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 • Radiculopathy – – • Neuropathy – – • 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 – – 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 – – – – – C5 C6 C7 C8 T1 • Branches – – – – – 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 • • 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 • Neck pain and “radiculopathy” into arms • Interscapular pain – Cloward 1959- Disc herniations of lower cervical levels induced spasms of para-scapular muscles • Motor/sensory exam not localizing • Myelopathic with hyperactive reflexes • Negative Spurling’s • Positive discogram – Reproduced pain at levels and no pain at adjacent levels • 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 • No neck pain or radiculopathy – Pain present in hand • Weakness in muscles supplied by one peripheral nerve branch • Sensory deficit in one peripheral nerve – More than 1 spinal root involved (C6 and C7) • Reflexes normal • Positive Tinel’s and Phalen’s • Concordant NCS Case Example • • • 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 • Negative Spurling’s • PMHx- Long standing poorly controlled diabetes • 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 • Patient flexes interphalangeal joint and finger tips touch • 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 • Minimal neck pain, but no radiculopathy into arms – 60 yo so very common symptom • Weakness of hand intrinsics supplied by ulnar nerve only – Maintained median nerve function • Sensory loss in ulnar nerve distribution – Radial half of ring finger spared- not C8 palsy • No reflex abnormalities • No pain or numbness in median nerve distribution to suggest carpal tunnel syndrome – Failed prior carpal tunnel release • Negative Spurling, but +Tinel’s test at elbow • NCS concordant with ulnar neuropathy at elbow • 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