Clinical Electrodiagnostics in the Diagnosis of Radiculopathy January 2021

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
   Slowing may not occur                  studied
    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 (

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

•   Johnson EW, Melvin J: Value of electromyography in lumbar
    radiculopathy. Arch Phys Med Rehabil 1971;52:239-243.
•   MacIntosh JE, Valencia F, Bogduk N, Munro RR: The morphology
    of the human lumbar multifidus. Clin Biomech 1986;1:196-204.
•   Nicotra A, Khalil NM, O'neill K.Br J: Cervical radiculopathy:
    discrepancy or concordance between electromyography and
    magnetic resonance imaging? Neurosurg. 2011 Sep 7
•   Tong HC.Am J: Specificity of needle electromyography for
    lumbar radiculopathy in 55- to 79-yr-old subjects with low back pain
    and sciatica without stenosis Phys Med Rehabil. 2011
    Mar;90(3):233-8
•   Plastaras CT, Joshi AB The electrodiagnostic evaluation
    of radiculopathy. Phys Med Rehabil Clin N Am. 2011 Feb;22(1):59-
    74. Epub 2010 Dec 3.
•   Cauda equina anatomy II: extrathecal nerve roots and dorsal root
    ganglion. Spine 1990; 15:1248-51.

References

•   Lambert E: Electromyography, in Youmans J (Ed): Neurological Surgery, Vol 1. Philadelphia, W.B.
    Saunders, 1973, pp 358-367
•   Wilbourn AJ: The value and limitations of electromyography in the diagnosis of lumbosacral
    radiculopathy. In Hardy (Ed): Lumbar disc disease. New York, Raven, 1982 pp 65-109.
•   Yoss RE et al: Significance of asigns and symptoms in localization of involved roots in cervical disc
    protrusion. Neurology 7:673-683, 1957.
•   Dillingham TR: Electrodiagnosis of radiculopathies: How many and which muscles to study. AANEM
    course 2000 pp23-35.
•   Lauder TD, Dillingham TR. The cervical radiculopathy screen: optimizing the number of muscles
    studied. Muscle Nerve 1996;19:662-665.
•   Haig AJ, Talley C et al: Paraspinal Mapping: Quantified needle electromyography in lumbar
    radiculopathy. Muscle Nerve 1993;16:477-484.
•   Haig AJ, Lebreck DB et al: Paraspinal Mapping: Quantified needle electromyography of the paraspinal
    muscles in persons without low back pain. Spine 1995;20:715-721.
•   Dillingham TR, Lauder TD, Andary M, Kumar S, Pezzin LE, Stephens RT, et al.Identifying lumbosacral
    radiculopathies: an optimal electromyographic screen. Am J PhysMed Rehabil 2000;79:496–503.
•   Dillingham TR, Lauder TD, Andary M, Kumar S, Pezzin LE, Stephens RT, et al.
    Identificationofcervicalradiculopathies:optimizingtheelectromyographicscreen.AmJPhys Med Rehabil
    2001;80:84–91.
•   T.R. Dillingham, Electrodiagnostic approachto patients with suspected radiculopath. Phys Med Rehabil
    Clin N Am 13 (2002) 567–588

References

•   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