Nir Hus Absite Review Q8

8/3/2019 Nir Hus Absite Review Q8

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Absite Topic Review

General Surgery

Nir Hus, MD, PhD.Mount Sinai Medical Center

Miami Beach


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Post Op Neuropathy

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Common Peroneal Neuropathy

The common peroneal nerve is superficial as itwraps 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 legholders has commonly been considered the

primary mechanism of injury in peroneal

neuropathy.

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Sciatic Neuropathy The same forces that contribute to stretch injuries of the

hamstring group muscles (for example, biceps femorismuscle) may stretch the sciatic nerve.

Simultaneous hyperflexion of the hip and extension ofthe knee will stretch and possibly injure the sciatic nerve.

This set of actions can occur during the establishmentand maintenance of some variants of the lithotomyposition.

A patient in a lithotomy position may passively shifttoward the caudal end of an operating table when placedin a head-up position or be actively shifted caudally by amember of the operating team in an attempt to obtainincreased exposure of the perineum.

This movement may increase flexion of the hips andeither flexion or extension of the legs

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Femoral Neuropathy

Unlike most other neuropathies in which the anesthesiaprovider is often considered to have actedinappropriately in order for the neuropathy to occur,those involving the femoral nerve and its cutaneous

branches are often considered to result frominappropriate placement of abdominal wall retractors anddirect compression of the nerve.

When a neuropathy is related to retractors, theassumption is that a retractor used for an abdominalsurgical approach to the pelvis places continuouspressure on the iliopsoas muscle and either stretches thenerve or causes it to become ischemic by occluding theexternal iliac artery or its branches (or both) thatpenetrate the nerve as it passes through the muscle

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Upper Extremity Neuro

Any nerve that passes into the upperextremity may sustain an injury or convert

from an abnormal but asymptomatic stateto a symptomatic state perioperatively.

The ulnar nerve and brachial plexusnerves are the most likely to becomesymptomatic and lead to major

perioperative disability.

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Median Neuropathy

This injury occurs most often in muscular men in theyoung to middle-age groups.

Preoperatively, these patients often are unable to extendtheir arms completely at the elbows because their largebiceps muscles and tendons are relatively inflexible.

When they receive muscle relaxants, undergoanesthesia, and are positioned for an operation, theirrelaxed forearms may be extended flat onto arm boardsor at their sides; consequently, their median nerves maybe stretched. .

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Ulnar Neuropathy

Ulnar nerve and itsprimary bloodsupply in proximalforearm, posterior

ulnar recurrentartery, aresuperficial and canbe susceptible tocompression fromexternal pressureas they pass

posteromedially totubercle of coronoidprocess.

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Brachial Plexus Neuropathy

may masquerade as ulnar neuropathies or beassociated with symptoms that suggest injuriesto other nerve structures.

In general, brachial plexus neuropathies areassociated 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.

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Neuropathy associated with median sternotomyoften 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 sternalretraction is most common during internalmammary artery dissection.

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Retraction posteriorly displaces the upperrib 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 neuropathymay be difficult to distinguish from aperipheral ulnar neuropathy.

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The brachial plexus may be vulnerable tostretch in a patient who is positioned

prone. Theoretically, stretch of the plexus,

especially its lower trunks, may occurwhen the head is turned contralaterally,the ipsilateral arm is abducted, and theipsilateral elbow is flexed

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Head position stretching plexus against anchors in shoulder (A). Closure ofretroclavicular 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 ofvulnerability of radial nerve to compression above elbow (E).Nir Hus

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Nir Hus Absite Review Q8