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Cervical Myelopathy - Complete Explanation with Standard Book References

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What is Cervical Myelopathy?

• Bailey and Love's Short Practice of Surgery, 28th Ed.: "Degenerative change in the cervical spine leading to spinal cord compression is the commonest cause of cervical myelopathy in patients over 55 years."
• Campbell's Operative Orthopaedics 15th Ed. 2026: Symptoms are unique and varied - pain is poorly localized; global numbness in upper extremities and difficulty with fine motor coordination are common; gait disturbances may be the first symptom.

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I. MYOTOMES (Upper & Lower Limb)

Upper Limb Myotomes

Lower Limb Myotomes

From Campbell's Operative Orthopaedics: "The level of the lesion can be localized by evaluating multiple motor groups, multiple levels of deep tendon reflexes, and sensory abnormalities."

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II. CLINICAL SIGNS OF MYELOPATHY

A. Myelopathic Signs (Miller's Review of Orthopaedics, 9th Ed.)

1. Weakness of upper and lower limbs - corticospinal tract involvement; lower extremity weakness associated with worse prognosis
2. Myelopathic hand - global numbness + difficulty with fine motor coordination (handwriting deterioration, finger clumsiness, difficulty with pinch)
3. Loss of manual dexterity - dropping objects, inability to button shirts
4. Finger escape sign - fingers kept in extension and adduction; the little finger spontaneously abducts due to weakness of intrinsic muscles (T1 level)
5. Grip and release test (+ve) - patient fails to make a fist and release 20 times in 10 seconds (normal = 20 times)
6. Loss of proprioception - dorsal column affected → positive Romberg test

B. Upper Motor Neuron Signs (Below the Level of Compression)

Campbell's Operative Orthopaedics: "Funicular pain - central burning and stinging with or without Lhermitte sign (radiating lightning-like sensations down the back with neck flexion)"

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III. SPECIAL CLINICAL TESTS

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IV. NURICK CLASSIFICATION OF MYELOPATHY

Nurick classification is purely functional - it does not assess upper limb function, which is why the modified Japanese Orthopaedic Association (mJOA) score is now preferred in most research.

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V. NATURAL HISTORY

• Stepwise deterioration then stability - most common (65-80%)
• Slowly progressive decline over months to years - 20-25%
• Rapid decline over days to weeks - 3-5% (most serious)

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VI. RADIOLOGY - X-RAY CHANGES IN CERVICAL SPINE

How to Read a Cervical Spine X-Ray - Step by Step

1. Lateral view - most important; shows alignment, disc spaces, osteophytes
2. AP view - shows disc spaces, vertebral heights, uncovertebral joints
3. Oblique views - shows neural foramina (best for radiculopathy)
4. Flexion-extension laterals - shows instability (subluxation)
5. Open-mouth (odontoid) view - for C1-C2 pathology

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Systematic Approach to Cervical X-Ray (ABCS Method)

• Trace 4 lines on lateral view:
  1. Anterior vertebral body line (should be smooth curve)
  2. Posterior vertebral body line
  3. Spinolaminar line
  4. Spinous process tips
• Any step-off = subluxation/instability

• Check each vertebral body for height, fractures, density
• Check pedicles on AP view

• Normal cervical disc spaces are roughly equal
• Narrowing = disc degeneration

• Prevertebral soft tissue: >7mm at C2 or >22mm at C6 = abnormal (hematoma, abscess)

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X-Ray Changes in Cervical Spondylosis/Myelopathy

1. Loss of Cervical Lordosis → Straightening or Kyphosis

• Normal: Cervical spine has a gentle lordotic (concave posteriorly) curve
• Spondylosis causes muscle spasm → lordosis is lost → spine becomes straight
• Advanced cases → kyphosis (convex posteriorly = reversed curve)
• Kyphosis worsens cord compression by stretching cord over anterior structures
• How to assess: Draw a line from posterior C2 body to posterior C7 body on lateral X-ray; normal cord hangs 1-3 mm behind this line

2. Kyphosis Angle

• Measured on lateral view
• Progressive kyphosis indicates instability and is a contraindication to laminoplasty

3. Disc Space Narrowing

• Reduced height between vertebral bodies
• Most common at C5-C6 and C6-C7 (highest motion segments)
• Indicates disc degeneration; the disc loses water content (nucleus pulposus desiccation)

4. End Plate Sclerosis

• Increased density (whitening) of the superior and inferior surfaces of vertebral bodies
• Reactive bone formation from repetitive microtrauma
• Indicates chronic degenerative change

5. Osteophyte Formation

• Bony spurs projecting from vertebral body margins
• Anterior osteophytes: large and visible on lateral X-ray, usually do not cause cord compression
• Posterior osteophytes: smaller, project into spinal canal - the dangerous ones that compress cord and nerve roots
• On lateral X-ray: appear as "beaking" or "lipping" at disc-vertebral body junction

6. Facet Arthrosis

• Degenerative changes in the posterior facet joints
• Seen on oblique/lateral views as joint space narrowing, sclerosis, osteophytes
• Contributes to foraminal stenosis → radiculopathy

7. Flexion-Extension Views → Instability

• If one vertebral body slides forward on another during flexion > 3.5 mm or angulation > 11° = pathological instability
• Important before surgery planning

8. Torg Ratio (Pavlov's Ratio) = Spinal Canal Diameter / Mid-Cervical Body Diameter (Lateral X-ray)

• Normal: approximately 1.0
• Canal stenosis: ratio < 0.8
• Miller's Review of Orthopaedics 9th Ed.: "Pavlov (Torg) ratio of less than 0.80 or a sagittal diameter of less than 14 mm are considered risk factors for late neurologic involvement."
• Absolute stenosis: AP canal diameter < 10 mm (severe risk of myelopathy)
• How to measure on X-ray: AP canal diameter is the distance from posterior surface of vertebral body to spinolaminar line; mid-body diameter is the AP width of the vertebral body itself

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Summary Table: What to Look For on Cervical X-Ray

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VII. MRI FINDINGS (from textbook page)

1. Disc herniation - loss of T2 signal in nucleus (degeneration), bulge or protrusion
2. Hypertrophy and buckling of ligamentum flavum - seen posteriorly, especially during extension
3. Degree of cord compression - most important MRI assessment
4. Cord edema - T2 hyperintensity (bright signal), indicates acute/subacute compression
5. Myelomalacia - also T2 bright signal in cord; indicates chronic irreversible cord damage; poor prognostic sign for surgical recovery
6. Cervical canal and foraminal stenosis - multi-level involvement common in spondylosis
7. Syrinx formation - CSF cavity within cord from chronic compression
8. Tandem stenosis - cervical + lumbar canal stenosis together

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Compression Ratio (on Axial MRI)

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Quick Clinical Summary

Myelopathy = cord compression → UMN signs below the level + LMN signs at the level

Radiculopathy = root compression → LMN signs in dermatomal/myotomal distribution

X-ray shows the bony disease; MRI shows the cord damage - always need both.

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Cervical Spine X-Ray: How to Read It + What Changes to Look For

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STEP 1: NORMAL ANATOMY - KNOW WHAT YOU'RE LOOKING AT FIRST

What to identify on the Lateral View:

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STEP 2: SYSTEMATIC APPROACH - "ABCDS"

A - Adequacy

• Must see from skull base (occiput) to C7/T1 junction on lateral view
• If C7 not visible, request Swimmer's view
• Check: patient is straight (not rotated) on AP view

B - Bones

• Check each vertebral body height - should be roughly equal
• Look for fractures, loss of height, density changes
• Check posterior elements (spinous processes, pedicles)

C - Cartilage (Disc Spaces)

• All disc spaces should be approximately equal height
• Check each level: C2/3, C3/4, C4/5, C5/6, C6/7
• C5/6 and C6/7 most commonly affected in spondylosis

D - Disc / Degenerative changes

• Osteophytes, end plate sclerosis, facet changes

S - Soft Tissues

• Prevertebral soft tissue:
  • Above C4 = should be less than 1/3 of vertebral body width (normal = 7mm at C2)
  • Below C4 = should be less than one full vertebral body width (normal = 22mm at C6)
  • Widening = hematoma, abscess, fracture

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STEP 3: THE 4 ALIGNMENT LINES ON LATERAL VIEW

  LINE 1 (Anterior Vertebral Line)    - runs along anterior surface of all bodies
  LINE 2 (Posterior Vertebral Line)   - runs along posterior surface of all bodies
  LINE 3 (Spinolaminar Line)          - runs along anterior edge of spinous processes
  LINE 4 (Spinous Process Tips)       - connects tips of all spinous processes

• Any step-off (>3.5 mm) between adjacent vertebral bodies = subluxation
• Any angulation (>11°) between adjacent levels = instability
• The posterior vertebral line defines the anterior border of the spinal canal - this is the most important line for canal stenosis

Normal Cervical Lordosis:

• The spine should show a gentle concave-backward (lordotic) curve on lateral view
• Measured as C2-C7 Cobb angle = approximately 40° in normal adults

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STEP 4: X-RAY CHANGES IN CERVICAL SPONDYLOSIS / MYELOPATHY

Finding 1: Loss of Lordosis / Straightening

• What to look for: The 4 alignment lines lose their normal curve - they become straight or even reverse (kyphosis)
• How to measure: Draw a line along inferior endplate of C2 and another along inferior endplate of C7; measure the Cobb angle between perpendiculars to these lines
• Normal = ~40°; Straightening = <20°; Kyphosis = negative angle
• Clinical significance: Loss of lordosis indicates muscle spasm (early sign) or fixed degenerative deformity. Kyphosis worsens cord compression by stretching the cord over anterior osteophytes

Finding 2: Disc Space Narrowing

• What to look for: Reduced height of the dark gap between vertebral bodies compared to normal levels
• Most common at: C5/6 and C6/7 (highest motion segments)
• Clinical significance: Disc degeneration - loss of nucleus pulposus water content and proteoglycans
• Tip: Compare with the disc space above and below; significant narrowing = at least 50% reduction

Finding 3: End Plate Sclerosis

• What to look for: Increased whiteness (density) of the top and bottom surfaces of vertebral bodies adjacent to the diseased disc
• Clinical significance: Reactive bone formation (eburnation) from chronic mechanical stress

Finding 4: Osteophyte Formation (Spur)

• What to look for: Bony projections ("beaking" or "lipping") from the corners of vertebral bodies
• Anterior osteophytes: Large, visible on lateral X-ray projecting forward - usually not clinically significant for cord
• Posterior osteophytes: Smaller, project backward into the canal - these are the dangerous ones causing cord compression (called "hard disc")
• Uncovertebral osteophytes: Seen on AP view at the lateral margins of vertebral bodies (Luschka joints/uncinate processes), causing foraminal stenosis and radiculopathy
• On the AP view image above, note the uncinate processes - degenerative spurring here narrows the foramen

Finding 5: Facet Joint Arthrosis

• What to look for: On lateral view, the posterior facet joints show loss of joint space, sclerosis (whitening), osteophyte formation
• On the AP view, the facet joints appear as overlapping butterfly-like structures posteriorly

Finding 6: Torg (Pavlov) Ratio < 0.8

• What to look for: On the lateral X-ray, measure the AP diameter of the spinal canal and divide by the AP diameter of the vertebral body at the same level
• How to measure:
  • Canal diameter = distance from posterior vertebral body surface → spinolaminar line
  • Body diameter = AP width of the vertebral body
• Normal = approximately 1.0
• Canal stenosis = ratio < 0.8
• Absolute stenosis = canal diameter < 10 mm (from Miller's Review of Orthopaedics 9th Ed.)

Finding 7: Instability (Flexion-Extension Views)

• What to look for: Compare lateral X-ray in full flexion vs full extension
• Pathological instability = >3.5 mm translation or >11° angulation at any level
• Clinical significance: Requires surgical stabilization; dynamic compression of cord during motion

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STEP 5: SUMMARY CHECKLIST - WHAT TO SAY WHEN REPORTING

"This is a [lateral/AP] view of the cervical spine of a [male/female] patient. The view is [adequate/inadequate]..."

Alignment: "There is [normal lordosis / loss of lordosis / straightening / kyphosis] of the cervical spine."

Bones: "Vertebral body heights are [maintained / reduced at C_]. No obvious fracture is seen."

Disc spaces: "There is disc space narrowing at [C5/6, C6/7]."

Degenerative changes: "Anterior and posterior osteophyte formation is seen at [levels]. End plate sclerosis is present. Facet joint degeneration is seen posteriorly."

Soft tissue: "Prevertebral soft tissue is [normal / widened]."

Impression: "These findings are consistent with cervical spondylosis at [levels], with evidence of [canal stenosis / foraminal stenosis / instability]."

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Quick Reference: X-Ray Findings vs What They Mean

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Cervical Spine X-Ray - How to Read & Identify Changes

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IMAGE 1: Normal Lateral X-Ray Anatomy

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IMAGE 2: AP (Front) View Anatomy

• C6 vertebral body (green) - note the rectangular shape
• Uncinate processes (pink) - small upward projections at lateral edges of vertebral bodies - when these form osteophytes, they narrow the neural foramen and cause radiculopathy
• C5 lamina (yellow) - the posterior arch
• C4/5 facet joint (cyan lines) - when degenerate, shows as sclerosis/narrowing here
• Transverse processes (pink line at edge) - lateral projections
• C2 dens (red outline at top) - check alignment with lateral masses of C1

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IMAGE 3: Lordosis Measurement + Osteophyte (Spondylosis X-Ray)

How to Measure Lordosis (Cobb angle method):

1. Draw a line along the inferior end plate of C2
2. Draw a line along the inferior end plate of C7
3. Draw perpendiculars to each line
4. Measure the angle where the perpendiculars intersect

• Normal: ~40°
• Straightening: < 20°
• Kyphosis: negative angle (spine bows forward)

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STEP-BY-STEP READING SYSTEM: "ABCDS"

A - Adequacy

• Must see skull base to C7/T1 junction on lateral
• If C7 not visible = request Swimmer's view (arm raised)
• Patient should not be rotated on AP view

B - Bones

• Check every vertebral body height - should be roughly equal
• Look for fracture lines, loss of height, areas of increased whiteness (sclerosis)
• Count vertebrae: C1 (atlas, ring-shaped, no body), C2 (axis, has dens), C3-C7 (typical)

C - Cartilage / Disc Spaces

• Each disc space should be roughly equal height on lateral view
• Most commonly narrowed in spondylosis: C5/6 and C6/7
• Compare each level with the one above and below it

D - Degenerative Changes

S - Soft Tissue

Widening = hematoma from fracture, abscess, tumor

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THE 4 ALIGNMENT LINES (Lateral View)

ANTERIOR  → Line 1: Along FRONT surface of all vertebral bodies
           Line 2: Along BACK surface of all vertebral bodies  ← most important for canal
           Line 3: Along SPINOLAMINAR junction (front edge of spinous processes)
POSTERIOR → Line 4: Tips of all spinous processes

• A step-off > 3.5 mm between adjacent bodies = subluxation (instability)
• Angulation > 11° between adjacent levels = pathological instability
• The space between Line 2 and Line 3 = the spinal canal - measure this for Torg ratio

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Summary: X-Ray Findings in Cervical Spondylosis