Transcript EVALUATION - VCU Physical Medicine & Rehabilitation

FOCAL NEUROPATHIES
William McKinley MD
Associate Professor PM&R
Virginia Commonwealth University
ETIOLOGY
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Compression (any external pressure)
Entrapment (anatomical compression site)
Repetitive trauma/overuse
Direct trauma (missile, laceration)
ischemia
Stretch
PATHOPHYSIOLOGY:
Compression vs Ischemia
 Compression vs Ischemia
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Focal demylination vs axonal injury
 Mechanical compression
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30 mmHg - decreased blood flow
30-60 mmHg - block of axoplasmic transport
>60 mmHg - absent blood flow
 Ischemia
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15-45 min causes dec conduction (neuropraxia)
• less than 60 min - reversible
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greater than 8 hours - not reversible
MECHANICAL COMPRESSION
 Pressure will lead to:
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paranodal demyelination
• conduction abnormalities (slowing, conduction
block)
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Axonal injury - wallerian degeneration
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Pressure selectively affects
• large Type A fibers (motor, LT, vib) > small Type C
(pain/temp)
• Peripheral (sensory) >central (motor) fibers
Nerve Recovery after injury
 Peripheral N’s (unlike CNS) can regenerate.
 Remyelination - takes up to 3 months
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however myelin is thin and internodes short (slow!)
 Axonal Reinnervation
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Collateral Sprouts from adjacent intact axons
Growth cones (NGF) from axon stump - span “gap” &
travel via endo tube 1-3 mm/d (1 inch/month)
• Abberant re-innervation & neuroma
• Muscle atrophy irreversible begins at one year
• Sensory receptors survive for many years
CLASSIFICATION OF NERVE
INJURY
 Seddan’s Classification
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Neuropraxia - local cond. “block” with
demyelination (reversible)
Axonotmesis - axonal injury w/wallarian
degeneration (endoneurium intact, reinnervation possible)
Neurotmesis - complete disruption of axon and
endoneurial sheath (no innervation possible)
PM&R approach to the patient
with focal neuropathy
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History
PE
?Electrodiagnosis
?additional tests (rad, U/S, vasc studies)
PHYSICAL EXAM
 Inspection, palpation, Motor/Sensory, DTR,
provocative tests
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Tinels, phalens, pinch, froments, spurlings,
SLR
 Know nerve anatomy & innervations!
 Know common sites of entrapment!
HISTORY
 Timing: acute vs. insidious, ? Inciting event,
what…better/worse
 Occupation & Handedness: association with
repetitive trauma
 PMH: related to diseases? (DM, CTD)
 Location of: paresthesias (not always
anatomically distributed), numbness,
Weakness
DIFFERENTIAL dx
 Peripheral neuropathy (DM, ETOH, uremia;
drugs, toxins)
 Plexopathy
 Radiculopathy
 “Double Crush” or “vulnerable nerve
syndrome (ie: radic + focal neuropathy)
 Spinal Cord Injury
 Myofacial/referred pain
Electrodiagnosis (Edx):
 Can assist with:
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localization of injury
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extent of injury (mild, moderate, severe)
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assessment for underlying dz (DM, hypothy)
and/or concomitant issues (“double crush”)
Electrodiagnosis = NCS + NEE
 Sensory (SNAP) NCS
 Motor (CMAP) NCS
 Proximal (“late”) NCS: (H Reflex, F Wave)
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limited use in focal neuropathy
 Needle EMG (NEE)
NCS findings with Focal
Demyelination
 Loss of conduction
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prolonged latency, slow CV
 Abnormal proximal (to injury) stim response (dec amplitude) compared with distal
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conduction block
if normal distal (to injury) amplitude = no axonal
degeneration
NCS findings with Axonal loss
 NCS amplitude (measures # of fibers) loss
• Motor and sensory amplitudes can help predict degree of axon loss
(comparison: with normal, proximal vs distal & side to side)
 Distal wallerian degeneration
• depends on distance (injury site to muscle)
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Preservation of sensory NCS for up to 10
days
preservation of motor NCS for up to 7
days (NMJ)
NEEDLE EMG (NEE)
 Severe compression will cause axonal
injury and lead to signs of muscle fiber
injury (positive sharp waves, fibrillations).
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Needle EMG is helpful 3- 4 weeks post injury
 Nerve fiber recruitment is assessed.
 “Pattern” of involvement will help localize!
 You can also monitor “progression or
recovery” (reinnervation) with needle EMG.
Conduction Block
CB & Axonal loss
Case Example: AXONAL loss vs
DEMYELINATION
 Ulnar Motor NCS to ADQ muscle
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Rt Amplitude = 10 MV (BE), 10 MV (AE)
Lt Amplitude = 5 MV (BE), 2.5MV (AE)
 Thus: Abnormal Lt ulnar motor with:
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50% Axonal loss, 5 vs 10 (BE) - Lt vs Rt
50% Conduction block, 2.5 vs 5 -( AE vs BE)
LT
PROXIMAL NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Facial
Interosseus
Bell’s palsy
Facial, Frontalis
Sp Accessory
Neck
Tumor, Surg
Upper Trapezius
Long Thoracic
Supraclavic
Trauma, Stretch Serratus Anterior
PROXIMAL NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Suprascapular
Suprascp Notch
Backpack palsy
Supra, infraspinatus
Musculocutaneous
Pierces Coracbrachial
Overuse
Biceps, Brachials
coracobr.
Axillary
Axilla
Hum.fx
Deltoid teres min
MEDIAN NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Median
Lig. Struthers
LOS
Pro Teres Involved
Median
Pro Teres M
Pronator
Teres Syndrome
Pro Teres. Spared
Median
A.I.N
Anterior
Int Syn
FPL, FDP (I II),
PQ
Median
Carpal Tunnel
Carpal Tunnel
Syndrome
Intrinsic hand
Median Neuropathy
 Carpal Tunnel Syndrome- most common
entrapment syndrome
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CT encloses 9 tendons and median nerve under
transverse carpal lig.
CTS site is 3-4 cms distal to wrist crease
CTS bilateral in 55%
CTS: Clinical exam
 Symptoms: Numbness to lateral 3 digits,
weakness in flexing fingers or abducting
thumb, nighttime exacerbation, trophic
changes.
 ddx: C6-7 radiculopathy, or polyneuropathy
 Signs: Phalens, “reverse” Phalens, Tinels,
“flick” sign
Median Neuropathy: Fun Facts
 “Hand of benedictine” - Median Neurop seen w/ finger flexion
 “Double Crush” Syndrome (decreased axoplasmic flow predisposes
for CTS) cervical radiculopathy and CTS
 Martin-Gruber anastamosis (median to ulnar crossover of ulnar fibers).
Seen 15-30%, bilat in 70% , most common M. innervated is FDI
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larger amp with stim elbow (vs. wrist)
initial positive deflection in CTS
increased NCV in CTS
 Canieu Riche Anomaly (Anastomosis between the recurrent branch of
the median N. and the deep br. of the ulnar N.) “Ulnar hand “ to FPB
and opponens
Ulnar NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Lower trunk
Thoracic outlet
TOS
All Ulnar M’s +
median motor
Ulnar
Ulnar Groove
Tardy Ulnar
Palsy
+/- FCU
Ulnar
Betw Heads of
FCU
Cubital Tunnel
Syn
Spares FCU
Ulnar
Pisaform/Hamate Guyon’s Canal
Ulnar
Palm
“Walker, Bike”
Ulnar Intrins
Motor Only (FDI,
Add Poll)
Ulnar Neuropathy at elbow
 2nd most common entrapment syn
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Ulnar N superficial in UG & Cubital tunnel
Ulnar Groove (UG - behind med. epic) - Most
common site
• due to pressure (leaning on elbow), repetitive
motion (F/E), subluxation (18%, prior trauma
(“Tardy Ulnar Palsy”), valgus deformity
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Cubital tunnel (beneath aponeurosis joining 2
heads of FCU) is 2 cm distal to UG.
Ulnar Neuropathy: clinical exam
 Ddx: C8-T1 radiculopathy, lower plexus
lesion (TOS), CTS
 Froment’s Sign, tinel, Horners (T-1),
 Ulnar Claw hand - seen w finger extension
Edx of Ulnar neuropathy @elbow
 assess NCV across elbow
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“tricky” Edx findings
ulnar N is “lax” in extension, and will tighten
w/flexion, also can sublux
perform NCS with Elbox flexion 70-90 deg
consider SSIS (“inching”) testing across elbow
(20% drop in amp is signif)
NEE - FDI & forearm m’s
Ulnar Nerve: Fun Facts
 Guyon’s Canal - etiol: ganglion cyst 30%, 25% recurrent
trauma, 23% acute trauma
 Shea-McClean Classification
• proximal canal: Motor and sensory deficits (30%)
• distal canal : Deep motor branch only (50%)
• superficial sensory branch to 4th and 5th digits
(20%)
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Dorsal ulnar Cutaneous N (DUC) - given off 8-10 cm
proximal to wrist (does not go thru Guyons canal)
RADIAL NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Radial
Axilla
Crutch Palsy
Includes Triceps
Radial
Spiral Groove
Saturday Night
Palsy/Fx
Spares Triceps, weak
ECR, sup, BR
Posterior
Inteross
(Radial)
Acrade of
Frohse
(supinator)
Posterior
Inteross N.
Synd (PIN)
ECU, but spares
sup, ECR, BR
SupRadial
Wrist
“Chiralgia”
Sensory only
Radial Nerve: Fun Facts
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Good prognosis in radial nerve injuries
Lead toxicity commonly affects radial nerve
Test BR muscle with forearm in “neutral” position
Superficial Radial N (sensory) given off proximal
to supinator m
 PIN (Post. Interosseous N.) traverses supinator
thru Arcade of Froshe
 Exam may reveal apperent weakness of interossei
(ulnar) or thumb abduction (median)
LE NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Illioinguinal nerve, Genitofemoral nerve, Lateral femoral cutaneous nerve
(meralgia paresthetica), sural nerve, all rarely subject to isolated lesioins
Femoral
Psoas/Retroperitoneal
Hip Flex/Knee Ext
Femoral
Inguinal
Knee ext
Saphenous
Hunter’s
Canal
Sensory only
Obturator
Pelvis
Adductors
LE NERVE ENTRAPMENT SYNDROMES
NERVE
Superior Gluteal
LOCATION
Hip
Inferior Gluteal
Sciatic
Under Pyriform
SYNDROME
MUSCLE INVOLVED
Injections
Glut min/med
Injections
Glut max
Pyriform
Syndrome
Short head bicep
SCIATIC NERVE
 Course: thru greater Sciatic Foramen, beneath pyriformus
M.
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20% pass “thru” pyriformis (esp. peroneal division)
 Peroneal division is most commonly involved (larger, fixed
at fibula)
 Etiology: Pelvic, hip or SI joint fractures, stretch injury,
injections (SN), vaginal delivery (OBT), retropetroneal
hematoma
 Stim.site between ischeal tuberosity and gr. trochanter
PERONEAL NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
Common
Peroneal
Head of Fibula
Deep Peroneal
Distal to Fib
Deep Per
“Ant” tarsal
Tunnel
SYNDROME
MUSCLE INVOLVED
Dorsiflex,
Evertors
Boot
Dorsiflex, Dorsal
Web Sens
E.D. Brevis
Peroneal Neuropathy
 Ddx: L5 radiculopathy
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check ankle inversion & hamstring DTR (both
abnl in L5 radic), tib post, glu med m’s
 Etiology : leg crossing, weight loss,
depression, casts, ankle injuries (stretch)
 SHB (short head of Biceps Femoris) - thigh
 pierces PL m (fibular tunnel)
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then divides into sup/deep peroneal
 Accessory Peroneal (20%) - lat malleolus
TIBIAL NERVE ENTRAPMENT SYNDROMES
NERVE
LOCATION
SYNDROME
MUSCLE INVOLVED
Tibial
Under Flexor
Compart
Tarsal Tunnel
Intrinscs
Plantar
(Digital)
3/4 Toe
Morton’sSens/Pain
Neuroma
“failure is not an option”!
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IOH
CYL
TTL
GTG/MDAF