Peripheral Neuropathies
Andrew G. Rudikoff
2/2/09
PACU Rotation
Dr. Edward Park
Why Peripheral Neuropathies are important?
-Of all claims settled against anesthesiologists, nerve damage comprises 16%, the second
most. Death (32%) trumps nerve damage; third on the list is brain damage (12%).
I.
Pre-Operative Assessment
a. Risk Factors include: smoking, DM, PVD, body weight (BMI greater than
38), age (older at higher risk), male (particularly ulnar nerve injuries)
prolonged bed rest, acromegaly, amyloidosis, cryoglobulinemia,
hypothyroidism, liver disease, uremia, multiple myeloma**.
b. Perform a focused physical exam pre-operatively to determine pre-existing
neuropathies.
c. Medications that predispose to neuropathy: amiodarone, hydralazine,
dapsone, isoniazid, metronidazole, phenytoin, vincristine.
**Data have not shown causal relationship between aforementioned co-morbidities and
acquiring post-operative peripheral neuropathies.
II.
Upper Extremity
a. Brachial Plexus injuries (2nd most common injury -- 20 %)
i. Mechanism: shoulder brace coupled with abnormal head tilt during
positioning for surgery, post sternotomy, trauma to 1st ribs,
stretching due to internal mammary dissection, compression of
humeral head with hyper-abduction.
ii. Recognition: radial, ulnar, median, axillary nerve damage.
iii. Recommendations:
1. Supine patients must abduct their arms less than 90 degrees
(consensus statement).
2. Alternatively, supine patients may tuck their arms. There
has been no difference in the incidence of brachial
plexopathies in either position (consensus statement).
3. Prone patients may abduct arms greater than 90o
(consensus statement).
4. Use arm boards and chest rolls as needed.
iv. Exceptions/Caveats:
1. In a recent liver transplantation lasting 16 hours, the patient
suffered bilateral brachial plexus injuries postoperatively.
His arms were in fact 90o.
2. There has been no randomized clinical trial evaluating
brachial plexus injuries.
b. Radial Nerve Injuries
i. Mechanism: pressure on spiral groove of humerus through which
the radial nerve travels.
ii. Recognition: inability to extend wrist and fingers; to supinate
forearm; sensory damage to dorsum of hand (dorsoradial 3.5
fingers).
iii. Recommendations: pad the arm to prevent excess pressure on the
spiral groove; BP cuff has not been shown to have a causal
relationship with radial nerve damage.
c. Median Nerve Injuries
i. Mechanism: IV insertion, elbow hyperextension.
ii. Recognition: loss of pronation, flexion of wrist and fingers, loss of
1st and 2nd lumbricals, no abduction of thumb. Sensory to 1st 3.5
fingers. Ape hand deformity.
iii. Recommendations: Keep arms tucked at side or abducted, keep
elbows flexed less than 30 degrees.
d. Ulnar Nerve Injuries: Most common nerve injury (28%)
i. Mechanism: compression on ulnar groove perioperatively.
ii. Recognition: claw hand, intrinsic muscles of hand, sensory to
ventral and dorsal 1.5 fingers (ring and pinky).
iii. Recommendations: use padding to decrease pressure on ulnar
nerve (consensus statement).
e. Arm: 1 nonrandomized study indicates there is no difference in nerve
injuries with arm supination vs. pronation.
III.
Lower Extremity:
a. Sciatic Nerve Injury
i. Mechanism: stretching of hamstring
ii. Recognition: sciatica, inability to plantar-flex and evert foot.
Sensory damage to back of thigh, lateral and posterior
compartment of leg, and lateral aspect of foot. Foot drop can
occur.
iii. Recommendations: flexion of hip to 90o in supine position to
prevent sciatic nerve damage; when hip is flexed 90o in sitting
position, sciatic nerve injury has been observed.
b. Peroneal Nerve Injury
i. Mechanism: compression by equipment on lateral aspect of knee.
ii. Recognition: inability to evert foot, damage to posterior and lateral
compartment of leg, damage to posterior compartment of foot.
Foot drop can occur.
iii. Recommendation: Pad lateral aspect of knee.
c. Femoral Nerve Injury:
i. Mechanism: flexion of hip causing stretch of femoral nerve
ii. Recognition: inability to extend leg, sensory loss on anterior aspect
of leg.
IV.
Mechanism of Injury:
a. Stretching: only 10% stretch can result in nerve damage.
b. Compression: by equipment, surgeons. Hyper-abduction of the arm
causing the humeral head to compress the brachial plexus
c. Ischemia: systemic hemodynamic instability vs. local ischemia.
d. Trauma: sternotomy, surgical incision
e. Metabolic derangements
V.
Pathophysiology of Nerve Injury
a. Transient ischemia: lasts minutes; confers no structural nerve damage
b. Neurapraxia: lasts 4-6 weeks; causes demyelination of the peripheral
fibers of the nerve trunk.
c. Axonotmesis: complete recovery unlikely; causes disruption of axons
within nerve sheath.
d. Neurometesis: complete disruption; repair produces partial recovery.
VI.
Post-Operative Evaluation
a. Examining patients may lead to early recognition of peripheral
neuropathies, but does not affect outcome.
b. In PACU, continue to pad areas to prevent stretch and compression.
Distribute pressure over a large surface.
c. Decipher whether or not there is a motor or sensory deficit. Sensory
deficits usually resolve in 5 days. On the other hand, motor deficits
require neurology consult with EMG monitoring.