Term
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Definition
| electrodiagnostic medicine via percutaneous needle examination (not surface) often used to dx radiculopathy and distal focal entrapment syndrome. |
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Term
| what does the electrodiagnostic consultation consist of? |
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Definition
| hx, exam, EMG/NCS, clinical correlation, and recommendations |
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Term
| what does electrodiagnostic testing only test? |
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Definition
| the LMN (anterior horn cell and distal) |
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Term
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Definition
| sensory, motor and mixed - but only large fibers and subject to temperature/height+length/age |
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Term
| what are late responses (type of NCS)? (*exam question*) |
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Definition
| these test the more proximal aspects of the nerve and are the: **H-reflex, which electrically tests the equivalent of the achilles reflex (S1) via the gastroccoleus complex** and the *F-wave, which is obtainable in every muscle: assessing the efferent pathway for plexopathy or AIDP (acute inflammatory demyelinating plexopathy/guillain-barre). |
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Term
| where are needles placed in EMG? how is the muscle evaluated? |
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Definition
| needles are placed in the muscle belly paraspinally and in the limbs and the muscle is evaluated at rest, needle insertion/movement, submaximal contraction and maximal contraction. |
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Term
| what are parameters are evaluated in an EMG? |
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Definition
| waveforms (amplitude, shape, phases, duration, audio quality), firing rate (frequency), and recruitment pattern. |
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Term
| what information is obtained w/EMG? |
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Definition
| chronicity, severity, location and neuropathic vs myopathic |
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Term
| what is repetitive stimulation? |
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Definition
| this type of NCS is used to dx neuromuscular junction disorders (myasthenia, botulism). single fiber EMG can also be used for this purpose. |
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Term
| what is the blink/corneal reflex? |
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Definition
| this tests the afferent CN5 and efferent CN7 fibers by wiping the cornea w/a cotton swab. this is part of the bell's palsy dx which also includes NCS and prognosticates best @ 1 week post-symptom onset. |
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Term
| what are the evoked potentials electrodiagnostic tests? when are they used? |
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Definition
| evoked potential tests: somatosensory, brainstem auditory, visual, and dermatomal. clinical uses: demyelinating disorders (MS), CPA (cerebellopontine angle) tumors, myelopathy, and intraoperative monitoring. |
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Term
| when is EMG testing most commonly used in a clinical setting? |
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Definition
| for symptoms of pain, paresthesia, and weakness |
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Term
| what are the clinical uses of electrodiagnostic testing? |
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Definition
| to confirm clinical suspicion, determine/quantify severity, prognosticate, and r/o concurrent pathology |
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Term
| what kinds of radiculopathy are EMGs used to dx? |
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Definition
| cervical, thoracic (least common), and lumbosacral (most common) |
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Term
| when is the best time do undergo electrodiagnostic testing? |
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Definition
| **3 wks post condition onset (esp w/radiculopathy) |
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Term
| what is a common form of focal neuropathy? |
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Definition
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Term
| what is the most common focal entrapment neuropathy? etiology? (*exam question*) |
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Definition
| carpal tunnel - which is due to focal median compression neuropathy at the wrist. |
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Term
| what is the gold standard for carpal tunnel syndrome dx? |
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Definition
| NCS. EMG is optional and may be used to r/o radiculopathy, plexopathy, double crush (prox/distal pathology) etc. |
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Term
| what is the 2nd most common focal entrapment neuropathy? |
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Definition
| focal ulnar neuropathy at the elbow - cubital tunnel syndrome |
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Term
| what is peroneal neuropathy? |
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Definition
| this division of the sciatic nerve usually becomes compressed at the fibular neck (but can also occur at the ankle). clinically this manifests as a foot drop. |
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Term
| what is radial neuropathy? |
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Definition
| "saturday night palsy" - called such due to the association where intoxicated pts would fall asleep on their arm, compressing the radial nerve on the humerus and wake up w/wrist drop. |
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Term
| what is meralgia paresthetica? |
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Definition
| lateral femoral cutaneous neuropathy due to compression by abdominal fat (along w/tightening of belts and cell phone clips) along the lateral femoral cutaneous nerve as it passes by the ASIS. (also sometimes occurs in pregnant women). pts present w/paresthesias in the anterolateral thigh - which may be confused w/radiculopathies (should be in ddx). |
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Term
| what is tarsal tunnel syndrome? |
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Definition
| tibial nerve compression at the ankle due. less common than the carpal variant - this should be on the ddx for refractory plantar fasciitis. |
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Term
| what is long thoracic nerve syndrome? |
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Definition
| this causes scapular winging exacerbated by protraction clinically and is usually due to mastectomy or strenuous overhead activity (volleyball). |
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Term
| what characterizes suprascapular neuropathy? |
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Definition
| pts w/this will present w/chronic shoulder pain and rotator cuff weakness/atrophy - and needs to be differentiated from the much more common rotator cuff tear (sometimes hard to do, b/c as pts age there is some physiologic tearing which may not be the cause of pain). can be due to a ganglion cyst or impingement at the glenoid notch into the infraspinatus. |
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Term
| what are common causes of sciatic neuropathy? |
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Definition
| postoperative (from total hip arthroplasty), trauma - open/closed hip dislocation, mass, or fracture. the sciatic nerve becomes the tibial/peroneal nerve (peroneal nerve division more commonly affected). |
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Term
| why are EMGs helpful in dx of peripheral polyneuropathy? |
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Definition
| they can help classify pathology - whether it be demyelinating, axonal, both, or hereditary/aquired. also what kinds of nerves are affected: sensory, motor, mixed. |
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Term
| can electrodiagnostic testing determine the cause of polyneuropathy? |
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Definition
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Term
| what are the clinical features of myopathy? |
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Definition
| *proximal weakness (glutes, quads, deltoids, pecs, etc): difficulty w/chairs, steps, and overhead. |
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Term
| what characterizes EMG testing in pts w/myopathy? |
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Definition
| needle EMG testing reveals spontaneous potentials. motor units are small as opposed to the large potentials seen in neuropathy. generally NCS is normal. |
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Term
| are biopsies performed for myopathy? |
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Definition
| yes, and EMG testing should not be performed on areas which area going to be biopsied. |
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Term
| how is an EMG/NCS ordered? |
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Definition
| order to r/o (extension of the clinical evaluation), check b/l?, include previous studies, and list symptoms of concern |
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Term
| what conditions should EMG be used for diagnosing? |
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Definition
| myopathy, neuropathy, motor neuron disease, radiculopathy, and plexopathy |
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Term
| how does electrodiagnostic testing compare to imaging (CT/MRI etc)? |
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Definition
| electrodiagnostic testing assesses nerve *function - not structure (as w/imaging). this makes it a good adjunct to imaging. |
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Term
| when is premedication used for electrodiagnostic testing? |
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Definition
| usually just for children - only a little uncomfortable. |
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Term
| what contraindications exist for electrodiagnostic testing? |
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Definition
| bleeding diathesis, local/systemic infection, pacemaker/defibrillator (relatively safe), and phobia |
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