Injuries to the peripheral nerves can occur in many different situations, but the leading cause of injured nerves is trauma. This can happen with injury to the peripheral nerves anywhere from the large nerves near the spine to the very small nerves in the hands or feet. Other causes for nerve injury are genetic conditions with nerve dysfunction, injury to nerves during or following surgery for an unrelated condition, or medical problems such as diabetes.
If a nerve is cut or stretched, it will no longer work to conduct the signal to the muscles that allow the brain to control the body’s movements or feel something touching the skin. Within the first few weeks after injury, a cut nerve can often be primarily repaired to partly restore function. After a little more than three weeks from the injury, nerve grafting with nerves taken from the back of the leg, or even synthetic tubes, can be used to help repair the injured nerve.
The plastic surgery and limb specialists at The Center for Restorative Nerve Surgery have a particular interest in peripheral nerve surgery. Among their many functions, peripheral nerves allow us to move, allow us to sense our environment (touch), and give us the protective aspect of pain to avoid dangerous activities. A problem with the peripheral nervous system can cause difficulties with movement, decreased feeling in our arms or legs, or even pain.
Dr. Barbour is a fellowship-trained expert in peripheral nerve surgery, with an interest in brachial plexus reconstruction, removal of nerve tumors, repair of cut nerves, and he has special expertise in treating patients with painful neuromas. He treats all types of peripheral nerve problems in his practice, including injury or compression to nerves of the upper or lower extremities.
The most common causes for patients to seek a peripheral nerve specialist such as Dr. Barbour are listed below:
Many factors can lead to compression of the peripheral nerves in the arms or legs. Over time, with compression of any nerve, there is a breakdown of the lining around the nerve. This protective barrier within the nerve keeps the inside of the nerve isolated from anything outside of it. When the barrier is broken, it causes leakage of outside fluid into the nerve and fluid will accumulate. This fluid build up causes swelling and pressure within the nerve. The swelling can lead to inflammation and scarring, and the scarring can interfere with the function of the nerve itself.
Dr. Barbour specializes in surgical treatment of compression neuropathy with a minimum length of incisions and scar tissue. Often, if the pressure on the nerve is released, this cascade can be broken. The nerve will begin to heal, and barrier will be restored, and pain will be improved. Injury to the inside of the nerve (the axons or the insulating myelin) will eventually be able to heal itself. Most often, symptoms that result from compression of a nerve can be reversed, even in long-standing cases. But when noticeable motor loss or severe sensory loss occurs, full recovery may not be possible.
Repair of Injured or Cut Nerves
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 not work properly, and a loss of feeling in the injured area. Pressure or stretching injuries can cause fibers within the nerve to break. This may interfere with the nerve’s ability to send or receive signals, without damaging the cover. When a nerve is cut, both the nerve and the insulation are severed. Sometimes, the fibers inside the nerve break while the insulation remains intact and healthy. If the insulation has not been cut, the end of the fiber farthest from the brain dies. New fibers may grow beneath the intact insulating tissue until it reaches a muscle or sensory receptor. If both 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.
If there is a space between the ends of the nerve, it may be necessary to take a piece of nerve (nerve graft) from a donor part of the body to fix the injured nerve. This may cause permanent numbness in the area where the donor nerve graft was taken. Once the nerve is repaired, the nerve generally begins to heal several weeks after the injury. Nerves usually grow one inch every month, depending on the patient’s age and other factors. With an injury to a nerve in the arm above the elbow, it may take up to a year before feeling returns to the fingertips. The feeling of pins and needles in the fingertips is common during the recovery process. While this can be uncomfortable, it usually passes and is a sign of recovery.
Several things can be done to keep up muscle activity and feeling while waiting for the nerve to heal. Physical therapy will keep joints flexible. If the joints become stiff, they will not work, even after the muscles begin to work again. After the nerve has recovered, sensory re-education may be needed to improve feeling to the hand or finger. Dr. Barbour will recommend appropriate physical therapy based on the nature and location of the injury. Factors that may affect results after nerve repair include age, the type of wound and nerve, and location of the injury. Although nerve injuries may create lasting problems, proper surgical treatment and therapy helps patients return to more normal function.
Extremity Nerve Transfers
A nerve transfer is a surgical technique that may be used when a patient has a nerve injury resulting in complete loss of muscle function or sensation. Nerve transfers involve taking nerves with less important roles — or branches of a nerve that perform redundant functions to other nerves — and “transferring” them to restore function in a more crucial, severely damaged nerve. Peripheral nerve surgeons will use functioning nerves close to the target muscle or sensory area, and these nerves are “transferred” (or divided and connected) to the injured nerve that no longer functions. The transferred nerve now supplies that function. Motor nerves are used to reinnervate muscles and regain movement, and sensory nerves are transferred to regain sensitivity in very important areas. This technique provides a nearby nerve source for faster recovery.
An example of an injured nerve that may be treated with this technique is the ulnar nerve. The ulnar nerve travels down the arm and controls both movement of the small muscles of the hand and sensation in a portion of the hand including the fourth and fifth fingers. A surgeon may use a motor branch of the median nerve to revive muscle function and a sensory branch of the same nerve to restore feeling in the hand.
An example of a reliable nerve transfer is the one used to restore the ability to flex the elbow. This nerve transfer uses small branches of the large ulnar and median nerves to plug into the nerve branches of the muscles that bend the elbow (called the biceps and brachialis). Elbow flexion is usually restored over time while the nerve is given time to regenerate into the paralyzed muscle.
Nerve transfers can be performed for injury to either nerves that control motor function or nerves that allow for sensation. Because of the need to reconnect the nerve to the muscle to prevent permanent paralysis, nerve transfers for motor nerve injuries should ideally be performed within the first 6 months from the initial injury. The decision to perform this procedure is made after adequate time is allowed for the muscles to improve on their own as well as in combination with EMG test results. Specially trained hand therapists are needed to help retrain the muscles to work well after surgery, and sometimes the procedure may take several months before the improvement is obvious. In contrast to motor nerve transfers, sensory nerve transfers can be performed at any time after the injury, even several years later. There is no therapy needed after these transfers to maximize their outcomes, but similar to motor nerve transfers, the results may not be evident immediately as the nerves need to regrow.
Facial Nerve Injuries
The facial nerve controls all facial expressions. This includes the ability to eat without food falling from the corner of the mouth, showing emotions such as a normal smile, and maintaining normal vision by closing the eye. Injury to the facial nerve can occur after surgeries to remove tumors, after some illnesses such as Bell’s palsy, from birth trauma or congenital deficits, or from trauma to the area near the cheek. Some facial nerve injuries, if recognized early, can be repaired by finding the cut nerve ends and putting them together. Occasionally, the space between the nerve endings requires using nerve grafts from another part of the body to restore the lost function.
Nerve injuries over several months in age are more difficult to repair. Dr. Barbour occasionally will perform what is called a “functional muscle transfer” in several stages to allow a new muscle to move the corner of the mouth. In order to restore a smile, new nerves as well as a new muscle from the leg must be transferred to the cheek in a delicate microsurgical procedure.
Peripheral Nerve Tumors
Peripheral nerve sheath tumors (PNSTs) are uncommon masses which grow from the nerve itself and generally are benign (non-cancerous). Neurofibromas and schwannomas are the most common forms of nerve sheath tumors. These tumors can occur in isolation or as part of a syndrome, such as congenital neurofibromatosis. Once they start to cause pain or other problems, it may be good to remove them to prevent them from growing too large and causing problems. Removal of tumors can often be performed without causing paralysis in the muscles supplied by that nerve, and typically only a small area of the skin experiences some numbness, which is usually temporary. Surgery to remove a schwannoma is the least complicated and to remove a neurofibroma slightly more complex.
The operation becomes significantly more difficult when peripheral nerve surgeons remove malignant tumors or plexiform neurofibromas, which are thick, irregular and can entwine supportive structures. With either of these tumors, the surgeon may need to remove the nerve. If this occurs, nerve transfers or nerve grafting can be used to restore function.
It is thought that sensory nerve irritation near muscle is involved in trigger sites for migraines. Some of these trigger sites can be targeted by surgical intervention. Many people who suffer from migraines have several migraines each month. In patients who routinely have more than two migraines each month, it may be better to try to prevent the migraines from occurring (prophylactic surgical therapy) rather than trying to stop them after they start (medical therapy).
The normal contraction and relaxation of muscles in the head and neck can squeeze nearby nerves, causing irritation that eventually leads to a migraine. Depending on the specific areas of migraine trigger points, muscle or nerve release surgery may be performed through an upper eyelid (blepharoplasty) approach or through the scalp. Treatment of the frontal zone focuses on the glabellar muscle group. Release and removal of the muscles can be performed directly through an incision in the upper eyelid. Occipital migraines often arise in the back of the neck and head before spreading. Occipital migraines are often initiated by stress or heavy exercise. This type of migraine is treated through nerve release surgery via an incision on the back of the neck to release the greater occipital nerve from the surrounding muscle.