Clinical Electrodiagnostics in the Diagnosis of Radiculopathy January 2021
Jeremy Simon, MD Assistant Professor of Rehabilitation Medicine Sidney Kimmel Medical College of Thomas Jefferson University Division Chief, Department of Physical Medicine and Rehabilitation The Rothman Institute Outline
Pathophysiology Nerve conduction studies Late responses Needle Electromyography Cases Rothman Institute of Orthopaedics at Thomas Jefferson University My Clinical Criteria for Diagnosing Radiculopathy
Myotomal pain Dermatomal symptoms Physical exam findings Provocative Reflex changes/pathologic Gait/balance testing
Rothman Institute of Orthopaedics at Thomas Jefferson University What Do I Use Electrodiagnostics For?
Rule out other IN A CLEAR CUT conditions: RADICULOPATHY, I CTS DON’T BELIEVE THAT AIDP/CIDP EDX CONTRIBUTES TO Diabetic amyotrophy MANAGEMENT Peroneal Neuropathy
Rothman Institute of Orthopaedics at Thomas Jefferson University
Anatomy
Rothman Institute of Orthopaedics at Thomas Jefferson University Pathophysiology
Compressive Pathophysiology
Compressive Pathophysiology (other)
Idiopathic (autoimmune/microvascular?) Diabetic/Non‐Diabetic Lumbosacralradiculoplexopathy (Bruns‐Garland Syndrome) Neuralgic amyotrophy (Parsonage‐Turner Syndrome) Electrodiagnostics in Radiculopathies Nerve Conduction Studies
Motor NCS Latency Conduction velocity Amplitude Dysmyelination/conduction block vs axonopathy Sensory Nerve Conductions
Preganglionic sensory neurons
Anterior disc horn cell
Post‐ganglionic motor neurons L5-S1 Axial View Late Responses F‐Waves
Motor‐motor,5% CMAP Dual innervation of Roots studied? muscle Frequently normal Sensory neurons not studied Slowing may not occur in the fibers tested, F waves in compressive obscured radiculopathy (Wilbourn)?
Rothman Institute of Orthopaedics at Thomas Jefferson University H‐Reflex
Sensory‐motor Like F‐wave, abnormal if any portion is affected in the pathway Mostly performed in the S1 pathway Can use amplitude ratio and/or latency side to side (<0.4 amplitude ratio symptomatic/non‐ symptomatic) (Jankus and Robinson 1994) Acute? Chronic? Old? Needle Electromyography
Oldest/most established method of defining nerve root compromise (Johnson 1965) Assesses motor fibers only, majority of findings in axonal loss (Wilbourn 1988) Fibrillations/sharp waves in specific nerve root distribution with absence in other myotomes if axonal death is recent. Needle Electromyography
Fibrillations/sharp waves: MOST sensitive indications of recent motor axon loss Motor unit action potential abnormalities may be minimal and not detectable (Wilbourn 1988, Dumitru 2002) Sensitivity 50‐71% (AANEM practice parameters 1999) Correlation with imaging and surgical findings 65‐85% (ibid) Needle EMG (Lumbosacral)
Utility for : Peripheral limb EMG (Class II, Level B rec.) Paraspinal mapping (beyond scope, Class II Level B) H reflex for S1 (Class II and III, Level C) Low sensitivity for : F waves Cho et al Utility of edx testing in evaluating pts with ls radiculopathy: an evidence based review MuscNer 2010 Needle EMG
Fibrillations occur in proximal to distal sequence in recent axonopathy Acute lesion: can take up to 5 to 6 weeks to develop fibrillations in the distal lower extremity muscles, usually seen in 3 weeks (Lambert 1971) Needle EMG
Total myotomal involvement rare (Wilbourn 1998) Variable root innervation of muscles Root compromise often incomplete/minority of fibers affected Timing Irregular fibrillations and acuity (Wilbourn) Needle EMG
• Earliest finding can be REDUCED RECRUITMENT PATTERN • “Chronic” polyphasic –what does it imply? • Old static lesions polys only; not an indicator of an active ongoing lesion (Wilbourn 1998) NORMAL NERVE CRUSH from DISK CRUSH > AXONAL DEATH AXONAL DEATH > SCHWANN CELL PROLIFERATION CALLED BAND of BUNGNER AXONAL REGENERATION after MORE AXONAL REGENERATION 6 MONTHS. SMALLER AXON & after 1 YEAR. FURTHER SHRINKAGE INCREASED INTERNODES DISTAL ENDONEURIAL TUBE DISTAL ENDONEURIAL > FIBROTIC INTRANEURAL NEUROTMESIS: = INTRANEURAL NEUROTMESIS ONLY REINNERVATION from REMAINING INTACT AXONS CRUSH from DISK AXON DEMYELINATED > RAPID REMYELINATION and RECOVERY Needle EMG
• C5 and C6 radiculopathy – Difficult to distinguish, often grouped together – Difficult to make a distinction from upper trunk lesion – Rhomboids – C6 more common clinically (Dumitru 2002) • C7 radiculopathy – Most common cervical radiculopathy (Yoss 1957) – Easiest to localize; circumscribe lesion by normal C5/6 and C8/T1 innervatedmuscles and abnormalities in C7 distribution Needle EMG
C8/T1 radiculopathy Significant myotomal overlap C8 more common clinically (C7‐T1 disc herniation) Lower trunk lesions may mimic Paraspinals helpful Medial antebrachial cutaneous response Needle EMG
L2,3,4 radiculopathies Significant overlap Tibialis anterior Mostly proximal lower limb muscles therefore reinnervate sooner Diabetic amyotrophy? No reliable sensory NCS for evaluating L2‐4 Difficult to distinguish from plexopathy. Saphenous technically difficult Needle EMG
• L5 radiculopathy – EMG findings – Normal superficial peroneal response…except if not (Levin K 1998) – CMAPs • S1/2 radiculopathy – Often lumped together, but S2 radiculopathy clinically rare – H-reflex – CMAP amplitude – Can be bilateral (Hasegawa 1996) – Location of DRG may be vulnerable (more medial in canal) Guidelines
(NOT standards) EMG/NCS‐ What to test?
• American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) guidelines, for radiculopathy screen, a “reasonable examination consists of”: • Cervical radiculopathy – A sensory and motor NCS (low threshold for examining ulnar and median) – An F wave to exclude polyneuropathy (optional) – A needle EMG screen: 6 upper limb muscles, including the paraspinals (marginal increase in sensitivity if 7) (Lauder TD 1996, Dillingham 1999, 2001, 2002) – Contralateral 1 or more muscles if abnormalites (optional) – At least 1 muscle innervated by C5, C6, C7, C8, T1 in symptomatic limb. What to study (guidelines)?
Lumbar radiculopathy: One motor and sensory NCS F wave or H‐reflex to exclude polyneuropathy (optional) Needle EMG screen: 5 lower limb muscles including the paraspinals (adding one muscle marginally increases sensitivity). If s/p posterior lumbar surgery, can exclude paraspinals and 8 distal muscles optimal (Dillingham 2000, 2002) Pitfalls
DRG location (Levin 1998) L5 up to 40% DRG in spinal canal Abnormalities in foot muscles Dysmyelation vs predominance of axonal pathology Timing/reinervation Overlap of innervation Prior spinal surgery/paraspinals Cases
(names have been changed) 50 year old with pain radiating right posterior limb Lifting twisting injury 3 months ago pain worse w/sitting and flexion activities, can’t sit >20 mins
“Can I return to work today?” Positive SLR and slump test on right 4/5 FHL, gastroc, TFL strength on right Decreased sensation to light touch in S1 dermatome right Absent right ankle jerk Why do it? Electrodiagnostic study
Normal sensory and motor NCS Reduced right H‐reflex amplitude, normal left H‐reflex (ratio 0.2) Needle EMG: +1 fibs/sharp waves in the medial gastroc, TFL and lower lumbar paraspinals remainder normal. Clinical and Electrodiagnostic Impression
There is clinical and electrodiagnostic evidence of SUBACUTE RIGHT S1 RADICULOPATHY as demonstrated by the fibrillations in the S1 innervated muscles. ‐‐‐does the H reflex abnormality say it’s a new problem? ‐‐‐what if sural response had reduced amplitude? REASONS FOR PROGNOSIS
Seddon & Sunderland’s classification systems can be broadened to include the potential for an axonotmesis to evolve into an intraneural neurotmesis. PRE-CRUSH – 4 NORMAL INTERNODES
(NEURAPRAXIA0 • pain radiating right posterior limb for 1 month • 3 previous work comp claims for back pain over 12 years, months of PT, anti- inflammatory meds, muscle relaxers, membrane stabilizers, oxycodone • MRI disc bulges at L4-5, L5- S1 • “I can’t go back to work! They don’t follow the restrictions you gave!”
Rothman Institute of Orthopaedics at Thomas Jefferson University • Positive supine SLR right, negative slump and seated SLR • Decreased sensation to pin prick but not light touch in a non-dermatomal distribution – Why is that important? • Normal reflexes except +1 right ankle jerk • 5/5 strength left, poor effort right/give-way weakness • Why do the study? Electrodiagnostic study
Normal sensory and motor NCS Prolonged right H‐reflex, normal left H‐reflex Needle EMG: polyphasic motor units of increased duration in the medial gastroc, TFL, remainder normal PRE-CRUSH – 4 NORMAL INTERNODES Clinical and Electrodiagnostic Impression
There is electrodiagnostic evidence for an OLD (static) RIGHT S1 RADICULOPATHY. Clinically, this does not support the patient’s sensory symptoms involving the entire right lower extremity as well as the imaging findings. Bigg Hits‐ History
• Professional football safety • Head-first tackle 4 weeks ago, immediate pain in neck and right arm • 4/5 strength in right deltoid, biceps, and triceps • Altered sensation in the 1st digit of left hand, reduced bicep reflex • MRI right C5-6 HNP
Rothman Institute of Orthopaedics at Thomas Jefferson University Electrodiagnostic Study
Normal median/ulnar CMAPs Normal median, ulnar, radial and lateral antebrachial cutaneous SNAPs Needle EMG: +2 fibrillations in the right deltoid, biceps and cervical paraspinals without polyphasia, remainder of study normal Clinical and Electrodiagnostic Impression
There is clinical and electrodiagnostic evidence of a acute right C6 radiculopathy.
Uh, oh! Bad, right? Addendum…
This player had a cervical epidural steroid injection, no pain and full strength at 4 weeks, went back to play pro football! PRE-CRUSH – 4 NORMAL INTERNODES CRUSH from DISK AXON DEMYELINATED > RAPID REMYELINATION and RECOVERY Mya Sholdahurtz
• 58 year old female factory worker with h/o neck pain • September 28, 2012 awoke at 2 am with severe right shoulder pain • Went to ER, rx with pain meds, muscle relaxer and antiinflammatories • Pain subsided 3 days later, followed by inability to raise right arm • Sent to shoulder surgeon, minimal arthritic and cuff tendonosis on MRI shoulder Physical examination
2/5 right external rotator cuff, biceps strength 4/5 wrist extensor, 4+/5 right triceps Sensation normal Absent right biceps reflex Negative Hoffman’s sign Mya Sholdahurtz
MRI cervical spine large right sided C5‐6 disc/osteophyte complex, C4‐5 small foraminal disc Electrodiagnostic Study
• Normal Motor NCS Median, Ulnar, Radial • Normal Sensory NCS Median, Ulnar, Radial, Lateral and Medial Antebrachial cutaneous • EMG 3+ large irregular fibs and sharp waves, reduced recruitment in deltoid, biceps, polyphasic units • Pronator and ECRB 2+ large fibs, psw, reduced recruitment, polyphasic motor units • +1 fibs, small in cervical psp Diagnosis?
Acute right motor axonal brachial plexopathy involving the upper trunk consistent with neuralgic amyotrophy (Parsonage‐Turner Syndrome) with superimposed chronic C6 radiculopathy Iya Trojenick
71 year old female with bilateral lower limb claudication and back pain Severe L4/5 foraminal and central stenosis and grade 2 spondylolithesis,moderate L5 central stenosis, severe bilateral L5-S1 foraminal stenosis Underwent bilateral L5 TF ESI Left side ok, severe pain during and after right side procedure Right foot drop following procedure Dr. Charlatan orders MRI knee:“Baker’s cyst” Told nothing to do for it Exam: 2/5 right TFL, tib anterior, 4/5 gastroc, reduced sensation in the dorsum of right foot Trendellenberg and steppage gait EMG: right peroneal amplitude 0.5mV, left 2.5mV, +3 fib/sharp waves in TA, TFL, peroneus longus, reduced recruitment with polyphasic units of increased duration Electrodiagnostic Impression
There is clinical and electrodiagnostic evidence for a SEVERE RIGHT L5 RADICULOPATHY. GIVEN THE TIMING AND MECHANISM OF THE INJURY WITH PERSISTENT WEAKNESS AND SPONTANEOUS ACTIVITY IN BOTH THE PROXIMAL AND DISTAL MUSCULATURE THE PROGNOSIS FOR RECOVERY IS POOR. INTRANEURAL NEUROTMESIS: ONLY RINNERVATION from REMAINING INTACT AXONS
ENDONEURIAL FIBROSIS = INTRANEURAL NEUROTMESIS Fancy Mainline- Sonsadoc
90 year old female with history of mild low back pain Awoke with acute onset of bilateral lower cramping pain, lower extremity weakness and tingling Previously ambulatory without assistive device, now in wheelchair after 2 days Peasant’s Examination
Reduced sensation to light touch, pinprick, and vibration in a stocking distribution in the legs Absent patellar and quad reflexes 3/5 TA, gastroc, peroneus longus 5/5 Quad, TFL, hip abductor strength NCS findings
Peroneal distal latency 12.5ms, amplitude 0.8mV, increased duration, conduction velocity 20m/s Tibial distal latency 13ms, amplitude 1mV, increased duration, conduction velocity 21m/s Absent sural, superficial peroneal and F waves Ulnar prolonged, increased duration, reduced velocity, prolonged F waves EMG findings
Reduced recruitment with 1+fib in bilateral TA, gastroc, peroneus longus Impression
There is clinical and electrodiagnostic evidence for an ACQUIRED DIFFUSE SENSORY AND MOTOR DYSMYELINATING PERIPHERAL POLYNEUROPATHY CONSISTENT WITH GUILLAIN-BARRE SYNDROME Summary
CLINICAL SUSPICION Electrodiagnostics are a useful tool in confirming your clinical impression and ruling out other causes of patient symptoms and signs Limitations/Pitfalls Keep in mind the timing and potential for false negatives Thank you! References
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• Levin K: L5 Radiculopathy with reduced superficial peroneal responses: intraspinal and extraspinal causes. MuscNerv.1998;213-7. • Hasegawa, Toru et al: Morphometric Analysis of the Lumbosacral Nerve Roots and Dorsal Root Ganglia by Magnetic Resonance Imaging. Spine. May 1996, Volume 21(9), 1;1005-1009. • Jankus WR, Robinson LR et al: Normal limits of side- to-side H-reflex amplitude variability. Arch Phys Med Rehabil.; 1994 Jan75(1):3-7 • Cho SC, Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: an evidence based review MuscNer; 2010 42:276-82