FACTORS INFLUENCING THE REGENERATION AFTER NERVE SUTURE
Many are the factors, on which the regeneration of an interrupted and sutured peripheral nerve depend. The most important of them to be taken into consideration in determining the operative indications and evaluating the outcome are the following:
1. Characteristics of the injury. The smooth cutting injuries are those most fully and quickly re, all othercovered conditions being equal, while the lacerated injuries with segmental damage have a poorer outcome.
2. Time elapsed after injury. Outcome deteriorates with increasing delay between the time of injury and repair, but determining a specific time interval in which to repair the nerve is difficult. In general the suture made later than 3 months after the injury is less favourable to the regeneration and it is even more so, if this time is longer.
3. Level of injury. The nearer the injury is to the spinal column the more the regeneration process is not complete. This is due to anterograde degeneration, which is much more expressed the nearer the injury is to the spinal column. The interruption of the nerve is a real separation of a part of the protoplasm of the ganglion cells. The ganglion cells perish, when a greater part of the protoplasm is torn off, ie. injury is proximal.
4. The distance from the injury to the terminal ends of the injured nerve is also an important factor. The regenerating axons grow at a speed of 1 - 2 mm a day, and it is natural that the longer the period of penetration of the regenerating axons toward the peripheral receptors and muscle fibres, the lesser the possibility for their regeneration. Numerous clinical studies have demonstrated that distal injuries have a better prognosis.
5. The type of the interrupted nerve, i.e. whether it is primary motor, sensory or mixed, is of great significance for the outcome. In primary sensory or primary motor nerves the possibility of the regenerating axons of the proximal segment penetrating into their respective motor or sensory Schwann cells tubes of the distal nerve segment is greater.
6. The age of the patient. Clinical observations have proved that the regeneration of an interrupted nerve after repairing is better with children and young people. This is due to better regenerative ability of the axons, the shorter distance, and the better functional adaptation in children.
7. Quality of the nerve suture. When the suturing of the nerve is made with good adaptation of the section surfaces, using suitable materials, and microsurgical technique, it is natural that results will also be better. This is the only factor that depends on the surgeon's experience.