Peripheral Nerve Flashcards
name 5 symptoms associated with general peripheral nerve entrapment.
pain numbness tingling weakness atrophy
nerves can be compressed within the canal or outside the canal, and within the canal it can be extrinsic or intrinsic… what are two examples of an extrinsic cause? How about an intrinsic?
extrinsic: tumor, #, subluxation of carpal bone…
intrinsic: diabetes, fluid accumulation from pregnancy etc, tissue proliferation from endocrine dysfunction etc
peripheral nerve entrapment pathogenesis begins with something compressing the nerve, leading to what?
localized demyelination –> diffuse demyelenation –> axonal degeneration
name six factor types associated with peripheral nerve entrapment. The seventh is Tumor.
vascular inflammatory trauma anatomical metabolic iatrogenic
what are the issues surrounding electrodiagnostics with peripheral nerve entrapment?
- evaluates only large myelinated fibers
- does not assess small unmyelinated fibers at all which are the first affected.
- have to wait 4-6 wks post trauma or it won’t be as accurate
- examiner dependent
what is involved in conservative therapy of nerve entrapment?
- PT
- rest
- behaviour modification
- splint
- anti-inflammatory ie ice etc if swelling is cause
surgery if conservative measures don’t work
median nerve lies anterior to which muscle in the arm? which two structures in this same area does it pass through?
brachialis
ligament of struthers connecting supracondylar process with medial epicondyle, plus it passes under the bicipital aponeurosis.
the median nerve passes through which muscle at the cubital fossa? It then passes under a fibrous arch connected to which muscle?
- pronator teres
- flexor digitorum superficialis
what are the three main branches of the median nerve?
- deep branch which goes through carpal tunnel (gives off recurrent thenar motor and digital sensory branches)
- anterior interosseus branch (runs btw flexor pollicis longus and flexor digitorum profundus to terminate in pronator quadratus)
- palmar cutaneous branch (starts at wrist, passes over carpal tunnel)
the median nerve DOES NOT supply which flexor muscles of the F/A?
flexor carpi ulnaris and the 4th and 5th digits of flexor digitorum profundus (both supplied by ulnar nerve).
which muscles does the main branch of the median nerve innervate?
flexor carpi radialis, pronator teres, palmaris longus (superficial level)
flexor digitorum superficialis (intermediate level)
which muscles does the AIN innervate?
1/2 flexor digitorum profundus (2nd and 3rd)
flexor pollicis longus
pronator quadratus
this is the deep level
thenar recurrent branch supplies which muscles?
- LOAF muscles Lumbricals 1 and 2 opponens pollicis abductor pollicis brevis flexor pollicis brevis superficial head
what is the name of the branch of the median nerve that supplies the lateral 3 1/2 fingers on the palmar and fingertip side?
digital sensory branches, aka terminal sensory branches
what are the three main entrapment sites for the median nerve?
carpal tunnel
pronator teres
AIN
carpal tunnel syndrome’s MOI can be from the canal size decreasing or the content size increasing. Name some specific causes of both
canal smaller:
- OA
- Trauma
contents bigger
- non-specific enlargement (diabetes, pregnancy, congestive heart failure)
- anomalous muscle/tendon
- synovial hypertrophy in inflammatory conditions
- trauma (hematoma, swelling)
what is the pain/parasthesia site for carpal tunnel syndrome?
palmar aspect of the lateral 3 1/2 fingers and hand, and dorsal aspect of these fingers too.
what is the pain pattern for carpal tunnel syndrome?
increases with :
- sustained wrist flexion or extension
- night pain
decreases with:
- shaking or massaging hand
pt also may c/o cluminess
what two things might you note with more severe carpal tunnel upon observation?
- thenar muscle wasting
- hand of benediction with finger flexion (only flexes 4th and 5th digits)
strength wise, what might you expect to see with more advanced carpal tunnel syndrome?
- decreased hand dexterity (assess grip and pinch strength)
- weakness of thenar ms (LOAF!)
what are three tests you can do to rule in carpal tunnel syndrome? which one is the best? Also note how long to hold each one..
- Durkan’s - best one, hold 30s
- Phalens - 60s
- Tinels - whack whack whack quick…
name four structures that can cause nerve compression leading to pronator teres syndrome. What can make these areas more compressed?
- ligament of struthers
- bicipital aponeurosis
- 2 heads of pronator teres
- flexor digitorum superficialis aponeurotic arch
these areas can have less space due to fibrosis and/or hypertrophy of the muscles of the F/A, so think beefy popeye arms
what is the pain site for pronator teres syndrome?
- pain/parasthesia in lateral 3 1/2 fingers and palm, and pronator teres area of F/A
what is the pain pattern for pronator teres syndrome?
increases with resisted/repetitive pronation and elbow flexion
night pain usually not a thing
what other condition may be associated with pronator teres syndrome?
golf elbow
while not a usual sign, what three muscles may get weak with pronator teres syndrome?
- flexor pollicis longus
- PDP??? (2-3 fingers) maybe means flexor digitorum profundus?
- pronator quadratus
what tests could you use to rule out/in a pronator teres syndrome in general?
- tinels at proximal F/A rule in
- tinels and phalens at wrist should be negative
- wrist flexion should do nothing
what test could you use to see if pronator teres syndrome was caused by:
the two heads of pronator teres?
the bicipital aponeurosis?
the fibrotendinous arch of FDS?
for 2 heads of pronator teres:
- pronator teres syndrome test (resisting isometric pronation in handshake, extend pts elbow maintaining this resistance)
for bicipital aponeurosis”
- compression at bicipital aponeurosis (resist elbow flexion at 120-130 in supination
for fibrotendinous arch of FDS:
- compression at FDS (resist middle finger flexion at PIP)
AIN causes sensory only, motor only, or both motor and sensory changes?
motor changes only
name two structures that may cause AINS (MOI)
- compression by deep head of pronator teres or FDS fibrotendinous arch
what is the pain site for AINS?
not painful, but may have history of F/A pain before other symptoms
what is the pain pattern for AINS?
- weakness in grip and pinch, esp thumb and first 2 fingers, may report difficulty writing, picking up small objects.
- no night pain
name the test you can do to rule in AINS? what about rule out?
- pinch grip test (“OK sign”)
- tinels, compression, and phalens should be negative
your patient has paresthesia in the first three fingers somewhere, what three things could it be?
- peripheral nerve entrapment
- radiculopathy
- neuromeningeal
what four things can help distinguish between a CTS and pronator teres syndrome?
- MOI, pain pattern
- pain over proximal F/A
- sensory disturbance in palmar cutaneous branch
- night pain
your patient is complaining of pain in medial side of F/A, what three things are you thinking?
- peripheral nerve entrapment
- golfer’s elbow
- neuromeningeal
name three conditions that can be part of a double crush syndrome along with CTS
- TOS
- radiculopathy
- pronator teres syndrome
where does the ulnar nerve originate from?
medial cord of C8-T1 of brachial plexus
when the ulnar nerve passes from the anterior to posterior compartment of the arm, where/what does it go through?
pierces intermuscular septum at the arcade of struthers
what tunnel does the ulnar nerve pass through at the elbow?
cubital tunnel
the ulnar nerve gives off two branches in the F/A after passing through the two heads of flexor carpi ulnaris but before reaching the wrist. What are the names of these two nerves?
dorsal and palmar ulnar cutaneous branches - both sensory
which two structures make up the sides of Guyon’s canal?
pisiform and hook of hamate
what are the names of the final two branches the ulnar nerve splits into in the hand? Are these motor or sensory?
deep terminal - motor
superficial terminal - sensory
name the 5 muscles/muscle groups the deep terminal branch innervates
HILA ms (intrinsics):
- hypothenar ms group
- interossei
- lumbricals (3 and 4)
- adductor pollicis brevis
- deep head of flexor pollicis brevis
what does the dorsal ulnar cutaneous nerve innervate?
what about the palmar ulnar cutaneous?
skin of the medial back 1/2 of hand, back of the pinky finger, and medial 1/2 of the back of the 4th finger
palmar branch supplies proximal medial 1/2 of palm of hand
what does the superficial terminal branch innervate?
distal palmar aspect of hand and fifth finger, and 1/2 of the 4th finger/hand on the palmar side
what are the main entrapment sites for the ulnar nerve?
cubital tunnel (CuTS) guyon tunnel
where can CuTS originate from other than the cubital tunnel?
arcade of struthers
between two heads of FCU
what is an associated condition of CuTS?
golfer’s elbow
name six possible causes of cubital tunnel syndrome
hypertrophy of F/A flexor muscles repeatedly leaning on elbow bending elbow for long time valgus stress subluxation, dislocation HU jt contusion and/or trauma to medial elbow
what is the pain site for CuTS?
pain/paraesthesia on ulnar side of F/A, 5th finger, 1/2 4th finger, and hypothenar area
what is the pain pattern for CuTS?
increases with:
- sustained or repeated elbow flexion
- direct pressure
decreases with:
- elbow extension
night pain can be caused by sleeping position, usually is relieved by shaking the hand
what are two motor symptoms related to CuTS?
- progressive loss of grip and pinch strength & interosseous ms function
- clumsiness
what might you expect if a patient has a more advanced stage of CuTS?
- muscle wasting of hypothenar and intrinsics
- claw hand deformity
- paralysis of extrinsic and intrinsic ms
- decreased sensation of ulnar digits
what four tests can be used to rule in/out CuTS?
- tinels at the cubital tunnel - should feel tingling
- pressure provocation test - pressure just above cubital tunnel 60s on ulnar nerve while elbow is flexed to 20 degrees and supinated.
- elbow flexion test - max flexion and supination held 60 sec
- froment’s sign - thumb flexion holding paper due to weakness of adductor pollicis brevis
name 5 potential causes of compression of the ulnar nerve at Guyon’s canal
- ganglion cyst (80% of cases)
- sustained pressure over tunnel (ie cycling)
- repetitive trauma
- hook of hamate #
- thickened piso-hamate ligament
what is the pain site for Guyon tunnel syndrome?
pain over tunnel, 5th finger and 1/2 of 4th finger but only in distal part, dorsal and palmar cutaneous branches unaffected.
what is the pain pattern for Guyon tunnel syndrome?
increase:
- direct pressure
- sustained hyperextension or hyperflexion of wrist
- night pain
what would you expect to see in a more advanced case of Guyon tunnel syndrome?
- clawing of 4th and 5th digit
- paralysis of intrinsics
name some provocative tests for Guyon tunnel syndrome
- froments sign
- tinels
- vascular (intolerance to cold, allen test positive)
your patient has pain/paraesthesia in 4th and 5th digit area and above, what four things are you thinking?
- peripheral nerve entrapment (CuTS or Guyon)
- radiculopathy C8
- TOS
- neuromeningeal
your patient has weakness of the interossei, what three things is it possible to be?
- peripheral nerve entrapment (CuTS vs Guyon)
- radiculopathy T1
- TOS (rare)
you are unsure if your patient has CuTS or Guyon syndrome. If they had CuTS rather than Guyon, what would you expect to see that would not be there if it was Guyon?
- less clawing than if Guyon
- pain in elbow and F/A
- numbness on dorsum of hand and proximal palm
- motor deficit to ulnar extrinsic ms
- tinels at elbow
- position of reproduction related to elbow
name two double crush syndromes associated with the ulnar nerve
- radiculopathy & CuTS
- CuTS and Guyon
which nerve roots make up the radial nerve?
C5-T1
the radial nerve splits into which two branches in the forearm? Are these motor or sensory or both?
deep branch - mainly motor (ECRB and supinator)
superficial branch - sensory
the deep branch passes through the ________, under the _____________ and into the ______
radial tunnel
arcade of Frohse,
supinator muscle
the deep branch of the radial nerve turns into which nerve? What does this nerve innervate?
PIN - innervates forearm extensors: extensor communis including digiti minimi, extensor carpi ulnaris , APL, EPB, EPL, extensor indicis
what are three compression syndromes one might see in the radial nerve?
PIN syndrome
Radial tunnel syndrome
superficial radial syndrome
name some causes of PIN syndrome and where the nerve gets compressed
compressed in arcade of Frohse (supinator)
causes:
repeated pronation/supination (raquet sports, golf, etc)
trauma, Fx, dislocation
tumour, RA
what is the pain site and type for PIN syndrome?
deep F/A pain
what might you see clinically strength-wise on someone that has PIN?
- weakness of finger extensors
- wrist will extend but with RD
- unable to extend and abduct thumb
what structures make up the radial tunnel?
- brachialis and biceps tendon
- extensor carpi radialis and brevis
- capsule of RH joint
what are three sites of compression within the radial tunnel?
extensor carpi radialis brevis edge
fibrous bands around RH joint
arcade of Frohse
what is the pain site for RaTS?
dorso lateral forearm 4 cm distal to lateral epicondyle
what is the pain pattern for RaTS?
pain increases with supination and lifting things. note that there should not be weakness unless it is weakness due to pain.
what four tests would you expect to be (+) with RaTS?
- pain with wrist extensor stretch
- resisted wrist extension
- resisted long finger extension
- resisted supination (with elbow and wrist extended)
what are the usual MOIs for superficial radial syndrome? What is an associated condition?
- compression by scissoring of brachioradialis and ECRL tendons
- common site for traumas
- tight casts, watches etc
associated condition is DeQuervains
what is the pain pattern for superficial radial syndrome?
repetitive wrist flexion, ulnar deviation, and forearm pronation
what are two tests that can be positive with superficial radial syndrome?
- tinels
- finkelsteins test
your patient has weakness in wrist extension, what two things could it be?
PIN, C6 radiculopathy
what could be a cause of pain around the lateral elbow?
RaTS
tennis elbow
neuromeningeal
C6 facilitated segment
name two elements to differentiate between DeQuervains and superficial radial syndrome?
paraesthesia - will be present with superficial radial but not De Quervains
pronation - will not elicite increase in pain with DeQuervains but will in superficial radial
what can cause pain/paraesthesia of the dorsum of the later hand?
- superficial radial
- DeQuervains
- neuromeningeal
- radiculopathy c6-7
what is one type of double crush injury of the radial nerve mentioned in class?
radiculopathy and raTS
