Test 3- PNS Injuries Flashcards
Motor Nn
- Nn originate from the Ventral Horn and terminate at the end plate of muscle
- MOVE: MOtor, Ventral, Efferent
Sensory Nn
- Nn originate from the dorsal root ganglia and terminate as free nerve endings
- SAD: Sensory, Afferent, Dorsal root
Layers of Nn
- Epineurium: Outermost layer of Nn. Cushions from eternal pressure and allows movement/motion
- Perineurium Connective tissue that makes up the wall of fascicles
- Endoneurium: Surrounds individual Nn fibers/ supports and protects axons.
Mesoneurium function
Slick loose connective tissue that facilitates gliding
-Needed for movement because Nn require mobility- they slide up to 2 cm as we move and often cross jts
Ideal conditions for a nerve
Nn need:
- Space
- Movement
- Limited sustained tension
Anterograde and Retrograde flow speed
- Anterograde: fast= 400 mm/day, slow= 1-6 mm/day
- Retrograde: 200 mm/day
Nutrition used for the Nervous System
- 20% of the oxygen we breath is used by the nervous system
- 20-25% of the calories we consume are used by the nervous system
Sensory changes with peripheral nerve dysfunction
- Decreased sensation
- Absent sensation
- Abnormal sensation: allodynia (pain when you shouldn’t feel it), ectopic foci, etc.
Autonomic changes with peripheral nerve dysfunction
- Loss of sweating
- Loss of “shunting” from superficial capillaries
Motor changes with peripheral nerve dysfunction
- Paresis
- Paralysis
- If denervation: Atrophy of denervation and fibrillations
Trophic changes with peripheral dysfunction
- Blood supply changes
- Loss of autonomic innervation
- Loss of sensation
- Loss of movement
Neuropathy classified by number of Nn affected
- Mononeuropathy- one N; aka carpal tunel
- Multiple mononeuropathy- several Nn; aka cubital and bilateral carpal tunnel
- Polyneuropathy- many Nn: aka diabetic Nn damage, stocking/glove sensation loss
Seddon’s classification of nerve injury
Three degrees of nerve injury:
- Neuropraxia: nerve compression; tingling sensation
- Axonotmesis: traumatic nerve damage; Wallerian degeneration
- Neurontmesis: Severance of Nn
Nerve recovery rate
- 1” per month, 12” per year
- 1-2 mm/ day
Thoracic Outlet Syndrome
Symptoms arising from the UE, chest (Pec Minor) and neck (Scalenes)
-symptoms produced by positions that compress the brachial plexus and/or subclavian artery/vein
Ulnar nerve entrapment
Can become entrapped in either the cubital tunnel (in elbow- “funny bone” pain/sensation) or guyan cannal (in wrist- causes pain in extension and decreased pinch/grip strength)
Ortho interventions for ulnar nerve damage
- Cubital tunnel: elbow pad for protection and static night splint with elbow at 35-60 degrees flexion
- Guyon’s canal: neutral wrist splint
- Ulnar nerve palsy: hand splint to block MP hyperextension
Sensation impairment from ulnar nerve entrapment
- Sensation is impaired proximally and dorsally with cubital tunnel
- Sensation is impaired only on the volar side with guyan canal
Carpal Tunnel Syndrome (CTS)
- Carpal Tunnel houses: median nerve, flexor pollicis longus, and 8 flexor tendons of 4 digits
- Medial nerve is softest and most volar structure so it is very prone to compression
- Leads to (in order): decreased sensation to light touch> hypersensitivity> night pain> paresthesia
How does CTS patient present?
- Numbness and night pain
- Paresthesia (numbness/tingling) in medial nerve distribution
- Decrease in pinch and grip strength
- Thenar atrophy in long term cases
- complaints of pain or dropping items
Treatment of CTS
- Neutral wrist splint
- Night splint for MP blocking
- AVOID putty squeezing exercises, or full digit flexion grip exercises
- AVOID repetitive or sustained flexion and extension
- AVOID pressure or carpal tunnel
Dellon Method for recovery
Based on re-education:
- First goal: re-educate localization of stimulus; stimulate with eyes occluded> if wrong repeat with vision> repeat with vision occlude
- Second goal: recovery of tactile recognition; object identification and tracing of letters/numbers out of sandpaper
Pronator Syndrome
- LOOKS LIKE CTS: EMG does not identify it well, often mistaken for CTS
- Tight muscles in the forearms: pronator and FDS
- compression of nerve between two heads of pronator teres: symptoms include weakness in resisted pronation at the medial proximal forearm
Splint for pronator syndrome
Splint to prevent pronation and supination as well as wrist flexion and extension
-forearm neutral and elbow flexed at 90 degrees
