CERVICAL DISC DISEASE
Radiculopathy | Dermatomal Patterns | ACDF Indications
CLINICAL PATTERNS
Critical Must-Knows
- C5-C6 and C6-C7 are most common levels
- MRI is gold standard imaging
- Conservative treatment 90% effective
- ACDF gold standard for surgical cases
- Progressive motor weakness is urgent surgical indication
Examiner's Pearls
- "C5 = deltoid and biceps, C6 = biceps reflex, thumb
- "C7 = triceps, middle finger (most common)
- "Spurling sign confirms radicular origin
- "Red flags: myelopathy, progressive deficit
Clinical Imaging
Imaging Gallery
Critical Exam Concepts
Radiculopathy vs Myelopathy
PRIMARY distinction. Radiculopathy = Root (Pain/Weakness). Myelopathy = Cord (Balance/Dexterity/UMN signs). Missed myelopathy fails the station.
Anatomy Trap
Roots exit ABOVE the pedicle. C5/6 Disc → C6 Root. (Contrast with Lumbar where L4/5 Disc → L5 Root).
Dermatomal Patterns
Must know root levels. C5=deltoid/shoulder. C6=biceps/thumb. C7=triceps/middle finger. C8=hand intrinsics/small finger.
Myelopathy Red Flags
Urgent surgical indication. Gait disturbance, hand clumsiness, hyperreflexia, Babinski positive. Do not delay surgery.
Bakody Sign
Shoulder Abduction Relief Sign. Pain relief with arm over head = cervical radiculopathy. Key exam finding.
ACDF Rationale
Anterior approach removes disc directly, decompress neural elements, restore height. High fusion rates with cage and plate.
Conservative Trial
6-12 weeks of conservative treatment for uncomplicated radiculopathy. 90% improve without surgery.
Quick Decision Guide
| Presentation | Key Features | Management |
|---|---|---|
| Pure radiculopathy | No myelopathy, no motor deficit | Conservative 6-12 weeks |
| Radiculopathy with motor weakness | Grade 4 power or better | Conservative trial, close follow-up |
| Progressive motor deficit | Worsening weakness | Urgent surgical decompression (ACDF) |
| Myelopathy | Gait, hand function, hyperreflexia | Surgical decompression indicated |
C5-6-7-8Cervical Root Levels
Memory Hook:5-6-7-8, shoulder down to digit eight!
FAILSurgical Indications
Memory Hook:If conservative FAILS, consider surgery!
HARDSACDF Complications
Memory Hook:ACDF can be HARD on the throat and spine long-term!
Overview and Epidemiology
Natural History
Most cervical radiculopathy improves without surgery. 90% of patients improve with conservative management over 6-12 weeks. Surgery indicated for failed conservative treatment, progressive deficit, or myelopathy.
Risk Factors
- Degenerative changes (age)
- Smoking
- Heavy manual labor
- Prior disc disease
- Genetic predisposition
Pathophysiology
- Disc herniation (soft)
- Osteophyte formation (hard)
- Neuroforaminal narrowing
- Neural compression
- Inflammatory mediators
Pathophysiology and Mechanisms
Cervical Disc Structure
Nucleus pulposus: Central gelatinous material, high water content, provides cushioning.
Annulus fibrosus: Outer fibrous ring, contains nucleus, attaches to vertebrae.
Uncovertebral joints (Luschka): Posterolateral, common site of osteophyte formation.
Posterior longitudinal ligament: Thin in cervical spine, less protection against posterolateral herniation.
Disc degeneration leads to height loss, osteophyte formation, and neural compression.
Nerve Root Numbering
Cervical roots exit ABOVE their numbered vertebra (C6 root exits C5-C6). This differs from lumbar spine where roots exit BELOW (L5 root exits L5-S1).
Classification Systems
Disc Pathology Classification
| Type | Description | Treatment Implication |
|---|---|---|
| Soft disc | Acute herniation | May resorb, good surgical outcome |
| Hard disc (spondylosis) | Osteophyte, chronic | May require osteophyte removal |
| Combined | Disc plus osteophyte | Common, address both elements |
Soft disc herniations may resolve naturally; hard discs rarely do.
Clinical Assessment
History
- Pain: Neck, arm (radicular pattern)
- Sensory symptoms: Numbness, tingling
- Motor: Weakness, clumsiness
- Aggravating factors: Extension, rotation
- Red flags: Gait, bladder, bilateral symptoms
Examination
- Spurling test: Radicular reproduction
- Motor: Deltoid, biceps, triceps, grip
- Sensory: Dermatomal pattern
- Reflexes: Biceps (C5-C6), triceps (C7)
- Upper motor signs: If myelopathy
Root Level Correlations
| Root | Motor | Reflex | Sensory |
|---|---|---|---|
| C5 | Deltoid, biceps | Biceps | Lateral arm |
| C6 | Biceps, wrist extensors | Brachioradialis | Thumb, lateral forearm |
| C7 | Triceps, wrist flexors | Triceps | Middle finger |
| C8 | Finger flexors, intrinsics | None reliable | Small finger, medial forearm |
Myelopathy Warning Signs
Do not miss myelopathy: Gait disturbance, hand clumsiness (buttons), hyperreflexia, Hoffmann sign, upgoing plantars, clonus. Requires urgent referral and imaging.
Investigations
MRI - Gold Standard
Indications:
- Suspected radiculopathy or myelopathy
- Failed conservative treatment
- Progressive neurological deficit
- Preoperative planning
What to assess:
- Disc herniation level and side
- Neuroforaminal stenosis
- Cord compression and signal change
- Multi-level disease
T2 signal in cord = myelomalacia, poorer prognosis.
Management Algorithm
Conservative Management
Conservative Protocol
Activity modification. Analgesia (NSAIDs, neuropathic agents). Soft collar short-term if needed.
Physiotherapy. Postural education. Cervical exercises. Traction if helpful.
Reassess symptoms and function. If improving, continue. If not, consider intervention.
90% improve with conservative management. Patience is key.
Surgical Technique
Anterior Cervical Discectomy and Fusion
Gold standard for single or two-level disease.
Approach:
- Left-sided anterior approach (protects recurrent laryngeal nerve)
- Smith-Robinson between carotid sheath and midline
- Disc excision under microscope/loupe
Key steps:
- Complete discectomy including posterior annulus
- Decompress neuroforamen bilaterally
- Endplate preparation (preserve subchondral bone)
- Cage placement (PEEK or titanium)
- Plate fixation (optional for single level)
Fusion rate greater than 95% with modern techniques.
Recurrent Laryngeal Nerve
Left-sided approach preferred for primary ACDF because right recurrent laryngeal nerve has more variable course. Still protect esophagus and avoid excessive retraction.
Complications
| Complication | Incidence | Notes |
|---|---|---|
| Dysphagia | 5-30% early | Usually resolves, retraction-related |
| Hoarseness (RLN) | 1-5% | Usually temporary, protect nerve |
| Pseudarthrosis | 2-5% | May need revision |
| Adjacent segment disease | 2-3% per year | Long-term concern, may need extension |
| Spinal cord injury | Very rare | Devastating, meticulous technique |
Adjacent Segment Disease
ASD is long-term concern after fusion. Rate approximately 2-3% per year requiring surgery. Disc replacement may reduce but not eliminate risk.
Postoperative Care
ACDF Recovery
Monitor swallowing (dysphagia common). Watch for hematoma (airway compromise). Mobilize day 1.
Soft collar optional (surgeon preference). Avoid neck flexion or rotation. Light activity. Swallowing usually improves.
Gentle ROM exercises. Physiotherapy. Driving when comfortable and off narcotics.
Return to most activities. Fusion consolidating. X-ray to confirm fusion.
Postoperative Dysphagia
Dysphagia is common after ACDF (up to 30% early) but usually resolves. Related to esophageal retraction. Persistent dysphagia may indicate hardware prominence or esophageal injury.
Outcomes and Prognosis
Prognostic Factors
Better outcomes:
- Shorter symptom duration
- Single-level disease
- Predominant arm pain (vs neck)
- No myelopathy
Worse outcomes:
- Long-standing symptoms
- Multi-level disease
- Myelopathy with cord signal change
- Workers compensation (psychosocial)
Evidence Base and Key Studies
ACDF vs Conservative
- ACDF faster improvement than conservative
- Similar outcomes at 2 years
- Surgery indicated for failed conservative or progressive deficit
- 90% conservative success validates trial
Arthroplasty vs ACDF
- Similar clinical outcomes
- Arthroplasty preserves motion
- Trend toward lower ASD with arthroplasty
- Long-term data still accruing
Myelopathy Timing
- Earlier surgery for myelopathy = better outcomes
- Delay associated with worse recovery
- Cord signal change is poor prognostic sign
- Surgery recommended within 6 months of diagnosis
Posterior vs Anterior for Myelopathy
- Both effective for myelopathy
- Anterior for kyphotic alignment
- Posterior for multi-level (greater than 3)
- Hybrid approaches for complex cases
Smoking and Fusion
- Smoking increases pseudarthrosis significantly
- Cessation improves fusion rates
- Nicotine impairs bone healing
- Counsel cessation preoperatively
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Typical C7 Radiculopathy
"A 45-year-old office worker presents with 6 weeks of right arm pain radiating to the middle finger with some weakness in triceps. MRI shows C6-C7 right posterolateral disc herniation. How do you manage?"
Scenario 2: Cervical Myelopathy
"A 62-year-old man presents with 3 months of gait unsteadiness, difficulty with buttons, and bilateral hand numbness. Examination shows hyperreflexia, positive Hoffmann sign, and broad-based gait. MRI shows multi-level stenosis C3-7 with cord signal change at C5-6."
Scenario 3: ACDF Complication
"You performed a single-level ACDF at C5-6 yesterday. The patient calls the ward complaining of difficulty breathing and voice change. What is your management?"
MCQ Practice Points
Root Level Question
Q: Which root is affected by a C5-C6 disc herniation? A: C6 root. In the cervical spine, the root exits ABOVE the disc (C6 root exits at C5-C6).
C7 Radiculopathy Question
Q: What dermatomal pattern characterizes C7 radiculopathy? A: Middle finger sensory changes, triceps weakness, triceps reflex diminished. C7 is most common radiculopathy.
Myelopathy Question
Q: What is the most important surgical indication in cervical disc disease? A: Myelopathy. Long tract signs indicate cord compression and require urgent surgical decompression.
ACDF Approach Question
Q: Why is left-sided approach preferred for ACDF? A: Recurrent laryngeal nerve protection. Right RLN has more variable course around subclavian artery.
Conservative Duration Question
Q: How long should conservative treatment continue before considering surgery? A: 6-12 weeks for uncomplicated radiculopathy. 90% improve without surgery.
Australian Context
Australian Practice
- ACDF remains gold standard
- Disc arthroplasty available in centers
- Evidence-based conservative first approach
- Multidisciplinary spine management
- Registry development for spine surgery
Orthopaedic Relevance
- Common viva topic
- Know dermatomal patterns
- ACDF technique expected knowledge
- Distinguish radiculopathy from myelopathy
- Recognize surgical emergencies
Australian Guidelines
Conservative management first for uncomplicated radiculopathy. Spine surgery should be performed by trained specialists. Myelopathy requires timely surgical intervention.
CERVICAL DISC DISEASE
High-Yield Exam Summary
Root Levels
- •C5: Deltoid, shoulder abduction, lateral arm
- •C6: Biceps, wrist extension, thumb
- •C7: Triceps, wrist flexion, middle finger
- •C8: Intrinsics, finger flexion, small finger
Conservative Trial
- •6-12 weeks for uncomplicated
- •90% success rate
- •NSAIDs, neuropathic agents, PT
- •Red flags require urgent surgery
Surgical Indications (FAIL)
- •Failed conservative (6-12 weeks)
- •Advancing weakness (progressive)
- •Intolerable pain (refractory)
- •Long tract signs (myelopathy - urgent)
ACDF Pearls
- •Left-sided approach (protect RLN)
- •Complete discectomy and decompression
- •Cage plus or minus plate
- •Greater 95% fusion rate
Complications (HARDS)
- •Hoarseness (RLN injury)
- •Adjacent segment disease
- •Recurrent symptoms (pseudarthrosis)
- •Dysphagia (common, resolves)
- •Spinal cord injury (rare)
Myelopathy Signs
- •Gait disturbance
- •Hand clumsiness (buttons)
- •Hyperreflexia, Hoffmann, Babinski
- •Do not delay surgery