Neuromuscular

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Vasculitic neuropathy Labs/studies: 1. NCS: Look nL but are asymmetric
2. CSF: nL
3. Sensory n. bx: vasculitis
4. Muscle bx: increases yield
Vasculitic neuropathy Clinical Features: 1. ASYMMETIC weakness & sensory loss
2. Painful
3. Tx w/ immsupp
Vasculitic neuropathy Etiologies: 1. Pimary PNS vasculitis 25-30%
2. Systemic Vascultitis (RA SLE PAN Wegener)
3. DM
4. Leprosy
5. Sarcoid
6. Amyloidosis
7. Amphetamine-induced
Vasculitic Neuropathy Definition: Primary attack on small to medium sized bl vessels-->ischemia and infarction of isolated periph n.
Axonopathy Clinical features: 1. Distal wknss & atrophy
2. Distal sensory loss
3. Tingling/burning (stocking/glove)
4. Loss of AJ
5. No facial wkness
6. Chronic course
7. (decr potential for Tx/Rx)
Axonopathy Definition: Degeneration of distal axons w/secondary degen of myelin sheaths. Length-dep process.
Axonopathy Common Causes (categories): 1. Metabolic
2. Endocrine
3. Drug/toxic
4. Idiopathic
Myelinopathy Labs/studies: 1. NCS: slow prolonged distal & F-wave latencies
2. CSF elev protein
3. Albumino-cytologic dissoc
4. Sensory n. bx = demyel-remyel and inflamm.
Myelinopathy Clinical features: 1. Prox AND distal wknss
2. Facial wkness
3. Variable sensory loss
4. AREFLEXIA
5. Acute or chronic course
6. Often good recovery
Myelinopathy Etiologies: 1. Idiopathic (GBS CIDP aMAG Ab)
2. Hepatitis
3. Sarcoid
4. Mononucleosis
5. Lymphoma
6. HIV
7. Lead intox
8. Diphtheria (w/ l/o pupil accom)
Myopathy Name major inflammatory myopathies: 1. Polymyositis
2. Dermatomyositis
3. Inclusion body myositis
4. HIV myositis
Myopathy Polymyositis Clinical Features: 1. Age <20
2. Subacute to chronic onset
3. LIMB GIRDLE wknss
4. Neck flexors/pharyngeal m affected
5. Myalgia
Myopathy Polymyositis Associated dz: 1. Interstitial lung dz
2. Cardiomyopathy
3. ARRHYTHMIAS
4. Esophageal paresis
Call Pulm, Cards, ENT
Myopathy Polymyositis Labs/Studies: 1. CK 5-10x nL
2. Assoc w/aAbs: Jo-1 PM-1 Mi-2
3. NCS/EMG: +Sharp waves/fibs and low ampl short dur polyphasic MUP
4. Muscle bx: necrosis phagocytosis endomysial inflamm (mix of CD8/MO
Myopathy Polymyositis Pathophyz: Cell-mediated autoimmune
Myopathy Dermatomyositis Pathophyz: Humorally mediated autoimm dz
Myopathy Dermatomyositis Clinical features: 1. Children and adults
2. Subacute to chronic onset
3. LIMB GIRDLE wknss
4. ERYTHEMATYOUS SCALING MALAR AND EXTENSOR RASH w/ MCP/ICP Gottron's papules.
5. Periorbital edema
6. Joint contractures
Myopathy Dermatomyositis Labs/studies: 1. CK elevated but no corr w/ dz
2. NCS/EMG: Pos Sharp wvs/fibs w/ small ampl and brief dur polyphasic MUP
3. Muscle bx: PERIFASCICULAR ATROPHY w/ perimysial/perivascular inflamm w/CD4 and B. Also MAC imm dep'n.
Myopathy Dermatomyositis ASSOCIATED dz.: 1. MALIGNANCY
2. ARRHYTHMIAS
3. Angina
4. Uveitis
5. Retinopathy
6. Interstitial lung dz
Call Cards Pulm Ophtho
Myopathy Myositis Inclusion Body Myositis Epid & Clinical features: 1. MC inflamm myop >50 yo
2. M>F
3. ONSET LATE ADULT
4. CHRONIC
5. DISTAL ARM/PROX LEG: WRIST & FINGER FLEXORS AND QUADS
6. Dysphagia
Myopathy Myositis Inclusion Body Myositis ASSOCIATED dz: None, & no assoc w/ malig!
Myopathy Myositis Inclusion Body Myositis Labs/Studies: 1. CK<10x nL
2. NCS/EMG: MUP are COMBINED NEUROPATHIC and MYOPATHIC/ SNAPs often abn.
3. Muscle bx: rimmed vacuoles w/eosinophilic inclusions (trichrome)/amyloid dep'n/ENDOMYSIAL INFLAMM.
Myopathy Myositis Inclusion Body Myositis Treatment: ?? Prednisone or IVIG
Myopathy Myositis Polymyositis/dermatomyositis Treatment: 1. Prednisone
2. MTX
3. Cyclophsphamide
4. Cyclosporine
5. IVIG
Myopathy Myositis HIV Myositis Time of onset: Early in the course of dz
Myopathy Myositis HIV Myositis Clinical features: 1. Painless
2. Limb-girdle wknss (no pharyngeal m. or resp m. involvement)
Myopathy Myositis HIV Myositis Labs/studies: 1. NCS/EMG: similat to PM/DM
2. Muscle bx: interstitial perimysial inflamm and necrosis w/ nemaline rods in 50%.
Myopathy Myositis HIV Myositis Treatment: 1. Prednisone
2. PEX
3. IVIG
F response Define: Small CMAP (1-5%). Pure motor, non-synaptic, antidromic to spine AHC-->firing for small # of AHC-->orthodromic to muscle. Gain must be 200 mcV. Turn cathode around. nL times: 25-32 msec UE and 45-56 msec LE. Often absent in peroneal n. Reinforce w/Jendrassik. F's abent in sleeping/sedated Pts.
F response Uses: Early GBS
C8-T1 and L5-S1 radic (b/c these have recordable muscles)
Polyneurop
Internal control
F estimate: Fest=(2X/NCV * 10)+1msec+Z
(the 10 is for conversion to msecs)
X=Stim to AHC (msr by distance/NCV)
Y= AHC turnaround (~1msec)
Z=Distal latency
(uses nerve length, NCV, latency; helps determine whether delay in F resp. is truly prox n. segment problem)
NMJ EMG: -CMAP nL post synaptic (ie. MG)
-CMAP low ampl at rest in pre-synaptic (ie. LEMS, botul)
-NORMAL NCV and latency
-Use repetitive stim or exer testing to show NMJ dz.
Myopathy EMG: -If Myop affects PROX muscle, nL CMAP ampl & distal latencies
-If distal muscle, decr CMAP ampl.
-nL NCS and latency unless superimposed neuropathy
Demyelinating polyneuropathy DDX: HEREDITARY:
HMSN I (CMT)
HMSN III (Dejerine-Sottas)
HMSN IV (Refsum)
HNPP
Adrenoleukodystrophy
Metachrom. Leuk.
Krabbes
Cockayne's
Neimann-Pick
Cerebrotendinous xanthomatosis
ACQUIRED
-CIDP (idio, HIV, MGUS IgM, aMAG, osteosclerotic myeloma, Waldenstrom)
-MMN w/condxn block +/-GM1 Ab
-Diptheria
-Toxic (Amiodarone, Perhexiline, arsenic, glue-sniffing, buckthorn shrub)
Conduction block Describe: 1. Any drop in either CMAP ampl or area >20% (if suspect incr temporal dispersion w/phase cancellation, use >50% drop between prox & distal sites)
2. Any incr in CMAP dur of >15% (abn temp disp).
Demyelination EMG: 1. Any motor, sensory, or mixed NCV <35 msec (UE) or 30 msec (LE)
2. Amplitude nL
Axon loss EMG: 1. Decreased amplitude
2. nL or slightly decr NCV
3. nL or slightly decr latency
SNAP low amplitude (dx?): Definite disorder of peripheral nerve.
SNAP conduction velocity Compare to CMAP CV: Direct msrmt (no NMJ or muscle to interfere)
SNAP Normal amplitude and stim qty.: 10-20 mcV (vy diff fr CMAP)
and usu stim = 5-30 mA
CMAP Define latency: A time including nerve travel, NMJ, and depolarization time of muscle
CMAP duration: Time from initial deflection to 1st baseline crossing. Measures synchrony and tends to increase in conditions slowing some fibers but not others (eg demyel. dz)
CMAP ampl Definition and stim qty: # of muscle fibers that ultimately fire.
Gain = 2-5 mV
Stim = 10-50 mA, incr by 10s to 50
Motor Conduction velocity Definition and mechanism: CV not same as latency! (requires 2 stim sites: measure at muscle: subtracting time 1 from tine 2 will erase distal nerve, NMJ, and muscle time, leaving only NCV. Both CV & latency measure only FASTEST FIBERS.
CMAP ampl decrease Causes: 1. Axonal neuropathy
2. Conduction block betw stimulator and recorded muscle
3. some NMJ dz and myop.
Myopathy categories (6): 1. Muscular Dystrophies
2. Inflammatory
3. Toxic
4. Congenital
5. Metabolic
6. Endocrine
NMJ dz (5): 1. MG
2. LEMS
3. Botulism
4. Toxic
5. Congenital
Neuropathy broad causes (3): 1. Entrapment
2. Polyneuropathy (demyel, axonal)
3. Mononeuritis multiplex
Plexopathy broad causes (6): 1. Radiation
2. Neoplastic
3. Entrapment
4. DM
5. Hemorrhagic
6. Inflamm.
Radiculopathy broad causes (6): 1. Disk
2. Spondylosis
3. Neoplastic
4. Infarction
5. Infectious
6. Inflammatory
Sensory neurop. categories (4): 1. Paraneoplastic
2. Autoimm
3. Toxic
4. Infectious
Motor Neurop categories (4): 1. ALS
2. SMA
3. Polio
4. Monomelic amyotrophy
Overall PNS organization: Muscle--myopathy
NMJ
Nerve--neuropathy
Plexus--plexopathy
Root--radiculopathy
Motor or sensory neuron--neuronopathy
EMG: List the spontaneous discharges of NMJ/muscle fibers (5)w/discharge, source, rate, stability and pattern.: 1. Endplate noise MEPP 20-40Hz irreg pattern
2. Endplate spike terminal axon twig 5-50Hz sputtering
3. Fibrillation m.fiber 0.5-10Hz occ hi (30Hz) +stable +regular
4. Positive wave (same as fibs)
5. Myotonia m. fiber 20-150Hz wax/wane amplitude & regularity
EMG: List the spontaneous discharges of Motor units (5: one is odd): 1. cplx repet discharges Multiple time-linked m. fibers (appear as discrete firings unlike motor unit) 5-100Hz usu stable&perfectly regular
2. Fascics Motor units 0.1-10Hz not stable&irreg.
3. Myokymia Motor unit 1-5Hz (if inter-burst) 5-60Hz (if intra burst) not stable & burstng.
4. Cramp Motor unit 20-150Hz Not stable Interference pattern of several MU
5. Neuromyotonia Motor Unit 150-250Hz Not stable Decrementing amplitude & waning
EMG: muscle fiber action postential (MFAP) is seen under what consitions?: Spontaneous depolarization from 1. denervation
2. depolarization of an individual axon twig->NMJ->fiber
Blink reflex: describe anatomy and what makes up R1 and R2.: Afferent: V1
Efferent: VII
R1 circuit: V1 to Vmain nucleus to VII nucleus to VII (ipsi)
R2 circuit: V1 to Vspinal nucleus to ipsi and contra VII nucleus and VII nerves.
EMG: name two common anomalous innervations or the limbs: 1. Martin-Gruber Anastomosis. (15-30%: fibers from Median n. travel with Ulnar n.)
2. Accesory peroneal nerve. (connection between superficial peroneal n. and ext dig brev.)
EMG: list common repetitive stim patterns: normal 3Hz, postsynaptic dz 3 Hz, and presynaptic dz 3 and 50 Hz.: 1. EPP ampl 40-32-26-20-26 (last rise b/c of secondary stores; no discharge below threshold (safety margin)
2. 1st EPP above threshold: all others decrementing below.
3. Smaller disharges than presynaptic: all below threshold.
4. Initial discharges very small but building above threshold b/c of retained calcium at high firing rate.
Repetitive stim technical factors: 1. T>33
2. Arm or m. of interest immobilized
3. Supramax stim
4. AChE inhibitors withheld 4 h prior to study.
Martin-Gruber and Carpal Tunnel Syndrome: what doae a median n. trace look like?: 1. Fast CV (b/c some of the fibers being tested to not go through the canal)
2. Prox>distal CMAP amplitude
Effect of temperature on NCS & EMG?: 1. Decr CV
2. Incr distal latency
3. Incr ampl and duration (CMAP & SNAP)
4. MUAPs may be slightly large & polyphasic as well.
Effect of age on NCV? CMAP & SNAP?: 1. NCV: birth = 50% of adult CV (incomplete myelination)
2. 20-40 = nL
3. >40: decr by 0.5-4.0 msec/decade.
4. CMAP/SNAP: decr w/ age (50% of nL by age 70)
5. MUAP: incr duration w/ age.
Effect of height on NCV?: decr NCV by 2-4 m/s below lower limit of nL for extreme height (6'10", for ex.)

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