Slides with topics that are covered and were tested in the recent Absite exams. Nir Hus MD., PhD. http://www.nirhus.com

1. Absite Topic Review
General Surgery
Nir Hus, MD, PhD.
Mount Sinai Medical Center
Miami Beach

2. Post Op Neuropathy
Nir Hus

3. Lower Extremity Neuropathies
 most occur in patients who are undergoing
procedures while in a lithotomy position.
 considered preventable and to occur because of
poor intraoperative care (for example,
inappropriate positioning or padding) or
judgment (for example, excessively prolonged
use of the lithotomy position).
 the nerves most often involved were:
 The common peroneal (81%)
 Sciatic (15%)
 Femoral (4%).
Nir Hus

4. Common Peroneal Neuropathy
 The common peroneal nerve is superficial as it
wraps around the head of the fibula. Because it
is exposed at this level, it may be easily
compressed and injured.
 The absence of overlying tissue in extremely thin
people may increase this risk.
 Direct compression of the peroneal nerve by leg
holders has commonly been considered the
primary mechanism of injury in peroneal
neuropathy.
Nir Hus

5. Nir Hus

6. Sciatic Neuropathy
 The same forces that contribute to stretch injuries of the
hamstring group muscles (for example, biceps femoris
muscle) may stretch the sciatic nerve.
 Simultaneous hyperflexion of the hip and extension of
the knee will stretch and possibly injure the sciatic nerve.
 This set of actions can occur during the establishment
and maintenance of some variants of the lithotomy
position.
 A patient in a lithotomy position may passively shift
toward the caudal end of an operating table when placed
in a head-up position or be actively shifted caudally by a
member of the operating team in an attempt to obtain
increased exposure of the perineum.
 This movement may increase flexion of the hips and
either flexion or extension of the legs
Nir Hus

7. Femoral Neuropathy
 Unlike most other neuropathies in which the anesthesia
provider is often considered to have acted
inappropriately in order for the neuropathy to occur,
those involving the femoral nerve and its cutaneous
branches are often considered to result from
inappropriate placement of abdominal wall retractors and
direct compression of the nerve.
 When a neuropathy is related to retractors, the
assumption is that a retractor used for an abdominal
surgical approach to the pelvis places continuous
pressure on the iliopsoas muscle and either stretches the
nerve or causes it to become ischemic by occluding the
external iliac artery or its branches (or both) that
penetrate the nerve as it passes through the muscle
Nir Hus

8. Nir Hus

9. Upper Extremity Neuro
 Any nerve that passes into the upper
extremity may sustain an injury or convert
from an abnormal but asymptomatic state
to a symptomatic state perioperatively.
 The ulnar nerve and brachial plexus
nerves are the most likely to become
symptomatic and lead to major
perioperative disability.
Nir Hus

10. Median Neuropathy
 This injury occurs most often in muscular men in the
young to middle-age groups.
 Preoperatively, these patients often are unable to extend
their arms completely at the elbows because their large
biceps muscles and tendons are relatively inflexible.
 When they receive muscle relaxants, undergo
anesthesia, and are positioned for an operation, their
relaxed forearms may be extended flat onto arm boards
or at their sides; consequently, their median nerves may
be stretched. .
Nir Hus

11. Ulnar Neuropathy
 Currentlyavailable data suggest that
perioperative ulnar neuropathy may be
caused by factors other than inappropriate
patient positioning and padding of
extremities intraoperatively.
Nir Hus

12. Ulnar Neuropathy
 Ulnar nerve and its
primary blood
supply in proximal
forearm, posterior
ulnar recurrent
artery, are
superficial and can
be susceptible to
compression from
external pressure
as they pass
posteromedially to
tubercle of coronoid
process.
Nir Hus

13. Brachial Plexus Neuropathy
 may masquerade as ulnar neuropathies or be
associated with symptoms that suggest injuries
to other nerve structures.
 In general, brachial plexus neuropathies are
associated with:
 median sternotomy.
 Head-down positions in which shoulder braces are
used for support and stabilization.
 Rarely, they may be found in patients in a prone
position.
Nir Hus

14. Brachial Plexus Neuropathy
 Neuropathy associated with median sternotomy
often involves stretch or compression of the
brachial plexus during sternal separation.
 Another potential mechanism of injury is direct
trauma from fractured first ribs.
 Brachial plexus nerve injury during sternal
retraction is most common during internal
mammary artery dissection.
Nir Hus

15. Brachial Plexus Neuropathy
 Retraction posteriorly displaces the upper
rib cage and may stretch or compress the
C-8 through T-1 nerve trunks.
 These nerve trunks later join to form the
major contribution of the ulnar nerve.
 Therefore, this brachial plexus neuropathy
may be difficult to distinguish from a
peripheral ulnar neuropathy.
Nir Hus

16. Brachial Plexus Neuropathy
 The brachial plexus may be vulnerable to
stretch in a patient who is positioned
prone.
 Theoretically, stretch of the plexus,
especially its lower trunks, may occur
when the head is turned contralaterally,
the ipsilateral arm is abducted, and the
ipsilateral elbow is flexed
Nir Hus

17. Brachial Plexus Neuropathy
Head position stretching plexus against anchors in shoulder (A). Closure of
retroclavicular space by chest support with arms at side; neurovascular bundle trapped
against first rib (B). Head of humerus thrust into neurovascular bundle if arm and axilla
are not relaxed (C). Compression of ulnar nerve in cubital tunnel (D). Area of
vulnerability of radial nerve to compression above elbow (E).
Nir Hus