Nerve Injuries and Microsurgical Nerve Repairs in Ankara, Turkey

Nerve lacerations are the disruption of the anatomical integrity of peripheral nerves as a result of traumatic injuries. This condition can lead to serious motor and sensory losses. The type and location of the laceration directly affect the degree of functional loss and the success of repair.

In traumatic nerve lacerations, diagnosis is made through physical examination and electromyography (EMG). By evaluating deep tendon reflexes and muscle functions, it is determined which nerve is affected. Imaging methods reveal accompanying tissue damage.

Microsurgical nerve repairs are performed by directly suturing the nerve ends together (epineural or perineural suture) or by using grafts. These procedures performed under a surgical microscope require high precision. The goal is to restore nerve conduction.

The rehabilitation process after surgery is critically important for functional recovery. Nerve regeneration is supported through physical therapy, electrostimulation, and protective splint applications. The complete recovery process may take months and requires close follow-up.

What Are Nerve Lacerations and Microsurgical Nerve Repairs?

Nerve lacerations are the disruption of peripheral nerve integrity as a result of trauma or surgical interventions and may result in sensory loss, muscle weakness, or paralysis. Microsurgical nerve repairs are treatment methods aimed at reconnecting severed nerve ends using specialized microscopes and delicate surgical techniques. The goal is to restore nerve conduction and minimize functional loss. Early intervention increases the success of recovery.

What is the structure of the peripheral nervous system and nerves?

To understand the nerve network in our body, imagining the electrical cables we use in our homes would be the most accurate analogy. Just as inside a thick electrical cable there are copper wires that actually transmit electricity and colored insulation materials that protect these wires and prevent them from mixing with each other, our nerves also have such an architecture.

The most fundamental component of this structure is the long extensions called “axons” that extend from the body of the nerve cell. These axons are the main lines that carry the command from the brain such as “move your finger” to the muscles or transmit the information from the fingertip such as “this tea is very hot” to the brain. However, the system is not composed only of these wires. Around these wires there is a special sheath that accelerates signal transmission and provides insulation:

The most critical point for us surgically is the way these structures are packaged. Axons do not stand scattered on their own. They come together in small bundles called “fascicles.” There are protective sheaths surrounding these bundles and a main sheath that holds all these bundles together and forms the outer surface of the nerve.

When repairing a nerve laceration, what we do is not only stitching the sheath visible from the outside. Our main goal is to ensure that these thousands of micro cables, namely the axons, enter the correct tunnels on the opposite side. If the cables carrying movement commands accidentally enter sensory tunnels, the muscle will not function. Therefore, mastering the microscopic anatomy of the nerve determines the fate of the operation.

What happens in the body when a nerve laceration occurs?

When a nerve is cut, the event is not only a physical rupture in that area. At the moment the cut occurs, a stormy process begins at the cellular level. In the part of the nerve remaining toward the fingertip or muscle from the point of injury, that is, the nerve piece remaining at the distal end of the body, nerve fibers begin to break down rapidly because they cannot be nourished.

During this process, the transmission lines inside the severed part dissolve and only empty tunnels remain. The body’s defense and cleaning cells immediately attack the area and clean the debris here. This cleaning is actually a preparation necessary for healing; because the path must be opened and the debris must be removed for new nerve sprouts to come.

On the side closer to the brain, the situation is very different. The nerve cell first experiences a shock. However, shortly afterward it switches to survival mode and begins to extend new sprouts from the cut end. This is where the importance of surgery comes into play. If we do not surgically bring these two ends together, these new sprouts do not know where to go. They grow randomly in every direction and form extremely sensitive and painful lumps that feel like an electric shock when touched. We call this a “neuroma,” and it is a condition that seriously reduces patients’ quality of life.

What are the types of nerve injuries?

Not every nerve injury is the same, and our treatment plan is shaped entirely according to the severity of the damage. In some injuries surgery is required, while in others only follow-up is sufficient.

The injury degrees we frequently encounter are:

• Neuropraxia
• Axonotmesis
• Neurotmesis

Neuropraxia is the mildest type of injury. It is usually a temporary loss of conduction due to lying on the nerve, remaining in an awkward position for a long time, or trauma. Here the integrity of the nerve is not disrupted; the nerve is simply in a temporary shock. Patients feel numbness or weakness, but this condition usually resolves on its own within weeks without surgery.

In axonotmesis, the wires inside the nerve, namely the axons, are ruptured but the outer sheath remains intact. Because the tunnels remain in place, the nerve can find its own path and heal. However, this process is slow and requires close monitoring.

Neurotmesis is the most serious condition. The nerve is completely severed with all its layers including the sheaths. Knife, glass, and machine cuts fall into this group. Here the nerve has no chance of healing on its own because the guiding tunnels are separated. This is the group where microsurgical repair is mandatory.

What are the symptoms of nerve damage?

In nerve lacerations, symptoms vary depending on the function carried by the severed nerve. Some nerves carry only movement commands, some carry only sensation, and most carry both (mixed nerves).

The symptoms we most frequently observe in our patients are:

• Numbness
• Tingling
• Loss of strength
• Muscle wasting
• Burning pain
• Loss of reflex
• Dry skin

Especially in hand and finger injuries, numbness is very critical. The patient may not feel that they have cut or burned their finger. In motor nerve lacerations, the most obvious finding is the inability to perform a specific movement (for example, inability to lift the thumb or bend the wrist). Over time, visible thinning, namely wasting, begins in unused muscles.

Why is the timing of surgery important?

In nerve repairs, timing is one of the most critical factors determining the result. Ideally, the repair should be performed as soon as possible after the injury occurs. We call this “primary repair.” The first 24 to 72 hours are the “golden hours” when tissues have not yet swollen, the anatomy has not deteriorated, and it is easiest to find the nerve ends.

However, in some situations repair may be postponed if the wound is very contaminated or if the patient has a life-threatening condition. The most important factor that limits us here is the condition of the muscles. When a nerve is cut, the muscles stimulated by that nerve stop working and begin to waste over time. If nerve repair is delayed too long, usually after 12–18 months, even if the nerve heals and reaches the muscle, there may no longer be viable muscle tissue left to receive it. The muscle is replaced by connective tissue and there is no longer any return.

In sensory nerves this period is slightly more flexible. Even years later, if repair is performed, some sensation may return. However, in nerve lacerations involving muscle function, the principle of “the earlier, the better” never changes.

Why is microsurgical technique necessary?

The sutures we use when repairing nerves in plastic surgery are so thin that it is almost impossible to see them with the naked eye. If you left these threads on the table, you might think they were dust and blow them away. To use such fine material and stitch millimetric nerve fibers, we need high-magnification microscopes:

The main reason we use a microscope is not only to “see better”; it is to respect the tissue. Nerve tissue is extremely delicate and fragile. Holding it with coarse instruments, crushing it, or stitching it in the wrong place leads to the formation of a hard scar tissue called “scar” within the nerve. Scar tissue is like an insurmountable wall in front of nerve fibers trying to heal and blocks their passage.

Under the microscope, we can distinguish the millimetric cable bundles inside the nerve. We try to map which bundle carries movement and which carries sensation. We also see and preserve the tiny vessels that feed the nerve. While in a repair performed with normal vision the nerve ends are only roughly brought together, in microscopic repair the nerve ends are anatomically perfectly aligned.

Which suture materials are used?

The suture materials we use in nerve repair are much thinner than a strand of hair. The thickness of the thread varies according to the thickness of the nerve and the region where it is located.

The characteristics of the surgical threads we use are:

• Monofilament structure
• Nylon material
• Size 9-0
• Size 10-0
• Size 11-0
• Atraumatic needle

The thread we call size 11-0 is so thin that it is difficult to see even under a microscope. We prefer these threads to be non-absorbable because dissolving threads create a reaction as they melt, and this can cause adhesions around the nerve. Nylon threads are tissue-friendly and hold the structure together until the nerve heals.

What are the methods of nerve repair?

As surgeons, the technique we choose while repairing a nerve varies depending on the location of the laceration and the thickness of the nerve. Our goal is always to provide the strongest and most accurate union with the fewest sutures.

The methods we most frequently use are:

• Epineural repair
• Fascicular repair
• Group fascicular repair

Epineural repair is the most common technique. The ends are joined by passing fine sutures through the epineurium, the outermost sheath of the nerve. This method is frequently preferred in finger nerves because it does not damage the structures inside the nerve too much and is faster to perform.

In fascicular repair, we open the outer sheath of the nerve and stitch the small cable bundles inside one by one opposite each other. This method theoretically provides a more precise match; that is, it increases the chance that motor fibers will meet motor fibers. However, since more suture material is used, the risk of scar formation may also increase.

Regardless of which technique is used, our golden rule is “tension-free repair.” When the nerve ends are joined, there must not be the slightest tension on the suture line. Tension disrupts blood circulation inside the nerve and stops healing. If the ends are forced together, the probability of that repair failing is very high.

What is a nerve graft?

Sometimes due to the severity of trauma, a part of the nerve may be torn away and lost, or due to crushing the nerve ends may be so damaged that we need to shorten them by cutting until we reach healthy tissue. In this case it becomes impossible to connect the two ends without tension. A gap, a chasm forms between them. At this point “nerve grafts,” namely nerve patches, come into play.

A nerve graft is a piece of nerve taken from another region of the body that can be sacrificed. We most commonly use the “Sural Nerve,” which runs along the back of the leg. This nerve carries only the sensation of the outer edge of the foot and its removal does not create a walking disorder or serious functional loss in the patient; there is only a small area of sensory loss on the side of the heel.

We place this piece of nerve we take like a bridge into the gap in the hand or arm. In grafting, the nerve piece we take actually acts as a passive pipeline. Living nerve sprouts coming from the proximal side pass through these borrowed tunnels and reach the other side.

The graft sources that can be used are:

• Sural nerve
• Antebrachial cutaneous nerve
• Synthetic tubes
• Vessel grafts

How are nerve lacerations managed in hand injuries?

A very large portion of plastic surgery emergencies consists of hand injuries. Our hand is our primary organ through which we interact with the world. Digital nerves running just beneath the skin can be damaged with the smallest knife cut or with an object entering the palm.

Cutting of finger nerves may sometimes be misinterpreted by patients as “I just cannot feel it, I can move it, so it is not important.” However, fingertip sensation is of vital importance. The miraculous sensory network at the fingertip is what allows you to distinguish a coin from a key when you put your hand into your pocket. If the nerve laceration is not repaired, that finger becomes blind. The function we call the “seeing hand” is lost.

In addition, a numb finger is defenseless against burns and injuries. The patient does not realize that they are touching a hot surface, does not notice that they have cut their hand, and serious infections may develop. Therefore, finger nerve lacerations must definitely be repaired with microsurgery.

How is facial paralysis surgery performed?

The facial nerve, namely the facial nerve, is the motor that runs the facial expression muscles on our face. Smiling, frowning, and closing our eyes occur thanks to this nerve. Cutting or damaging this nerve deeply affects the patient both physically (inability to close the eye, dryness) and socially.

In these cases our repair strategy changes according to time. In fresh cuts, end-to-end repair is performed. However, in old cases “nerve transfer” or “muscle transfer” is required.

The applied methods are:

• End-to-end repair
• Nerve graft
• Hypoglossal nerve transfer
• Masseter nerve transfer
• Gracilis muscle transfer

Especially muscle transfer (Gracilis) is the peak of microsurgery. A muscle taken from the leg is transferred to the facial region together with its vessels and nerve. This muscle is connected to a healthy nerve in the face or to the chewing nerve, giving the patient a dynamic smile again.

How long does the recovery process take?

The most difficult part for our patients is usually the waiting period after surgery that requires patience. Nerve healing is measured not in days like skin healing but in months and even years. After the repair is performed, the nerve ends do not immediately join and begin transmitting electricity.

The growth rate of the nerve is on average “1 millimeter per day,” that is “3 centimeters per month.” You can think of it like a tree taking root. For example, if a cut at the wrist level is repaired and the distance to the fingertips is 15 cm, the sensation reaching the fingertip will take at least 5–6 months in the best case.

To follow the healing process we use an examination method called the “Tinel Sign.” When we tap along the course of the nerve with a finger, the most distal point where the patient feels an electric shock or tingling shows us where the nerve sprouts are at that moment. The movement of this point downward toward the fingertip over the months is the best proof that healing is progressing well.

What factors impair healing?

No matter how perfectly we as surgeons perform our job, there are biological factors that affect the success of the outcome. Not every patient heals at the same speed or quality.

The conditions that negatively affect healing are:

• Advanced age
• Smoking
• Diabetes
• Crush-type injury
• Contaminated wound
• Delayed repair
• Tension repair

Here I have to open a separate parenthesis for smoking. Smoking is the greatest enemy of microsurgery and nerve healing. The nicotine it contains constricts the vessels and reduces the blood flow going to that delicate nerve tissue that is trying to heal. A nerve deprived of oxygen cannot heal. In patients who smoke, recovery is much slower and results are worse. Therefore, we strictly prohibit smoking after surgery.