Positioning

Question 1

Most common cause of litigations against anesthetists

Answer 1

Peripheral nerve injury 16% of claims

Question 2

Most commonly injured nerves?

Answer 2

–ulnar nerve (28%)

–brachial plexus (20%)

–lumbosacral root (16%)

–spinal cord (13%)

–Injury is less common for the sciatic, median, radial and femoral nerves.

Question 3

Predisposing factors to nerve injury

Answer 3

• Thin or obese body habitus
• Old age
• History of vascular disease, diabetes, smoking
• Male gender
• Hypotension, hypovolemia, dehydration
• Coagulopathy or presence of hematoma near nerve
• Infection/presence of abscess near nerve
• Pre-existing generalized neuropathy
• Hereditary predisposition
• Structural anomaly/congenital abnormality

–(e.g. constriction at thoracic outlet or condylar groove, or arthritic narrowing of joint space)

•Hypothermia, especially induced

Question 4

How are peripheral nerves damaged?

Answer 4

This outermost tissue layer is called the epineurium. Injury to the myelin sheath or axon of a nerve can lead to focal conduction block, degeneration and demyelination.

Question 5

What happens if a nerve is severely damaged, denervation?

Answer 5

If a nerve is severely damaged, whether by compression, stretch or other means, there is distal degeneration of the axon and, with it, the myelin, (Wallerian degeneration) over a period of 2-3 days

Question 6

Three groups of Seddons Classification?

Answer 6

–Neurapraxia: damaged myelin with intact axon. Impulse conduction across the affected segment fails. Mild and reversible nerve injury. Recovery usually occurs in weeks to months (good prognosis)

–Axonotmesis: axonal disruption. Endoneurium and other supporting connective tissue are preserved. (variable prognosis)

–Neurotmesis: nerve is completely severed. There is complete destruction of all supporting connective tissue structures. (surgery may be required)

Question 7

Five types of Sunderland’s Classification?

Answer 7

• Type 1: Local myelin injury (equivalent to Seddon’s ‘neurapraxia’ group). Recovery in weeks to months. (Good prognosis)
• Type 2: Disruption of axonal continuity with Wallerian degeneration. Regeneration of axon required for recovery. (Good prognosis)
• Type 3: Loss of axonal continuity and endoneurialtubes. Perineurium and epineurium preserved. Scarring can compromise recovery. (Guarded prognosis. Surgery may be required)
• Type 4: Loss of axonal continuity, endoneurial tube and perineurium damaged. Epineurium remains intact. (Poor prognosis. Surgery necessary)
• Type 5: Nerve entirely severed (equivalent to Seddon’s ‘neurotmesis’ group). (Surgery required. Prognosis poor)

Question 8

Symptoms of ulnar nerve injury?

Answer 8

–loss of sensation of medial portion of hand

–Inability to abduct or oppose the fifth finger (claw hand)

Prevented by positioning arms in supination. Hypotension increases the risk.

Question 9

Where is the brachial plexus located?

Answer 9

Question 10

Diagnosis of nerve involved in brachial plexus injury

Answer 10

Median – “Ape hand” deformity, inability to oppose thumb

Axillary – inability to abduct the arm

Ulnar – “Claw hand” deformity

Musculocutaneous – inability to flex forearm

Radial – wrist drop

Question 11

Compression of the spiral groove of the humerus can cause radial nerve injury, what are the symptoms?

Answer 11

–wrist drop

–weakness of abduction of thumb,

–loss of sensation in web space between thumb and index finger

Question 12

Common peroneal nerve injury

Answer 12

–Lateral aspect of knee is compressed against stirrup

–Adequate padding between leg and stirrup

–Better yet, rotate stirrup away from leg

Question 13

At risk- thin patients placed on a hardoperating table for a long operation

Stretching in the lithotomy position

CABG surgeries

Question 14

Femoral nerve injury

Answer 14

Impinged under inguinal ligament from flexion and abduction of thighs

Question 15

Saphaneous leg injury

Answer 15

Medial tibial condyle compressed by leg supports.

Question 16

Orbturator nerve injury

Answer 16

Mother- difficult forceps delivery or by excessive flexion of the thigh to the groin

Question 17

Anterior tibial nerve injury

Answer 17

Plantar flexion – foot drop
–Increases the approximate 90 degree angle between the front part of the foot and the shin
–Depressing an automobile pedal.

Question 18

Identification of major peripheral nerve injuries

Answer 18

Question 19

Identification of major peripheral nerve injuries

Answer 19

Question 20

Physiological effects of common positioning table

Answer 20

Question 21

Physiological effects of common positioning table 2

Answer 21

Question 22

Common complications of certain positions and how to prevent them

Answer 22

Question 23

Common complications of certain positions and how to prevent them

Answer 23

Question 24

Preop assessment of potential nerve injuries

Answer 24

extremes of age or body weight

preexisting neurologic symptoms

diabetes mellitus

peripheral vascular disease

alcohol dependency

smoking

arthritis