الفهرس 
HISTORYOnly 14 pages are availabe for public view
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Abstract
Peripheral nerve injury is a world wild problem, with many medical and social impacts. The problem that was illustrated at the beginning was; if the injured nerve has the ability to regenerate or not. After it was known that nerves could benefit from surgical repair and the mechanism of nerve regeneration was illustrated, the following question arose: When would surgical repair improve on the natural outcome of a nerve injury?
One of the fundamentals of neuroscience is that the peripheral nervous system regenerates whereas the central nervous system lacks the capacity to regenerate. Histologically, peripheral nerve fibers may be divided into myelinated and unmyelinated varieties on the basis of absence or presence of myelin sheath. The peripheral nerve trunk consists of both neural (nerve fiber) and non-neural (connective tissue) elements. As regard connective tissue elements, the peripheral nerve is composed of the following 3 main layers of tissue: the epineurium, perineurium, and endoneurium.The fascicle is the smallest segment of the nerve that is generally visible by the operating microscope.
Following peripheral nerve injury and division of the nerve fiber, Wallerian degeneration occurs in the distal axon. Degeneration of the axon also occurs for a variable distance proximal to the site of nerve division. After this period of degeneration, myelinated and unmyelinated fibers from the proximal stump will sprout, forming regeneration units and attempt to re-innervate the distal stump. However, in some instances, spontaneous reinnervation fails to occur due to the size of the nerve gap, neuroma formation and scar tissue. In the absence of spontaneous reinnervation, surgical reinnervation with nerve repair becomes necessary.
As regard frequency of these injuries in children and infants stretch trauma to the brachial plexus is the most common peripheral nerve injury of the neonatal period. A child experimenting with crawling and walking may be prone to accidents from falls and occa¬sional glass cuts. Falls and-with increasing frequency-cuts, are the most common causes of peripheral nerve injury in the 3-to-8-year-old age group.
For diagnosis of peripheral nerve injury in pediatrics the most important methods to be done include Precise neurological examination and electrodiagnostic testing.
The aim of nerve repair is to direct regenerating fibers from the proximal end to the distal stump. Deciding the timing of surgery is very important, either primary or secondary repair. Electrophysiologic monitoring during surgery has been used for over 25 years. It can help the surgeon during nerve repair by helping guide dissection, identify the zone of injury, aid alignment, and monitor function.
Nerve repair is either direct, or with grafting using different natural and synthetic materials as graft. Direct nerve repair was, and still, the most effective method in restoring nerve function, what ever the type of direct repair (epineural, fascicular, group fascicular). Unfortunately, direct repair is not always available, especially with wide nerve gap, so nerve graft is used in these circumstances to guide the regenerating nerve fibers to the distal end. The most popular and effective graft is nerve graft, but many other materials are used as graft materials, such as, synthetic tubes, muscles graft, vein graft, and other materials, and most of these materials are still experimental.
Nerve transfer methods are used, as peroneal nerve transfer and intercostal nerve transfer, to replace damaged nerves.If the injury is not complete, or with short gap, we can use some materials as glue, such as, fibrin glue, aliginate solutions, and cyano-2-ocrylate substance. Physical methods are also tried as laser welding, thermal treatment, and radiotherapy, but they are not popular, and with minimal success rates.Biological materials are used as, extra cellular matrix molecules, and neurotrophic factors to enhance nerve regeneration.
Currently, the most widely accepted method of addressing segmental nerve loss with peripheral nerve repair remains autografting. However, this method has significant limitations, including donor site morbidity and limited effective functional regeneration.
Each procedure has advantages and disadvantages. Surgical decision should be made by through evaluation of all aspects of the nerve injury and surgical methods. All nerve injuries can not be repaired using only one type of nerve repair method. The surgeon should be familiar with all the techniques and should be able to use them correctly in appropriate situations.
Outcome after nerve repair depend on many factors as type of the nerve, age of patient and tension of the repair So recovery of function tends to be more complete in juveniles than in adults and prognosis is much more better in children than adults.