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