BROAD FRAME WORK OF MANAGEMENT IN PERIPHERAL NERVE LESIONS , TERMINAL COMPLICATIONS OF UNTREATED PERIPHERAL NERVE LESIONS

Dr. J.V Subba raju

Final year PG

As in any other injury, initial management of a patient with peripheral nerve damage should begin with careful assessment of the vital functions.

When indicated, appropriate actions to prevent cardiopulmonary failure and shock should be taken, and systemic antibiotics and tetanus prophylaxis should be provided.

Open injuries

In complete penetration injuries of laceration type , early exploration is appropriate.

In grossly contaminated injuries or nerve is transected with ragged ends, nerve ends are tagged and delayed repair ( 2-6 weeks) can be done.

Closed injuries

For complete or incomplete injuries in which surgery is contemplated serial EMG should be obtained.

If clinical evidence of regeneration or recovery ensues and progresses during time frame ( usually 12 weeks ) surgery is most likely not indicated .

If at 12 weeks no EMG or clinical evidence of regeneration or return of function exists , operative treatment is indicated.

Factors influencing prognosis of recovery

Age – best results are seen in children following repair as adaptations of central cortex both for sensory and motor function is excellent in children.

Level of injury – more proximal the injury the more incomplete is the overall return of motor function especially in more distal structures.

Delay between time of injury or repair – delay of repair affects motor recovery more profoundly than sensory recovery.

Satisfactory reinnervation of muscles can occur after denervation upto 12 months. (Sunderland )

Irreversible changes develop in muscle after 24 months.

With respect to sensory recovery nerve can be repaired even after 2 years for satisfactory recovery. However early repair has the best results.

Gap between nerve ends.- gaps between nerve ends can be over come by

a)Nerve mobilistaion.b)Nerve transpostionc)Position of extremity.d)Bone resection e)Nerve grafting

Condition of nerve ends - a clear cut sharp nerve injury has got better prognosis following primary repair than crushed or avulsion injuries which needs secondary repair.

Types of nerves - pure motor and pure sensory recovery is fast when compared to mixed nerves.

Conservative management

Is indicated in neuropraxia or axonotmesis . In closed injuries, compression injuries., Main objective is to preserve mobility of

whole limb . Regardless of level or cause of injuries ,

affected muscles are kept in a state of relaxation by supportive splints.

Tone of muscles is maintained by galvanic stimulation and light massage until nerve regenerates

Splinting – purpose of splinting is To immobilize all part of hand in

position that will promote healing and prevent deformity.

To correct an existing deformity and promoting function in that part.

To compensate weaknessTwo types of splints. Static splints – which prevents

motion Dynamic splints – which assists

motion

Surgical

Indications When a sharp injury has obviously divided

a nerve, early exploration is indicated for diagnostic, therapeutic, and prognostic purposes.

When abrading, avulsing, or blasting wounds have rendered the condition of the nerve unknown, exploration is required for identification of the nerve injury and for marking the ends of the nerve with sutures for later repair.

When a nerve deficit follows blunt or closed trauma, and no clinical or electrical evidence of regeneration has occurred after an appropriate time, exploration of the nerve is indicated.

When a nerve deficit follows a penetrating wound, such as that caused by a low-velocity gunshot, the part is observed for evidence of nerve regeneration for an appropriate time. If there is no evidence of regeneration, exploration is indicated.

Time of surgery

Primary repair- indicated in clean sharp nerve injuries done in the first 6 to 8 hours or

Delayed primary repair done in the first 7 to 18 days is appropriate the wound is clean, and there are no other major complicating injuries.

Secondary repair- done in crushed , avulsed injuries with life of patient is endangerd . It is done at delay of 3 – 6 weeks

Surgical techniques

Coaptation – the key to functional recovery is coaptation of motor to motor and sensory to sensory funiculi. These can be brought about by anatomical , electrophysiological and histochemical methods.

Maintenance of coaptation can be brought by suture materials like 8.0 to 10.0 nylon.

Suture less maintenance can be brought by fibrin clot , micropore tape , collagen tubulization and adhesives.

Endoneurolysis (Internal Neurolysis)

It is an endoneurial exploration for assesing the injury of fasciculi .

If most of the fasciculi are intact and can be separated and traced through the neuroma, nothing further should be done.

If stimulation fails to elicit a response, and few if any intact fasciculi can be found, resecting the neuroma and neurorrhaphy are probably indicated

Neurorraphy Techniques of neurorraphy includes

a) Partial neurorraphy –done in partial severance of larger nerves such as sciatic and cords of brachial plexus. At cut ends END TO END neurrorraphy is done.

b) Epineural neurorraphy .involves suturing epineurium.

c) Perneural neurorrhaphy – involves matching of fasciculi and suturing them.

d) Epiperineural neurorrhaphy – involves both epineurium and fascicular approximation.

e) Inter fascicular nerve grafting –fascicular gap can be overcome by nerve grafting technique.

A gap between cut ends of nerve of more than 2.5 – 4 cms is un acceptable for neurorrhaphy and nerve grafting may be required.

Source of graft sural nerve (most commonly used) , medial and lateral cutaneous nerve of forearm, posterior interroseus nerve at wrist (for digital

nerve grafting), superficial radial nerve( for radial nerve injuries), dorsal branch of ulnar nerve.

Types of graft Trunk graft Cable graft Pedicle nerve graft Interfascicular nerve graft vascularised nerve graft (helps to increse

number of schwann cells that survive during grafting procedure., increases rate of axonal regeneration , decreases amount of intra neural fibrosis)

Tendon transfers

Useful in restoring lost functions due to peripheral nerve injuries.

Transfer of tendons is the final step in rehabilitation.

It should not be done until scar tissue has healed.

A satisfactory range of passive movements is needed before transfer.

Malalignment of bone must be corrected by osteotomy before transfer.

Indications.. Irrepairable nerve damage. Loss of function of

muculotendinous unit due to trauma or diseases.

In non progressive or slowly progressive neurological disorders like multiple sclerosis and cerebral palsy.

Complications

Motor When a peripheral nerve is severed at a

given level, all motor function of the nerve distal to that level is abolished

All muscles supplied by branches of the nerve distal to that level are paralyzed and become atonic.

Atrophy of muscle bulk progresses rapidly to 50% to 70% at the end of about 2 months

Atrophy continues at a much slower rate, and the connective tissue component of the muscles increases.

Striations and motor end plate configurations are retained for longer than 12 months, whereas the empty endoneurial tubes shrink to about one third their normal diameter .

Complete disruption and replacement of muscle fibers may not become complete until after 3 years.

Sensory Sensory loss usually follows a definite

anatomical pattern After severance of a peripheral nerve, only a

small area of complete sensory loss is found. This area is supplied exclusively by the severed nerve and is called the autonomous zone

A larger area of tactile and thermal anesthesia is readily delineated and corresponds more closely to the gross anatomical distribution of the nerve

Reflex Complete severance of a peripheral nerve

abolishes all reflex activity transmitted by that nerve. This is true in severance of the afferent or the efferent arc.

Autonomic Interruption of a peripheral nerve is

followed by loss of sweating and of pilomotor response and by vasomotor paralysis in the autonomous zone.

The area of anhidrosis usually corresponds to, but may be slightly larger than, the sensory deficit.

affected area becomes colder than the adjacent normal areas, and the skin may be pale, cyanotic, or mottled in an area often extending beyond the maximal zone of the injured nerve.

Trophic changes occur commonly and are most evident in the hands and feet.

The skin becomes thin and glistening and, when subjected to trauma that ordinarily does little harm, breaks down to form ulcers that heal slowly.

fingernails become distorted, often ridged or brittle, and may be lost entirely

Osteoporosis Osteoporosis often follows peripheral nerve

injuries. It is more likely to be pronounced in incomplete

lesions associated with pain. Incomplete lesions of the median nerve seem to

be associated more often with osteoporosis, with changes occurring in the distal phalanges of the thumb and index and long fingers.

Partial ankylosis from fibrosis of the periarticular structures also may develop.

Reflex Sympathetic Dystrophy a clinical entity characterized by pain, swelling,

stiffness, discoloration, hyperhidrosis, and osteoporosis in an extremity resulting from an abnormal and prolonged response of the sympathetic nervous system.

It occurs as a complication in about 3% of major nerve injuries.

The clinical picture varies as the patient passes through the early, intermediate, and late stages of this disorder.

The late stage may last several months or many years and is characterized by a stiff, cool, and atrophic extremity. The degree of pain experienced during this stage varies. The skin may be devoid of hair or, in contrast, may have an abnormal growth of hair .

Osteoporosis as classically described by Sudek in 1900 typically is found during this stage.

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