Cervical spondylosis is a common condition, briefly described as osteroarthritis of the cervical spine. It arises as a result of age-related dryness of nucleus pulposus and its collapse, causing bulging of the annulus fibrosus. This causes increased mechanical stress at the cartilaginous end plates of the vertebral body lip, leading to osteophytic spurs, which helps to stabilise the hypermobile vertebrae as a result of loss of disc space.5,6
These osteophytes cause cord space narrowing. Age-related hypertrophy of the ligamentum flavum and thickening of bone may result in further narrowing of the cord space.5
Cervical spondylosis affects around 10% in the fourth decade of life and is radiologically present in more than 95% of people over the age of 70 years, hence a common finding in apparently healthy individuals above 50 years. It is slightly more prevalent in males.7 It can be asymptomatic but once symptomatic it produces pressure symptoms mainly on surrounding structures, especially spinal cord and originating nerves causing cervical myelopathy or radiculopathy respectively.
It usually presents as intermittent neck and shoulder pain with or without neurological deficit,5 although one-third of the patients present with headache, often in sub-occipital area radiating to vertex of the skull.8 Presentation with neurological deficit is usually divided into three clinical categories:
1. Primarily radiculopathy: Root dysfunction reflected by radicular pain and focal neurological deficit
2. Primarily myelopathy: Cord involvement with pyramidal tract signs involving lower limbs
3. Mixed: Root and cord involvement, eg. neck pain with root deficit and clumsy hand along with spastic paraparesis and gait disturbances.
Some of these symptoms are exacerbated by movements and hence can lead to cervical dystonia in severe disease.
Mechanism of cervical vertigo and supporting evidence
Vertigo resulting from cervical spondylosis is not a widely accepted phenomenon. It was first described by Claude Bernard in 1858, followed by Barré in 1926. In cervical spondylosis, vertigo is normally provoked by head movements, hence the term cervical vertigo. In fact the vertigo can be relieved by eliminating neck torsion against the head.9
The pathogenesis of cervical spondylosis leading to vertigo presented in the literature is quite complex and contentious. There are numerous studies in the literature discussing the underlying aetiology and based on the information from these studies, the pathogenesis is broadly divided into two major categories.
Afferent impulses from the neck travel via posterior cervical roots to the vestibular nuclei, which when intersected in experimental rabbits causes positional vertigo when the head is moved on the trunk.10 Also the transverse section of suboccipital muscles, surgical deafferentation of C1-C3, or suboccipital anaesthesia results in locomotor ataxia.
Local anaesthesia of deep posterolateral neck tissue in humans usually elicits a transiently increased ipsilateral and decreased contralateral extensor muscle tone with a tendency to fall, gait deviation, and pastpointing towards the injected side.11
In cervical spondylosis, alteration in the cervical afferent flow may be due to the pressure on the cervical nerve roots by disc protrusions.12
In 1976, Mangat and McDowall investigating the incidence of vertigo in 55 patients with cervical spondylosis, illustrated the resolution of vertigo and nystagmus with anterior cervical decompression, and suggested that abnormal afferent flow in the posterior cervical nerves in patients with cervical spondylosis lead to unstable vestibular tone, which is further upset by neck torsion.13
Barre et al14 proposed that the irritation of sympathetic nerves around vertebral arteries could play a part in production of vertigo and nystagmus as a result of cervical osteophytes, since vertigo in Meniere's disease can successfully be treated with cervical sympathectomy.
The vertebrobasilar circulation supplies the vestibular labyrinth, VIII nerve, brain stem, cerebellum and occipital lobes.1 Cervical osteophytes can press on the vertebral artery causing its occlusion during head turning to the same or opposite side.15, 16, 17
The most common complaint in patients with vertebrobasilar insufficiency is vertigo.18,19 As the blood supply to vestibulocochlear organ, is an end artery, it is totally reliant on vertebrobasilar circulation and hence more susceptible to vertebrobasilar insufficiency20 leading to vestibular vertigo.
Olszewski et al.16 examined 80 patients with radiological evidence of cervical spondylosis but with normal CT or MRI brain examination and no neurological symptoms (except cervical radicular symptoms) with 40 patients complaining of positional vertigo of at least six months durations. These patients had neuro-otological examinations and cochlear function tests to exclude other causes of vertigo and extracranial vertebral artery and carotid artery stenosis were also ruled out. All patients had transcranial doppler ultrasound with head rotations and it confirmed significant association between flow velocity in basilar artery after neck rotation and age, prevalence of vertigo and grade of radiological changes. It was also shown that vertebral artery flow velocity in neutral position was not affected by degenerative changes in cervical spine.
Bayrak et al21 also found no considerable changes in vertebral artery flow in neutral position on Doppler measurements of 91 patients with radiologically confirmed cervical degenerative changes.
Sheehan et al22 demonstrated vertebrobasilar insufficiency from vertebral artery compression due to cervical spondylosis on vertebral arteriography, during head turning. It is critical in those who have vascular risk factors that may compromise the integrity of the circle of Willis, particularly the elderly20,23,24 when there is 25% reduction in basilar flow between 20 and 70 years of age.16, 21
Moubayed and Saliba in Montreal University performed a double blinded retrospective cohort study in 258 patients. They reviewed their MRA reports describing vertebral arteries and compared 72 patients with normal vertebral arteries with 61 patients with stenotic vertebral arteries. It found 85.7% of patients with stenosed vertebral arteries complained of isolated positional vertigo on the questionnaire.25
Another factor thought to have contributed to positional vertebrobasilar insufficiency is that in cervical spondylosis there is diminution in the size of the disc spaces causing a reduction in the length of cervical spine with a concomitant decrease in length of the vertebral arteries. As this causes increased tortuosity of both vertebral arteries, any neck rotation causes further compromise in vertebral artery blood flow. Surgical fusion and neck traction post-operatively restore the length and hence the flow of vertebral artery, which result in resolution of symptoms.13
Several case reports have been published that showed significant relief from vertigo in patient with significant vertebral artery compression from cervical osteophytes.26-30
Mazloumi and Samini17 compared 16 patients with cervical spondylosis, suffering from vertigo, who had dynamic angiography and/or Doppler sonography with head rotations to show vertebral artery compression. They showed better symptomatic relief in surgically treated patients (75%) than conservatively managed, and recommended that vertebral artery should be released if there is significant compression confirmed radiologically and symptoms are poorly controlled with conservative management.
The widely used initial investigation is the plain C-spine radiographs to demonstrate the disc-space narrowing, osteophytosis, loss of cervical lordosis and vertebral canal diameter.15
As these degenerative changes are commonly seen in asymptomatic subjects, the use of plain x-rays can be misleading and inconclusive.29 Adams et al reported no significant difference in the severity of the radiological changes between C-spine radiographs of 32 elderly patients clinically diagnosed as having symptomatic cervical spondylosis causing pressure effect with those of 32 age- and sex-matched controls.31
MRI is a non-invasive imaging that provides excellent imaging of the spinal cord and of the neural elements and thus it has become the standard diagnostic study for spondylotic disease with pressure effect, to rule out soft tissues compression and when contemplating surgery.32
CT scanning is another important imaging modality, superior to MRI in its definition of bony anatomy including neural foramina and canal diameter.32
Myelography is useful for demonstrating nerve root lesions to localise the exact nerve encroachment but is an invasive imaging and hence particularly useful in patients needing surgical intervention.
Transcranial doppler ultrasound,16,33 magnetic resonance imaging/angiography34 and selective arteriography35 can be used to assess vascular compression from cervical osteophytes.
Neurological, vestibular, and psychosomatic disorders must first be excluded before the dizziness and unsteadiness in cervical pain syndromes can be attributed to a cervical origin.3
Treatment of cervical spondylosis is dependant on symptoms severity and response to conservative management, which is the mainstay of treatment.
Conservative options including neck immobilisation, pharmacological treatments including analgesia and muscle relaxants, lifestyle modifications, and physical modalities ie. spinal manipulation, and an exercise programme in minor non-progressive disease.5
Patients with progressive neurological dysfunction or fixed deficit of short duration should be considered for surgery5 after careful assessment and in full discussion with the patients. Surgical options include decompression via posterolateral or anterolateral approach, laminectomy, foraminotomy and neurolysis, which may be combined with osteophyte excision.
The treatment of cervical vertigo is less well defined but should be multidisciplinary. It should involve the otorhinolaryngologist, orthopaedic surgeon, physiotherapist, physician, psychiatrist and neurosurgeons to prevent the chronicity of symptoms.15, 31
For non-significant cervical vertigo, the usual treatment for cervical spondylosis should be offered, as the relevance and mechanism of cervical vertigo is more of theoretical interest.4
Patients with severe cervical spondylosis, complaining of significant disabling positional vertigo, unresponsive to conservative management should be examined by transcranial doppler ultrasound with head rotations. If vertebrobasilar insufficiency is seen, it should be confirmed with further angiographic examination so as to plan suitable treatment13-17,26,30 involving the multidisciplinary team.
Conflict of interest: none declared
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