Entrapment Neuropathies and Nerve Conduction Studies No financial interest or other relationship with the manufacture(s) or provider(s) of products or services presented. Entrapment Neuropathies and Nerve Conduction Studies Hans L. Carlson, M.D. Assistant Professor, Dept. of Orthopaedics & Rehabilitation Physical Medicine & Rehabilitation Oregon Health & Science University

Entrapment Neuropathy

Mononeuropathy caused by direct pressure resulting in motor and/or sensory deficits in single nerve distribution. (Deficits may involve several nerve roots.) Compression neuropathy, Nerve compression syndrome.

Diagnostic Tools = Electrodiagnostic History Physical Exam Studies Electrodiagnostic Studies Robinson et al, Muscle & Nerve 1998 Nerve Conduction Studies Lew et al, Muscle & Nerve 2000 Electromyography (EMG) Carlson et al, Int J Clin Rheum 2010

Review the timing of ordering electrodiagnostic studies.

Review the timing of ordering electrodiagnostic studies. Assess whether the study conclusions are consistent with the clinical assessment. Assess whether the study conclusions are consistent with the clinical assessment. Discuss management options based on outcomes. Discuss management options based on outcomes.

1 Timing of the Electrodiagnostic Study

Timing Ideal time to test following an acute injury is after 4-6 Timing of the test in relation to the onset of symptoms is critical! weeks.

Timing of the Timing of the Electrodiagnostic Electrodiagnostic Study Study Testing early Entrapment Neuropathies Study may be unremarkable even Commonly chronic at the with significant nerve injury and time of presentation. abnormal exam.

Potential for some useful Test may help with prognosis information depending on for acute compression clinical situation. neuropathies.

Assess whether the study conclusions are consistent with Overview of the clinical assessment Electrodiagnostic Studies Review the timing of ordering electrodiagnostic studies.

Discuss management options based on outcomes.

2 Hand Pain Hand Pain

44 y.o. female with a 9 month history of progressive Mild left APB weakness. No intrinsic atrophy. Normal right hand/thumb numbness. interosseii and finger flexor strength.

Complaints of grip weakness. Normal sensation.

Intermittent pain radiating to the elbow and shoulder. Equivocal Tinel’s at wrist and Phalen’s maneuvers.

Hand Pain Hand Pain

Electrodiagnostic studies Electrodiagnostic studies

Nerve Conduction Study Sensory Nerve Action Potential (SNAP) Ulnar

Nerve Conduction Study Supramaximal stimulation

3 Nerve Nerve Conduction Conduction Study Study Compound Motor Action Late Responses: F-Waves Potential Ulnar Ulnar

Nerve Nerve Conduction Conduction Study Study Sensory Nerve Action Compound Motor Action Potential Potential Median Median

Nerve Conduction CTS Internal Study Comparisons Late Responses: F-Waves Mixed Nerve: Palmar Study Median Median vs. Ulnar latency Preston & Shapiro 1998

4 CTS Internal Comparisons EMG Lumbrical-Interosseous Evaluate for denervation and abnormal motor unit Study characteristics. Median vs. Ulnar Latency Selection of muscle representing Brannegan, R. Bartt 2007 nerves and nerve roots relevant to clinical query.

Electromyography Electromyography

FDI FDI Spontaneous Activity Spontaneous Activity Normal (No activity) Normal (No activity) VIDEO

Electromyography

FDI Motor Unit Action Potential (MUAP) Morphology Analysis

Electromyography FDI Spontaneous Activity (Denervation) - Normal findings

5 Electromyography Electromyography

FDI FDI Motor Unit Action Potential (MUAP) Motor Unit Action Potential (MUAP) Morphology Analysis Morphology Analysis VIDEO

Electromyography

FDI MUAP Recruitment – Normal findings

Electromyography FDI MUAP Morphology Analysis

Electromyography

FDI MUAP Recruitment – Normal findings

Electromyography FDI MUAP Recruitment - Normal findings

6 Electromyography

APB Spontaneous Activity 1+ Fibrillations

Electromyography APB (Median C8-T1) Spontaneous Activity

Electromyography Electromyography

APB APB Spontaneous Activity Spontaneous Activity 1+ Fibrillations 1+ Fibrillations

Electromyography

APB Spontaneous Activity 3+ Positive Sharp Waves, Fibrillations

Electromyography APB Spontaneous Activity - Abnormal findings

7 Electromyography Electromyography

APB APB Motor Unit Action Potential (MUAP) Motor Unit Action Potential (MUAP) Morphology Analysis Morphology Analysis 2-3+ Polyphasia 2-3+ Polyphasia

Electromyography

APB Motor Unit Action Potential Morphology Analysis 2-3+ Polyphasia Electromyography APB Motor Unit Action Potential (MUAP) Morphology Analysis

Electromyography Electromyography

APB APB MUAP Recruitment – Abnormal findings MUAP Recruitment – Abnormal findings Markedly decreased recruitment Markedly decreased recruitment

8 EMG APB (Median C8-T1)

FDI (Ulnar C8-T1)

EIP (Radial C7-8)

PT (Median C6-7)

FCU (Ulnar C7-8) Electromyography Bicep (Musculocutaneous C5-6) APB Tricep (Radial C6-7-8) MUAP Recruitment - Abnormal findings Deltoid (Axillary C5-6)

Cervical PS (C5-T1)

Clinical Mononeuropathy Assessment

Patterns of Neurologic Assess whether the study Deficits Radiculopathy

conclusions are consistent with the clinical assessment. Plexopathy Review the timing of ordering electrodiagnostic studies.

Discuss management options based on outcomes.

Patterns of Patterns of Neurologic Neurologic Deficits Deficits Mononeuropathy Radiculopathy

Single nerve, multiple nerve Single nerve root, multiple roots. nerves.

9 Patterns of Neurologic Carpal Tunnel Deficits Syndrome Plexopathy Median Neuropathy at the Wrist Multiple nerves, multiple nerve roots. Paresthesias with repetitive or forceful activity, rest, etc. Weakness thenar activities/dexterity. Radiation from shoulder to hand occasionally.

Carpal Tunnel Carpal Tunnel Syndrome Syndrome Examination: Single study results dependent on technical issues and have surgical Median sensory and/or implications. motor deficits CTS provocative maneuvers CTS comparisons best with uninvolved nerve of the Phalen’s, Tinel’s ipsilateral hand (internal Atrophy of thenar eminence comparison).

CSI - Combined Sensory Indexing : Sum of latency differences.

Combined Sensory Index

Sum of latency differences Carpal Tunnel Normal < 0.9 ms Syndrome Superior sensitivity and Electrodiagnostic Evaluation specificity Two abnormal median studies Superior test-retest Motor, Sensory, Internal Comparison. reliability One abnormal internal comparison Robinson, Micklesen, study Wang; Muscle & Mixed Palmar, Nerve 1998 Lumbrical/Interosseous, Sensory Digit 1 or 4 Lew, Wang, EMG Robinson; Muscle & APB and C6-7 muscles Nerve 2000 Rule-out ulnar neuropathy

10 Proximal Median Cubital Tunnel Neuropathies Syndrome Median Neuropathy at the Elbow Ulnar Neuropathy at the Pronator Syndrome Elbow Sensory and/or motor deficits. Paresthesias at night, with Elbow symptoms. pressure or repetitive flexion of the elbow. Anterior Interosseous Neuropathy Kiloh-Nevin Syndrome Weakness with digit spread or Motor deficits. grip or wrist flexion.

“OK Sign”. Sensory symptoms may not isolate to ulnar distribution.

Cubital Tunnel Cubital Tunnel Syndrome Syndrome Examination: Electrodiagnostic Ulnar sensory and/or motor Evaluation deficits. Two abnormal ulnar studies Provocative maneuvers: Motor(FDI,ADM,inching), Tinel’s at elbow Elbow flexion Sensory, F-wave Ulnar claw hand Localizable to elbow Wartenberg’s sign Froment’s test Motor, Inching Wasting FDI muscle. EMG FDI and FDP(uln) or FCU C8-T1 muscles Rule-out median neuropathy

Distal Ulnar Radial Neuropathy Neuropathy Cyclist’s Palsy Saturday Night Palsy, Honeymoon Palsy Ulnar nerve entrapmant at Guyon’s canal. Acute weakness with wrist and finger extension. Intrinsic hand muscle weakness. Paresthesias at back of hand. Sensory loss only in palmar ulnar distribution.

11 Radial Radial Neuropathy Neuropathy Examination: Electrodiagnostic Evaluation Wrist and finger drop. Abnormal radial studies Motor Sensory deficits at the Sensory superficial radial nerve. Localizable to spiral groove Inching May have tenderness at the spiral groove. EMG Radial muscle distal and Elbow extension preserved. proximal, Triceps C7-8 muscles Rule-out radiculopathy, brachial plexopathy

Radial Peroneal Neuropathy Neuropathy Superficial sensory radial neuropathy Handcuff Palsy, Trauma, masses, fractures, Cheiralgia Parasthetica, compartment syndromes, Wartenberg’s Syndrome braces, prolonged or Sensory deficits only. repetitive flexion. Posterior Interosseous Neuropathy Supinator Syndrome, Generally acute weakness Radial Tunnel Syndrome of ankle dorsiflexion Motor deficits with finger and some wrist and/or eversion. extension.

Sensation in radial distribution preserved. Paresthesias at dorsum of foot.

Peroneal Peroneal Neuropathy Neuropathy Examination: Electrodiagnostic Evaluation Peroneal Motor and Sensory Ankle dorsiflexion, eversion Studies weakness. Peroneal (EDB, TA), F-wave Superfical Peroneal Sensory deficits at the superficial and or deep peroneal nerve. EMG Deep Peroneal (2) May have positive Tinel’s at knee. Sup. Peroneal (1) SHBF Plantar flexion preserved. Tibial distal and proximal muscles Steppage, circumduction or foot Rule-out tibial, sciatic slap gait. neuropathy

12 Radiculopathy Electrodiagnostic Evaluation Motor and Sensory Studies In distribution of suspected radiculopathy Sensory studies may be normal with radiculopathy Late Responses F-waves, H-reflex EMG (Mandatory) At least 2 muscles with same Radiculopathy myotomes / different nerves Patterns of neurologic deficits Proximal and distal muscles Paraspinals Single nerve root, multiple nerves. Rule-out mononeuropathy, plexopathy

Prognostic value of

Discuss management options electrodiagnostic studies Limited based on outcomes.

Review the timing of ordering electrodiagnostic studies. Assess whether the study conclusions are consistent with the clinical assessment.

History Exam

EDX

Diagnosis Entrapment neuropathies Electrodiagnostic Studies multiple treatment options… an extension of the clinical exam. Carlson et al; Int. Journal Clinical Rheumatology, 2010.

13 Severity of entrapment Monitor for progressive neurologic deficits.

Severity of electrodiagnostic findings does not necessarily correlate with symptoms. Acute nerve injuries Electrodiagnostic studies… is there axonal continuity?

Electrophysiologic Electrophysiologic Evidence Evidence Needs to correlate with clinical findings. Needs to correlate with clinical findings. Is there more than one piece of evidence to support the finding?

Electrophysiologic Electrophysiologic Evidence Evidence Needs to correlate with clinical findings. Needs to correlate with clinical findings. Is there more than one piece of evidence to support the Is there more than one piece of evidence to support the finding? finding? Is there denervation vs. abnormal motor unit morphology? Is there denervation vs. abnormal motor unit morphology? Are the diagnostic criteria met?

14 Foot Drop

65 y.o. female

6 month history of right leg pain and numbness/foot drop.

Foot Drop Foot Drop Weakness of ankle evertors and dorsiflexors on right leg. Electrodiagnostic studies Normal knee extension, flexion and ankle plantar flexion strength.

Normal and symmetric Achilles and patellar reflexes.

Decreased sensation top of foot.

Foot Drop Foot Drop

Electrodiagnostic studies Electrodiagnostic studies Peroneal (EDB) CMAP Peroneal (TA) CMAP

15 Foot Drop Foot Drop

Electrodiagnostic studies Electrodiagnostic studies Tibial CMAP Sural Sensory Nerve Action Potentials

Foot Drop Foot Drop

Electrodiagnostic studies Electrodiagnostic studies Superficial Peroneal SNAP

Foot Drop Foot Drop

Summary This is an abnormal study. There are electrophysiologic findings consistent with a right peroneal neuropathy distal to the innervation of the short head of the biceps femoris.

16 Arm Weakness

27 y.o. male with a history of multiple right upper extremity fractures three months ago.

Symptoms of right arm weakness and numbness.

Arm Weakness Arm Weakness Weakness of the right upper extremity with wrist and digit extension. Electrodiagnostic Studies Normal strength of finger and wrist flexors and elbow and shoulder.

Decreased sensation of right dorsal hand.

Normal biceps and triceps reflexes, decreased brachioradialis reflex.

Arm Weakness Arm Weakness

Electrodiagnostic Studies Electrodiagnostic Studies Median SNAP Ulnar SNAP

17 Arm Weakness Arm Weakness

Electrodiagnostic Studies Electrodiagnostic Studies Radial SNAP Median CMAP

Arm Weakness Arm Weakness

Electrodiagnostic Studies Electrodiagnostic Studies Ulnar CMAP Radial CMAP

Arm Weakness Arm Weakness

Electrodiagnostic Studies

18 Arm Weakness

Summary This is an abnormal study. The electrophysiologic findings are consistent with a right radial neuropathy at or above the innervation of the right brachioradialis. There is no electrophysiologic evidence of a right median neuropathy or right ulnar neuropathy.

Elbow Pain Elbow Pain

36 y.o. male with a 10 month history of right upper Weakness of the right upper extremity with 4 and 5 weakness and medial hand numbness. digit grip and digit spread.

Symptoms aggravated with work (construction) and at Normal strength of finger and wrist extensors, no night. intrinsic hand muscle atrophy.

Decreased sensation of right medial hand.

Normal biceps, triceps and brachioradialis reflex.

Elbow Pain Elbow Pain

Electrodiagnostic Studies Electrodiagnostic Studies Median SNAP

19 Elbow Pain Elbow Pain

Electrodiagnostic Studies Electrodiagnostic Studies Ulnar SNAP Radial SNAP

Elbow Pain Elbow Pain

Electrodiagnostic Studies Electrodiagnostic Studies Median CMAP Ulnar CMAP

Elbow Pain Elbow Pain

Electrodiagnostic Studies Electrodiagnostic Studies Ulnar (FDI) CMAP

20 Elbow Pain Elbow Pain Summary This is an abnormal study. The electrophysiologic findings are consistent with a right ulnar neuropathy at the elbow. There is no electrophysiologic evidence of a right median neuropathy at the wrist (carpal tunnel syndrome). The prolonged right median CMAP and SNAP latency by themselves are of uncertain clinical significance but may be suggestive of a non-localized median neuropathy.

Elbow Pain

Electrodiagnostic Studies Ulnar CMAP Conduction Block

Sciatica Sciatica

47 y.o. male with a 6 month history of low back pain Weakness of the right TA and EHL. and leg pain s/p lifting injury at work. Normal strength throughout the remainder of the right Right-sided low back pain and leg pain, numbness and lower extremities. weakness aggravated with bending, lifting and sneezing. Decreased sensation of right dorsal foot.

Mildy decreased right patella and Achilles reflexes.

Positive right straight leg raise.

21 Sciatica Sciatica

Electrodiagnostic Studies Electrodiagnostic Studies Sural SNAP

Sciatica Sciatica

Electrodiagnostic Studies Electrodiagnostic Studies Superficial Peroneal SNAP Tibial CMAP

Sciatica Sciatica

Electrodiagnostic Studies Electrodiagnostic Studies Peroneal CMAP

22 Sciatica Sciatica Summary This is an abnormal study. The electrophysiologic Summary findings are most consistent with a right L5 lumbosacral radiculopathy.

Left Arm Pain/Weakness

76 y.o. male 12 months s/p C6-7, C8-T1 left cervical decompression / laminectomy

Continued significant left upper extremity and neck pain and intrinsic hand weakness.

Left Arm Pain/Weakness Left Arm Pain/Weakness Left intrinsic hand muscle atrophy with interosseii, APB weakness Electrodiagnostic studies Decreased sensation digit 5 and medial digit 4

Mildly decreased left triceps reflex

23 Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies Electrodiagnostic studies Median SNAP Ulnar SNAP

Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies Electrodiagnostic studies Radial SNAP Median CMAP

Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies Electrodiagnostic studies Median F-waves Ulnar CMAP

24 Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies Electrodiagnostic studies Ulnar F-waves Ulnar (FDI) CMAP

Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies Electrodiagnostic studies Mixed Palmar Comparison Lumbrical / Interosseuos Comparison

Left Arm Pain/Weakness Left Arm Pain/Weakness

Electrodiagnostic studies

25 Left Arm Pain/Weakness

Summary This is an abnormal and complex study. There are electrophysiologic findings consistent with a left median neuropathy at the wrist (carpal tunnel syndrome). The electrophysiologic findings are also suggestive of a left non-localized ulnar neuropathy vs. a left C8-T1 cervical radiculopathy.

26