Introduction
Hand nerve injuries can occur due to cuts, pressure, stretching, or crushing. When a nerve is damaged, it loses the ability to send signals, potentially causing sensory and motor issues like numbness or weakness. While some nerve injuries may heal naturally, more severe cases often require surgical intervention.
Anatomy
Nerves serve as communication pathways between the brain and the rest of the body. Each nerve is composed of neurons, which have a cell body, dendrites, and an axon. Dendrites transmit information to the cell body, while the axon carries signals away from it. Many nerves are covered by a protective myelin sheath that aids in efficient signal transmission.
Motor nerves control movement by transmitting signals from the brain to muscles, while sensory nerves send information about sensations like pain and pressure back to the brain. The primary nerves in the hand are the radial, ulnar, and median nerves.
- Radial Nerve: Provides sensation to the thumb side of the back of the hand and controls movement in the arm and wrist extensor muscles.
- Ulnar Nerve: Controls feeling in the little finger and half of the ring finger, as well as muscle movements that allow you to spread and bring together your fingers.
- Median Nerve: Supplies sensation to the thumb, index, middle finger, and half of the ring finger on the palm side. It also controls thumb movements crucial for grasping objects.
Symptoms
Nerve injuries in the hand most often affect the dominant hand and are more common in men than women. The ulnar and radial nerves are frequently involved. Damage to a nerve can result in loss of sensation, movement, or both, and may stem from cuts, pressure, or stretching due to trauma, such as falls or car accidents.
In cases of severe injury, such as nerve cuts, both the nerve and its protective sheath may be damaged, requiring surgery. If untreated, nerves may form painful neuromas, where scar tissue forms at the site of injury.
Diagnosis
To diagnose a nerve injury, doctors conduct a thorough examination and may use specific tests like:
- Tinel’s Test: Tapping along the nerve to detect sensitivity and pinpoint the injury.
- Wrinkle Test: Submerging the hand in water to identify areas where the skin does not wrinkle, indicating a lack of nerve function.
- Monofilament Test: Thin fibers are pressed against the skin to map areas of sensation.
Additional studies like nerve conduction tests and electromyography (EMG) may be performed to assess the extent of nerve damage and muscle response.
Treatment
Nerve injuries vary in severity, ranging from mild (first-degree) to severe (fifth-degree). First- to third-degree injuries often heal on their own, but fourth- and fifth-degree injuries typically require surgery. Immediate surgery is preferred for clean cuts, while crush injuries may need time for swelling to reduce before surgical intervention.
Surgery
The type of surgery depends on the extent of nerve damage and the size of the gap between the severed nerve ends. Surgical options include:
- End-to-End Repair: The most ideal method, stitching the two ends of a severed nerve together if the gap is small.
- Nerve Grafting: For larger gaps, a segment of nerve tissue from another part of the body is used to bridge the space.
- Conduits: A synthetic or biological material (such as veins or muscles) is used to help nerves regrow when grafting is not possible.
Recovery
Post-surgery, the hand is immobilized with a splint, and patients begin hand therapy to improve circulation, movement, and strength. Nerves regenerate slowly, typically at a rate of about one inch per month. Full recovery depends on various factors like age, injury severity, and the location of the damage.
