Peripheral Nerve Injuries
Damage to the nerves that carry signals between the brain and the hand, causing numbness, weakness or pain in the territory that nerve supplies.
Nerves carry signals in two directions: sensation from the hand back to the brain, and instructions from the brain out to the muscles. Three main nerves serve the hand - the median, the ulnar and the radial - and each supplies a distinct territory of skin and a distinct set of muscles.
Because the territories are distinct, the pattern of numbness and weakness is informative. Which fingers are numb, and which movements are weak, points toward which nerve is involved and roughly where along its course the problem lies.
Nerves can be cut, stretched, crushed, or compressed gradually over time. They can recover - but they recover slowly, roughly a millimetre a day, and the outcome depends heavily on the type of injury, the level, and how long the muscles have been without a nerve supply.
Loading anatomy
Common symptoms
- Numbness or altered sensation in a specific pattern of fingers
- Weakness of particular movements - pinch, spreading the fingers, or lifting the wrist
- Burning, electric or shooting pain
- Muscle wasting, often first visible between the thumb and index finger or on the back of the hand
- Sensitivity of a scar, or an electric sensation when a particular point is tapped
- Dryness of the skin in the numb area, and changes to nail growth
Causes and contributing factors
- Cuts and penetrating injuries
- Stretch injuries and traction, as in some falls and higher-energy trauma
- Crush injuries and fractures, where a nerve is injured alongside bone
- Sustained compression - carpal tunnel syndrome at the wrist and cubital tunnel syndrome at the elbow are the common examples
- Pressure from swelling, scar tissue, a mass or a previous operative field
- Medical conditions that affect nerves generally, including diabetes
If you have already had surgery for this
Nerve symptoms that persist or return after previous surgery are a common reason for referral, and they warrant a systematic reassessment.
How it is evaluated
Evaluation maps the problem. Sensation is tested territory by territory, and muscles are tested individually, because a specific pattern of loss identifies both the nerve and the likely level of injury.
Time matters in nerve injury more than in most areas of hand surgery. Muscles that have been without a nerve supply for a prolonged period may not recover even if the nerve does, which is why early assessment is emphasised.
- Mapping of sensation across each nerve territory
- Individual muscle testing to establish which nerve and which level
- Examination for muscle wasting and for changes in the skin and nails
- Nerve conduction studies and electromyography where they will change management
- Ultrasound or MRI in selected cases to look at the nerve itself
- Serial examination over time, since recovery has a predictable pattern that can be tracked
Clinical detail
Injuries are classified by severity - from neurapraxia through axonotmesis to neurotmesis - because the classification predicts whether spontaneous recovery is possible and whether surgery is required.
The advancing Tinel sign, motor and sensory recovery patterns and serial electrodiagnostic studies are used together to distinguish a recovering nerve from one that is not going to recover without intervention.
Motor endplate degeneration over time sets a practical window for reinnervation, which is why decisions about exploration or reconstruction are time-sensitive.
Nonsurgical treatment
When a nerve has been compressed or bruised rather than divided, recovery without surgery is possible and observation is often appropriate - with a clear plan for how progress will be monitored and what would change the plan.
Alongside this, treatment focuses on protecting the numb hand and keeping joints supple while the nerve recovers.
- Removing the source of pressure, including changes to posture and activity
- Splinting to protect the limb and support weakened muscles
- Hand therapy to maintain joint movement and prevent contracture
- Sensory re-education as sensation returns
- Care of the insensate hand - numb skin is easily burned or injured without being noticed
- Medication for nerve pain where appropriate
Surgical treatment
Surgery is considered when a nerve has been divided, when recovery has not occurred within the expected timeframe, or when a nerve is compressed and not improving with nonsurgical care.
Where a nerve has been cut, the ends are repaired directly if they can be brought together without tension. Where a segment is missing or scarred, the gap has to be bridged rather than pulled closed - tension is the enemy of nerve repair.
Nerve surgery is microsurgical work, performed under magnification with very fine suture.
- Release of a compressed nerve
- Direct microsurgical repair of a divided nerve
- Nerve grafting to bridge a gap
- Nerve transfer, where a nearby expendable nerve branch is redirected to restore an important function
- Neurolysis - freeing a nerve from surrounding scar tissue
- Management of a painful neuroma
Recovery
Nerve recovery is slow and it is measured in months to years, not weeks. A regenerating nerve advances at roughly a millimetre per day, so the further the injury is from the hand, the longer recovery takes.
Sensation usually returns before fine discrimination does, and it often passes through an uncomfortable, tingling phase on the way - which is generally a sign of progress rather than a problem.
- Regular reassessment to track the advancing front of recovery
- Hand therapy throughout, including sensory re-education
- Protection of numb skin from heat, cold and injury
- Recovery is often incomplete after severe injuries, and expectations are discussed frankly
When to seek urgent care
Seek immediate medical attention - an emergency department - if you experience:
- Numbness or weakness immediately after a cut or penetrating injury
- Sudden loss of hand function after trauma
- Rapidly progressive numbness or weakness
- Severe pain with a swollen, tense forearm or hand after injury
- A cold, pale hand alongside numbness
This list is not exhaustive. If something about your hand worries you, have it looked at.
Frequently asked questions
How long does a nerve take to recover?
A recovering nerve regrows at roughly one millimetre per day. A nerve injured at the wrist may therefore take several months to reach the fingertips; one injured higher up takes longer. Recovery is tracked over time rather than judged at a single visit.
Will sensation come back completely?
It depends on the type of injury, where it happened, the person’s age and how quickly it was treated. Compression injuries treated early often recover well. Nerves that were cut and repaired usually recover useful protective sensation, though fine discrimination may not fully return. Honest, individual expectations are part of the discussion.
My hand is still numb months after surgery. Is that expected?
Sometimes it is exactly what would be expected from the timeline of nerve regeneration, and sometimes it indicates that something else is going on. Persistent numbness after nerve surgery is worth re-evaluating properly rather than simply waiting longer.
Related conditions
Carpal Tunnel Syndrome
Pressure on the median nerve where it passes through a narrow tunnel at the wrist, which can cause numbness, tingling and weakness in the hand.
Complex Hand Trauma
Severe injuries that damage more than one tissue system at once - bone, tendon, nerve, blood vessel and skin together.
Tendon Injuries
Cuts, ruptures or damage to the cords that connect muscle to bone and make the fingers and thumb move.
Discuss nerve injuries with Dr. Champagne
A consultation begins with understanding your symptoms, how they affect what you do, and what has already been tried.