Peripheral Nerve Disorders I - Exam 4 Flashcards
_____ carries information away from the cell body. _____ carries information to the cell body
axon= away from cell body
dendrite: to the cell body
__________ a fatty layer of tissue that insulates the axon to allow for faster neurotransmission. ________ a chemical synapse formed by the motor neuron and a muscle fiber
Myelin sheath
Neuromuscular junction
_____ is the blood supply of nerve fibers?
vasa nervorum
______ nerves carry sensory signals toward the CNS for review. ____ nerves carry motor signals from the CNS to the target
Afferent
Efferent
What are the 3 types of peripheral nerves?
large myelinated
small myelinated
small unmyelinated
type of fiber depends on the type of sensation
Draw the breakdown of the peripheral nervous system.
What kind of neuropathy affects the cell body? What type?
neuronopathy or ganglionopathy
usually only motor or sensory RARELY mixed
What kind of neuropathy affects the axon? What type of dz? Where does it occur first? What type of nerve fiber? What are the associated sensations?
axonopathy
metabolic
distally first
small nerve fibers
think pain/burning
What kind of neuropathy affect the myelin? What does it result in? What type of nerve fiber? What are the associated sensations?
myelinopathy
slower nerve conduction
large nerve fiber
buzzing and tingling
What kind of neuropathy affects the vascular supply? Where do they tend to occur?
neurovascular disorders: Inflammation (vasculitis) or ischemic
Usually distal ⅔ of limb
neuropathies that affect the neuromuscular junction are called ______. What is the problem?
NMJ disorders
dysfunction of chemical synapse
______ is when only one nerve is affected. What is the usual underlying cause? How will the s/s present?
Mononeuropathy
Injury/compression to specific nerve
Sensory/motor dysfunction distal
to affected area
What is Mononeuritis Multiplex (Multiple Mononeuropathy)? What are they associated with?
Damage to 2+ specific nerves
in unrelated areas
commonly associated with systemic diseases: think DM, RA, SLE, vasculitis
______ is when multiple nerves are affected and present in a patchy multifocal disease process. Are they usually symmetric? proximal or distal? Give an example
polyneuropathy
symmetric: can be sensory, motor or both
distally
diabetic peripheral neuropathy
What is this pattern called? What disease it is associated with?
stocking-glove distribution
diabetic peripheral neuropathy
_______ damage or irritation to one or more spinal nerve roots with a _____ distribution pattern
radiculopathy
dermatomal distribution
______ is damage or irritation to nerve plexus. What are the 2 MC? What is it usually due to? Give an example
plexopathy
brachial and lumbosacral plexus
Usually due to trauma or radiotherapy
Erb palsy
What is Erb’s palsy? What is a common underlying cause?
damage to the cervical plexus especially C5-6 due to traumatic childbirth when the should gets stuck behind the mother’s pelvis
How will metabolic causes usually present in peripheral neuropathy?
metabolic will present distally first
Define acute, subacute and chronic in peripheral neuropathy
Acute (days to 4 weeks)
Subacute (4 to 8 weeks)
Chronic (>8 weeks)
What is a telling sign that the underlying cause of peripheral neuropathy might be hereditary?
the pt will not notice lack of sensory symptoms despite having sensory signs because they have always been like that and do not know what “normal” feels like
When doing a PE, what is an easy way to tell if the problem is bone or muscle?
active vs passive ROM
if the provider and the pt cannot successfully complete full ROM think the problem is bone
_______ assess function of motor and sensory nerves and helps determine the extent/location of neuropathy. What does it measure?
Nerve Conduction Studies (NCS)
Measures how fast an electrical impulse moves through a nerve (BOTH kinds of nerves)
_____ assess electrical activity in skeletal muscles. What should you order when working a pt up for peripheral nerve disorders?
Electromyography (EMG)
combo NCS and EMG
What are the CI to a NCS (nerve conduction test)? When should you consult cardio?
external pacemaker wires - risk of electrical injury to the heart
Consult cardiology if pt has implantable cardioverter-defibrillator (ICD) or internal pacemakers. NCS are generally safe to use within 6 inches of pacemakers or ICDs
What are the interfering factors in a NCS? Give a brief summary of each
Age - nerve conduction velocities (NCV’s) are slower in infants and children
Sex - NCV slower in men than women
Temperature - decreased NCVs in colder temperatures
What will axonal degeneration show up like on NCS? demyelination?
Axonal degeneration - reduced amplitude
Demyelination - slow internodal conduction and reduced conduction velocity
What is the procedure of a NCS?
What is the procedure for EMG? What is an interfering factor?
deep brain stimulator can create electrical artifact
What are the 12 cranial nerves with functions. Which ones are sensory vs motor?
Some Say Marry Money But My Brother Says Big Brains Matter Most
What is the difference between parosmia and cacosmia?
parosmia: Parosmia is a distorted sense of smell. Things that used to smell pleasant now smell foul to people with parosmia
cacosmia: With cacosmia, the smell is often described as similar to feces, or a burning, rotten, or chemical odor.
What are some causes that would present as a olfactory nerve disorder? What is the associated timeline?
trauma, compression, systemic diseases, URI
May see improvement in 1st 4-6 weeks after acute injury but some patients never regain function
What will a disorder of the optic nerve present like? What is the tx?
Partial or complete monocular blindness
visual field deficits, blurring, scotomata, monocular diplopia, pupillary defect
+/- pain
surgical decompression or high dose steroids, depending on the cause
ptosis; lateral, slightly depressed eye, EOM restricted except laterally
+/- pupillary involvement
Loss of depth perception, reading and visual scanning problems
What CN?
Oculomotor Nerve (CN III)
Upward deviation of eye with failure of depression on adduction
Vertical diplopia worst on looking down
Loss of depth perception, reading and scanning problems
What CN?
Trochlear Nerve (CN IV)
pain, corneal drying, numbness, impaired mastication
What CN? What do you need to test?
Trigeminal Nerve (CN V)
need to test if it is affecting all branches of the nerve or just one
What is the nerve pattern distribution of the trigeminal nerve?
Affected eye turned medially - inability to abduct
Horizontal diplopia; increases with gaze to affected side
Loss of depth perception, reading and scanning problems
What CN?
abducens nerve CN VI
What is Bell’s palsy? What CN? What are some s/s?
complete or partial paralysis of face, progresses from weakness→paralysis over 48 hours
facial nerve, CN VII
Pts may report facial drooping, poor eyelid closure
Hyperacusis, pain in/behind ear, and/or impaired sense of taste
What are the viral association of Bell’s palsy? What are some additional causes?
suspected viral (HSV, VZV)
inflammatory, AI, ischemic, trauma
What time of the year is Bell’s palsy seen more? What is a common pt?
MC in colder months
MC in 20-40 y/o pts, pregnant or DM pts
How do you dx Bell’s palsy? What else do you need to consider?
clinical dx through facial nerve testing
consider EMG/NCS is complete ongoing paralysis or CT/MRI is concerned about tumor or additional nerve involvement
What is the tx for Bell’s palsy? What is the associated timeline?
high dose Prednisone 60-80 mg PO QD x 7 d, followed by 5 d taper)
valacyclovir 1000 mg PO TID x 7 d especially if no forehead movement, cannot close eye and/or vesicular lesions
eye protection: eyepatch and artificial tears to protect eye from drying out
Within 5 days
When do you need to get imaging in Bell’s palsy?
Imaging (MRI, CT) if s/s >8 wks or progress after 3 wks
refer to ENT/Neuro/ophthalmology if needed or s/s do not improve
Positional vertigo, hearing loss, tinnitus, deafness
What CN?
What testing?
Vestibulocochlear Nerve (CN VIII)
Weber, Rinne, audiologic, brainstem auditory evoked response
dysarthria, dysphagia, loss of bitter/sour taste, impaired gag reflex, impaired pharyngeal sensation, voice change
What CN?
What is the associated testing?
Glossopharyngeal Nerve (CN IX)
Gag reflex, voice quality and tones, uvula and soft palate rise, pharyngeal sensation testing, attempt swallowing water
Weakness and atrophy of trapezius and sternocleidomastoid
What CN?
What will it present like?
Accessory Nerve (CN XI)
drooping or depression of affected shoulder with weak abduction
no sensory loss; pain often present
may see winged scapula
** What is the MC cause of accessory nerve damage? Name additional causes
medical procedures
trauma, brainstem lesions, tumors, systemic disease
dysarthria, swallowing difficulties
Tongue wasting and fasciculation
Tongue deviation
What CN?
What is the associated testing?
Hypoglossal Nerve (CN XII)
Protrusion and active ROM of tongue; lingual speech
What is carpal tunnel syndrome? Give specific anatomical features. MC in males or females?
compression of median nerve between transverse carpal ligament (flexor retinaculum), carpal bones, and other structures in the carpal tunnel
MC in females
In carpal tunnel, what does direct compression lead to?
damages nerve fibers which leads to impaired axonal transport
compression of the vessels leads to ischemia
What are risk factors for CTS? What pharm drug in particular?
Obesity
Pregnancy
Hypothyroidism
DM
Arthritis (OA, RA)
hx of median mononeuropathy
Aromatase inhibitors (anastrozole)
What nerve distribution will you see in a pt with CTS?
median nerve distribution
palmar surfaces of the thumb, index, and middle fingers, and the radial half of the ring finger
What are some aggravating factors for CTS? Alleviating factors?
aggravating:
Sleep (Night)
Sustained hand or arm positions (driving)
Repetitive movements of the hand or wrist
typing, writing, wait staff/tray carrying
alleviating:
Changing hand posture (not as effective in late dz)
Shaking/wringing of the hands
What are 3 late findings associated with CTS? What is the initial PE reveal?
Atrophy of the thenar eminence (see picture)
(+) sensory changes along median nerve but not thenar eminence
(+) weak thumb abduction and opposition
basic exam is often benign
What are the 4 provocative maneuvers that you should perform when working a pt up for CTS? Give a brief description of each. Give the associated timeframe for each
What is important to note about 3 of the 4 CTS PE manuevers? Which one is different? Which CTS test provides instant feedback?
Phalen/“Prayer” sign
carpal compression test
hand elevation test** this one is at least for 60 seconds!!!
all require the pt to hold the position for 30-60 seconds
Tinel sign is instant shock like pain with wrist percussion
Which CTS maneuver has the best sensitivity and specificity of all PE tests? How long do you need to hold it for?
Hand elevation test
at least 60 seconds!!
____ is first line testing for CTS? What will mild/moderate/severe CTS show?
NCS/EMG
Mild CTS - sensory conduction delay only
Moderate CTS - sensory and motor delays
Severe CTS - evidence of axon loss (low amplitude of action potential)
When would you want to order imaging with CTS?
US or MRI
Indicated if suspected structural abnormality of the wrist
What is the goal of tx for CTS? What are the non-surgical tx options?
relief of pressure on median nerve
Modify activities and avoidance of precipitating activities
NEUTRAL (volar) position wrist splints
What are the 2 invasive tx options for CTS? When should you refer out for CTS? What about if a pt is pregnant?
steroid injection
or
surgical decompression
-Symptoms last >3 mo despite conservative treatment
-thenar muscle weakness or atrophy
-severe symptoms that limit ADLs
Recommended to delay surgery till after pregnancy is completed
What is tarsal tunnel syndrome? Give specific anatomical landmarks. What ligament?
Posterior tibial nerve supplies plantar flexors of foot and toes. Passes through tarsal tunnel behind and below medial malleolus
Nerve compression in ankle region as nerve passes under transverse tarsal ligament (flexor retinaculum)
What is the MC pt with tarsal tunnel syndrome? What is the MC cause?
think athletes
fracture or dislocation
What is the pattern of paresthesia/pain associated with tarsal tunnel syndrome?
Paresthesias (itching, burning, numbness, and tingling) and pain involving the sole of the foot, the distal foot, the toes, and occasionally the heel
What makes TTS s/s worse? What PE test should you do?
night, walking/prolonged standing, dorsiflexion, eversion
+/- Tinel’s sign over nerve posterior to the medial malleolus and pt will have weakened toe flexion
What will severe TTS present like?
Atrophy of intrinsic foot musculature
What will the foot xray/MRI of a pt with TTS look like? ______ may help to confirm dx. What will it show?
typically will be NORMAL
NCS
Typically must compare to unaffected foot
(+) - prolonged tibial motor latencies and slowed conduction velocities
What is the tx for TTS?
trial conservative therapy if no trauma hx
NSAIDs, shoe modification, orthotics
Steroid injection may provide relief
Surgical decompression if severe or refractory but is less effective than in CTS
What is ulnar nerve palsy? Give the anatomical landmarks
ulnar nerve passes through the condylar groove between the medial epicondyle and the olecranon at the elbow “cubital tunnel” and at wrist pases through Guyon’s canal
_____ is the MC focal neuropathy. _____ is the 2nd MC
1: carpal tunnel 2: ulnar nerve palsy
What are the risk factors for ulnar nerve palsy? ** What is the highlighted one from lecture?
occupation (leaning on elbows/prolonged elbow flexion),
cycling, baseball, karate
What is the nerve paresthesia pattern associated with ulnar nerve palsy?
paresthesias (numbness and
tingling in 4th and 5th digits, elbow pain, night awakening
Are motor symptoms more or less common in ulnar nerve palsy?
motor symptoms overall are LESS common
aka LESS likely to have trouble gripping or dropping items
What is claw hand deformity? What is it associated with?
mild weakness in the ring and picky finger, ulnar nerve palsy
What is froment’s sign? What nerve disorder is it associated with? How are the s/s reproduced?
Froment sign - thumb adductor weakness
Flexion of thumb at IP joint when attempting to oppose thumb
ulnar nerve palsy
flexion + compression
What testing should you order if you suspect ulnar nerve palsy? How do you dx?
NCS: to determine if s/s are coming from elbow or wrist
EMG: for muscle weakness
MRI or US: to demonstrate compression
confirm with electrodiagnostic testing or imaging when suspected on the basis of clinical s/s
What is the tx for mild/moderate ulnar nerve palsy? How is that defined?
Avoid leaning on the elbows, prolonged elbow flexion
Brace or wrap elbow with towel at night to limit flexion
Padded gloves for protection with occupational or recreational activities
NSAIDs/steroids - not as much evidence to support
mild-moderate - sensory loss, weakness WITHOUT wasting
When do you consider sx in ulnar nerve palsy? What do you do if the compression is in the cubital tunnel? condylar groove? at wrist?
moderate to severe ulnar neuropathy at elbow >6 mo refractory to conservative tx or moderate -severe progressive s/s
If in cubital tunnel - release procedure
If in condylar groove - nerve transposition
At wrist - decompression
What is the etiology behind radial nerve palsy? Where is it likely to compress?
winds around the proximal humerus in the spiral groove and proceeds down the lateral arm and enters the forearm, dividing into the posterior interosseous nerve and superficial nerve
Predisposed to compression where adjacent to the humerus (spiral groove)
What are the risk factors for radial nerve palsy?
crutches
inebriation (“Saturday night palsy”)
improper positioning (limited mobility pts)
frequent tight straps or tight gloves on wrists
trauma
Where are the 3 places the nerve is getting compressed in radial nerve palsy?
axilla
spiral groove
posterior interosseus
What will radial nerve palsy at the axilla present like?
weakness/paralysis of all the muscles supplied by the nerve, including triceps
Sensory - hand (radial distribution), possibly posterior forearm
What will radial nerve palsy with compression at the spiral groove present like? what are the 2 specific signs?
Same as axilla but spared triceps - weakness of wrist extensors (“wrist drop”), finger extensors, brachioradialis
cannot make “thumbs up” sign: weakness in thumb abduction
What will compression of the radial nerve present like at the posterior interosseus?
purely motor; supplies
extensors of the wrist and fingers
may be able to extend wrist
but not finger
Pain and/or weakness with extension of wrist and fingers
How do you dx radial nerve palsy?
clinically, can confirm with NCS/EMG. consider imaging if hx of trauma
What is the tx for acute/one time radial nerve palsy? What is the tx for severe injury/trauma?
ock-up wrist and finger splints, avoiding further compression
physical therapy to avoid flexion contracture
Surgical decompression
When should you refer a pt for radial nerve palsy?
Not improved in 2–3 wks, NCS/EMG to confirm and determine severity
Lack of improvement warrants further imaging or surgery
What is the trigeminal neuralgia? Specifically _______.
Usually due to compression of the trigeminal nerve root that causes demyelination of large myelinated fibers and the fibers becomes hyperexcitable and electrically coupled with smaller unmyelinated or poorly myelinated pain fibers in close proximity
Aberrant arteriovenous loop - 80-90%
What are the risk factors for trigeminal neuralgia? Who is the MC pt?
increasing age
female gender
MS
vascular disease
middle-aged and older women
What are the primary symptoms of trigeminal neuralgia? What branches are the MC?
paroxysmal, stereotyped attacks of usually intense, sharp, superficial or stabbing pain in distribution of 1+ trigeminal branches
(V2, V3 MC)
What are the facial muscle spasms called that are associated with Trigeminal neuralgia?
tic douloureux
If V1 is involved, what are the associated s/s?
may see increased lacrimation, conjunctival injection, rhinorrhea
What does the distribution look like from the from for V1,V2, V3 TN? What will the PE look like?
PE will be normal, light touch of “trigger zones” may reproduce symptoms
What are some clinical features that would make you think it is secondary TN?
______ may help differentiate classic TN from secondary TN. Is it always neccessary?
MRI/CT w and w/o contrast
recommendation for imaging varies
How does cluster HA differ from TN?
cluster HA has V1 distribution and the pain lasts longer than TN
TN: attacks are shorter in duration but frequent
What is first line tx for TN? Need to asses for _____ in pts of Asian ancestry. Why?
Carbamazepine (Tegretol) for 1 month and then try and taper as tolerated
HLA-B*15:02 allele
risk of SJS/TEN
What is the major possible SE of carbamazepine/oxcarbazepine? Which one is worse?
agranulocytosis
carbazepine carries higher risk of bone marrow problems
What are second line tx options for TN?
Second-line:
Antiepileptics - lamotrigine (Lamictal), gabapentin, phenytoin (Dilantin), pregabalin (Lyrica)
Muscle relaxants - baclofen, tizanidine (Zanaflex), botulinum toxin injection
What are the surgical tx options for TN? Give a brief description of each
