Nerves form the central nervous system and are involved in conducting messages from the brain to other parts of the body. They are of two types – motor, which help in movement and sensory, which lets us sense pressure, temperature and pain. Many nerve fibers are grouped together to form a bundle and are protected by an insulating cover.
Messages, in the form of electric pulses can pass through nerves, to and from the brain, through cells called neurons. Neurons are made up of a cell body, a long tube-like axon, which transmits signals to the next nerve cells, and dendrites that receive signals from other neurons.
Nerves are fragile and can get easily injured by stretching, pressure, or breaking. Injury can involve only the nerve or the outer protective covering as well, which obstructs the transmission of messages to and from the brain. This stops the muscles from moving the affected part of the body and sensations from being felt in the part supplied by the damaged nerve.
Diagnosis: Nerve conduction velocity (NCV) and electromyography (EMG) tests help evaluate the transmission of electric currents through the nerves. Imaging tests, including CT scans, MRI and MRI neurography, also help identify the extent of injury. Nerve injury can be classified into five types:
- First-degree injury blocks message transmission locally and is reversible, usually recovering within hours to a few weeks
- Second-degree injury involves a loss of continuity in axons
- Third-degree injury damages axons and their supporting structures
- Fourth-degree injury harms axons and surrounding tissues, creating scars that prevent regeneration of the nerve
- Fifth-degree injuries usually involve tearing or severe stretching where the nerve is separated into two
Treatment: Nerve injuries can be treated with medication and conservative treatments including rehabilitation, physical and massage therapy, acupuncture, orthotics, and weight loss management. Surgery may include a simple cleaning of the nerve (neurolysis) or grafting when the tests show that there is passage of electric signals through them.
Nerves may get compressed or ‘pinched’ when pressure is exerted as a result of repetitive movement or holding the body in one position for a long time. Compression usually occurs between bones, ligaments and tendons present in various sites of the body. Nerves get inflamed when pressure is applied and do not function properly. If the pressure is released within a short time, no permanent damage occurs and the nerve continues its normal functioning. However, nerves that remain compressed for a long time produce chronic pain, swelling, scarring and cause permanent nerve damage.
Causes: A pinched nerve in the spine can be caused by weakness or tears in spinal discs. Injury, osteoarthritis, poor posture, certain sports activities, hobbies, repetitive actions, and obesity can also exert pressure on nerves.
Symptoms: A nerve compressed in the spine can lead to pain in neck or lower back, or may even spread to the shoulders and arms, or leg and foot. Other common symptoms include
- Numbness or reduced sensation
- Sharp pain that may radiate outward
- Tingling sensations
- Twitching or muscle weakness
- Sensation of your hand or foot falling asleep
If these symptoms continue for many days and do not improve with rest and over-the-counter pain relievers, you would have to visit your doctor.
Diagnosis: Your doctor may conduct a few tests including
- Nerve conduction study passes a mild electric impulse to the affected area to note the damage of nerves
- Electromyography measures the electric activity of muscles when they are moved
- Magnetic resonance imaging (MRI) helps the doctor take /images of your body
Treatment: Your doctor will first start you off on conservative treatment including
- Immobilization of the affected region with a splint or brace
- Physical therapy exercises or modification of activities that cause or aggravate the pressure on nerves
- Pain relievers such as non-steroidal anti-inflammatory drugs
If these methods do not help even after several weeks or a few months, your doctor may recommend surgery. The surgery will involve the removal of a part of the herniated disk or bone spurs in the spine if the nerves in the spine are compressed. If the nerves in the wrist are affected, your surgeon will cut the ligament pressing against the nerve to create more space for it to go through the wrist.
Prevention: Maintaining good posture and healthy weight, doing flexibility and strength exercises, minimizing repetitive movements, and taking frequent breaks during such activities can significantly help prevent nerve compression.