 Oct. 7 (4):251-5. ^[6]
7. Kanji HD, Neitzel A, Sekhon M, McCallum J, Griesdale DE. Sixty-four-slice computed tomographic scanner to clear traumatic cervical spine injury: systematic review of the literature. J Crit Care. 2014 Apr. 29 (2): 314.e9-13.^[7]
8. Hutting N., Diagnostic Accuracy of Upper Cervical Spine Instability: A systematic Review. Journal of the American Physical Therapist Association, July 2013, vol.93, 1686-1695 ^{[8]Level of Evidence 1A)}
9. Magee DJ, Zachazewski JE,Quillen Ws : Cervical spine in Pathology an intervention in Musculoskeletal Rehabilitation p17-63 ,2009, St-Louis, Saunders Elsevier ^{[9] Level of Evidence 5}
10. K.A. Olson, D. Joder, Diagnosis and treatment of Cervical Spine Clinical Instability, Journal of Orthopaedic & Sports Physical Therapy, April 2001. ^{[10]Level of Evidence 4}
11. M. Takeshi et Al., Soft-Tissue Damage and Segmental Instability in Adult Patients with Cervical Spinal Cord Injury Without Major Bone Injury, Spine Journal, December 2012.
^{[11]Level of Evidence 2B}
12. C. Cook et Al., Identifiers Suggestive of Clinical Cervical Spine Instability: A Delphi Study of Physical Therapists, Journal of the American Physical Therapy Association, September 2005 ^{[12]Level of Evidence 2C}
13. P.G. Osmotherly et Al., Knowledge and use of craniovertebral instability testing by Australian physiotherapists, Elsevier, 2011. ^{[13]Level of Evidence 2B}
14. Howard S. An, Scott D. Boden, William C. Lauerman, Lawrence G. Lenke, Robert F. McLain. “The adult and pediatric spine: Volume 2” by Lippincott Williams & Wilkins. 2004. (3th edition) ^{[14]Level of Evidence 5}
15. Kenneth A. Olson et al. “Diagnosis and Treatment of Cervical Spine Clinical Instability”.
Journal of Orthopaedic & Sports Physical Therapy 2001;31(4):194-206
^{[15] Level of Evidence 4}
16. Steilen D., Hauser R., Woldin B. and Sawyer S. “Chronic Neck Pain: Making the Connection Between Capsular Ligament Laxity and Cervical Instability” The Open Orthopaedics Journal, 2014, volume 8, 326-345. ^{[16]Level of Evidence 2B}
17. R. Banerjee et Al., Catastrophic Cervical Spine Injuries in the Collision Sport Athlete, Part 1 Epidemiology, Functional Anatomy, and Diagnosis, The American Journal of Sports Medicine, 2004. ^{[17]Level of Evidence 2A}
18. W.Platzer, Atlas van de Anatomie, Bewegingsapparaat, Sesam, 1999.^{[18]Level of Evidence 5}
19. C.Liebenson, Rehabilitation of The Spine, Lippincott Williams & Wilkins, p927, 2007.^{[19]Level of Evidence 5}