Differentiating Cervical Radiculopathy and Peripheral Neuropathy Adam P. Smith, MD

Differentiating
Cervical Radiculopathy and
Peripheral Neuropathy
Adam P. Smith, MD
I have no financial, personal, or professional
conflicts of interest to report
Radiculopathy versus Neuropathy
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Radiculopathy
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Neuropathy
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Usually involves one spinal nerve root distribution following “myotomal” and “dermatomal”
patterns
Pathology often proximal (disc or osteophyte)
Usually involves one peripheral nerve branch
Pathology often entrapment distally
“Double Crush” phenomenon
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–
Rare
Both radiculopathy and neuropathy present
Key Features of Differentiation
• Neurologic examination
• Neurologic examination
• Neurologic examination
Willie Sutton
• Supplement exam with tests
Roots versus Branches
• Roots
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C5
C6
C7
C8
T1
• Branches
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–
–
–
–
Musculocutaneous (C5,6,7)
Axillary (C5,6)
Radial (C5,6,7,8, T1)
Median (C5,6,7,8)
Ulnar (C8, T1)
Abundant overlap between
motor and sensory
distributions
C8 versus Ulnar nerve- Motor
• C8 spinal nerve root
– Present in ulnar, median, and radial peripheral nerve branches
– Myotome based
• Weakness in muscles of one spinal root but multiple peripheral nerve
branches, so usually partial or incomplete
– Atrophy rare (unless long-standing)
– Fasciculations rare (visible “motion” of muscle)
– C8 palsy will cause some weakness in nearly all intrinsic hand
muscles, including those innervated by median nerve
C8 versus Ulnar nerve- Motor
• Ulnar nerve (C8 and T1)
– Muscle based
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•
Weakness usually complete
Worse with use and better with rest
– Atrophy “early”
– Fasciculations common
– Innervates:
• 1 ½ muscles in forearm (flexor carpis ulnaris and flexor digitorum profundus 3 & 4)
• Majority of hand intrinsic muscles, except LOAF (median)
Sensory Exam
Branches
Roots
• Sensory distribution of spinal nerve roots overlap
• Sensory distribution of peripheral nerve branches are very discrete
C8 versus Ulnar nerve- Sensory
• C8
– Dermatome based
• Sensation to entire ring finger affected (and pinky finger)
– Total sensory loss virtually never occurs
C8 versus Ulnar nerve- Sensory
• Ulnar nerve (C8 and T1)
– Sensation to only ulnar half of ring finger affected (and pinky
finger)
Reflexes
• Radiculopathy
– Appropriate DTRs depressed or absent early
• Neuropathy
– Rare reflex changes
– Depends on location of entrapment
Pain
• Radiculopathy
– Common history of neck pain (abrupt-disc, slow-osteophyte)
– Occasional radiation into suboccipital area and interscapular area
– Pain down arm in spinal nerve root distribution
– Leaning head away from affected side and neck traction may
improve pain
– May worsen with valsalva
• Neuropathy
– Rarely neck or radicular pain
– Pain may be distal near joint (entrapment often proximal to joint)
– Depends on entrapment
• Carpal tunnel- Pain predominant symptom early in course
• Cubital tunnel- Pain may or may not be present
Maneuvers/ Signs
• Spurling’s test
Radiculopathy
• Tinel’s test
• Phalen’s test
Neuropathy
• Clawing
• Froment’s
• Wartenberg’s
Neuropathy
Electrodiagnostic Studies
• Radiculopathy
– NCS usually normal
• Usually sensory normal
• Motor may be abnormal
– EMG quite sensitive
• Single motor axon can innervate many muscle fibers, the loss
of only a few axons can produce detectable EMG changes
• “Fibrillations” of muscles at rest supplied by spinal nerve root
– Not seen until >3-4 weeks after compression
• “Denervation” ipsi paraspinal muscles
– Posterior rami (“sensory”) innervates paraspinal muscles
» Can only be compressed in foramen
Electrodiagnostic Studies
• Neuropathy
– Conduction delay often at site of compression
– Absence of denervation in posterior myotomes
(paraspinal muscles)
• EMG usually normal
Imaging
• Radiculopathy
– MRI or CT myelogram
– Require clinical and electrodiagnostic
correlation
• Nearly 28% of asymptomatic adults >40yo have
“abnormal” imaging
• Neuropathy
– Rarely useful
Most Crucial Differentiations
• Difference in distribution of motor and sensory deficits
– Neuropathy has weakened muscles and disturbed sensation
solely within distribution of one peripheral nerve branch
• Discrete
• Lack of neck and radicular pain in neuropathy
• Neuropathy has absence of denervation in posterior
myotomes
• Frequent presence of Tinel’s sign at point of entrapment
or compression
Case Examples
Case Example
• 45yo male with neck pain radiating into
right arm, right deltoid/bicep weakness,
and numbness in right thumb and index
finger
• No reflex abnormality
• + Spurling’s test to the right
Spurling’s Test
C5
C6
Right
Left
C5-6
Key Factors
• Neck pain and radiculopathy
• Weakness in muscles supplied by same spinal nerve root (C6), but
different peripheral nerve branches (deltoid- axillary n., bicepmusculocutaneous n.)
• Sensory disturbance concordant with C6
• Reflexes normal
• Positive Spurling’s test
• Concordant MRI
1.5cm
C5
C6
C6
C6
C5
C5
Case Example
• 64 yo female with diffuse neck pain
– Radiates bilateral arms
• No weakness or numbness
• Slightly hyperactive reflexes
• Negative Spurling’s
C5-6
C5
C6
C7
C6-7
Discography
Discography
Discography
Key Factors
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Neck pain and “radiculopathy” into arms
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Interscapular pain
– Cloward 1959- Disc herniations of lower cervical levels induced spasms of para-scapular
muscles
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Motor/sensory exam not localizing
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Myelopathic with hyperactive reflexes
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Negative Spurling’s
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Positive discogram
– Reproduced pain at levels and no pain at adjacent levels
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Concordant MRI
Anterior Cervical Discectomy
and Fusion
C5
C6
Case Example
• 58yo female with right lateral hand
numbness, and weakness
– Pain thenar eminence, no neck/arm pain
– Weakness in opponens pollicis
– Numb in first 3 ½ digits
– No reflex abnormalities
– Negative Spurling’s sign, +Phalen’s/Tinel’s
Tinel’s Test
Phalen’s Test
NCS
Normal
•
Latency < 2.3 ms or
difference <0.3ms
• demyelination
•
Amplitude >15μV
(ulnar) or >50μV
(median)
• axonal
Abnormal
Courtesy of Simon Oh, MD
Colorado Neurology Specialists
Key Factors
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No neck pain or radiculopathy
– Pain present in hand
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Weakness in muscles supplied by one peripheral nerve branch
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Sensory deficit in one peripheral nerve
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More than 1 spinal root involved (C6 and C7)
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Reflexes normal
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Positive Tinel’s and Phalen’s
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Concordant NCS
Case Example
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•
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60yo female with left hand numbness and weakness
– Weakness hand intrinsics
• “Clawing” present
• Left pinky weak adduction
– Numbness 4th and medial 5th digits
4 Issues
– Reflexes normal
• Neck pain
Mild neck pain without radiculopathy
• No radiculopathy, but DM
• Prior dx carpal tunnel
No hand pain
• Motor/sensory findings
ulnar problem
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Negative Spurling’s
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PMHx- Long standing poorly controlled diabetes
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History of left hand carpal tunnel release
– No symptom improvement
Wartenberg’s Sign
• Ask patient to adduct fingers
• “Pinky” finger of affected
hand cannot adduct
• Patient may notice “pinky”
caught on pant pocket
• Ulnar innervated palmar
interossei weak
Ulnar Clawing
• Ask patient to leave fingers “at rest”
• 4th and 5th metacarpal-phalangeal joints
extend while interphalangeal joints
slightly flex but are somewhat paralyzed
• Weak medial lumbricales and 3rd/4th
flexor digitorum profundus (both ulnar
innervated)
Froment’s Sign
•
Ask patient to adduct the thumb and
index finger so the finger pads touch
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Patient flexes interphalangeal joint
and finger tips touch
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Ulnar innervated adductor pollicis
weak so ulnar/median innervated
flexor pollicis brevis compensates
Testing flexor digitorum
profundus 3 and 4
Tinel’s Test
C4-5
C5-6
C4
C6-7
C5
C6
C7-T1
C7
T1
Stimulate ulnar nerve
transcutaneously and
record EMG/NCS of
abductor digiti minimi
Across elbow
Across wrist
NCS
Decreased amplitude (>6mV)
Conduction velocity delayed (>51m/sec)
Courtesy of Simon Oh, MD
Colorado Neurology Specialists
Key Factors
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Minimal neck pain, but no radiculopathy into arms
– 60 yo so very common symptom
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Weakness of hand intrinsics supplied by ulnar nerve only
– Maintained median nerve function
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Sensory loss in ulnar nerve distribution
– Radial half of ring finger spared- not C8 palsy
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No reflex abnormalities
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No pain or numbness in median nerve distribution to suggest carpal tunnel syndrome
– Failed prior carpal tunnel release
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Negative Spurling, but +Tinel’s test at elbow
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NCS concordant with ulnar neuropathy at elbow
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Non-concordant MRI with spinal root palsy
Biceps m.
Tricepts m.
Medial
epicondyle
Olecrenon
Biceps m.
Proximal
Distal
Tricepts m.
Ulnar nerve
Medial epicondyle
Two heads of flexor carpis ulnaris m.
Olecrenon
NCS
Preoperative
Postoperative
Courtesy of Simon Oh, MD
Colorado Neurology Specialists
Preoperative
Postoperative
Thank You