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Transcript of 3nd Biennial Contemporary Clinical Neurophysiological ... · – Presence of conduction block and...
3nd Biennial Contemporary Clinical Neurophysiological
Symposium October 12, 2013
Abnormal Nerve Conduction Patterns
Peter D. Donofrio, M.D. Professor of Neurology
Vanderbilt University Medical Center
Diagnosis of Peripheral Neuropathy
Electrodiagnostic Tools
• Sensory nerve conduction studies • Motor nerve conduction studies and F-waves • Electromyography • Quantitative sensory testing • Autonomic reflex tests
– Quantitative sudomotor axon reflex test (QSART) – Sympathetic Skin Response – Heart rate variability, valsalva maneuver
The Motor Unit • Anterior horn cell (neuronopathy) • Motor Root (radiculopathy) • Nerve fiber (neuropathy) • Neuromuscular junction (pre/post-synaptic) • Muscle fibers (myopathy)
Patterns of Abnormalities in NCSs
• Require careful attention to: – CMAP amplitudes and distal latencies – SNAP amplitudes and distal latencies – Conduction velocities adjusted for age and
height, and especially for temperature – F-wave latencies adjusted for height – Presence of conduction block and temporal
dispersion – Temperature of the limb
Abnormal Patterns of NCSs
• Normal motor conduction studies and sensory studies – Early motor neuron disease – Mild to moderate radiculopathy – Myopathy – Myasthenia gravis – Small fiber neuropathy
Abnormal Patterns of NCSs
• Reduced CMAPS and normal sensory condition studies – Motor neuron disease – Severe radiculopathy – Motor neuropathies (Rare) – Lambert-Eaton Myasthenic Syndrome (LEMS) – Botulism – Congenital myasthenia gravis – Myopathies
Abnormal Patterns of NCSs
• Reduced or absent SNAPs, normal CMAPS – Sensory polyneuropathy – Mononeuropathy – Mononeuritis multiplex (early, sensory only) – Plexus lesion
Proposed Edx Studies in Evaluating Neuropathy
• Strategy differs depending upon severity of neuropathy by examination
Test most involved site, if mild or moderate. Test least involved site, if severe. • Peroneal motor. If no response: Tibial motor. If no peroneal or tibial responses: Peroneal motor, recording anterior tibialis. Ulnar motor. Median motor. • Sural sensory • Median sensory • Test additional nerves if finding equivocal • Definite abnormalities should result in test of: Opposite extremity. Evaluation of suspected focal abnormality. Modified from Donofrio PD, Albers JW
Motor > Sensory, Uniform Conduction
Slowing Polyneuropathy
Amiodarone Charcot-Marie-Tooth Disease Type I (Hereditary Motor Sensory
Neuropathy Type I) Cytosine arabinoside (ara-C) Dejerine-Sottas disease (Hereditary Motor Sensory Neuropathy
Type III) Doxorubicin Hexacarbon Toxicity Perhexiline maleate Sodium channel blockers
Motor > Sensory, Multifocal Conduction Slowing
Polyneuropathy Arsenic (acute intoxication) Acute Inflammatory Demyelinating Polyneuropathy (AIDP) Subacute Inflammatory Demyelinating Polyneuropathy (SIDP) Chronic inflammatory demyelinating polyneuropathy (CIDP) Chronic dysimmune polyneuropathy Monoclonal gammopathy of undetermined significance (MGUS) Osteosclerotic myeloma Multiple myeloma (substantial proportions are axonal) Waldenstrom’s macroglobulinemia Gamma heavy chain disease Castleman’s disease Lymphoma Systemic lupus erythematous Cryoglobulinemia Carcinoma HIV Multifocal motor neuropathy (MMN) with conduction block
CIDP: Tibial Nerve
Image courtesy of P. Donofrio.
Recording Site: Abductor halluci Stimulus Site
Lat1 ms
Dur Ms
Amp mV
Area mVm
s A1: Ankle 4.9 15.9 0.9 7.6 A2: Popliteal fossa
19.1 20.00
0.5 3.1
Segment Dist mm
Diff ms
CV m/s
Temp °C
Ankle-Popliteal fossa
390 14.2 27 32.2
Multifocal Motor Neuropathy Characteristics
• Mimics ALS • Chronic Asymmetric
Distal Motor Neuropathy • Pure Motor • Arms Greater than Legs • Fasciculations, Cramps • Multifocal Conduction
Blocks on NCSs • Antibodies against GM1
ganglioside (50-80%)
Motor or Motor > Sensory, Axonal Loss
Polyneuropathy
Charcot-Marie-Tooth Disease (Hereditary Motor Sensory Neuropathy Type II) Dapsone Disulfiram Acute motor axonal neuropathy (AMAN) Acute motor sensory axonal neuropathy (AMSAN) Hyperinsulinism Nitrofurantoin, often S>M Organophosphate Poisoning Porphyria Paraneoplastic motor neuropathy (lymphoma or carcinoma)
Sensory, Axonal Loss
Polyneuropathy
Carcinoma or Paraneoplastic
Cisplatin Carboplatin Oxaliplatin Congenital Metronidazole
Pyridoxine Sjögren’s syndrome Styrene Taxol Thalidomide HSN with autonomic SCAs
Sensory > Motor, Axonal Loss
Polyneuropathy Acromegaly Amyloidosis Critical illness neuropathy Connective tissue diseases Rheumatoid arthritis, SLE Periarteritis nodosa Degenerative disorders Friedreich’s ataxia, OPCA Gout Hypothyroidism Metals Arsenic (chronic) Gold, Mercury Nutritional B12 deficiency Post-gastrectomy Thiamine deficiency
Pharmaceuticals Colchicine Ethambutol Isonicotine hydrazine (INH) Nitrous oxide Phenytoin Thallium Vincristine Polycythemia vera Sarcoidosis Toxic Acrylamide Hexacarbons (glue sniffing) Organophosphorous esters Multiple myeloma Myotonic dystrophy
Sensory and Motor, Mixed conduction Slowing
and Axon-Loss Polyneuropathy
Diabetes mellitus End-stage renal disease
Axonal vs. Demyelinating
Distal Latency
Amplitude Conduction Velocity
Conduction Block
Temporal Dispersion
Axonal ↑ ↓↓ Nl or ↓ No No
Hereditary Demyelinating ↑ ↑ ↑ Nl or ↓ ↓↓↓ No No
AIDP or CIDP ↑ ↓ ↓ ↓ Yes Yes
Abnormal Patterns by Needle EMG
• Motor Neuron Disease: Abnormalities asymmetric, proximal and distal, tongue, face, SCM muscles, paraspinal muscles
• Radiculopathy: Follow a root or roots distribution • Polyneuropathy: Abnormalities, distal > proximal • NMJ: Early recruitment, may appear as a
myopathy. PSW rare, but may be seen. • Myopathy: Abnormalities: Proxmal > Distal.
Active denervation may be absent. Check paraspinals
Abnormal Patterns in Electrodiagnosis Summary
• Critical Interpretation of the CMAPs and SNAPS often gives clue to diagnosis
• Note distribution of the needle EMG abnormalities • MND is commonly asymmetric, same for radiculopathy • Neuropathies, NMJ defects and myopathies usually
symmetric • It is helpful to generate a differential diagnosis of the
electrodiagnostic findings. • State what patient has and does not have. • A great EMG report includes comments about possible
etiologies, and helps direct the referring doctor to an appropriate work up.