Digital Nerve Injury

Overview

Each finger is supplied by two digital nerves, one running along each side, that carry sensation from the skin back to the brain. These nerves sit just beneath the skin near the finger's blood vessels, so a cut along the side of a finger can easily damage them. A digital nerve injury interrupts the flow of sensory signals, leaving part of the finger numb, tingling, or oversensitive.

While the loss of feeling in a single finger may sound minor, normal sensation is important for fine tasks, protecting the fingertip from burns and cuts, and a comfortable, functional hand. Digital nerves do not provide the muscle power to move the finger, so movement is usually preserved unless a tendon is also injured. Many digital nerve injuries can be repaired with microsurgery, and even when a nerve is left to heal on its own, useful sensation often returns slowly over months.

Symptoms

Symptoms reflect the loss or disturbance of sensation in the area the nerve supplies, usually one side of a finger.

• Numbness or loss of feeling along one side of a finger
• Tingling, pins-and-needles, or a burning sensation
• Reduced ability to feel light touch, temperature, or texture
• Increased sensitivity or pain at the injury site (sometimes a small tender lump called a neuroma)
• Difficulty with fine tasks such as buttoning or picking up small objects

Because digital nerves are sensory only, the finger can usually still bend and straighten unless a nearby tendon is also cut. A finger that is both numb and unable to move suggests a more extensive injury.

Causes

Digital nerve injuries are most often caused by trauma to the side of a finger:

• Lacerations: Knives, glass, sharp metal, and similar objects can cut through the nerve, often along with a tendon or artery.
• Crush injuries: Doors, machinery, or heavy objects can bruise or sever the nerve.
• Pressure or stretch: Prolonged pressure or a forceful pull can stretch or compress the nerve and impair its function.
• Surgical or treatment-related injury: Rarely, a nerve can be injured during hand surgery or other procedures.

Risk Factors

• Work or hobbies involving knives, glass, or sharp tools
• Use of power tools and machinery
• Deep cuts along the side of a finger
• Previous hand trauma or surgery
• Activities with a high risk of finger lacerations

Diagnosis

A clinician diagnoses a digital nerve injury mainly through examination of sensation in the finger.

• Sensation testing: Comparing light touch and the ability to tell two close points apart on each side of the finger and against the uninjured hand.
• Examination of the wound: Inspecting any cut to see whether the nerve, tendon, or artery is involved.
• Movement and circulation check: Testing finger bending and the finger's color and warmth to detect associated injuries.
• Surgical exploration: For deeper cuts, the nerve may be examined directly during surgery to confirm whether it is divided.

Treatment

Treatment depends on whether the nerve is partly or completely cut and on what other structures are involved.

• Observation: Bruised or stretched nerves that are not severed may recover on their own, and feeling is monitored over time.
• Microsurgical repair: A completely cut nerve is often repaired under magnification by stitching the ends together. If a gap is too large, a nerve graft or conduit may be used.
• Wound care: Any laceration is cleaned, and associated tendon or vessel injuries are repaired at the same time.
• Therapy: Sensory re-education and protective strategies help the hand adapt while sensation gradually returns.

Nerves regrow slowly, roughly a small fraction of an inch per week, so it can take many months for feeling to improve, and some people are left with reduced sensation or a tender spot.

Prevention

• Use cut-resistant gloves and careful technique with knives and tools
• Keep guards in place on saws and power equipment
• Handle glass and sharp metal with caution
• Seek prompt evaluation of any finger cut with numbness
• Protect a numb fingertip from heat and sharp objects while sensation is reduced

When to See a Doctor

See a doctor promptly if a finger feels numb after a cut, crush, or injury, since early repair gives the best chance of recovering sensation. Seek urgent care if a wound will not stop bleeding, the finger looks pale or cold, or you cannot bend the finger, as these may signal injury to an artery or tendon along with the nerve. A numb fingertip should also be protected from burns and cuts until feeling returns.

Related Topics

Frequently Asked Questions

References

1. American Society for Surgery of the Hand (ASSH). Nerve Injuries.
2. American Academy of Orthopaedic Surgeons (AAOS). Peripheral nerve injuries.
3. MedlinePlus, U.S. National Library of Medicine. Peripheral nerve disorders.
4. OrthoInfo, American Academy of Orthopaedic Surgeons.