Evaluating the Patient with Focal Neuropathy
Nerve Conduction Studiesand Electromyography
Evaluating the Patient with Focal Neuropathy
Nerve Conduction Studiesand Electromyography
Lawrence R. Robinson, MDKathryn A. Stolp, MD, MS
Lawrence R. Robinson, MDKathryn A. Stolp, MD, MS
CP1076499-1
ObjectivesObjectives
• How do we use NCS and EMG to assess focal mononeuropathies?
• Why is it important to do a needle examination in these cases?
• What is the thought process used in evaluating cases of suspected mononeuropathy?
• How do we use NCS and EMG to assess focal mononeuropathies?
• Why is it important to do a needle examination in these cases?
• What is the thought process used in evaluating cases of suspected mononeuropathy?
Differentiating LesionsTimeframe
Differentiating LesionsTimeframe
CP1076499-16
Conduction block: Acute for all three types• Immediate decrease in CMAP amplitude when
stimulating above site of lesion• Immediate fall in SNAP but more difficult to
assessDistal amplitude drop• Depends on Wallerian degeneration• Sensory axons: 3-11 days• Motor axons: 3-9 days (NMJ fails sooner)• Cannot tell axonotmesis/neurotmesis until
>9 days
Conduction block: Acute for all three types• Immediate decrease in CMAP amplitude when
stimulating above site of lesion• Immediate fall in SNAP but more difficult to
assessDistal amplitude drop• Depends on Wallerian degeneration• Sensory axons: 3-11 days• Motor axons: 3-9 days (NMJ fails sooner)• Cannot tell axonotmesis/neurotmesis until
>9 days
Differentiating LesionsDifferentiating Lesions
Lesion Conduction block 1 month• Neurapraxia Acute; CMAP Normal
drop 20%;SNAP drop >50-75%
• Axonotmesis Acute then Lowdisappears amplitude
• Neurotmesis Acute then Lowdisappears amplitude
Lesion Conduction block 1 month• Neurapraxia Acute; CMAP Normal
drop 20%;SNAP drop >50-75%
• Axonotmesis Acute then Lowdisappears amplitude
• Neurotmesis Acute then Lowdisappears amplitude
Needle EMG in Axonotmesis / Neurotmesis
Needle EMG in Axonotmesis / Neurotmesis
• Length-dependent onset of fibrillations and positive sharp waves
– proximal muscles 10-14 days– distal muscles 3-4 weeks– fibrillation amplitude changes over time
• Indicates axon loss, but does not quantify• Beware of mixed lesions• Beware of muscle trauma
• Length-dependent onset of fibrillations and positive sharp waves
– proximal muscles 10-14 days– distal muscles 3-4 weeks– fibrillation amplitude changes over time
• Indicates axon loss, but does not quantify• Beware of mixed lesions• Beware of muscle trauma
Localization of Nerve InjuriesLocalization of Nerve Injuries
• Focal slowing of nerve conduction– requires demyelination or conduction block– not seen in pure axonal lesions
• Focal slowing of nerve conduction– requires demyelination or conduction block– not seen in pure axonal lesions
Localization by Needle EMGLocalization by Needle EMG
• Use branching pattern to determine lesion site.• Several potential problems:– variability in branching pattern– muscle trauma can be misleading– partial lesions sparing some fascicles can look
like more distal lesions
• Use branching pattern to determine lesion site.• Several potential problems:– variability in branching pattern– muscle trauma can be misleading– partial lesions sparing some fascicles can look
like more distal lesions
Evaluation of PrognosisEvaluation of Prognosis• Neurapraxia - best prognosis (< 3 months)• Partial Axon Loss
- depends upon axon regrowth and distance- larger initial distal CMAP is better prognosis
• Mixed Lesions - two phases of recovery
• Neurapraxia - best prognosis (< 3 months)• Partial Axon Loss
- depends upon axon regrowth and distance- larger initial distal CMAP is better prognosis
• Mixed Lesions - two phases of recovery
Evaluation of PrognosisEvaluation of Prognosis
• Complete Axon Loss- depends upon ability of axons to regrow- evidence of reinnervation in proximal muscles
• Complete Axon Loss- depends upon ability of axons to regrow- evidence of reinnervation in proximal muscles
CaseStudies
CaseStudies
CP1076499-19
Focal neuropathiesFocal neuropathies
Case StudiesCase Studies
CP1076499-20
Case 1HistoryPatient 38-year-old meat packing plant workerCC Forearm, wrist, hand pain, right > leftDuration 6 months superimposed on chronic
pain syndrome, multiple pain medsOnset InsidiousLocation Burning pain – palms and fingers
Numbness “entire hand”Pattern Awakened at night – relieved after
position changeOther Neck pain, back pain, headaches
Case 1HistoryPatient 38-year-old meat packing plant workerCC Forearm, wrist, hand pain, right > leftDuration 6 months superimposed on chronic
pain syndrome, multiple pain medsOnset InsidiousLocation Burning pain – palms and fingers
Numbness “entire hand”Pattern Awakened at night – relieved after
position changeOther Neck pain, back pain, headaches
Case StudiesCase Studies
CP1076499-21
Case 1ExamSensory ↓ pain, touch – palmar index and
middle finger on the rightMotor Normal strength and bulkReflexes Biceps, brachioradialis,
triceps – normalOther Tinels’ at R wrist, both elbows
Phalen’s + on R
Case 1ExamSensory ↓ pain, touch – palmar index and
middle finger on the rightMotor Normal strength and bulkReflexes Biceps, brachioradialis,
triceps – normalOther Tinels’ at R wrist, both elbows
Phalen’s + on R
Nerve Conduction StudiesCase 1
Nerve Conduction StudiesCase 1
CP1076499-22
Nerve Conduction LatenciesStimulate (record) Amplitude (μV) velocity (ms) Distal (ms)Motor
R median (thenar) 6,200 52 7.8R ulnar (hypothenar) 7,400 54 2.8L median (thenar) 6,800 54 4.3L ulnar (hypothenar) 6,900 54 3.6
SensoryR median (index) NRR ulnar (fifth) 20 65 3.0L median (palm-wrist) 180 64 1.8L ulnar (palm-wrist) 50 63 1.8
Nerve Conduction LatenciesStimulate (record) Amplitude (μV) velocity (ms) Distal (ms)Motor
R median (thenar) 6,200 52 7.8R ulnar (hypothenar) 7,400 54 2.8L median (thenar) 6,800 54 4.3L ulnar (hypothenar) 6,900 54 3.6
SensoryR median (index) NRR ulnar (fifth) 20 65 3.0L median (palm-wrist) 180 64 1.8L ulnar (palm-wrist) 50 63 1.8
Motor unit potentialsMotor unit potentials
ElectromyographyCase 1
ElectromyographyCase 1
CP1076499-23
Insertional Phases/Muscle activity Fibs Fascics Recruit Dur/amp turns
R FDI Normal 0 0 Normal Normal –
R APB ↑ + 0 ↓ ↑ ↑
R Normal 0 0 Normal Normal –pronatorteres
R FPL Normal 0 0 Normal Normal –
L APB Normal 0 0 Normal Normal –
L Other Normal 0 0 Normal Normal
Insertional Phases/Muscle activity Fibs Fascics Recruit Dur/amp turns
R FDI Normal 0 0 Normal Normal –
R APB ↑ + 0 ↓ ↑ ↑
R Normal 0 0 Normal Normal –pronatorteres
R FPL Normal 0 0 Normal Normal –
L APB Normal 0 0 Normal Normal –
L Other Normal 0 0 Normal Normal
Report WritingReport Writing
• Diagnosis?• Localization?• Pathophysiology?
• Diagnosis?• Localization?• Pathophysiology?
Case StudiesCase Studies
CP1076499-24
Case 2HistoryPatient 27-year-old T1 complete para;known myelomalacia @C8/T1CC Left hand numbness, weaknessOnset Insidious (poor historian)Duration 6 months daysOther Sx Bilateral shoulder and upper
back pain since injury
Case 2HistoryPatient 27-year-old T1 complete para;known myelomalacia @C8/T1CC Left hand numbness, weaknessOnset Insidious (poor historian)Duration 6 months daysOther Sx Bilateral shoulder and upper
back pain since injury
Case StudiesCase Studies
CP1076499-25
Case 2
Exam
Sensory ↓ pain, touch – 5th digit, medial4th digit, and hand
Motor Weak bilat. dorsal interossei, wrist flexors, lumbricalsSlightly weak thumb flexion, opposition
Reflexes Normal Vascular Normal
Case 2
Exam
Sensory ↓ pain, touch – 5th digit, medial4th digit, and hand
Motor Weak bilat. dorsal interossei, wrist flexors, lumbricalsSlightly weak thumb flexion, opposition
Reflexes Normal Vascular Normal
Nerve Conduction StudiesCase 2
Nerve Conduction StudiesCase 2
CP1076499-26
Nerve Amplitude Conduction DistalStimulate (record) (μV) velocity (ms) (ms)Motor
L median (thenar) 5,600 55 4.2L ulnar (hypothenar) 3.8
Wrist 6,300Below elbow 5,700 52Elbow 1,800 36 3.8Upper arm 1,400 39Supraclavicular 1,300 49
R ulnar (hypothenar)Wrist 8,700 3.5Elbow 8,400 53
SensoryL ulnar (fifth) 5 47 3.8L median (index) 12 52 3.8
Nerve Amplitude Conduction DistalStimulate (record) (μV) velocity (ms) (ms)Motor
L median (thenar) 5,600 55 4.2L ulnar (hypothenar) 3.8
Wrist 6,300Below elbow 5,700 52Elbow 1,800 36 3.8Upper arm 1,400 39Supraclavicular 1,300 49
R ulnar (hypothenar)Wrist 8,700 3.5Elbow 8,400 53
SensoryL ulnar (fifth) 5 47 3.8L median (index) 12 52 3.8
LatenciesLatencies
ElectromyographyCase 2
ElectromyographyCase 2
CP1076499-27
Motor unit potentialsMotor unit potentials
Insertional Duration/Muscle activity Fibs Fascics Recruit amplitudeR FDI ↑ + 0 ↓ ↑R APB ↑ + 0 Normal Mildly ↑R FPL Normal 0 0 Normal Mildly ↑R FCU Normal 0 0 ↓ NormalR pronator Normal 0 0 Normal NormalteresR triceps Normal 0 0 Normal NormalL FDI ↑ + 0 Normal ↑R lower ↑ + 0 – –cervicalparaspinals
Insertional Duration/Muscle activity Fibs Fascics Recruit amplitudeR FDI ↑ + 0 ↓ ↑R APB ↑ + 0 Normal Mildly ↑R FPL Normal 0 0 Normal Mildly ↑R FCU Normal 0 0 ↓ NormalR pronator Normal 0 0 Normal NormalteresR triceps Normal 0 0 Normal NormalL FDI ↑ + 0 Normal ↑R lower ↑ + 0 – –cervicalparaspinals
Report WritingReport Writing
• Diagnosis?• Localization?• Pathophysiology?
• Diagnosis?• Localization?• Pathophysiology?
Case StudiesCase Studies
CP1076499-28
Case 3HistoryPatient 27-year-old skier with tibial fracture –
crutch walking CC Tingling of hand, wrist dropOnset Tingling – 4 weeks after fracture;
wrist drop – 6 weeksExamSensory ↓ pain, touch dorsum of hand,
thumb, index, middle fingersMotor ↓ wrist, finger extensors
Normal elbow flexion, extension,supination, pronation, wrist andfinger flexion
Reflexes Biceps, triceps normalBrachioradialis decreased
Case 3HistoryPatient 27-year-old skier with tibial fracture –
crutch walking CC Tingling of hand, wrist dropOnset Tingling – 4 weeks after fracture;
wrist drop – 6 weeksExamSensory ↓ pain, touch dorsum of hand,
thumb, index, middle fingersMotor ↓ wrist, finger extensors
Normal elbow flexion, extension,supination, pronation, wrist andfinger flexion
Reflexes Biceps, triceps normalBrachioradialis decreased
Nerve Conduction StudiesCase 3
Nerve Conduction StudiesCase 3
CP1076499-29
Nerve Amplitude Conduction Distal F waveStimulate (record) (μV) velocity (ms) (ms) (ms)Motor
Radial (EIP)elbow 4,000 52 4.2spiral groove NR
Ulnar (hypothenar) 12,000 53 3.2 29.0Sensory
Median (index) 57 58 3.0Radial (dorsum NRof hand)
Nerve Amplitude Conduction Distal F waveStimulate (record) (μV) velocity (ms) (ms) (ms)Motor
Radial (EIP)elbow 4,000 52 4.2spiral groove NR
Ulnar (hypothenar) 12,000 53 3.2 29.0Sensory
Median (index) 57 58 3.0Radial (dorsum NRof hand)
LatenciesLatencies
ElectromyographyCase 3
ElectromyographyCase 3
CP1076499-30
Motor unit potentialsMotor unit potentials
Insertional Duration/Muscle activity Fibs Fascics Recruit amplitudeDeltoid Normal 0 0 Normal NormalBiceps Normal 0 0 Normal NormalbrachiiTriceps Normal 0 0 Normal NormalBrachio- ↑ + 0 ↓ ↑
radialisPronator Normal 0 0 Normal NormalteresExtenor ↑ +++ 0 ↓ ↓indicis proprius
InsertionalInsertional Duration/Duration/MuscleMuscle activityactivity FibsFibs FascicsFascics RecruitRecruit amplitudeamplitudeDeltoidDeltoid NormalNormal 00 00 NormalNormal NormalNormalBicepsBiceps NormalNormal 00 00 NormalNormal NormalNormalbrachiibrachiiTricepsTriceps NormalNormal 00 00 NormalNormal NormalNormalBrachioBrachio-- ↑↑ ++ 00 ↓↓ ↑↑
radialisradialisPronatorPronator NormalNormal 00 00 NormalNormal NormalNormalteresteresExtenorExtenor ↑↑ ++++++ 00 ↓↓ ↓↓indicis propriusindicis proprius
Report WritingReport Writing
• Diagnosis?• Localization?• Pathophysiology?• Prognosis?
• Diagnosis?• Localization?• Pathophysiology?• Prognosis?
Pain and Weakness in the LegPain and Weakness in the Leg
• 55 y/o man with onset of pain, weakness and numbness in the left lower limb 1 month ago:• Reports 40 pound weight loss• Has chronic low back pain• Pain in knee and leg• Numbness in dorsum of foot
• 55 y/o man with onset of pain, weakness and numbness in the left lower limb 1 month ago:• Reports 40 pound weight loss• Has chronic low back pain• Pain in knee and leg• Numbness in dorsum of foot
Exam of Pain and Weakness in the Leg
Exam of Pain and Weakness in the Leg
• Weak (4/5) in left ankle dorsiflexors and EHL. Eversion and inversion slightly weak (5-/5)
• Reduced sensation in the dorsum of foot• Normal ankle and knee jerks• Questions from referring doc:
• Localization, pathophysiology, prognosis
• Weak (4/5) in left ankle dorsiflexors and EHL. Eversion and inversion slightly weak (5-/5)
• Reduced sensation in the dorsum of foot• Normal ankle and knee jerks• Questions from referring doc:
• Localization, pathophysiology, prognosis
Motor NCSMotor NCS
330.4Popl Fs
391.1Fib Hd(left)
Absent1.35.1AnkleEDBFibular
418.1Knee(left)
55.28.74.2AnkleAHTibial
F-latCVAmplLatStimRecNerve
More Motor NCSMore Motor NCS
311.4Popl Fs(left)
3.03.7Fib HdTAFibular
CVAmpl.Lat.Stim.Rec.Nerve
Sensory NCSSensory NCS
43.9LegDors. Foot
Sup Fibular (right)
AbsentLegDors. Foot
Sup Fibular (left)
73.9LegLat FootSural (left)
Ampl.Lat.Stim.Rec.Nerve
Needle EMGNeedle EMG
0Paraspinals
FullNorm0TFL
FullNorm0Bic Fem sh
FullNorm0Soleus
RedNorm2+EDB
RedNorm3+EHL
RedNorm1+Fib Longus
RedNorm3+Tib Ant
RecruitMUAPsSpont ActMuscle
Report WritingReport Writing
• Diagnosis?• Localization?
• Root?, Sciatic?, Common vs. Deep Fibular?
• Pathophysiology?• Prognosis?
• Diagnosis?• Localization?
• Root?, Sciatic?, Common vs. Deep Fibular?
• Pathophysiology?• Prognosis?
Runner with Foot NumbnessRunner with Foot Numbness
• 41 y/o female physician with bilateral plantar foot pain and numbness, left > right• Minimal back pain• Likes to run• PMHx remarkable for jumping off bridge
when asked to document more for Level 3 clinic note• Had bilateral calcaneal fractures
• 41 y/o female physician with bilateral plantar foot pain and numbness, left > right• Minimal back pain• Likes to run• PMHx remarkable for jumping off bridge
when asked to document more for Level 3 clinic note• Had bilateral calcaneal fractures
Runner with Foot Pain / NumbnessRunner with Foot Pain / Numbness
• Exam remarkable for:• Normal lower limb strength• Normal knee and ankle jerks• Possible decreased sensation on sole of foot
• But has lots of callouses• Says she has callouses because clinical
income has been insufficient to buy new shoes• Positive Tinel’s over ankle.
• Brother in law is Orthopod – wants to do release.
• Exam remarkable for:• Normal lower limb strength• Normal knee and ankle jerks• Possible decreased sensation on sole of foot
• But has lots of callouses• Says she has callouses because clinical
income has been insufficient to buy new shoes• Positive Tinel’s over ankle.
• Brother in law is Orthopod – wants to do release.
Motor NCSMotor NCS
403.0Knee(left)
3.85.8AnkleADQPTibial
414.9Knee(left)
59.26.65.1AnkleAHTibial
F-latCVAmpLatStimRecNerve
Motor NCSMotor NCS
443.9Fib Hd(left)55.24.54.2AnkleEDBFibular
F-latCVAmpLatStimRecNerve
CNAPsCNAPs
30.8
30.9
31.0
Temp
44.9FootAnkleLateral Plantar (left)
34.5FootAnkleMedial Plantar (left)
93.7LegLat FootSural (left)
Ampl.Lat.Stim.Rec.Nerve
Needle EMG (left)Needle EMG (left)
0Paraspinals
FullNorm0Glut Max
FullNorm0Bic Fem lh
?Large2+AH
?Large3+FDI – pedis
FullNorm1+EDB
FullNorm0Soleus
FullNorm0Tib Ant
RecruitMUAPsSpont ActMuscle
Report WritingReport Writing
• Diagnosis?• Pathophysiology?• Treatment?
• Diagnosis?• Pathophysiology?• Treatment?
The EndThe End
Thanks for ListeningThanks for Listening
