Test on Peripheral Nerve Injury and Repair Techniques

Question 1: Prompt primary neurorrhaphy is always the ideal repair, even if performed under conditions of extreme tension and contamination.

A. Yes

B. No

Explanation: If a nerve repair is performed in the face of extreme tension and contamination, unfavorable scarring will occur. In this specific case, two neurorrhaphy sites under favorable conditions are preferable to a single neurorrhaphy under unfavorable conditions, indicating that primary neurorrhaphy is not always ideal under such circumstances.

Question 2: According to the study materials, which statement is true regarding the use of vein grafts for sensory deficits?

A. Vein grafts are primarily used for motor defects, not sensory deficits.

B. For sensory deficits less than 3 cm, vein grafts are considered equally reliable as other options like biological and synthetic conduits.

C. Vein grafts are a newer technique and are rarely used as primary conduits.

D. Vein grafts are only effective for bridging gaps larger than 20 cm.

Explanation: The study materials state, 'Current consensus is that for a sensory deficit less than 3 cm, any of these options [including vein grafts] is equally reliable.' It also mentions that 'Autologous vein grafts are the oldest conduit and are still used both as a primary conduit and as a wrap.' There is no information suggesting they are only for motor defects or for gaps larger than 20 cm.

Question 3: Mackinnon introduced a sixth degree to the classification of nerve injury.

A. Yes

B. No

Explanation: The study materials indicate that Mackinnon later included a sixth degree in the classification of nerve injury, which is described as a combination of degree I–IV ± normal fascicles.

Question 4: Blunt penetrating nerve injuries with an acute nerve deficit always require immediate surgical exploration.

A. Yes

B. No

Explanation: Blunt penetrating and blast injuries are usually treated conservatively, similar to closed crush and stretch injuries, because they may recover spontaneously. Immediate exploration is only warranted for penetrating trauma with an associated vascular injury, or semi-electively within the first week for sharp lacerations.

Question 5: Which of the following statements about the Seddon Sunderland nerve injury classification is accurate?

A. Seddon's original classification included five degrees of nerve injury, which Sunderland later expanded upon.

B. Neurapraxia (Degree I) involves a conduction block and typically has an excellent recovery.

C. Fourth-degree injuries, characterized by a complete scar block, are known for slow but incomplete recovery.

D. Both axonotmesis (Degree II) and neurotmesis (Degree V) are associated with complete transection and no recovery.

Explanation: According to the study materials, Seddon described three types of nerve injuries, and it was Sunderland who expanded upon Seddon's classification to emphasize five degrees of nerve injury. Neurapraxia (Degree I) is a conduction block that resolves spontaneously with fast/excellent recovery. Fourth-degree injuries result in a complete scar block and have no recovery. Axonotmesis (Degree II) involves axonal rupture without interruption of the basal lamina tubes and has slow/excellent recovery, whereas neurotmesis (Degree V) is a complete transection with no recovery.