Nerve Lacerations

Nerve lacerations, or cut nerves, can be seen after a variety of traumatic events.  Cut nerves can lead to problems with sensation and muscle control, depending on which nerve is injured and where along the nerve the injury occurs.  

Anatomy and Causes

Nerves function as your body’s wiring system.  The nervous system is extremely complex with full volumes written about it.  The description here is necessarily a gross simplification.  Nerves in your arms and legs (peripheral nerves) can carry sensory and motor signals.  Sensory signals carry information to your brain, such as when you feel something touching your finger.  Motor signals carry information to your muscles, allowing movement.  Peripheral nerves can be motor, sensory, or mixed (meaning they carry both motor and sensory signals).  Nerves in the hand are frequently sensory nerves, whereas many nerves in the forearm are mixed nerves.  

A common misconception is that nerves don’t heal.  This is not entirely correct.  Peripheral nerves do have a limited ability to regenerate under the right conditions.  Often surgery is required to help create these conditions to improve the chances of nerve recovery.

Symptoms and Associations

After a sensory nerve is cut, sensation in that nerve’s distribution (the area that it supplies) is decreased.  It may not be completely absent as other nearby nerves can have an overlapping distribution.  When a motor nerve is cut, the ability to control the innervated muscles is lost.  If that muscle is not reinnervated in a certain amount of time, the supplied muscles can shrink (atrophy).

Treatment

The goal in treating nerve injuries is to improve the chances of nerve recovery.  Most acute lacerations require surgery to optimize nerve recovery.

Non-operative

Non-operative treatment of nerve lacerations can be considered in some situations.  Fingertip injuries often involve nerves that are too small to directly repair, and in most cases, have overlapping innervation for nearby nerves.  In cases of sensory-only nerves, the area of decreased sensation might be acceptable to the patient.  Chronic injuries where a significant amount of time has passed since the initial injury may not be candidates for nerve repair for a number of reasons.  

Operative

Acute nerve lacerations usually benefit from surgery.  Nerves cut sharply, such as with a kitchen knife, can often be directly repaired.  In cases where the ends are not cleanly cut, a portion of the injured nerve must be removed to prevent scar tissue from forming inside the nerve and to promote regeneration.  If this area is large, a nerve graft may be required to repair the nerve without applying too much tension to the repair site.

Chronic injuries may need additional interventions depending on the location and nature of the injury.  Nerve transfers, where a less essential nerve is re-routed to provide a more important function, may be an option.  In very old injuries, tendon transfer may be an option to help restore lost function.  These injuries require careful evaluation and additional diagnostic tests may be ordered to evaluate your injury.