Motor disfunction/reflexes Flashcards
Deep tendon reflexes
aka stretch, myotatic
Spindle -> gray matter -> alpha (inhibits antag)
Wide normal range -> assym, symptoms
Hypo: peripheral sensory, gray or motor (lower)
- trace = flicker
- “0” = no movement even with distraction
Hyper: upper motor neuron damage
- clonus - stretch -> rhythmic beats
- pathologic spread (nearby muscles)
Jaw jerk: CNV Biceps: C5,6 Triceps: C6,7 Brachiorad: C5-7 Finger flex: C6-8 (musc-cut) Patella: L2-4 Achilles: S1,2
Superficial reflexes
Scrape skin -> nearby muscles
Sensory -> spinal -> brain -> spinal -> motor
- assesses spinal cord damage
Abdominal: umbilicus towards quadrant (T7-12) - abnormal if obese, mult preg, old, etc Cremaster: medial thigh -> elevate testes (S1) Plantar: scrape -> down-going toe (S1-2) - often + withdrawal Anal wink: S2-4 Corneal, nose tickle: V5 -> V7 Gag: V9 -> V10
Pathological reflexes
Babinski = superficial scrape -> up-going toe + fanning
- normally abolished by 6 mo
Reflex pathology
Muscle or NMJ: dec stretch, proportional
Peripheral nerve: dec stretch, more than proportional (afferent limb)
Nerve root: dec stretch, proportional, rare change to superficial (overlap)
Spine/brain stem:
- stretch hypo at, hyper below
- acute initial hypo/shock/diaschisis (degree and time proportional to damage) -> extreme hyper
- superficial hypo below/at, normal below
Cerebellar: normal or hypo, pendular (poorly checked)
Basal ganglia: no effect, may have primitive
Cortex: hyper stretch, dep or absent superficial, may have Babinski
- bilateral -> primitive, emotional released from inhibition (pseudobulbar)
Primitive reflexes
Suppressed unless b/l cortical disfunction
Feeding (rooting, suck, bite)
Grasp
Glabellar - tap on forehead -> blink
Oculoceph, nuccoceph
Visceral reflexes
Pupillary - CN 2 -> 3 Oculo-cardiac - CN 5 -> 10 - eyeball pressure or traction -> brady Baroreceptor, carotid sinus - CN 9 -> 10/SNS Bulbocavernosus - S2-4 Rectal (internal sphincter) - S2-4
Overview of upper motor neuron disease
Distal weakness
Inc tone (“clasp knife”), reflexes (-> clonus)
No atrophy
+ Babinski (LE), Hoffmans (UE)
+ LMN disease = “motor neuron disease” - ex ALS
Overview of lower motor neuron disease
Paralysis, variable
Dec tone, DTR
Significant atrophy
Fasciculations (discharge of motor unit, visible)
+ UMN disease = “motor neuron disease” - ex ALS
Overview of NMJ disease
Normal function - AP -> quantum vesicle release of Ach -> end-plate potential -> spread (4 m/s) -> Ca entry -> term by end-plate Ach-esterase
Variable strength - MS - decreases with repetitive - Lambert-Eaton - increases with repetitive Normal tone and reflexes, no atrophy Often improves with cold (ice pack test)
Overview of muscular disease
Dec strength (proximal, symmetrical) variable atrophy (pseudohypertrophy with storage dis) Normal tone and reflexes Aching, high CK EMG -> small, brief polyphasic Biopsy -> special stain, genetic
Destructive -> progressive weakness, wasting
- inflammatory - polymyositis, dermatomyositis (+ rash)
- metabolic - ex thyroid, statins
- dystrophy = genetic, r/o metabolic and inflamm, progressive, not curable
- Duchenne’s, Becker’s, myotonic, LGMD
- inclusion body - begins distal!
Functional - channelopathy
- myotonic, paralysis
Overview of peripheral nerve disease
Often includes sensory (paresthesias)
- Root/radiculopathy - rarely sensory dt overlap
- peripheral - specific sensory and motor distribution
- C5 -> shoulder abduct and ext rotators
- C6 -> elbow flexors
- C7 -> wrist and finger extension
- C8-T1 -> intrinsic hand
- L3-4 -> knee extension
- L5 -> great toe, ankle extension
- S1 -> plantar flexion
Positive - pain, dysesthesia
Negative - loss of sensation, weakness, areflexia
Irritant - fasciculations, paresthesias
Mononeuropathy - Tinel’s sign - trauma, compression
- multiplex - multiple, assymetrical - vasculitis
Polyneuropathy - stocking -> glove - metabolic
- axon - DM, EtOH
- myelin - GBS, B12
Radiculopathy - regional, worsened by provocative
Nerve conduction studies
Standard NCS - stimulate peripheral nerve -> outside of muscle
- measure latency (prolonged demyelinating)
-> compound muscle potential
(amplitude dt loss of axonal or NMJ conduction)
Electromyography - similar but needle inside muscle
- spontaneous activity (damage to nerve)
- size of motor unit potential
(inc if axonal injury due to collateral sprouting)
Compound nerve action potential - measure downstream on nerve
- only measures large, myelinated (dominate early)
MS - repeat stimulation -> decreasing muscle potentials
Struture of peripheral nerves
Connective tissue - endoneur, perineurium, epineurium
- nerve roots less protected from traction, trauma
Vessels - high metabolic demand, little reserve - collaterals usu sufficient but ischemia poorly tolerated
Myelination - Schwann -> inc velocity
- large myelinated - 40-70 m/s - most sensory (somatic, spindle, Golgi)
- intermediate - touch, proprioception
- lightly myelinated - sharp pain, autonomic pregang
- small, unmyelinated - 1 m/s - aching, burning pain, temp, SNS postg
Microtubules - necessary for transport of mitochondria, enzymes
- orthodromic (to periphery), antidromic (to nerve)
- trophic factors both directions (ex atrophy with LMN damage)
Innervation - nervi nervorum - most SNS -> pain with injury
Motor unit physiology
Nerve fiber -> multiple motor fibers (motor unit)
- impulse -> motor unit potential (amplitude = #, duration = range of latency)
- effort -> inc # of units, inc firing rate
- uneven LMN (neuron or axon) damage -> high firing rates of remaining
- UMN damage -> low firing rates (sim to low effort)
Fasciculations - entire motor unit (visible) dt irritation or damage of nerve -> spontaneous impulses
Fibrillations - hyperirritable motor fibers dt denervation (days-weeks)
- detect only through needle EMG
ALS
amyotrophic lateral sclerosis, aka “motor neuron disease”
LMN degeneration (anterior horn) -> fascic, atrophy
CN nuclei degeneration -> tonge, face, pharynx, palate
- eye movements spared
UMN degeneration (corticobulb, corticospinal) -> spastic, hyperreflex
40-60 yo Assymetric -months> b/l -> 3-5 y (resp failure) Toxins, low chronic inflammation Genetic -> lack of antioxidants Riluzole slightly delays progression
“Motor neuron disease”
Both upper and lower
Most common ALS
Variations: (all progress to ALS)
- primary lateral sclerosis (UMN -> both -> 10 yrs)
- progressive muscular atropy (LMN only -> both)
- progressive bulbar palsy (cranial only -> general)
Rare inherited ALS forms
LMN only but degenerative
- Werdnig-Hoffman - infant
- Kugelberg-Welander - children, young adults
Mononeuropathy
Trauma (acute) or compression, entrapment (chronic)
Higher risk if underlying polyneuropathy
Negative (loss of sensation, weakness, atrophy), positive (pain, paresth)
- Tinel’s sign - tap on site -> electrical paresthesia
Carpal tunnel - median nerve
- congenitally small tunnel, thick ligaments, inflammation
- numb, paresthesias in radial digits, thenar weakness/atrophy
- pain radiates past median nerve, unpredictable
Ulnar - elbow joint problems, flexion pressure
-> intrinsic atrophy, sensory loss
- bicycle riding -> wrist (minimal sensory)
Radial - humerus, lateral elbow -> extensor weakness, dorsal sensory
- wrist pressure (handcuffs) -> superficial -> paresth, numb dorsal
- supinator -> deep branch -> weak extensors, spares brachiorad
Lateral femoral cutaneous - inguinal (weight, preg, belt) -> lat thigh
Fibular - fibular head -> numb dorsal, weak dorsiflex, eversion
Tibial - medial ankle trauma, RA
Interdigital neuromas - between metatarsal heads
Thoracic outlet syndrome
Mechanical compression in upper thorax
- ex cervical rib, scalene, connective tissue
Vascular - subclavian or axillary in certain arm positions
- shoulder dep, arm abd and ext rotated, neck rotation and extension
- ischemic sx, no pulse
Neurogenic - lower brachial plexus -> ulnar nerve, ulnar side of elbow
Radiculopathy
Damage to nerve root
Herniation (young)
Degenerative (old) -> thickening -> narrowed foramina
- most common lower lumbar, mid-lower cervical
Sx follow nerve distribution - weak, dec reflex, less sensory (overlap)
Distal sx + spinal pain - burning, aching
- worsened by stretch (straight leg raise, lat neck bend) or compression (arch back, compress neck) or cough/strain
Polyneuropathy clinical
Affects longest nerves first -> stocking -> glove
- usu symmetrical
- numb, paresthesia
- sometimes proprioception/vibration (-> gait, Romberg)
- can have weakness, loss of reflexes
- small fibers - may lose pain, temp
Axon (dec transmission) or myelin (dec velocity) or both
May be idiopathic (25-40%, older, slowly progressing)
NCS/EMG routine
CBC, ESR, glu, A1c, TSH, serum protein electrophoresis
Acute - ? GBS, acute metabolic or toxic
Consider RPR, Lyme, HIV, ANA, rheumatoid, anti-neutrophil, heavy metals, porphyrins, sural or skin biopsy (young)
f/u months, sooner if rapid
Tx underlying cause, foot care, stability (cane)
Charcot-Marie-Tooth
aka hereditary motor sensory neuropathy (HMSN)
Genetic - multiple genes/defects -> genetic testing
- Type 1 - autosomal dom -> demyelin (inc latency on NCS)
- Type 2 - axonal degen
Begins in childhood -> high arches and hammer toes dt weakness
Slowly progressing
Other familial neuropathies - may not have clear pattern
- NCS/EMG -> genetic
Metabolic polyneuropathy
Most common = DM -> axons and myelin
EtOH, B12 deficiency -> myelin
Pyridoxine, porphyria, sprue
Heavy metals, solvents, industrial (carbon disulfide)
Meds - chemo, seizure, ARV’s
Syphilis, Lyme, HIV
Leprosy -> patchy
Abnormal proteins - amyloid, monoclonal gammopathy
Immune polyneuropathy
Acute immune demyelinating polyradiculoneuropathy
= Guillain-Barre syndrome (aka AIDP)
Antibodies vs myelin
- post viral/diarrheal - Campylobacter
Rapid weakness -> respiratory paralysis, autonomic
Early loss of reflexes (muscle stretch), ascending or descending, +/- sensory
CSF - high protein, no change cells (WBC)
Most recover, shorten with IVIg, plasmapheresis
Chronic (CIDP) - relapsing or progressing AIDP
- > assymetric weak, sensory, areflexia
- long-term immunosuppression
Mononeuritis multiplex
Multiple patchy mononeuropathies
Diabetes - poorly controlled, systemic sx (weight loss, fatigue)
-> lumbar plexus, rarely brachial
-> weak quad, adductors, iliopsoas absent patellar reflex (amyotrophy)
- control DM, IVIg, pulse steroids
Vasculitis
- SLE, polyarteritis nodosa, Sjorgren’s, Wegner’s
- infectious - Lyme (syphilis, HIV)
Idiopathic - rare -> middle age men, brachial plexus
- painful onset -> atrophy, weakness -> slow improvement
- “neuralgic amyotrophy” aka Parsonage-Turner, “idiopathic brachial neuralgia”
- IVIg, pulse steroids
Myasthenia gravis
Autoimmune vs nicotinic Ach receptors (end plate)
-> more Ach needed = dec safety factor (excess Ach above necessary)
- not all impulses followed by contraction -> fewer fibers involved per unit
Young adult women, middle aged men (thymic tumors cross-react)
Ocular (ptosis, diplopia) -> bulbar (pharynx, palate) -> generalized -> diaphragm, autonomic instability
- will generalize in first 2 years or not at all
-> weakness -> neurogenic atrophy (specific type II fibers)
Sustained, repetitive -> depletes presynaptic Ach -> worsens
- nerve stimulation -> decreasing compound muscle potential
Tx: immune suppression (IVIg, plasma exchange, meds/steroids)
Ach-esterase inhibitors (pyridostigmine)
thymectomy
Myasthenic syndrome
aka Lambert-Eaton
Ca channel defect in pre-synaptic -> dec quanta of Ach released
Improves with repetitive (facilitation)
Paraneoplastic - esp bronchogenic small-cell
Tx: Ach releasing - 4-aminopyridine
Meds/toxin vs NMJ
Botulism - injection, wound, infant gut
- cleaves synaptobrevin -> no vesicle release
- neck -> descending paralysis -> autonomic
Curare - blocks nicotinic receptor
Depolarization block - excess stim -> no repolarization
- organophos, insecticide, chemical warfare
Functional myopathies
aka channelopathies
Little wasting, atrophy vs destructive
EMG myotonic potentials, clinical dx, rare!
Myotonia -
- congenital myotonia - Cl- channel - improves with exercise
- paramyotonia congenita - Na channel - worse exercise, cold
Periodic paralysis - generalized periodic paralysis
- worse after meal, exercise
- thyrotoxic or familial (hypo, hyper or normoK, Anderson syndrome)
-
Metabolic myopathies
Acquired
- thyroid - both hypo and hyper
- Rx - statin, colchicine, hydroxychloroquine, EtOH
Genetic
- impaired metabolism of carbs or fats -> intracellular inclusions, myoglobinuria, cramping with exercise
- poorly defined inclusions - nemaline, myotubular
- mitochondria - excess replication of abnormal mitochondria -> accum
- eyes (tonic activity), heart, also brain
- exercise intolerance, elevated lactate
Inflammatory myopathies
aka myositis
Acquired - sarcoidosis, HIV, trichinosis Autoimmune - often paraneoplastic (lymph, lung, bladder, breast, ovary) -> immunosuppression, treat CA - often high ESR, CRP, CK
- polymyositis - 30-60yo, insidious, symmetrical, proximal (stairs, lifting of arms), sore
- dermatomyositis - 5-15yo, 50-60’s yo - usually underlying CA or auto
- insidious, proximal, more sore
- rash - red/purple - eyelid (heliotrope), extensor joints (fingers/toes, elbow, knee), face, chest, affected muscles
- inclusion body - > late middle-age, insidious
- > proximal, finger/wrist flexion
- inclusion bodies on biopsy, no tx
Duchenne muscular dystrophy
X linked -> dystrophin - attaches actin to membrane
Infancy - second protein with same fx
-> sx in childhood (walk don’t run)
- pseudohypertrophy of calves, hip and shoulder girdle weakness
- very high CPK, aldolase
-> progressive (wheelchair) -> death (20’s) dt cardiomyopathy
No tx, steroids may prolong
Becker - same gene, less severe mutation -> later onset
Myotonic dystrophy
Myotonia (delayed relaxation) + dystrophy
Type I - autosomal dominant - myotonic protein kinase
- trinucleotide repeat (longer -> earlier, usu childhood, young adult)
- distal - hands, face, neck
- non-neuro - frontal balding, testicular atrophy, DM, cardiac arrhythmias, cataracts
- progresses slowly -> respiratory, PNA in 40’s
Type II - complex repeat (CCTG) - transcription factor
- 20-30’s, less common
- proximal - elbow extension, hip flexor
Limb girdle muscular dystrophy
Heterogenous, 15 different mutations - some recessive or dominant
Adolescence, adult
Proximal -> slow progression or spontaneously stop
Facioscapulohumeral dystrophy
Chromosome 4 hypomethylation
- 2 defects (recessive, dominant) -> gene or methylation
Adolescence, early adult
Face -> scapula and upper arm
Slow progression, normal life expectancy
Mental retardation, cardiac arrhythmias
Oculopharyngeal dystrophy
Trinucleotide repeat, autosomal dominant
-> accumulation of intranuclear mRNA trafficking protein
40’s -> ptosis -> extraocular paralysis -> swallowing
Manage sx (feeding tube)
Must r/o MG, mitochondrial (Kearn-Sayer)
