EMG and Nerve Conduction Studies

EMG and Nerve Conduction Studies surface; needle; single fiber - ANS what are the different types of electromyography electrodiagnostics - ANS Types of _________: 1) Electromyography (electrical activity of mm) 2) Somatosensory evoked potentials (how sensory fibers from LE are firing all the way up to brain and vice versa) 3) Auditory or visual evoked potentials (auditory or visual pathway conduction) 4) Autonomic testing (autonomic neuropathy issues) 5) Sensory and motor nerve testing (how peripheral nerves are firing-- larger sensory and motor fibers) electromyography - ANS Needle placed into specific muscles to look for patterns of abnormalities nerve conduction study - ANS Assess speed and strength of nerve responses to look for focal or widespread injury PNS - ANS which parts of the nervous system does the EMG test? inside; muscle; NMJ (neuromuscular junction) - ANS MOTOR NERVE: -The cell body is located ______ the spinal cord -The nerve travels down to the _______ -The nerve and the muscle communicate via the ________ outside; skin - ANS SENSORY NERVE: -The cell body is located _______ of the spinal cord -The nerve travels down to the sensory receptors on the ________ axon - ANS the pathway that the nerve impulse travels down myelin - ANS the outer coating of the nerve that speeds up nerve conduction focal nerve problem; radiculopathy; plexopathy; peripheral neuropathy; myopathy; motor neuron disease - ANS what are common indications for EMG? carpel tunnel syndrome - ANS -focal nerve problem -median nerve entrapment at the wrist -is there a block in electrical activity around wrist? cubital tunnel syndrome - ANS -focal nerve problem -ulnar nerve entrapment at the wrist tarsel tunnel syndrome - ANS -focal nerve problem -tibial nerve entrapment at the ankle fibular (peroneal) nerve entrapment - ANS -focal nerve problem -entrapment at the fibular head sciatic nerve impingement - ANS -focal nerve problem -impingement in the buttocks after hip surgery, fracture or trauma femoral nerve impingement - ANS -focal nerve problem -impingement after a retroperiteonal bleed or surgery peripheral neuropathy (of any cause) - ANS -general nerve problem -widespread abnormalities (usually distal and LE first) -Diabetes -Alcohol -HIV -Critical illness neuropathy (prolonged time in the ICU, septic shock, intubation) -Chemotherapy related -Thyroid disease -Congenital (Charcot Marie Tooth) -Guillain-Barre Syndrome nerve; neuropathy - ANS EMG does not tell you underlying cause for peripheral neuropathy but can tell which ______ is affected or what type of ________ it is myopathy/nmj - ANS -genetic testing covers most of the diagnosis now so EMG used less frequently today -Critical illness myopathy - Dermatomyositisn -Rhabdomyolysisn -Myotonia -Myasthenia Gravis -Lambert Eaton syndrome MS (multiple sclerosis); joint pain; stroke; brain injury; SCI (central processes in general) - ANS For what things is an EMG not helpful to assess? physical examination; localize; guide; nerve; muscle - ANS UTILITY -Extension of the ________ ________ -Can _________ location or pattern of injury -Can help ______ additional testing or workup -Can diagnosis ______ versus ________ problem (peripheral neuropathy vs. myopathy-- difference important for prognosis) Pain; involved; underlying; conjunction - ANS First Step for EMG: Explain the Test -_____ (really need to talk to and explain to pt.) -Not an xray/CT scan/MRI (changing what you are doing in the moment & much more __________) -Does not treat the _______ condition (doesn't make you feel better-- more so for data collection) -Is used in _________ with history, physical exam and imaging to make a diagnosis. (The EMG is just one piece) bleeding/hematoma; infection; pain - ANS what are the risks associated with EMG that require informed consent? Cellulitis; pacemakers; LVADs; Lymphedema; Seizure - ANS CONTRAINDICATIONS -________/open wounds (no go) -____________/defibrillators (ok to test but avoid proximal studies & use lowest stimulation) -_________ (no data on safety; implanted pump to take over function of heart) -_________ (based on risk/reward profile; relative contraindication) -______ disorder (no clear contraindications) timing; location; individualized - ANS Second Step for EMG: Perform a Focused History and Physical Exam -Need to know ______ of symptoms and ________ of physical findings in order to plan out the proper study -Each study is _____ to the specific patient nerve conduction - ANS Third Step for EMG: ___________ ________ studies which; how - ANS What do nerve conduction studies tell us? 1) ______ nerves are affected (sensory, motor, sensory & motor) 2) ________ the nerves are affected (axons, myelin, axons & myelin) motor nerve conduction studies - ANS -Called a compound muscle action potential -Adds up the waveforms of all of the muscle fibers that are firing median; ulnar; tibial; fibular - ANS which motor nerves are commonly tested since they are easiest to reach femoral; axillary; musculocutaneous; suprascapular - ANS which motor nerves are less commonly tested since they are deeper and harder to test? recording; reference; stimulator - ANS Motor Nerve Conduction Studies -The _______ electrode is placed over the center of the muscle -The __________ electrode is placed nearby over a bone -The ____________ is placed over the nerve that supplies that muscle motor nerve conduction study - ANS -Measure amplitude, latency, and duration - large and easily reproducible - Correlate with muscle jumping latency; amplitude; duration - ANS With motor nerve conduction studies, _________ correlates to myelin and conduction velocity, _________ correlates to axon and robustness of response, and _______ correlates to how long response is. sensory nerve conduction study - ANS -Called a sensory nerve action potential -Adds up all of the waveforms from the sensory fibers firing -only record sensory fibers which have a much smaller response than motor -easiest in the hand median; ulnar; radial; sural; superficial fibular - ANS which nerves are most commonly tested for sensory nerve conduction studies saphenous; MAC; LAC - ANS which nerves are least commonly tested for sensory nerve conduction studies recording; reference; stimulator; superficial - ANS Sensory Nerve Conduction Study: -The _______ electrode is placed over the sensory nerve -The ________ electrode is placed nearby -The _________ is placed over the nerve that innervates that sensory pathway **easiest to get sensory response where nerve is most -______ and nerves don't know which was they are supposed to travel so that is why we can stimulate proximally and send signal distal for sensory nerve sensory nerve conduction study - ANS -Measure amplitude, latency, and duration -are small and less reproducible -could use peak latency point instead of onset of latency large; diagnose - ANS Limitations: 1) Only tests the ______ myelinated fibers 2) Cannot ______ problems with small fiber nerves -Some nerve problems only affect the smaller nerve fibers -pain/temperature/autonomic/vibration normal; pathologic; compare - ANS How do we determine what is abnormal? 1) We compare the values that we calculate with a set of "________" values obtained from an asymptomatic population (take age and height into account) 2) Anything that falls outside of the normal range may be related to a _______ process 3) Can _______ affected side to unaffected side decrease; number - ANS Axonal Injury: -Detected on nerve conduction studies as a ________ in amplitude -The size of the amplitude correlates with the _____ of functioning axons slowed; latency; speed - ANS Demyelinating Injury: -Detected on nerve conduction studies _____ conduction velocity or a delay in ________ - The _______ of the nerve conduction study correlates with the function of the myelin 50; 40 - ANS speed in UE is usually _______ and LE is usually _________ for rate of conduction CTS - ANS Example-- Referral for ___________ -Testing for carpal tunnel syndrome (median neuropathy at the wrist) -Test the median nerve recording at the abductor pollicis brevis muscle and stimulating above the wrist -Test the median nerve recording over the sensory nerves in the second digit and stimulation above the wrist -Test the ulnar nerve (motor + sensory) for comparison **Don't just test nerve you are interested in -- be sure to look elsewhere to confirm/rule out things **sensory fibers are usually affected first so conduction testing should also show sensory changes first ulnar neuropathy; elbow - ANS Example-- Referral for ________ ______ at the ________ -Testing for cubital tunnel syndrome (ulnar neuropathy at the elbow) -Test the ulnar nerve recording at the abductor digiti minimi stimulating above and below the elbow -Test the ulnar sensory nerve -Test the median nerve for comparison (and to rule out carpal tunnel syndrome) **Want to rule out carpal tunnel for anyone with UE complaints since it is so common anatomy; less - ANS Sensory vs. Motor Testing -use the same electrode and stimulator -based off ______ = will stimulate both (usually can use ______ stimulation to kick off sensory) but key is where we place the electrode for sensory vs, motor distribution electromyography - ANS Fourth Step for EMG: ___________ muscle; nerve - ANS With EMG can get info on... 1) The function of the _____ tested 2) The function of the ________ that supplies that muscle needle; AP (action potential) - ANS EMG -Done by sticking a ______ into the muscle of interest -Record the electrical activity generated from ______ generated in the muscle fibers short - ANS Normally when you insert the needle into the muscle there is a ______ burst of activity **findings: normal, increased activity, decreased activity quiet; denervation; spontaneous activity; inflammatory - ANS EMG- Spontaneous Activity -A muscle at rest is usually electrically _______ -Specific changes are seen if there has been ______ -"___________ ___________" - there will be potentials firing on the screen that are abnormal and are signs of muscle irritability **usually evidence of denervation or if muscle is injured in a way that muscle can't communicate with nerve well (ex. different _______ conditions) motor units - ANS After spontaneous activity, you ave the patient activate this muscle, and you can see (and hear) the muscle fibers (known as _______ ________) firing amplitude; duration; phases - ANS How do we describe MUPs (motor unit potentials)? 1) _______ (normal, increased, decreased, variable) 2) __________ (normal, short, long) 3) ________ (number of times it crosses baseline; consider polyphasic more than 4) neuropathic units - ANS -nerve problem -one MU loses innervation, so another MU can come in and innervate (creates larger unit) -longer duration , high amplitude, polyphasic (since not all firing in sync) myopathic units - ANS -muscle fibers die off -tinier response -short duration, small amplitude and polyphasic Fasciculation - ANS muscle fiber firing on its out without neural input abnormalities; neurologic - ANS EMG- Interpretation 1) Assess pattern of _______ 2) Localize to a specific ________ location (plexus, nerve root/radiculopathy, myopathy, mononeuropathy) Interpretation - ANS First Step-- ________ - History -Physical Examination -Nerve Conduction Studies -Electromyography radiculopathy - ANS Look for abnormalities in multiple muscles that have the same nerve root innervation with different peripheral nerve root innervation Ex. L5 -Tibialis anterior (L4, L5) innervated by deep peroneal nerve -Peroneus longus (L5, S1) innervated by superficial peroneal nerve -Gluteus medius (primarily L5) innervated by superior gluteal nerve Radiculopathy - ANS ________ is a nerve root compression (commonly from degenerative disc disease) resulting in demyelinating and/or axonal injury to the motor spinal roots. sensory - ANS Radiculopathy: -______ fibers are usually spared because dorsal root ganglion houses sensory cell bodies and is usually not compressed. physiologic; differentiating; Rarely - ANS Advantages of using EMG in Radiculopathies -Assesses _______ integrity of nerves - Great for ______ radiculopathy versus peripheral neuropathy or entrapment neuropathy. -For example, CTS vs C6 radic. -______ false positive exclude; confounding - ANS Limitations of using EMG in Radiculopathies -EMG can never be used to ______ radiculopathy. -________ changes occur in older patients (Diabetes with polyneuropathy; Remote polio) demyelinating; axon; 3 - ANS Limitations of using EMG in Radiculopathies -_______ lesions will not be picked up on needle EMG because the axon is preserved. -Even when there is ______ loss, it may not involve enough fibers to yield a positive needle EMG study. -Timing of the study is crucial. (Too early (within_____ weeks)) (abnormalities may not come out yet) confirming; characterizing; studies - ANS What's the role of electrodiagnostics in polyneuropathy? 1) _______ that a neuropathy is present 2) __________ the neuropathy in terms of: Demyelinating vs axonal Sensory/Motor Distribution Chronicity 3) ________ utilized Sensory and motor nerve conduction EMG F waves (H reflex) clinical; normal; cause - ANS Are electrodiagnostics useful to confirm a neuropathy? YES! But........ 1) They should support the _____ diagnosis 2) May be _____, even with a neuropathy present -Early in the neuropathy -Small fiber neuropathy 3) They may be abnormal, but it is not the ______ of the symptoms. electrodiagnostic; lower; three - ANS Motor Neuron Disease Findings Example: ALS -Clinical and _______ findings of upper and lower nerve involvement without other etiology identified -Electrophysiological tests used to demonstrate involvement of the ______ motor neuron in affected and frequently also in CLINICALLY NOT affected body regions. -Four body regions can be evaluated: (brain stem, cervical, thoracic, lumbosacral) **need at least _____ different body segments