pathologies Flashcards
What is neurapraxia?
-first degree nerve injury
-mild focal compression (causing a conduction block)
>segmental demyelination
-reversible in hours to months
-no break in the fibers
-motor function loss
How fast do nerves repair?
1-2 mm /day
What is axonotmesis?
- second degree nerve injury
- prolonged, severe compression
- Wallerian Degeneration
- endoneurium still intact
- prognosis >6months
- sensory and autonomic loss
What is Wallerian Degeneration?
- describes the path of destruction
- degeneration of an axon at a point of contact and distall
What is neurotmesis?
- third degree nerve injury
- -damaged endoneurium
- Wallerian Degeneration
- hard to regenerate
- surgical intervention to suture
Causes of peripheral nerve lesions
compression, tight muscles, crutches, trauma, boney growth, tumors, systemic conditions with swelling
A neuropathy in which a single peripheral nerve is affected.
a mononeuropathy
A neuropathy in which several peripheral nerves are involved.
a polyneuropathy.
a neuropathy that involves the nerve root as it emerges from the spinal cord.
a radiculoneuropathy
a neuropathy that involves several nerve roots and occurs when infections create an inflammatory response.
polyradiculitis
What is Erb-Duchenne palsy?
- injury to the superior roots of the brachial plexus.
- traction injury
- forceful pulling away of head from shoulder
- no sensation over lateral arm (sensory loss C5 and C6 dermatomes)
- waiter’s tip
What is the waiter’s tip position?
- arm is adducted
- medial rotation
- elbow extended
- forearm pronated
- wrist & fingers flexed
What is Klumpke’s paralysis?
- traction injury of lower brachial plexus
- poor positioning at birth (breech), or pulled by forceps
- falling from height and grabbing something to break fall
- results in medial and ulnar lesions
- whole hand claw hand - thumb on same plane as palm (wasting of thenar eminence)
- sensory loss affecting C8-T1 dermatomes
- can get Horner’s syndrome
What is Horner’s syndrome?
- on affected side
- miosis - constriction of pupil
- ptosis - drooping eyelid
- anhydrosis - loss of sweating to face and neck
- enophthalmas - recession of eyeball into orbit
What is the path of the radial nerve?
-branches just before supinator
-posterior motor branch “posterior interosseous nerve”
>it enters supinator and travels down the lateral radius to the wrist
-superficial branch - travels down the posterior forearm to the hand
What causes a radial nerve lesion?
- fractures - at the spiral/radial groove
- dislocations - of head of radius, humeroradial or radioulnar joint
- post-surgical complications
- compression
What are the symptoms of a radial nerve lesion?
- altered sensation at the posterior arm and hand (digits 1-3 and lateral 1/2 of 4)
- wrist drop
- if injury is proximal to elbow, both sensory and motor affected, if injury distal to elbow, only sensory or motor is affected
What is a radial nerve lesion at the axilla?
crutch palsy
What is a radial nerve lesion at the spiral groove of the humerus?
Saturday night palsy
What is posterior interosseous syndrome?
- comes off in front of the lateral epicondyle of humerus
- motor
- get wrist drop
- compression in the arcade/canal of Frohse
What is the arcade of Froshe?
- fibrous arch in the supinator
- between the 2 heads of supinator
- occurs in 30% of people
What is a compression of the radial nerve as it passes under the tendon of brachioradialis?
cheiralgia paresthetica
Describe cheiralgia paresthetica
- sensory
- pain at dorsum of wrist, thumb, and subspace
- cause: trauma, tight cast, swelling
What causes a median nerve lesion?
- fractures at elbow, wrist, and carpals
- dislocations at elbow, wrist, and carpals
- compressions
- trauma
What are the symptoms of median nerve lesions?
- Ape hand and Oath hand
- can’t grasp objects
- can’t pronate forearm (can’t do air quotes)
- weak wrist flexion, weak thumb movements
- altered sensation of digit 1-3 and half of 4.
What is ape hand?
wasting of thenar eminence due to no opposition
What is oath hand?
- only seen when asked to make a fist
- only digits 4 and 5 can be flexed
Where can a median nerve lesion occur?
- ligament of struthers
- carpal tunnel
- pronator teres
- anterior inerosseous
What is the ligament of struthers?
- runs from an abnormal spur on the shaft of the humerus to the medial epicondyle
- median nerve can be compressed above the elbow as it passes under
- only in 1% of population
What is pronator teres syndrome?
- compression at proximal attachment of pronator teres of the median nerve
- aching in anterior forearm
- numbness in thumb and index finger
- somes weakness in thenar muscles
What is carpal tunnel syndrome?
- compression through the carpal tunnel at the wrist
- most common entrapment condition in the arm
What makes up the carpal tunnel?
- carpal bones = floor
- flexor retinaculum = roof
- flexor retinaculum attaches to the scaphoid tubercle and the trapezium
What travels through the carpal tunnel?
- median nerve
- flexor digitorum superficialis (4 tendons)
- flexor digitorum profundus (4 tendons)
- flexor pollicus longus (1 tendon)
What are the symptoms of carpal tunnel syndrome?
- numbness and tingling in digit 1-3 and 1/2 of 4
- distinguishing feature = presence of nocturnal symptoms that wake person up
- muscle weakness and clumsiness of thumb and fingers. ie. opening jars and doors
- later get thenar wasting.
What are the 2 ways to compress the median nerve in the carpal tunnel?
- size of the tunnel decreases - bony callous, space occupying lesion, bony changes. ie. Rheumatoid arthritis
- size of contents passing through increases:
- repetitive actions. ie. edema then fibrosis & tendon thickening
- retinaculum thickening from scar tissue (repeated trauma
- systemic conditions that cause edema & fluid retention
What is the path of the ulnar nerve?
- travels over the flexor retinaculum between the pisiform and the hook of hamate (Guyon’s canal)
- ulnar groove
What are causes of an ulnar nerve lesion?
- fractures at the medial epicondyle, mid forearm and wrist
- dislocations of elbow
- post-surgical complications (badly positioned arm while under anesthetic)
- compression ie. resting elbow on hard surface; wearing tight wrist band; cycling
- repetitive actions
- direct trauma
What are the symptoms of an ulnar nerve lesion?
- ulnar claw hand
- froment’s sign
- tardy ulnar palsy
What is ulnar claw hand?
- baby finger hyperextended and abducted and MCP and flexed at IP
- ring finger is hyperextended at MCP and flexed at IP (loss of lumbricals)
- atrophy of inerosseous muscle
- muscle wasting of hypothenar
- altered sensation of little finger and medial 1/2 of ring finger (palmar and dorsal)
What is froment’s sign?
- hold paper between thumb and index finger
- it can’t be done without adductor pollicis muscle
- if positive the patient will flex thumb to use flexor pollicis longus
What is tardy ulnar palsy?
- common complication of elbow fractures
- can occur years after a fracture
- associated with callus formation of a valgus deformity of the elbow
- these produce a gradual stretching of nerve in ulnar groove of medial epicondyle
What is thoracic outlet syndrome?
- compression of brachial plexus from structures in the thoracic outlet (from interscalene triangle to inferior border of axilla)
- subclavian artery and vein may also be compressed
What are causes of TOS?
- whiplash
- backpacks
- apical breathing
What are symptoms of TOS?
- pain, numbness, weakness, tingling in the arm or across upper thoracic area or over scapula
- trophic changes in the tissue with blood vessel compression
Why would TOS happen?
- presence of cervical rib at C7
- anterior scalene syndrome - compression b/w anterior and mid scalene
- costoclavicular syndrome - compression b/w the clavicle and rib 1
- pectoralis minor syndrome - compression b/w coracoid process and pec minor
What makes up the interscalene triangle?
- anterior scalene
- middle scalene
- rib 1
- brachial plexus and subclavian artery pass through.
What is the name of the pathology for lateral femoral cutaneous nerve entrapment?
meralgia paresthetica
What can cause meralgia paresthetica?
- trauma (seat belt in MVA)
- during delivery (feet in stirrups)
- tight clothing
- complication of surgery (hernia)
Where does meralgia paresthica occur?
near the ASIS as the nerve passes under the inguinal ligament
What will meralgia paresthica present with?
sensory alteration and/or burning pain on the lateral thigh
What will injury to the femoral nerve present with?
- can’t extend leg (@ knee), trouble flexing hip
- wasting of quads
- no sensation over anterior/medial thigh
What is the path of the sciatic nerve?
- lateral to ischial tuberosity
- down posterior thigh
- split at knee
What causes a sciatic nerve lesion?
- fractures (pelvis, femur, tibia, fibular head, ankle)
- dislocation (hip, knee, ankle)
- iatrogenic reasons (glute injury, hip surgery, meniscal repair, improper positioning during surgery)
- compression from internal sources:
- piriformis (piriformis syndrome)
- ganglion
- morton’s foot
- flexor retinaculum (tarsal tunnel syndrome)
- compression from external sources:
- against fib. head (cast, splint)
- crossing legs
- trauma
What are the symptoms of a sciatic nerve lesion?
- pain at butt and down lateral leg and possibly to lateral foot
- foot drop - paralysis of dorsiflexors and everters
- leads to steppage gait
What forms the tarsal tunnel?
the medial malleolus, calcaneous, talus, and the flexor retinaculum
What is tarsal tunnel syndrome?
the tibial nerve being compressed at the ankle as it passes through the tarsal tunnel
what can cause tarsal tunnel syndrome?
-swelling after trauma
-space occupying lesion (ie. ganglion)
-inflammation (ie. paratendonitis)
-valgus deformity
chronic inversion
What are the symptoms of tarsal tunnel syndrome?
- pain and paresthesia into sole of foot
- symptoms often worse after long periods of standing or walking or at night
- pain localized or radiates over medial ankle, distal to medial malleolus
What is tarsal tunnel syndrome often misdiagnosed as?
plantar fascitis
What is neuritis?
- inflammation of the nerve
- mainly the sheath and CT are affected (usually the axon is not)
What are the symptoms of neuritis?
- constant dull pain
- can also get numbness and tingling
What are causes of neuritis?
- secondary to pathology (DM, leprosy, TB)
- trauma to nerve
- chronic exposure (to a toxin like lead, drugs, or alcohol)
What is neuralgia?
- nerve pain
- recurrent attacks of sudden excruiating pain along distribution of the nerve
- no associated pathology
- has a trigger zone
What is a trigger zone for neuralgia?
- area that causes an attack when stimulated
- usually it’s an area of skin supplied by the nerve
- movement of the area increases pain
What are commonly affected nerves of neuralgia?
trigeminal and intercostal nerves
What is intercostal neuraliga?
-neuralgia that affects intercostal nerves that travel between the internal and innermost intercostal muscles
What are causes of intercostal neuralgia?
- diabetes
- post-herpes zoster
What is the pathogenesis of Herpes Zoster?
- starts with chicken pox
- after recovered from chicken pox as a child the virus lays dormant in the sensory ganglia of the cranial or spinal nerves and becomes active later in life.
- when reactivated, patient gets a generalized inflammatory response starting in the sensory ganglion and spreading along the nerves causing demyelination and degeneration
What is Herpes Zoster commonly called?
Shingles
How many nerves are usually affected with Herpes Zoster?
usually only one nerve affected.
-thoracic and trigeminal nerves are most common
What are the symptoms of Herpes Zoster?
- inflammation producing pain; tingling in the involved dermatome with a rash and the vesicles burst and encrust.
- skin lesions can last up to a month and disappear as the effects of the virus resolve
- intermittent attacks of deep, burning, sharp shooting pain along the affected nerve
- trigger is often light touch and movement over affected area.
