Last Updated on August 22, 2023
Cervical spine instability is defined as the loss of the ability of the cervical spine under physiological loads to maintain relationships between vertebrae in such a way, that the spinal cord or nerve roots are not damaged or irritated and deformity or pain does not develop. Thus, cervical spine instability means one or more vertebrae can move beyond their normal range of motion when physiologically loaded.
While most of the definition is explanatory, the key term to remember is the physiological load.
Clinically, instability is present when the articular components are altered or become abnormal when loaded due to insufficiency of the stabilizing structures. Cervical instability carries an associated risk of neurological involvement especially when the instability is in the upper cervical spine.
Relevant Anatomy
Types of Cervical Spine Instabilities
The cervical spine is a complex structure that is responsible for the mobility of the head and neck. Any of the structures if affected – ligaments, tendons, discs, capsules, and deep muscles can cause issues. Most of the cases of cervical instability belong to the upper cervical spine in C1, C2 regions. These are
- Occiputocervical or Craniocervical instability – Between the occiput and the first vertebra [atlas]
- Atlantoaxial instability- Between C1 [atlas] and C2 [axis]
However, any part of the cervical spine can be unstable and thus any of the lower segments may be involved.
In addition to this the cervical spine instability can be acute [rcent onset] or chronic [long-standing]
Symptoms and Signs of Cervical Spine Instability
The symptoms vary from non-specific to specific.
Nonspecific symptoms like headache, neck pain and muscle pain may occur. Some patients may complain of sleep apnea. The involvent of the autonomic nervous system may lead to nausea, gastrointestinal disorders hot flashes and coldness, etc.
More specific symptoms are
- The head feels heavy and is difficult to hold up
- Dysphagia [difficulty in swallowing]
- Throat lump
- Dizziness
- Hearing issues like muffled hearing
- Syncope
- Disturbance of balance and motor skills
- Face tingling/numbness/paralysis
- Hypersensitivity to light and sound
- Twitching
- Dystonia
- Cognitive changes/mood changes
Diagnosis
A detailed physical examination including a neurological examination is an essential part of a diagnosis-making.
Stretch Test For Cervical Spine Instability
The stretch test involves stretching the cervical spine with traction and determining the changes on x-rays.
This test is contraindicated in an unstable injury and is always done under the supervision of a physician.
A head halter traction is applied and an x-ray is taken before applying weights to the traction. Weight is increased in steps and x-rays taken.
The test is considered positive if there is a neurological deficit or abnormal separation of anterior or posterior elements.
White and Punjabi Criteria of Spinal Instability?
Radiologically, instability is checked by criteria given by White and Punjabi which is as follows
- Destruction or loss of function of anterior elements
- Destruction or loss of function of posterior elements
- Relative translation of vertebra in sagittal plane > 3.5 mm
- Angulation of one vertebra to another > 11 mm
- Positive stretch test for the cervical spine.
- Damage to the cord
- Nerve root damage
- Abnormal narrowing of disc space
- Dangerous loading anticipated
Except for the last three points, each point is given a score of 2. The last three points are given a score of 1.
A positive score of more than 5 indicates instability.
X-rays
Flexion extension X-rays may show cervical spine instability but not always.
More on flexion-extension X-rays
MRI/CT
MRI/CT may show some structural abnormality or could be normal. Dynamic MRI may reveal dynamic cervical spine instability. Dynamic cervical spine instability may also be revealed by flexion-extension X-rays.
Treatment
Conservative
- Wear a brace when symptoms are severe
- Physical therapy
- Isometric exercises
- Muscle strengthening
- Posture improvement
- Relaxation and breathing techniques
Operative Treatment
Fusion of the mobile segments is the surgical treatment for cervical spine instability and should be considered a last resort when conservative treatments fail.
The drawback of fusion is that it blocks the motion of the adjoining segments making them prone to instability.
Prevention of Cervical Spine Instability
Prevention measures should be initiated early, especially in those cases who carry a high risk of developing cervical spine instability. These are people with connective tissue disorders like Ehler-Danlos syndrome, Down’s syndrome, etc.
The measures are
- Avoid contact or collision sports
- Avoid neck strain
- Keep neck devices like phones. computers at eye level
- Do not bend your neck for a prolonged time
- Use assistive devices to avoid strain on the neck. These can be
- Phone mounts
- Ergonomic work stations
- Good sitting and standing posture
- Good sleep posture
- Use firm mattress
- Use neck pillows
- Manage stress with relaxation techniques
Cervical Spine Instability in Down Syndrome
Generalized ligamentous laxity caused by the collagen defects in Down syndrome can result in atlantoaxial and atlantooccipital instability. In these patients, hypermobility of the spine is a feature but instability is that hypermobility that jeopardizes neurological integrity.
Atlantoaxial instability occurs in approximately 10% to 20% of children with Down syndrome and atlantooccipital in 60%.
The children might show gait abnormalities, hyperreflexia, and motor weakness.
Neck pain, occipital headaches, and torticollis are other features.
An atlantodens interval of more than 4 to 5 mm indicates instability. If the ADI is more than 6 to 7 mm, MRI or CT is necessary to evaluate the space available for the spinal cord to evaluate the risk of neurological compromise.
If the ADI is 10 mm or more, posterior fusion and wiring are recommended.
References
- Katz EA, Katz SB, Freeman MD. Non-Surgical Management of Upper Cervical Instability via Improved Cervical Lordosis: A Case Series of Adult Patients. J Clin Med. 2023 Feb 23;12(5):1797. doi: 10.3390/jcm12051797.
- Olson K.A., Joder D. Diagnosis and Treatment of Cervical Spine Clinical Instability. J. Orthop. Sports Phys. Ther. 2001;31:194–206. doi: 10.2519/jospt.2001.31.4.194.
