This document summarizes a presentation on electromyography (EMG) for sports medicine providers focusing on lower extremity mono-neuropathies. The presentation reviews the history and basics of EMG, explores common lower extremity mono-neuropathies including peroneal neuropathy, tibial neuropathy, femoral neuropathy and lumbar radiculopathy. It discusses the evaluation, expected EMG findings, and differential diagnosis for each condition. The presentation emphasizes interpreting EMG results in the context of the clinical history and examination.
4. Objectives
• A Touch of History
• Review Basic Neurophysiologic Concepts
• Define EMGFU
• Explore common LE Mono-neuropathies
N
• Run some cases
• Wrap Up
5. What it is NOT!
• The END of the conversation
• A talk on neuropathy management
• My recommendations on the selection of
6.
7. “Animation”
• 4 humors: sanguine, melancholic, choleric, phlegmatic
• Chi of the Oriental Mystics
• Soul of Christianity
9. A touch of History
• 1792: Galvani: Electricity can generate Muscle
Contractions
• 1849: Dubois-Raymond: record electrical
activity from a muscle contraction
• 1890: Term Electromyography coined
13. Nerve Conduction Studies
• Electrodes placed on the skin
• Peripheral nerves are stimulated with low
intensity electrical impulses
• Reference and active sensors then identify
characteristics of the electrical wave traveling
22. Basket of Reflexes
• Based on age and height
• H Reflex: Monosynaptic spinal reflex
– Side to side difference of 60%
• F Wave: low amplitude late response reflex
– Suggestive in Radicular rule out
23. Variables
• Age
• Technical :
– Lab norms
– Experience
– Temperament
– Temperature
• Velocity reduced by ≈ 2.4m/s/ degree Cel. < 32 (89.6)
– Timing
• > 3 weeks post injury/ of symptoms
– Placement
• Too close, too far distorts computer calculations
– Preparation
• Oily skin/dispersion
24. Basic EMG/Needle
• Sample muscles in affected/tested segment
• At least 1 in each major myotome
– 5 in UE
– 5 in LE
– Paraspinals where appropriate
26. In Review
• “EMG”:
– Nerve Conduction Studies
– Health of the Nerves
• Sensory
• Motor
– Needle EMG
– Health of the “Relationship” (nerve and muscle)
• Insertional
• Resting
• Exertional
38. Peroneal Neuropathy
• Most Common mononeuropathy on the LE
– Causes: compression, entrapment, ischemia,
direct trauma, Knee dislocation or bicruciate
injury, pneumatic compression devices
– Ex: rapid weight loss, tight cast or brace, crossing
legs, repetitive squatting, sitting on an airplane or
positioning during surgery
– Both> deep> superficial
39. Evaluation
• Rigorous history and physical
• Basic Labs: inflammatory panel etc
• Referral for EMG
• Safety: Appropriate Prosthetics
• ?Imaging: Lumbo-Sacral, Pelvic MRI
40. Peroneal Neuropathy
• Routine LE Assessment
– NCS and EMG
• NCS
– Sensory: sural, superficial peroneal
– Motor: peroneal(EDB, TA), Tibial(AHL)
– contralateral peroneal motor (EDB, TA) and
superficial peroneal sensory
– Drop of >20% amplitude in CMAP is abnormal
41. Fun Fact
• The SHBF
• only muscle proximal to fibular neck that is innervated by
the peroneal nerve, so if peroneal neuropathy at fibular
neck the SHBF should be intact
42. Classic Findings
• Reduced peroneal CMAP amplitude side to
side
• Focal Slowing Across the fibular head
• Normal sural sensory, tibial motor
• EMG findings of spontaneous activity and/or
reinnervation
• Normal findings in gastroc, quads, tib post,
paraspinals, SHBF
43. What you want to see!
• Associated Nerves are tested
– Peroneal motor, tibial motor, super. Per. Sensory,
sural sensory
• Abnormalities differentiated
• Contra-lateral side compared
– Same nerves
• Appropriate Muscles Sampled
– TA,BFSH, BFLH or Semitendinosis, Post. Tib
44. Case #2
25 y/o male golfer
presents to clinic
with pain
over the inner right ankle
and
numbness on the sole of his foot
52. Tibial Nerve:
2 sensory
M. & Lat.
Calcaneal Sensory
2 Mixed Motor and
Sensory
M. And Lat. Plantar
53. Evaluation
• Rigorous history and physical
• Intervention
vs:
• Referral for EMG
• ?Imaging: Lumbo-Sacral, Pelvic MRI
54. Tarsal Tunnel Syndrome
• Described by Keck in 1962
• compression neuropathy of the tibial nerve
– Flexor retinaculum
• Common Pre-Disposing Factors:
– Pes planus with valgus hindfoot
– crush injury, stretch injury, fractures, dislocations
of the ankle and hindfoot
– severe ankle sprains
55. Tarsal Tunnel Pressure
• Trepman et al.:
– anatomic space pressure in the tarsal tunnel
– Pronated: 32 mmHg
– Neutral: 1 mmHg
– Inversion of the foot as well as plantarflexion of
the ankle reduced the tarsal compartment
pressure significantly.
56. Classic EMG Findings
• Prolonged latency or low Amplitude Medial
or Lateral Plantar Sensory or mixed Nerve
Responses
• Prolonged distal Latency of the medial or
lateral plantar motor nerves
• Decreased amplitude of the above
• Spontaneous potentials
57. What you want to see!
• Appropriate nerves tested
• Associated Nerves are tested
– Sensory: Sural, Saphenous Sensory, Medial and
lateral plantar
– Motor: Peroneal, tibial
• Abnormalities differentiated
• Contra-lateral side compared
– Same nerves
• Appropriate Muscles Sampled
– Foot Muscles: ADM, FDM, Abductor hallucis, FDB
58. Case #3
35 y/o male
Police Officer
Presents with numbness and occasional
“weird feelings”
over the front and side of his thigh
65. Purely Sensory: NO Motor
Origin: L2-3 via Lumbar plexus
Through the Pelvis
Along the lateral border of
the psoas muscle
Under the inguinal ligament
≈1cm medial to the ASIS
66. Meralgia Paresthetica
Meros= thigh Algo= Pain
• Obesity
• Pregnancy
• Tight clothing (low rise jeans), leaning against
a table for work, uneven bar in gymnastics
• Tool belts, military gear, recent weight loss
• Diabetic and metabolic neuropathies
• Other: masses, hematomas in the
retroperitoneal space
67. EMG
• NCS
– peroneal and tibial motor (with F wave)
– sural sensory, LFCN bilaterally
• NEE
– L3-4: quadricep
– L4-5: tibialis anterior
– L5-S1: glut. med. (L5) or max. (S1), tibialis post. or
FDL, EDB
– S1-2: medial gastroc., abductor hallucis
– paraspinal
68. Of Note
• NCS: of the LFCN is technically challenging
and many patients are unable to tolerate
• NEE: Anticipated to be “normal” but can help
rule out “radiculopathy”
69. Case #4
65 y/o female recreational swimmer
Presents concerned
With difficulty climbing stairs
and occasional falls
because my “knee is buckling”
76. Femoral Nerve Neuropathy
• Findings:
– Weakness in thigh flexion and knee extension
– Decreased sensation over anterior thigh and
medial leg
– Loss of ipsilateral patellar reflex
• Causes:
– Compression (mass, hematoma), iliac aneurysm,
trauma in surgery, femoral line placement,
77. EMG
• NCS
– Motor: femoral (rectus femoris), peroneal and
tibial (with F wave)
– Sensory: sural, saphenous (bilaterally)
• NEE
– L3-4: quadricep
– L4-5: tibialis anterior
– L5-S1: glut. med. (L5) or max. (S1), tibialis post. or
FDL, EDB
– S1-2: medial gastroc., abductor hallucis
– paraspinal
78. What you want to see!
• Routine LE assessment
• NCS - B femoral motor
• NEE - at least 2 quads, iliopsoas, adductor
longus, upper lumbar paraspinals
79. Expected EMG Findings
• NCS:
– Motor: abnormal rectus femoris CMAP
– Sensory: abnormal saphenous findings, with
normal sural
• NEE:
– Abnormal activity in the femoral innervated
muscles, normal findings elsewhere
80. Quick Notes
• Femoral Nerve:
– Distal or at Inguinal Ligament
• quads affected
– If both quads and iliopsoas affected must rule out
lumbar radiculopathy vs retroperitoneal
involvement.
81. Case #5
21 y/o male lineman
football
player presents to clinic
with complaints of
being unable to raise his
right foot
86. Exam
• Weakness
– Ankle Dorsiflexion
– Ankle Inversion
• Decreased Sensation to LT, PP over medial
foot
• Absent Hamstring reflex on the right
• + SLR, XLR, Fem. Stretch Test
• TTP of Lumbar Paraspinals
87. Lumbar radiculopathy
• NCS:
– Distal motor and sensory often normal in a single-
level radiculopathy.
• Needle electromyography:
– High diagnostic yield. Timing is important, and the
study should be performed less than 4-6 months
(but >18-21 d) from symptom onset.
90. Expected EMG
• NCS:
– Sensory: Normal
– Motor: Normal, or slightly reduced amplitude
– Reflexes: H Reflex: possibly abnormal
• NEE:
– Abnormal Findings in L5 innervated muscles with
normal findings in L2-L4 and S1 myotomes
91. Wrapping Up
• EMG:
– “Extension of the physical exam”
– Only order if it will alter your management
– Order at least 3 weeks after symptoms begin
– Remember patient comfort
92. Personal Opinions
• Meet your “neighborhood” EMG’r
• Experience an EMG first-hand
• Find an EMG’r who is well trained and you
trust
93. Personal Opinions
• Send your patients to the same EMG’r once
you have done your research and found a
good fit
• Ask your patients about the experience and
respond accordingly
• Discuss concerning findings with the EMG’r
Velocity, amplitude, duration, area, Latency: Bespeaks conduction velocity…how rapidly information can go from point a to point b Amplitude….is a summation of motor unit potentials and reflects the health of the entire nerve bundle
Nerve fibers surrounded by endoneurium Fascicles surrounded by perneurium Several fascicles bundled together into Epineurium
Suggestive of demyelination or conduction block, however changes must be severe and modern studies suggest there is very limited value to the studies in most circumstances…and the info is less individually diagnostic and more supportive of a diagnosis already being considered.
Inc Age= slowed conduction, decreased amplitudes classicaly: decr by 1.5% per year over 65 Newborn = 50% of adult cv, 80% of adult by one year Equal to adult by 3-5 years
NCS: Does info travel from a to b and does all the info make it EMG: do the nerves and muscles communicate appropriately…..with normal response from the muscles to voluntary stimulation
After an excellent physical exam and additional history taking…………..referral for EMG and possible lumb0/sacral and pelvic imaging
Ankle Dorsiflexion =
Peroneal sensory distribution: Dark is from common peroneal nerve the lateral cutaneous nerve of the calf. The striped area is the superficial peroneal sensory distribution. The green solid area represents the deep peroneal sensory distribution. All 3 areas shaded would be numb in a patient with a common peroneal nerve lesion.
Compound muscle action potential
Tinel Sign, Compression test….pronate the foot
Adductor longus = obturator but L2-4,
After an excellent physical exam and additional history taking…………..referral for EMG and possible lumb0/sacral and pelvic imaging
Radiculopathy= intra-spinal…..herniated disc, foraminal stenosis, disc-osteophyte complexes…the DRG is intact since distal to this pathology……however if plexus, distal nerves affected than will see changes on sensory ncs
