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Slide 1
Shawn Jorgensen, MD Jeff Strakowski, MD Jeff Strommen, MD
Slide 2
Introduction Discuss role of US vs EMG in focal peripheral
neuropathies (FPN) Discuss role of US vs EMG in focal peripheral
neuropathies (FPN) Examine literature to determine roles in
specific FPN Examine literature to determine roles in specific FPN
CTS CTS Ulnar neuropathy at the elbow Ulnar neuropathy at the elbow
Fibular neuropathies Fibular neuropathies Less common Less
common
Slide 3
GoalsGoals Attendees should, after this course: Attendees
should, after this course: Have an evidence-based approach to
ordering EDX, US, or both in specific FPN Have an evidence-based
approach to ordering EDX, US, or both in specific FPN
Slide 4
GoalsGoals Attendees should, after this course: Attendees
should, after this course: Have an evidence-based approach to
ordering EDX, US, or both in specific FPN Have an evidence-based
approach to ordering EDX, US, or both in specific FPN Ideally, be
able to answer these three questions for any FPN Ideally, be able
to answer these three questions for any FPN 1. Which test should be
the primary test 1. Which test should be the primary test 2. Under
what circumstances the primary test would change 2. Under what
circumstances the primary test would change 3. Under what
circumstances the secondary test should be added 3. Under what
circumstances the secondary test should be added
Slide 5
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
is clearly superior to MRI and satisfactory for all FPN EDX is
clearly superior to MRI and satisfactory for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? MRI only when EDX
impossible MRI only when EDX impossible 3. Under what circumstances
should the secondary test be added? 3. Under what circumstances
should the secondary test be added? Very few MRI when EDX
non-diagnostic Very few MRI when EDX non-diagnostic US experimental
US experimental
Slide 6
Why discuss US? US is valid and reliable (Cartwright 2013) US
is valid and reliable (Cartwright 2013)
Slide 7
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
is clearly superior to MRI and satisfactory for all FPN EDX is
clearly superior to MRI and satisfactory for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? MRI only when EDX
impossible MRI only when EDX impossible 3. Under what circumstances
should the secondary test be added? 3. Under what circumstances
should the secondary test be added? Very few Very few MRI when EDX
non-diagnostic MRI when EDX non-diagnostic US experimental US
experimental US valid and reliable
Slide 8
Why discuss US? MRI is in the past MRI is in the past US is
superior to MRI and is changing the role of imaging in FPN US is
superior to MRI and is changing the role of imaging in FPN Greater
sensitivity (93% vs. 67%), equal specificity, better at multifocal
lesions than MRI (Zaidman 2013) Greater sensitivity (93% vs. 67%),
equal specificity, better at multifocal lesions than MRI (Zaidman
2013)
Slide 9
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
is clearly superior to MRI and satisfactory for all FPN EDX is
clearly superior to MRI and satisfactory for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? MRI only when EDX
impossible MRI only when EDX impossible 3. Under what circumstances
should the secondary test be added? 3. Under what circumstances
should the secondary test be added? Very few Very few MRI when EDX
non-diagnostic MRI when EDX non-diagnostic US valid and reliable US
valid and reliable ??? - US when EDX non-diagnostic US only when
EDX impossible EDX is clearly superior to US and satisfactory for
all FPN
Slide 10
Slide 11
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
is clearly superior to US and satisfactory for all FPN EDX is
clearly superior to US and satisfactory for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? US only when EDX
impossible US only when EDX impossible 3. Under what circumstances
should the secondary test be added? 3. Under what circumstances
should the secondary test be added? Very few Very few ??? - US when
EDX non-diagnostic ??? - US when EDX non-diagnostic US valid and
reliable US valid and reliable EDX is clearly superior to US but
not perfect for all FPN
Slide 12
Why discuss US? US may be offered for diagnosis of CTS
(Cartwright 2012 AANEM position statement) US may be offered for
diagnosis of CTS (Cartwright 2012 AANEM position statement)
Slide 13
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
is clearly superior to US but not perfect for all FPN EDX is
clearly superior to US but not perfect for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? US only when EDX
impossible US only when EDX impossible 3. Under what circumstances
should the secondary test be added? 3. Under what circumstances
should the secondary test be added? Very few Very few ??? - US when
EDX non-diagnostic ??? - US when EDX non-diagnostic US valid and
reliable US valid and reliable EDX may be superior to US but not
perfect for all FPN ??? ??? - US possibly in all patients? ??? -
Many or all
Slide 14
Why discuss US? US adds value to the diagnosis of CTS
(Cartwright 2013 AANEM position statement) US adds value to the
diagnosis of CTS (Cartwright 2013 AANEM position statement)
Slide 15
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
may be superior to US but not perfect for all FPN EDX may be
superior to US but not perfect for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? ??? ??? 3. Under what
circumstances should the secondary test be added? 3. Under what
circumstances should the secondary test be added? ??? - Many or all
??? - Many or all ??? - US possibly in all patients ??? - US
possibly in all patients Specific indications Specific indications
??? - US when EDX is non-diagnostic ??? - US when EDX is
non-diagnostic ??? - Failed intervention ??? - Failed intervention
??? - Unilateral CTS ??? - Unilateral CTS ??? - In the setting of
trauma ??? - In the setting of trauma ??? US possibly in all
patients bifid MN / PMA can alter tx
Slide 16
Slide 17
Why discuss US? 1. Which test should be the primary test for
all FPN? 1. Which test should be the primary test for all FPN? EDX
may be superior to US but not perfect for all FPN EDX may be
superior to US but not perfect for all FPN 2. Under what
circumstances would the primary test change? 2. Under what
circumstances would the primary test change? ??? ??? 3. Under what
circumstances should the secondary test be added? 3. Under what
circumstances should the secondary test be added? ??? - Many or all
??? - Many or all ??? - US possibly in all patients bifid MN / PMA
can alter tx ??? - US possibly in all patients bifid MN / PMA can
alter tx Specific indications Specific indications ??? - US when
EDX is non-diagnostic ??? - US when EDX is non-diagnostic ??? -
Failed intervention ??? - Failed intervention ??? - Unilateral CTS
??? - Unilateral CTS ??? - In the setting of trauma ??? - In the
setting of trauma ???
Slide 18
Ultrasound for nerves 101 Excellent anatomic detail Excellent
anatomic detail Can measure Can measure size size shape shape
doppler flow doppler flow echogenicity echogenicity mobility
mobility Cross sectional area (CSA) is the only measurement with
statistical utility currently Cross sectional area (CSA) is the
only measurement with statistical utility currently
Slide 19
1. Which test should be 1 st line for most circumstances? 1.
Which test should be 1 st line for most circumstances? Systematic
evidence-based medicine criteria for a useful diagnostic test
(Frybeck 1991) Systematic evidence-based medicine criteria for a
useful diagnostic test (Frybeck 1991) 1. Valid and reliable 1.
Valid and reliable 2. Accurate 2. Accurate 3. Changes the diagnosis
3. Changes the diagnosis 4. Changes the treatment plan 4. Changes
the treatment plan 5. Improves patient outcomes 5. Improves patient
outcomes 6. Good cost-benefit profile 6. Good cost-benefit profile
Carpal Tunnel Syndrome: EMG vs. US
Slide 20
What do we want a test for focal peripheral neuropathies to do?
What do we want a test for focal peripheral neuropathies to do? 1.
Diagnose/exclude CTS 1. Diagnose/exclude CTS 2. Rule out the other
likely diagnoses 2. Rule out the other likely diagnoses 3. Assess
severity 3. Assess severity 4. Establish timing of injury 4.
Establish timing of injury 5. Determine etiology 5. Determine
etiology 6. Determine prognosis 6. Determine prognosis 7. Guide
treatment 7. Guide treatment Carpal Tunnel Syndrome: EMG vs.
US
Slide 21
1. Diagnose/exclude CTS - reliably 1. Diagnose/exclude CTS -
reliably Electrodiagnostics Electrodiagnostics Test-retest
reliabilityGOOD Test-retest reliabilityGOOD CSI Spearman rho 0.95
(Lew 2000) CSI Spearman rho 0.95 (Lew 2000) Inter-rater
reliabilityPOOR Inter-rater reliabilityPOOR Large enough to limit
clinical trials (Dyck 2013) Large enough to limit clinical trials
(Dyck 2013) Reference values BEST Reference values BEST
Standardization of practiceAVERAGE Standardization of
practiceAVERAGE Identify dynamic pathologyWORST Identify dynamic
pathologyWORST Use side-to-side comparisonBEST Use side-to-side
comparisonBEST Quality assurance Quality assurance Operators
ABEMBEST Operators ABEMBEST Laboratories AANEMGOOD Laboratories
AANEMGOOD Carpal Tunnel Syndrome: EMG vs. US
1. Diagnose/exclude CTS EMG-negative 1. Diagnose/exclude CTS
EMG-negative Ultrasound GOOD Ultrasound GOOD Normal EDX Normal EDX
With sx of CTS 30.5% had a CSA>10.5mm 2 With sx of CTS 30.5% had
a CSA>10.5mm 2 Controls without sx of CTS 3.3% had a
CSA>10.5mm 2 (Koyuncuoglu 2005) Controls without sx of CTS 3.3%
had a CSA>10.5mm 2 (Koyuncuoglu 2005) Carpal Tunnel Syndrome:
EMG vs. US
Slide 34
Slide 35
2. Rule out other likely diagnoses - neurological 2. Rule out
other likely diagnoses - neurological ElectrodiagnosticsBEST
ElectrodiagnosticsBEST Series of failed carpal tunnel release
ultimate diagnosis (Witt 2000) Series of failed carpal tunnel
release ultimate diagnosis (Witt 2000) Polyneuropathy (2/12)
Polyneuropathy (2/12) Cervical radiculopathy (1/12) Cervical
radiculopathy (1/12) Motor neuron disease (4/12) Motor neuron
disease (4/12) Spondylotic myelopathy (1/12) Spondylotic myelopathy
(1/12) Syringomyelia (1/12) Syringomyelia (1/12) Multiple sclerosis
(2/12) Multiple sclerosis (2/12) TEST OF CHOICE Carpal Tunnel
Syndrome: EMG vs. US
Slide 36
2. Rule out other likely diagnoses - neurological 2. Rule out
other likely diagnoses - neurological UltrasoundPOOR UltrasoundPOOR
Cervical radiculopathy Cervical radiculopathy Brachial plexopathy
Brachial plexopathy Ulnar neuropathy Ulnar neuropathy Proximal
median neuropathy Proximal median neuropathy Polyneuropathy
Polyneuropathy Carpal Tunnel Syndrome: EMG vs. US
Slide 37
2. Rule out other likely diagnoses - MSK 2. Rule out other
likely diagnoses - MSK ElectrodiagnosticsWORST
ElectrodiagnosticsWORST Carpal Tunnel Syndrome: EMG vs. US
Slide 38
2. Rule out other likely diagnoses - MSK 2. Rule out other
likely diagnoses - MSK UltrasoundBEST UltrasoundBEST Tenosynovitis
Tenosynovitis Trigger finger Trigger finger Synovitis Synovitis
Ganglion cysts Ganglion cysts Carpal Tunnel Syndrome: EMG vs. US
TEST OF CHOICE / ALTERNATE
Slide 39
3. Establish timing of injury 3. Establish timing of injury
ElectrodiagnosticsBEST ElectrodiagnosticsBEST Needle EMG Needle EMG
Size of fibrillation potentials Size of fibrillation potentials
Size of motor unit action potentials (MUAP) Size of motor unit
action potentials (MUAP) Carpal Tunnel Syndrome: EMG vs. US
Slide 40
3. Establish timing of injury 3. Establish timing of injury
UltrasoundWORST UltrasoundWORST Carpal Tunnel Syndrome: EMG vs.
US
Slide 41
4. Assess severity 4. Assess severity Electrodiagnostics
Electrodiagnostics Electrophysiologic rating scales
Electrophysiologic rating scales Steven scale Steven scale
Canterbury scale Canterbury scale Combined sensory index (CSI)
Combined sensory index (CSI) Carpal Tunnel Syndrome: EMG vs.
US
Slide 42
Canterbury Scale (Bland 2000) Canterbury Scale (Bland 2000) 0
NORMAL 0 NORMAL no neurophysiological abnormality no
neurophysiological abnormality 1 VERY MILD 1 VERY MILD detected
only in two sensitive tests (inching, palm/wrist median/ulnar
comparison, ringdiff) detected only in two sensitive tests
(inching, palm/wrist median/ulnar comparison, ringdiff) 2 MILD 2
MILD index finger CV 6.5ms motor latency >6.5ms 6 EXTREMELY
SEVERE 6 EXTREMELY SEVERE motor amplitude
4. Assess severity 4. Assess severity Electrodiagnostics
correlates with surgical outcome Electrodiagnostics correlates with
surgical outcome Yes - Combined sensory index (Malladi 2010) Yes -
Combined sensory index (Malladi 2010) Normal (4.6 - 54% complete
resolution of sx Absent 37% complete resolution of sx Absent 37%
complete resolution of sx Carpal Tunnel Syndrome: EMG vs. US
4. Assess severity 4. Assess severity ElectrodiagnosticsGOOD
ElectrodiagnosticsGOOD Carpal Tunnel Syndrome: EMG vs. US
Slide 48
4. Assess severity 4. Assess severity Ultrasound POOR
Ultrasound POOR Carpal Tunnel Syndrome: EMG vs. US
Slide 49
4. Assess severity 4. Assess severity Ultrasound POOR
Ultrasound POOR Carpal Tunnel Syndrome: EMG vs. US
Slide 50
5. Determines etiology 5. Determines etiology
ElectrodiagnosticsWORST ElectrodiagnosticsWORST Carpal Tunnel
Syndrome: EMG vs. US
Slide 51
5. Determines etiology 5. Determines etiology UltrasoundBEST
UltrasoundBEST In patients with CTS In patients with CTS Ganglion
25% in unilateral CTS, 7% bilateral by US (Nakamichi 1993,
Buchberger 1991) Ganglion 25% in unilateral CTS, 7% bilateral by US
(Nakamichi 1993, Buchberger 1991) Tenosynovitis 10% in CTS by US,
confirmed in surgery (Buchberger 1991) Tenosynovitis 10% in CTS by
US, confirmed in surgery (Buchberger 1991) Fatty tissue on the
floor of CT 7% in CTS by US, confirmed in surgery (Buchberger 1991)
Fatty tissue on the floor of CT 7% in CTS by US, confirmed in
surgery (Buchberger 1991) Intrusive FDS 7% in CTS by US (Buchberger
1991) Intrusive FDS 7% in CTS by US (Buchberger 1991) Instrusive
lumbricals 22% (Touborg-Jensen 1970) Instrusive lumbricals 22%
(Touborg-Jensen 1970) Fracture Fracture Dislocation Dislocation
Carpal Tunnel Syndrome: EMG vs. US
Slide 52
5. Determines etiology 5. Determines etiology UltrasoundBEST
UltrasoundBEST Determining causation Determining causation Test can
potentially detect abnormality Test can potentially detect
abnormality Increased incidence in CT than in normals (association)
Increased incidence in CT than in normals (association) ? Treating
improving symptoms or other disease marker (causation) ? Treating
improving symptoms or other disease marker (causation) Carpal
Tunnel Syndrome: EMG vs. US
Slide 53
6. Determines prognosis 6. Determines prognosis
Electrodiagnostic Electrodiagnostic Carpal Tunnel Syndrome: EMG vs.
US
Slide 54
6. Determines prognosis 6. Determines prognosis US US Carpal
Tunnel Syndrome: EMG vs. US
Slide 55
7. Change treatment 7. Change treatment A. By severity (and
presumed natural history) A. By severity (and presumed natural
history) B. By etiology (and treatments specific to that cause) B.
By etiology (and treatments specific to that cause) Carpal Tunnel
Syndrome: EMG vs. US
Slide 56
7. Change treatment 7. Change treatment Electrodiagnostics GOOD
Electrodiagnostics GOOD A. By severity (and presumed natural
history) A. By severity (and presumed natural history) This does
not tell you whether a patient should have surgery or not! This
does not tell you whether a patient should have surgery or not!
Mild - probably shouldnt Mild - probably shouldnt Doesnt compare
outcomes with or without surgery, just surgery with different
severities Doesnt compare outcomes with or without surgery, just
surgery with different severities B. By etiology (and treatments
specific to that cause) B. By etiology (and treatments specific to
that cause) none none Carpal Tunnel Syndrome: EMG vs. US
Slide 57
Slide 58
7. Change treatment 7. Change treatment Ultrasound Ultrasound
A. By severity (and presumed natural history) A. By severity (and
presumed natural history) None None B. By etiology (and treatments
specific to that cause) B. By etiology (and treatments specific to
that cause) ?? ?? Carpal Tunnel Syndrome: EMG vs. US
Slide 59
Slide 60
Slide 61
7. Change treatment 7. Change treatment Ultrasound etiologies
that may change txAVERAGE Ultrasound etiologies that may change
txAVERAGE Any surgery relative contraindications Any surgery
relative contraindications Tenosynovitis 6% injection probably
favorable (Beekman 2003) Tenosynovitis 6% injection probably
favorable (Beekman 2003) Thrombosed persistent median artery
treated with thrombolysis? (Fumiere 2002, Bianchi book 465)
Thrombosed persistent median artery treated with thrombolysis?
(Fumiere 2002, Bianchi book 465) Endoscopic surgery relative
contraindications Endoscopic surgery relative contraindications
Space occupying lesion (Bianchi book 467) Space occupying lesion
(Bianchi book 467) Ganglion cyst 25% unilateral (Nakamichi 1993)
Ganglion cyst 25% unilateral (Nakamichi 1993) Persistent median
artery 9% (Padua 2011) Persistent median artery 9% (Padua 2011)
Bifid median nerve 9% (Padua 2011) Bifid median nerve 9% (Padua
2011) May have separate compartments requiring separate treatments
(Ianicelli 2000, Szabo 1994, Amadio 1987) May have separate
compartments requiring separate treatments (Ianicelli 2000, Szabo
1994, Amadio 1987) Carpal Tunnel Syndrome: EMG vs. US
Slide 62
Negatives of testing Negatives of testing Electrodiagnostics
Electrodiagnostics Tolerability WORST Tolerability WORST SafetyBEST
SafetyBEST Price AVERAGE Price AVERAGE 95908+95861 = ~$200
95908+95861 = ~$200 SpeedAVERAGE SpeedAVERAGE ~30 minutes ~30
minutes Readily available Readily available Equipment GOOD
Equipment GOOD Competent operators GOOD Competent operators GOOD
Carpal Tunnel Syndrome: EMG vs. US
Slide 63
Negatives of testing Negatives of testing Ultrasound Ultrasound
TolerabilityBEST TolerabilityBEST SafetyBEST SafetyBEST Price GOOD
Price GOOD 76881 = $114 76881 = $114 SpeedBEST SpeedBEST Full
anterior wrist, forearm comparison = ~12 minutes Full anterior
wrist, forearm comparison = ~12 minutes Readily available Readily
available Equipment GOOD Equipment GOOD Competent operators WORST
Competent operators WORST Carpal Tunnel Syndrome: EMG vs. US
Slide 64
USEDX GOODSensitivity BEST AVERAGESpecificityBEST
BESTReliabilityBEST POORpost CTRAVERAGE GOODPolyneuropathy GOOD
POOR (MSK) Rule out mimickers BEST (PN) POORTimingBEST
POORSeverityGOOD BESTEtiologyWORST POORPrognosticateGOOD
AVERAGEDirect treatmentGOOD
Slide 65
USEDX BESTTolerabilityWORST BESTSafetyBEST GOODExpense AVERAGE
BESTSpeedAVERAGE POORAvailabilityGOOD
Slide 66
US as a screening tool US as a screening tool US should be used
as a screen US should be used as a screen Screening test profile
Screening test profile Tolerable Tolerable Safe Safe Quick Quick
Cheap Cheap Can confirm borderline values with a gold standard
tests Can confirm borderline values with a gold standard tests
Carpal Tunnel Syndrome: EMG vs. US
Slide 67
US as a screening test US as a screening test TolerabilityBEST
TolerabilityBEST SafetyBEST SafetyBEST Time (12 minutes)BEST Time
(12 minutes)BEST Price ($114)GOOD Price ($114)GOOD Sensitivity
(65-97%)GOOD Sensitivity (65-97%)GOOD Specificity (72-97%)AVERAGE
Specificity (72-97%)AVERAGE SeverityWORST SeverityWORST
EtiologyBEST EtiologyBEST Rule out mimickersPOOR Rule out
mimickersPOOR PrognosisPOOR PrognosisPOOR Direct TreatmentGOOD
Direct TreatmentGOOD Carpal Tunnel Syndrome: EMG vs. US