Surgical nerve reconstruction may be necessary after torn nerves or severe strains. Such injuries often occur after overstretching, bone fractures and blunt or sharp force trauma. Nerve reconstruction is a microsurgical operation in which an autologous nerve graft reconnects two nerve ends. In 80 to 90 percent of cases, nerve reconstruction leads to a clearly perceptible nerve recovery.
Here you will find further information as well as selected specialists and centers for nerve reconstruction.
The body has numerous nerves, particularly in the extremities. The nerves have a diameter between a pencil lead and a pencil, some nerves are even thicker.
The nerve cord is only an extension of the actual nerve cell, which is located in or near the spinal cord. This extension, i.e. the nerve cord, can be up to two meters long.
Inside a nerve there are thousands of nerve fibers that transmit the nerve stimulus. A distinction is made between two types of nerve fibers:
Sensory nerve fibers transmit electrical stimuli to the spinal cord and brain. There they are interpreted as pressure, temperature or pain.
Motor nerve fibers conduct electrical stimuli to the periphery, where they lead to muscle contraction. The body therefore uses them to control the muscles.
Sensory or motor functions (or both) can therefore fail in the event of nerve damage or nerve severing.
Severe nerve injuries are caused by
joints. They often occur in the shoulder joint or knee joint, for example.
The nerve cords of the extremities lead to the spinal cord and the brain © SciePro | AdobeStock
After such a severe injury, a high level of activity can be observed in the affected nerve cells in the spinal cord. They try to grow their nerve cell extension back to where it originally exerted its effect.
This growth process after severing creates a connective tissue bridge between the two nerve endings. Nerve fiber growth is very slow, about 1 mm per day. The recovery process therefore takes many months.
Not every nerve fiber reaches the specific target organ again. For example, a specific muscle fiber must reach a muscle with a specific function again. This is why the result of such nerve reconstruction is worse than the former healthy state.
Losses after nerve injuries must therefore be taken into account.
Each limb nerve supplies a specific sensitive area of skin and controls certain muscle groups. A doctor can therefore easily deduce which nerve is affected from the patient's description of sensory impairments.
The same applies to the loss of motor functions. For example, the loss of the ability to stretch the wrist, long fingers and thumb upwards against gravity.
The pattern of loss allows the damaged nerves to be identified and named. It is then often clear exactly where in the limb the damage has occurred, e.g. on the upper arm, forearm or in between in the elbow area.
It is more difficult for the doctor if several nerves are damaged and the symptoms are more complicated to classify.
An electrophysiological examination by a neurologist is always helpful. They can probe each muscle with a fine needle. This allows him to check whether electrical stimuli coming from the brain are reaching the nerve or not.
In the latter case, the muscle itself develops electrical activity a few weeks after the injury. This proves a complete nerve injury.
Neurography can also determine nerve injuries. A nerve is stimulated at one point through the skin with a strong electrical stimulus. This nerve stimulus is conducted along the nerve fiber and can be conducted to another location, provided the nerve has not been torn by the injury.
Unfortunately, these very simple-sounding examinations are much more difficult to evaluate in everyday medical practice than described here. In the vast majority of cases, nobody knows whether a nerve injury with a tear has really occurred after an injury has been sustained. It could just be a severe strain with functional interruption.
This increases the responsibility in the assessment of neurological and neurophysiological findings immensely. It is quite possible that a nerve has not been torn and its connective tissue sheath structures have survived. In this case, there is a chance that the nerve fibers, which have only been torn internally, will grow back. In such an actually favorable situation, surgery is rather counterproductive.
However, the condition of the muscle fibers after a functional nerve failure creates a time limit. The muscle mass shrinks and is increasingly transformed into connective tissue after six months. This process, known as atrophy, cannot be reversed.
Nerves can grow again even after years if they are given the opportunity to do so surgically. However, the muscles then no longer play their part.
An affected patient must be made aware of all these complicated facts. They can then decide together with the consulting doctor whether and when nerve surgery should be performed.
There are no general rules here, as there are in other areas of medicine, but only discretionary decisions to be made jointly.
Every patient asks whether there is no imaging to answer all the questions. The informative value of all these devices is still unreliable today due to accident-related scar block.
The following generally applies to the surgical method:
The damaged nerve section is not found in the scar. Instead, the nerve is surgically identified in the healthy area above and below the scarred section. The damage can then be found by tracing the nerve to the scarred area.
The injury results in a soft tissue scar block, which
walled in. If you dissect directly into the scar, you destroy its contents and cause further damage. As a result, keyhole techniques are not an option today. Instead, according to current knowledge, long-distance miracle openings are still necessary.
Nerve endings with a distance of more than two centimetres must no longer be sutured together end-to-end. This realization came about in the mid-fifties.
The tension to be applied to the rejoined nerve endings persists after the operation. The nerve endings then threaten to gape apart internally. Scarring develops again between the nerve endings. Therefore, the nerve fibers would not be able to grow over this situation.
A few years later, H. Millesi in Vienna therefore developed the idea and technique of nerve transplantation under the operating microscope.
During this procedure, the surgeon makes several small incisions in the skin. He uses these to remove a nerve from the back of the patient' s lower leg, the sural nerve. This nerve has exclusively sensitive functions on the outside of the heel. The loss of sensitivity there must be paid for.
The removed nerve has a length of 30 to 40 centimeters and the diameter of a pencil lead. This long piece of nerve now serves as the body's own transplant. It can be used in several portions and inserted between the two endings of a main nerve on the arm or leg.
To do this, scarring on the nerve endings must first be removed under a surgical microscope. In addition, the microstructure recognizable in the main nerve must be prepared. This increases the former distance between the two main nerve endings slightly.
Several pieces of the removed nerve are then inserted without tension, taking into account the microstructure of the main nerve.
Sutures of the caliber of a human hair are used.
The nerve fibers grow from the main nerve reconstructed in this way into the nerve grafts, through them and finally back into the remaining peripheral nerve stump.
The use of such a graft leads to better results than the tugging together of the endings of torn nerves.
The form of nerve reconstruction described is called "microsurgical autologous nerve transplantation". "Autologous" means that the transplanted nerve is taken from the patient's own body. This has the advantage that the body does not reject the transplant, as is often the case with foreign transplants.
However, due to the long nerve fiber growth phase, the result of such an operation is only known after many months.
Drugs that can be used to promote nerve fiber growth have so far only been used in experiments.
There are repeated references to vitamins. However, the human nerve cell does this on its own, i.e. without needing help.
The surgical exposure of an injured nerve for nerve reconstruction must not lead to additional soft tissue injuries, in particular vascular injuries. The risk of vascular injuries increases if vascular reconstruction was already necessary during initial trauma surgery.
It may then be absolutely necessary to bring in red blood cell concentrates before nerve reconstruction by donating the patient's own blood. Erythrocyte concentrate is a blood reserve consisting of red blood cells.
After the microsurgical insertion of nerve grafts, the surgical region must not be surgically approached again. Otherwise the transplants would be destroyed.
The prerequisite for planning a nerve reconstruction is therefore that no further interventions are necessary in this region. Any bone injuries, if they have occurred at the same time, must heal safely so that they do not require further surgery.
This also applies to osteosynthesis materials, i.e. metal parts used to treat bone injuries, such as
It must either be possible to remove these parts at the same time as the nerve supply, or they must remain in place for the rest of the patient's life. Their later removal could lead to the destruction of the nerve grafts.
Nerve reconstruction should also be carried out as soon as possible. Otherwise, the affected muscles would no longer be usable.
The results of microsurgical nerve reconstruction are always a long time coming for the reasons mentioned above. Statistical summaries of the healing process can therefore only be obtained at long intervals. If changes in behavior are then made on the surgical side, it is again necessary to wait many years for the new results to be evaluated. The development is therefore very slow.
In the meantime, industrially manufactured artificial nerve transplants are occasionally used. We have to wait just as long for their results.
Artificial nerve transplants lack important cell elements, which means that there are still unresolved problems.
The transplantation of the body's own nerves leads to a noticeable nerve recovery in 80 to 90% of operated cases. A total failure rate of approximately 10% must be expected. This is due to the delicacy and technical fragility of the surgical method of nerve reconstruction.
Physiotherapy is used to treat the mobility of joints that are prone to stiffness. It also trains functioning muscles in the area of the lost muscle group so that they can replace the lost functions.
Electromyographic checks show whether electrical impulses reappear in the failed muscle group after the nerve fibers have grown out. Physiotherapy will then focus specifically on the previously paralyzed muscle group.
During the nerve failure phase, malpositions of the hands or feet can occur. These can be corrected using specially made splints. The primary aim here is to prevent joint stiffness and overstretching of certain tendons.
Unfortunately, there is no proven method of preventing muscle atrophy. The external stimulation of failed muscle groups using surface electrodes is supposed to have a preventative effect. There is no scientific proof of this, but experience suggests that it does.
The use of TENS devices is wrong, as they have other tasks.
Nowadays, nerve reconstruction after nerve injuries is a microsurgical, time-consuming and delicate operation. Autologous transplantation after removal of a cutaneous nerve from the lower leg leads to the best results.
Any return of function after a nerve injury is an invaluable gain and worth the attempt at surgery. However, one cannot expect full restoration of the former healthy condition.
The choice of when to operate is difficult. This is at the discretion of the patient and doctor after proper explanation. In the case of nerves that are very difficult to access surgically, greater reluctance will be expressed than in the case of easily accessible nerve courses.
Before any nerve reconstruction, it must be ensured that the surgical area does not need to be opened again for other reasons.
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