To understand the types of peripheral nerve injuries, let’s first be clear about what peripheral nerves are. Your body’s nerve system includes the central nervous system – brain and spinal cord – and the peripheral nervous system. Peripheral nerves are outside the brain and spinal cord. Their job is to send information from your brain/spinal cord to the rest of the body. They also relay sensory information, from throughout your body, back to the brain/spinal cord.
There are two types of peripheral nerves: autonomic and somatic. The autonomic nervous system controls bodily functions (digestion, breathing, heartbeats) automatically. The somatic nervous system controls your muscles and also sends information from your ears, eyes, and skin to the brain/spinal cord.
Every peripheral nerve serves a specific function. Sensory nerves transmit sensations from your skin. Motor nerves connect the brain/spinal cord to your muscles to cause movement. Autonomic nerves control involuntary functions like heart rate and pressure and digestion.
Fortunately, most people with peripheral nerve injuries can get better. Symptoms often improve with proper treatment. Movement and the ability to feel sensations can be restored because peripheral nerves can regrow after an injury or surgical repair. The central nervous system nerves (brain and spinal cord) cannot be repaired.
Grades of Peripheral Nerve Injury
Your doctor will classify your injury into one of five classifications. This helps get an accurate diagnosis and decide the best treatment for your needs. The Sunderland classification system defines peripheral nerve injury as:
First-degree injuries usually will recover on their own within a few hours to several weeks.
Second-degree injuries are caused by a loss of the nerves’ ability to transmit information but rarely require surgery.
Third-degree means damage has occurred to nerve cells that transmit information away from the brain. Recovery can be uncertain, so you may have a nerve conduction study to determine the best treatment, such as a nerve graft repair.
Fourth-Degree prevents peripheral nerves from healing themselves (regeneration). Testing to confirm that no electrical energy can be transmitted through the nerve usually confirms that nerve grafting is needed to repair the injury.
Fifth-degree injuries are the most severe. They usually happen after the nerve is torn in two or separated due to a severe stretching injury. Surgery is required.
Types of peripheral nerve injuries
Peripheral nerves continually perform numerous functions in the body, but they are fragile and easily damaged. Injuries may involve only one nerve or multiple nerves.
Symptoms of peripheral nerve damage or neuropathy include tingling, stabbing, or burning pain, or severe and unrelenting pain. Other symptoms can include extreme sensitivity to touch, lack of coordination, falling, and muscle weakness. Some people experience the feeling of wearing gloves or socks when they aren’t wearing any. Paralysis can occur if motor nerves are affected.
If the injury involves autonomic nerves, symptoms can include excessive sweating or inability to sweat, heat intolerance, changes in digestion, changes in your bowels or bladder, or changes in blood pressure. Dizziness or lightheadedness can result if your blood pressure changes rapidly.
Entrapment of nerves is the most common type of injury. The nerves become compressed due to thickened or shortened tendons or ligaments. Entrapment injuries can happen in the:
- Wrist, called carpal tunnel syndrome, the most common peripheral nerve injury, occurs three times more often in women than men. The nerve provides feeling and movement to the thumb and three middle fingers. Causes include frequent and repetitive hand movements (typing or sports), arthritis, changes in blood sugar levels, sprain or dislocation, or a broken bone. This type of injury is progressive and will get worse without care.
- Arm (ulnar nerve compression) occurs in the nerves along the back and inside of the arm. They provide sensation in the fourth and fifth fingers, part of the palm, and forearm. Severe cases can cause hand weakness and loss of muscle mass.
- Knee injuries occur when the peroneal nerve is compressed. This nerve runs down your leg, transmitting sensations to the front and sides of the legs and top of the feet. Nerve injuries can cause an inability to lift the ankle or foot or point toes upward, called foot drop. Injuries can also be caused by a fracture or dislocation of the knee, knee or hip replacement surgery, or a tumor or cyst.
- Thigh nerve damage (meralgia paresthetica) is caused by irritation of the nerve that runs through the pelvis, groin, and along the outer thigh. It can be caused by repetitive motion of the legs, hip injury, tight clothing, heavy belts, or being overweight.
- Ankle and foot injuries (tarsal tunnel syndrome) are more common in people who have diabetes, arthritis, or chronic foot swelling. It can be caused by having flat feet or fallen arches, arthritis or diabetes, ankle sprain, varicose vein, cyst, or bone spur.
Causes of Nerve Damage
- Vehicle accidents and falls can cause a cut or tear in the nerve tissue (laceration), severe bruising (contusion), or severe stretching (traction). Injuries can also be caused by gunshot wounds, drug injections, or electrical shock.
- Infections that cause nerve damage can include Lyme disease, shingles, Epstein-Barr virus, hepatitis B and C, leprosy, diphtheria, and HIV.
- Autoimmune diseases such as Sjogren’s syndrome, lupus, rheumatoid arthritis, Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, and vasculitis.
- Diabetes that is not well controlled is a common cause of nerve damage, called diabetic neuropathy. More than half of people with diabetes will develop some type of neuropathy.
- Tumors can develop on the nerves or press on nerves. Most are not cancerous and only need to be watched.
- Bone marrow disorders caused by a blood protein and some types of cancers – myeloma, lymphoma, amyloidosis, or cancers linked to the body’s immune system – can cause nerve damage, as can medications used to treat cancer (chemotherapy).
- Other diseases – kidney, liver, thyroid, and connective tissue disorders – can cause nerve damage.
- Alcoholism can cause nerve damage due to vitamin deficiencies. The B vitamins (B-1, B-6, and B-12) and vitamins E and niacin are very important for healthy nerves.
- Blood problems can decrease oxygen to peripheral nerves and cause damage to nerve tissue as a result of diabetes, smoking, narrowed arteries from high blood pressure or atherosclerosis, or blood vessel scarring from vasculitis.
- Exposure to industrial chemicals or heavy metals such as mercury and lead.
- Family history of nerve damage is another cause, although very rare.
It is important to receive expert treatment to avoid the complications of peripheral nerve damage. Common complications include:
- Weakness or a loss of ability to feel increases your fall risk
- Lack of balance can reduce mobility and cause health problems due to inactivity
- Burns or skin injuries are due to the reduced ability to feel the temperature
Receive Help For Nerve Damage
Do you think you may have a nerve injury? Tim Tollestrup, MD, focuses his practice on the diagnosis of and surgery for peripheral nerve injuries. Contact us today to schedule your consultation.