Peripheral Nerve Repair & Reconstruction

Peripheral nerves act as the body's intricate electrical wiring system, transmitting motor commands from the brain to the muscles and carrying sensory information (touch, temperature, and pain) back to the central nervous system. Because the hand and arm are highly exposed during work and daily activities, they are susceptible to nerve trauma from deep lacerations, crush injuries, fractures, or severe stretching forces.

At Erlanger Hayes Hand Center, our orthopedic surgeons are board-certified and subspecialty-trained in **microsurgery**. Reconnecting or rebuilding a severed peripheral nerve requires operating under high-powered surgical microscopes, utilizing specialized instruments and sutures finer than a human hair to restore physiological continuity and maximize functional recovery.

Anatomy of a Nerve Injury

Peripheral nerve injuries are generally classified into three mechanical categories based on the severity of tissue damage:

• Neurapraxia: A temporary conduction block resulting from mild compression or stretching. The internal nerve structures remain intact, and complete recovery typically occurs over weeks to months without surgery.
• Axonotmesis: A more severe injury where the internal conducting fibers (axons) are damaged, but the surrounding protective sheaths remain intact. Regeneration is possible but slow, occurring at a rate of approximately 1 millimeter per day.
• Neurotmesis: The most severe classification, where both the axons and the protective connective tissue sheaths are completely severed or disrupted. This pattern requires microsurgical repair to allow for any functional recovery.

Common Symptoms of Nerve Trauma

When a peripheral nerve (such as the median, ulnar, or radial nerve) is damaged in the upper extremity, symptoms present rapidly in the area supplied by that nerve:

• Sensory Deficits: Complete numbness, a "pins-and-needles" sensation (paresthesia), or a burning sensation in specific parts of the hand or fingers.
• Motor Weakness or Paralysis: Inability to move specific muscles, resulting in finger droop, loss of thumb opposition, or a weakened grip.
• Muscle Atrophy: Visible wasting away of muscle mass in the hand or forearm, which occurs over time if the motor nerve fibers remain disconnected.

Advanced Microsurgical Procedures

The choice of surgical technique depends on the nature of the laceration, the gap between the nerve ends, and the time elapsed since the initial trauma.

1. Primary Direct Repair

If a nerve is cleanly severed (e.g., by a sharp glass or knife cut) and evaluated promptly, a primary direct repair is performed. The surgeon gently trims the damaged ends back to healthy tissue and aligns the outer protective sheath (the epineurium) precisely using microscopic sutures. This allows the regenerating axons to grow cleanly down their original pathways.

2. Nerve Grafting & Conduits

In high-energy crush or blast injuries, a segment of the nerve may be destroyed, leaving a gap between the healthy ends that cannot be brought together without tension. Stretching a repaired nerve restricts its blood supply, preventing regeneration. To safely bridge this gap, our surgeons utilize:

• Nerve Conduits: Small, hollow bioabsorbable tubes placed across short gaps (typically under 3 centimeters). These tubes guide the growing nerve fibers across the gap while protecting them from scarring.
• Nerve Autografts: For larger gaps, a small, less critical sensory nerve (such as the sural nerve in the leg) is harvested and used as a structural bridge. This provides a natural scaffold for axon growth.

3. Nerve Transfers

In cases of proximal nerve injuries or delayed care where muscle function is at high risk, a nerve transfer may be performed. The surgeon takes a redundant, functioning branch from a healthy neighboring nerve and redirects it directly into the injured nerve close to the muscle. This significantly shortens the regeneration distance and recovery time.

Post-Operative Rehabilitation and Regeneration

Surgical alignment provides the necessary pathway, but biological nerve regeneration is a slow process, averaging about 1 millimeter per day (roughly 1 inch per month). Our **certified hand therapists (CHTs)** guide patients through an essential, long-term rehabilitation protocol:

• Immobilization and Protection: Initially, a custom splint protects the microscopic repair from tension or stretching for the first few weeks.
• Sensory Re-education: As sensory fibers grow back into the hand, patients often experience hypersensitivity or misinterpret sensations. CHTs use specialized exercises to help the brain correctly re-identify textures, temperatures, and touch.
• Electrical Stimulation and Range of Motion: Therapy protocols maintain joint flexibility and use stimulation to protect resting muscle tone while the nerve fibers grow back down to reconnect with the muscle.