Cervical Spondylosis

Imaging Gallery

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Definition

Cervical spondylosis describes the age-related degenerative cascade affecting the cervical spine, involving intervertebral discs, vertebral bodies (osteophytes), facet joints, and ligaments. It represents a spectrum from asymptomatic radiographic findings to debilitating myelopathy.

Epidemiology

• Prevalence: Increases linearly with age. 25% at age 40, over 85% at age 60.
• Risk Factors:
  • Non-Modifiable: Age (primary), Genetics (family history of early degeneration).
  • Modifiable: Smoking (accelerates disc desiccation), Heavy labor (axial loading), Vibration exposure (jackhammering), Contact sports.
  • Trauma History: Previous whiplash or cervical injury often initiates the cascade early.
• Natural History: Generally benign. Most symptomatic cases resolve or stabilize. Myelopathy is the exception (stepwise deterioration).

Pathophysiology

The process begins with disc desiccation (loss of water content). This leads to:

1. Loss of disc height: Which reduces the tension on the annular fibers and ligaments.
2. Segmental Instability: The vertebral bodies move more than normal ("wobble").
3. Osteophyte Formation: The body responds to this instability by forming bony spurs (osteophytes) to increase surface area and restabilize the joint.
4. Uncinate Hypertrophy: The Uncovertebral joints carry more load as the disc collapses, leading to osteophytes that project into the foramen (Radiculopathy).
5. Facet Hypertrophy: Posterior joints degenerate, causing pain and encroaching on the canal.
6. Ligamentum Flavum Buckling: With loss of height, the ligamentum flavum becomes redundant and buckles inward, compressing the cord from behind (Myelopathy).

OPLL (Ossification of Posterior Longitudinal Ligament):

• A distinct but related pathology often co-existing, particularly in Asian populations (Japanese/Korean).
• Causes severe, hard compression of the anterior cord.
• Risk: Hard to remove anteriorly (dural tear risk is high as ossification can merge with dura).
• Presence of OPLL often dictates a posterior approach (Laminoplasty) or corpectomy to avoid dural tear.

The Degenerative Cascade (Kirkaldy-Willis)

Key Anatomy

Ligamentous Structures:

• Anterior Longitudinal Ligament (ALL): Strong broad band. Prevents hyperextension. Often site of large anterior osteophytes (DISH).
• Posterior Longitudinal Ligament (PLL): Narrower band behind bodies. Prevents hyperflexion. Can ossify (OPLL) causing stenosis.
• Ligamentum Flavum: Connects laminae. Elastic (yellow). Hypertrophy or buckling in extension causes posterior cord compression.

Neural Foramen Boundaries:

• Anterior: Uncovertebral joint, disc, vertebral body (posterior aspect).
• Posterior: Facet joint (Superior articular process of lower vertebra), ligamentum flavum.
• Superior/Inferior: Pedicles of the levels above and below.
• Contents: Exiting nerve root (Dorsal Root Ganglion is usually in the foramen), radicular artery, venous plexus.
• Pathology: Osteophytes from the uncinate process compress the nerve root from the Anterior direction. Facet hypertrophy compresses from Posterior.

Spinal Canal Dimensions:

• Normal: 17-18mm
• Relative Stenosis: less than 13mm (watch for symptoms)
• Absolute Stenosis: less than 10mm (high risk of cord injury)
• Cord Compression: less than 8mm effective diameter. The ratio of canal diameter to vertebral body diameter (Torg Ratio) less than 0.8 suggests stenosis, but has high false positive rate; absolute measurement on MRI is preferred.

Blood Supply of the Cord:

• Anterior Spinal Artery: Supplies anterior 2/3 of cord (motor tracks, spinothalamic). Prone to compression from anterior osteophytes or disc herniations.
• Posterior Spinal Arteries: Supply posterior columns (proprioception). Paired vessels.
• Watershed: The gray matter is highly vascular, but the watershed zone makes the anterior cord susceptible to ischemia from compression (osteophytes). This contributes to the pathophysiology of CSM (Cervical Spondylotic Myelopathy).
• Radicular Arteries: Enter via the foramen. The largest is the Artery of Adamkiewicz (usually T9-L1, but can be higher).

Vertebral Artery:

• Ascends in the transverse foramen from C6 to C1.
• Note: It usually skips C7 transverse foramen (enters at C6).
• Segments: V1 (Pre-foraminal), V2 (Foraminal C6-C2), V3 (Extradural/Atlas loop), V4 (Intradural).
• Vulnerable to injury during lateral dissection or screw insertion (lateral mass/pedicle).
• Dominance: Left is often larger than Right. Occlusion of a dominant artery can be fatal (Wallenberg syndrome/Stroke).

History

Differentiate the three main syndromes:

Differential Diagnosis

Must exclude mimics:

1. Peripheral Entrapment: Carpal Tunnel (CTS), Cubital Tunnel. (Double Crush phenomenon: CTS + Cervical Radiculopathy).
2. Shoulder Pathology: Rotator cuff tear, arthritis. Differentiate with shoulder exam (pain with active ROM, vs neck pain with passive ROM).
3. MS / AS: Multiple Sclerosis (younger, vision issues), Ankylosing Spondylitis (stiffness).
4. ALS (Motor Neurone Disease): Progressive weakness, fasciculations, without sensory loss. Painless.
5. Tumor/Infection: Red flags (Night pain, fever, weight loss).
6. Parsonage-Turner Syndrome: Acute brachial neuritis. Viral prodrome, severe pain followed by weakness.

Physical Examination

Provocative Tests:

• Spurling Test: Extension + Lateral Rotation + Axial Load. Positive = Radicular pain. High specificity (93%).
• Shoulder Abduction Test (Bakody): Relief of arm pain with hand on head = C5/C6 radiculopathy (relieves tension).
• Lhermitte's Sign: Shock sensation down spine on flexion = Myelopathy/Cord compression.
• Finger Escape Sign: Unable to hold fingers extended and adducted (Myelopathy, C8/T1 weakness).
• Grip and Release Test: Normal is 20 times in 10 seconds. Slower in myelopathy.
• Inverted Radial Reflex: Tapping supinator causes finger flexion instead of wrist/supinator reflex. Indicates C5/6 cord compression.
• Valsalva Maneuver: Increases intrathecal pressure, aggravating radiculopathy.

Neurological Assessment:

• C5: Deltoid (Motor), Lateral Arm (Sensory), Biceps (Reflex).
• C6: Wrist Ext (Motor), Thumb index (Sensory), Brachioradialis (Reflex).
• C7: Triceps (Motor), Middle finger (Sensory), Triceps (Reflex).
• C8: Finger Flex (Motor), Little finger (Sensory).
• T1: Interossei (Motor), Medial forearm (Sensory).

Imaging Algorithm

Multimodal Imaging Examples

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Dysphagia:

• Most common complaint (up to 70% transient).
• Prevention: Minimize retractor pressure, intermittent relaxation of retractors, use endotracheal tube cuff deflation during retraction.
• Management: Reassurance (most resolve), Speech pathology review, Nasogastric tube if severe aspiration risk, Steroids (dexamethasone) intra-op may help edema. chronic dysphagia is rare.

Adjacent Segment Disease (ASD):

• Rate: ~2.9% per year (clinical), up to 92% radiographic at long term.
• Cause: Increased existing stress at levels above/below fusion.
• Management: Conservative initially, extension of fusion if symptomatic.

C5 Palsy:

• Incidence: 5% in posterior decompression (Laminoplasty/Laminectomy), less common in ACDF.
• Pathophysiology: Posterior drift of the cord tethers the C5 root (which has a shorter, more direct course) causing traction injury. Also reperfusion injury.
• Prognosis: Good. Most resolve spontaneously over 6-12 months.

Other Major Risks:

• Recurrent Laryngeal Nerve (RLN) Palsy: Hoarseness. 1-2%. More common on Right side (nerve is variable). ENT scope if persistent.
• Esophageal Injury: Rare but catastrophic. Can lead to mediastinitis. Immediate repair vs flap. Early recognition is key.
• Vertebral Artery Injury: Rare. Can occur during drilling or screw insertion. Tamponade vs sacrifice (if contralateral patent).
• Horner's Syndrome: Sympathetic chain injury (ptosis, miosis, anhidrosis).
• Dural Tear: Risk of CSF leak. Repair primarily or use patch/sealant. Bed rest/Drain.

Medicare and Public System Public hospital waiting lists for elective spine surgery can be lengthy, often prioritizing progressive myelopathy over simple radiculopathy or axial pain. Specialists can access MRI rebates for specific indications such as radiculopathy or trauma.

Medication Regulations Access to certain neuropathic pain medications like Pregabalin and Gabapentin is restricted under the PBS Scheme, often requiring Authority approval for subsidized prescription in non-palliative settings. Opioids are tightly regulated for chronic non-cancer pain, emphasizing multidisciplinary management.

Driving Guidelines (Austroads) Patients must not drive in a rigid cervical collar. Return to driving is permitted when the patient can comfortably rotate the head to check blind spots and perform an emergency stop, usually 2-6 weeks post-operatively depending on surgery type.

WorkCover and Compensation Cervical spondylosis is a common source of workers' compensation claims. Establishing causation (acute injury aggravating pre-existing degeneration vs natural history) is often complex. The AMA Guides (GEPI) are used for impairment assessment in many jurisdictions.