Nerve injuries

Types of nerve damage

Nerve injuries fall into three categories based on severity:

1. Neurapraxia (nerve contusion): the nerve experiences temporary dysfunction from compression or mild trauma while maintaining structural integrity. All internal fibers remain continuous. Recovery is typically complete without residual deficit.

2. Axonotmesis (fibre disruption): the internal nerve fibres sustain damage while the outer protective sheath remains intact. The portion of each fibre beyond the injury site degenerates, leaving hollow tubes. Since the parent nerve cells near the spinal cord remain viable, fibres can potentially regenerate down these tubes. Recovery from this injury pattern is less predictable.

3. Neurotmesis (complete division): both the outer sheath and all internal fibres are severed. This injury requires surgical repair for any hope of recovery.

When internal fibres are damaged, regeneration occurs at approximately 1 millimeter per day as fibres slowly regrow through their tubes. However, many fibres fail to reconnect successfully, and those that do often connect to incorrect target tissues - imagine telephone lines connecting to wrong addresses. Your brain attempts to reinterpret these scrambled signals but cannot fully compensate. Consequently, even after successful repair, some permanent functional loss persists.

Recovery varies considerably. Unfortunately, nerve healing diminishes with advancing age, partly because younger nervous systems demonstrate greater adaptive capacity.

Nerves can also suffer compression injuries - see the separate information sheets on carpal tunnel syndrome and cubital tunnel syndrome for details.

Note: Brachial plexus injuries (involving the complex nerve network in your neck and shoulder) require highly specialised management. Patients with these injuries are best treated in dedicated brachial plexus services.

• Altered or absent sensation in the affected distribution

• Muscle weakness causing grip dysfunction or general clumsiness

• Pain of variable intensity - chronic nerve injuries occasionally produce severe discomfort

• Cold intolerance

• Abnormal sensitivity where light touch produces unpleasant sensations (less common)

Examination may reveal:

• Diminished sensation in specific patterns

• Dry skin from absent perspiration

• Muscle weakness on individual testing

• Later changes including fingertip atrophy, loss of normal joint skin creases, and visible muscle wasting

• Tinel's sign (tingling sensation when tapping along the nerve course)

With open wounds and suspected nerve injury:

Surgical exploration is necessary to visualise the nerve and repair partial or complete lacerations with microsurgical techniques.

Without open wounds:

Observation typically guides initial management. Electrodiagnostic testing (neurophysiology studies) may be performed, measuring nerve conduction velocity by applying electrical stimulation. Electromyography uses fine needle electrodes inserted into affected muscles to record electrical activity. These studies help characterise injury severity, guide treatment planning, and establish prognosis.

In some cases, if recovery is incomplete or investigations suggest significant nerve damage, surgical treatment may be recommended. This can include nerve exploration, release of scar tissue around the nerve (neurolysis), or repair of the nerve itself, sometimes using a nerve graft.

Outcomes depend on numerous variables. I'll discuss realistic expectations for your specific situation. Remember that nerve regeneration requires many months - growing at roughly 1mm daily means recovery from significant injuries may take two years or longer to reach maximum improvement.

Neuroma formation:

When damaged nerve fibres cannot navigate down their intended pathways, they sprout chaotically, forming a tangled bundle of nerve endings called a neuroma. Since these endings remain connected to the nervous system, neuromas can generate significant discomfort when knocked or pressed.

Management depends on symptom severity and impact on function. Options may include hand therapy focused on desensitisation, a period of watchful waiting, or surgical treatment. Surgery may involve removal of the neuroma itself, sometimes combined with additional techniques designed to reduce the risk of recurrence.

Nerve grafting:

Extensive nerve damage sometimes creates gaps too large for direct repair, or repairs may fail to heal. In these situations, nerve grafting becomes necessary - using segments harvested from less critical nerves elsewhere. The donor site may have permanent numbness in a small area.

I'll discuss additional potential complications relevant to your specific injury and surgical plan, and your hand therapist will guide your rehabilitation.