Pain/Regional Flashcards
A-delta
myelinated, sharp, well localized pain, temp, touch (somatic)
C fibers
unmyelinated, poorly localized mechanical, thermal, chemical (visceral)
pain course
a-delta/c fibers send signal to doral horn (near substantia gelatinosa), travel up spinal cord to the thalamus via ipsilateral spinoreticulothalamic tract or contralateral spinothalamic tract, some travel to somatosensory cortex and some to anterior cingulated gyrus (limbic forebrain) for emotional processing
allodynia
pain due to non painful stim
hyperalgesia
increased response to pain
hyperesthesia
exaggerated pain to noxious stimuli
hypoalgesia
decreased pain to painful stimuli
dyesthesia
unpleasant, abnormal sensation (spon/evoked)
how many nodes of ranvier need to be blocked
3
CRPS 1 vs CRPS 2
no known insult, gradual onset vs known major nerve damage and distal to central spread, both don’t follow dermatomes
CRPS acute
(first stage) 1-4 weeks; red, hot, dry skin
CRPS dystrophic
(second stage) 4 weeks - 4 months; cold, clammy, white
CRPS atrophic
(third stage) after 4 months; muscle wasting, joint destruction, bone demineralization, hair loss, nail changes, thinning of skin
CRPS triad
- sensory (pain, allodynia, hyoeralgesia) 2. autonomic (edema, skin color, skin temp) 3. motor (muscle weakness, spasm, decreased ROM)
phantom limb pain
all amputees get over time, no difference traumatic or not, worse with more proximal amputation, can reactivate with spinal/epidural
phantom treatment
carbamazepine or calcitonin, TENS, narcotics (epidural/PO), peripheral/central neurolysis or nerve blocks, trigger point injections
TENS
transcutaneous electrical nerve stimulation - low intensity electrical stim releases endogenous endorphins that are inhibitory at spinal cord
spinal cord stim placement technique
needle into epidural space via paramedian using fluoro
myofascial pain syndrome
widespread aching, stiffness, erythema, fluctuations in pain intensity, 3rd/4th decade of life, can have trigger points
myofascial treatment
exercise, PT, massage, LA injections
Post herpetic neuralgia treatment
4-6 weeks post outbreak; TCAs, anticonvulsants, oral analgesics, sympathetic nerve blocks, topical LA, capsaician
ethyl alcohol
painful, immediate and profound neurolysis, hypobaric, long duration, high incidence of post neurolysis neuralgia, pure - somatic blocks, diluted - sympathetic
phenol
painless, delayed and less intense neurolysis, hyperbaric, short duration, LA properties, used for peripheral nerve blocks
methgb susceptible
benzocaine, prilocaine (build up o-toluidine), NO, G6P deficiency, methbg reductase deficiency (<4 months have this), nitrites/nitrates, anti-malaria meds, phenytoin
methgb treatment
methylene blue 1-2 mg/kg over 5-10 min to avoid toxicity (restlessness, tremor, precordial pain), reduction in 30-60 min or ascorbic acid 2mg/kg
Methgb percentage
70% death
signs of total spinal in infant
apnea –> hypoxemia –> bradycardia
cervical plexus superficial block
C1-4, posterior lateral border of SCM from inferior surface of mandible to clavicle
cervical plexus deep block
C1-4, 10 ml at level of C4 transverse process or 3 injections at levels C2, 3, 4 transverse processes
cervical plexus block complications
horner’s, RLN block, epidural/intrathecal injection, phrenic or SLN block, intravascular injection
interscalene block
C6 between anterior and middle scalene, blocks roots, spares lower trunk (supplemental block for ulnar)
supraclavicular block
lateral SCM and clavicle, block trunks
infraclavicular block
blocks at cords
axillary block
blocks at branches (distal to elbow), need sup for musculocutaneous at coracobrachialis, intercostobrachial (posterior medial arm) and medial cutaneous nerve (medial forearm) by arm cuff
push, pull, pinch, pinch
push radial, pull musculocutaneous, pinch (thumb to pinky) median, pinch (pinky to thumb) ulnar
radial injury
wrist drop
ulnar injury
can’t adduct thumb or abduct pinky
median injury
can’t oppose thumb and pinky
radial wrist block
anatomic snuff box (btw extensor pollicus longus & brevis)
ulnar wrist block
medial to ulnar artery(btw flexor carpi ulnaris & ulnar art)
median wrist block
btw palmaris longus & flexor carpi radialus tendons (injured at AC fossa with drug extravasation or needle injury
Intercostal nerve blocks
8-10 cm from back midline
TAP block location
between internal oblique and transverse abdominus fascia
femoral nerve block
L2-4, sensory to ant thigh & knee, medial aspect of leg
saphenous nerve block
only branch of femoral that innervates below the knee, block near saphenous vein at level of tibial tuberosity
ilioinguinal/iliohypogastric block
T12/L1, 2 cm medial and 2 cm superior to ASIS
lateral femoral cutaneous block
2 cm medial and 2 cm inferior to ASIS
obturator block
1-2cm distal and lateral to pubic tubercle, hit pubic bone then redirect cephalad to obturator canal
sciatic nerve injury
(innervateds hamstrings and muscles of leg and foot, sensory to outer leg and whole foot except instep and medial malleolus) weakness to all muscles below knee, L4-S3
tourniquet contraindications
sickle cell, infection, ischemic vascular disease
which LA associated with thrombophlebitis and bier block
chloroprocaine
bier block doses
prilocaine 3-4, lidocaine 1.5-3, ropivicaine 1.2-1.8
tourniquet inflation guidelines
250-275 of 100 mm Hg > SBP
tourniquet times
minimum of 25 minutes before deflation, if before –> deflate then re-inflate immediately, wait 1 minute then deflate
physio changes after tourniquet deflation
1-8 mm HG CO2 increase, 10-15% increase in HR, 5-10% potassium increase, ass with cerebral embolism
describe symptoms from nerve impingement in vertebral foramina and treatment
unilateral numbness/parethesias, in UE with movement (extension); treat with NSAIDs, steroids, surgery
common peroneal damage
no dorsal flexion of toes, no eversion of foot
lumbar sympathetic block
7cm lateral and 2 cm inferior to L2 vertebral body, success leads to vasodilation of LE, elevated skin temp, decreased skin resistance
lumbar/celiac sympathetic block complications
aorta/IVC puncture, perforation of renal pelvis/other organs, subarachnoid injection, somatic spread,bretroperitoneal hemorrhage, pneumo (celiac)
celiac plexus block and success
T5-12 in retroperitoneal space anterior to L1, posterior to aorta and IVC; hypotension, diarrhea
intraspinal narcotic symptoms
pruritis>n/v>urinary retention
spinal additions
alpha agonists and neostigmine have some analgesic properties
block succession
sensory then sympathetic then motor
block lag spinal
sensory lags 2 dermatomal segments behind sympathetic
spinal segment anesthetic requirements
1-2 ml per spinal segment in 20-40 yo, 2/3 blocked above, 1/3 blocked below (increase in age 0.75-1.5 ml)
large dose of intrathecal LA
pupil dilation
caudal landmarks
PSIS and sacral hiatus (between sacral cornua)
spinal/subarachnoid space block factors
baricity and patient position most important for sensory level
epidural block factors
increased dose (mass) more effective at faster onset and longer duration
Taylor approach
L5-S1 interspace epidural injection, find PSIS and use paramedian approach
neuraxial contraindications
coagulopathy, increased ICP, local/systemic infection, hypovolemic, R-L cardiac shunt, fixed cardiac lesions (AS, MS, IHSS), multiple sclerosis, spina bifida occulta
cutting needles
quinke, pitkin
conical needles
whitacre, sprotte, greene
epidural hematoma
rapid onset of backache, b/l muscle weakness, sensory deficit, urinary retention, paraplegia, treatment within 8 hours
epidural abscess
slow (5 days) onset of backache and loss of function, stage1: back pain→stage 2: radicular pain→stage 3: motor/sensory deficits→stage 4: paraplegia, dx w/MRI
anterior spinal artery thrombosis
rapid, painless, flaccid paralysis 2/2 to arteria radicularis magna damage
spinal cord blood supply
1 anterior spinal artery (vertebral aa at base of skull) supplies anterior 2/3, 2 posterior spinal aa (cerebellar aa) supplies posterior 1/3
spinal cord blood supply feeders
intercostal arteries T9-12 (75%), lumbar arteries L1-2 (10%), artery of adamkiewitz arises from aorta on left (T9-L2/T5) –> major blood supply for anterior spinal a and lower 2/3 of spinal cord
cauda equine syndrome
low back pain, BLE weakness, saddle anesthesia, loss of blowel/bladder control, assoc w/large micro catheters for cont spinal
transient neurologic syndrome
pain/dyesthesia in back, buttock & LE w/IT LA esp lido (w/o sensory/motor loss or bowel/bladder dysfunction), ↑risk w/lithotomy, ambulatory, obesity, onset of sx 12-24 hours, resolves in 3 days, tx: NSAIDs
total spinal
LOC 2/2 ischemic paralysis of medullary ventilatory centers b/c profound ↓BP or penetration of local thru foramen magnum, Pupilary dilation & loss of light reflex
neuraxial pruritits treatment
opioid ant, mixed opioid ag-ant, diphenhydramine and hydroxyzine, propofol
intralipid therapy
20% lipid emulsion, 1mk/kg bolus (can repeat), then followed by 0.25ml/kg/min after stable
LMWH catheter placement
12 hours after prophylaxis, 24 hours after treatment
Heparin catheter placement
4 hours after dose
clopidogrel neuraxial
7 days
ticlid neuraxial
14 days
abciximab neuraxial
2 days
tirofiban neuraxial
8 hours
eptifibatide neuraxial
8 hours
streptokinase/urokinase neuraxial
avoid
transdermal fentanyl mechanism of action
fentanyl depot in the upper layer of skin, takes about 1 hour before seen in serum and continues to circulate for about 24 hours after patch removed
lumbar plexus
ventral rami L1-4, variable contribution from T12 and L5
