Nerve Injuries in the Hand and Fingers
Nerves connect our brain and spinal cord to the rest of our body.
- They carry signals from the body to the brain about pain, pressure, temperature, etc. For instance, when your finger gets hit by a ball, the nerves signal to the brain that your finger is hurt, and you feel pain.
Nerves carry signals from our brain to our body, facilitating our ability to perform daily tasks and move our limbs. However, nerves are fragile and can be damaged by pressure, stretching, or cutting. Injury to a nerve can stop signals to and from the brain, causing muscles to stop working correctly and resulting in loss of feeling.
While many nerve injuries can be managed with treatment, it’s crucial to understand that nerves are intricate structures and their recovery is not as straightforward as ligaments, tendons, and bones. Even with the best treatment, some nerve injuries may lead to a certain degree of permanent dysfunction in the hand or fingers.
Anatomy
Nerves are part of the “electrical wiring” system of our bodies that carries messages between the brain and the rest of the body.
- Motor nerves carry messages between the brain and muscles to move the body.
- Sensory nerves carry messages between the brain and different body parts to signal pain, pressure, temperature, etc.
Nerves are very complex:
- Nerves are covered by a ring of protective tissue (epineurium), similar to the insulation surrounding an electrical cable.
- Within the epineurium, the nerve fibers are grouped into several cables called fascicles. Another protective layer called perineurium surrounds these extended groups of nerve fibers.
- The individual nerve fibers are made up of a very specialized part of a cell called an axon, which allows cells to communicate with one another via electrical signaling. The axon is covered by a final protective layer called endoneurium. Injury to this complex inner structure can disrupt the signal and cause the nerve to malfunction.
Cause
Pressure or stretching injuries can cause fibers within the nerve to break. The outer epineurium is stronger than the other layers and often remains intact (unbroken). However, the complex inner layers of the nerve are disrupted. This may interfere with the nerve’s ability to send or receive signals despite relatively minor damage to the outer layer.
Inside the intact outer layer, the end of the nerve farthest from the brain dies and degenerates (deteriorates). However, the end that is closest to the brain does not die. If the epineurium is intact (unbroken), the nerve may begin to heal after some time as the living nerve fibers find their way back to the muscle and skin.
In severe cases, the pressure or stretch is so great that even the epineurium is damaged. These cases often require surgery to achieve any meaningful recovery since the roadmap provided by the outer layer of the nerve is disrupted, and the living nerve fibers can’t find their way back to the muscle and skin.
Similarly, the inner nerve layers and the outer epineurium are damaged when a nerve is completely cut. Surgery is often needed in those cases to put the epineurium back together so the nerve fibers can find their way back to where they need to go.
If the nerve and insulation have been severed and the nerve is not fixed, the growing nerve fibers may form a painful nerve scar or neuroma. This is caused by the disorganized growth of nerve fibers, which results in a large and painful ball of nerves.
Symptoms
Symptoms of nerve injuries vary.
- Injured sensory nerves typically cause pain and numbness. The nerve-controlled area no longer tells the brain about pain, temperature, and pressure. The raw nerve end can be very painful.
- Injured motor nerves result in loss of function of the controlled muscle. For example, injury to the radial nerve will result in an inability to straighten your fingers or thumb and extend your wrist. Many nerves are “mixed,” meaning an injury to these nerves results in both sensory (feeling) and motor (function) issues.
In severe cases, injury to nerves can result in a severely painful condition called complex regional pain syndrome (CRPS).
Doctor Examination
Your doctor will typically start by asking about the injury and your health history. They will want to know:
- How the injury occurred, and how long ago it happened
- What your symptoms are — including whether you are having problems with sensation (feeling) or function
- If you have had any previous treatments for this injury or past issues in the affected hand
- If you have any other medical issues, such as a chronic health condition like diabetes or heart disease
- Which medications and supplements you are taking
Physical Examination
The doctor will likely examine you and focus on the area of injury. They will:
- Test the feeling in the injured limb and your ability to move various muscles.
- Check for other injuries associated with the nerve injury (e.g., vessel, tendon, bone, etc.) that may also need to be addressed.
Imaging Tests
Depending on the injury, a variety of imaging tests may be helpful.
- Your doctor may order X-rays for associated broken bones or dislocated joints.
- MRI or Ultrasound may help show the nerve injury and the “zone of injury” around the nerve, which can help with surgical planning.
Electromyography and nerve conduction studies (electrodiagnostic testing) can help diagnose and treat nerve injuries. Your doctor may request these studies, depending on the type of nerve injury.
Nonsurgical Treatment
Many minor “nerve palsies” can be treated non-operatively. These are pressure or stretching injuries to the nerve that do not damage the outer protective layer (epineurium). If the outer layer is intact (unbroken), nerves can often heal over time, allowing for function return. The location and function of the nerve will determine the healing potential and time to healing.
- Sometimes, EMG/NCS can help with prognosis (the likely course of the injury) and recovery prediction in these situations.
- To ensure proper recovery, you may need a series of visits with your doctor, including examinations of the affected hand(s).
- Therapy is often helpful for keeping joints supple (flexible) until muscle function returns and for helping with strengthening when it does return.
Temporary splints may also be helpful to keep joints aligned (lined up) properly while waiting for nerve recovery.
