Gets Relief in Peripheral Spinal Nerve Pain :

The dorsal and ventral  nerve  roots  arising  from  the spinal cord join at the intervertebral foremen to form a spinal nerve. In the thoracic  segments,  these  mixed spinal nerves retain their  autonomy  and  supply  one intercostals segment both  dermatome  and  myotomal. In virtually all others segments,  spinal  nerves  join with others to form a plexus.  There  are 31 pairs  of  spinal nerves consisting of 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.

A spinal nerve has three  components:  motor, sensory and sympathetic. The sympathetic components of all 31 mixed spinal nerves leave along the 14 motor roots (12 thoracic and  2  lumbar  roots).  Each  spinal  nerve now divides into anterior and posterior rami. The anterior rami of the upper four cervical nerves form the cervical plexus and the  lower  four  cervical  together with upper thoracic nerves  form  the  brachial plexus. The anterior rami of  the first  three lumbar  nerves and part of the fourth nerve form the lumbar plexus .The saspinal rami except for upper three cervical posterior rami. The sacral anterior rami along with the anterior rami of the fifth lumbar and part of fourth lumbar form the lumbosacral plexus. The posterior rami supply the para spinal muscles and the skin of the back. They are smaller than anterior rami except for upper three cervical posterior rami.The spinal nerves are then distributed to the limb buds through several peripheral nerves. Therefore, a peripheral nerve is a/so a mixed nerve like the spinal nerve .

Dermatome is an area of skin supplied by a single spinal root. Myotome represents a muscle uni supplied by a single spinal root.

PRINCIPLES OF NERVE INJURY

NERVE DEGENERATION

Any part of the neuron detached from its nucleus degenerates and .is destroyed by phagocytosis. This process of degeneration distal to a point of injury is called secondary or wallerian degeneration. Reaction in proximal end is called primary or retrograde degeneration. Time required for degeneration varies between sensory, motor, and is related to the size and myelination. In secondary degeneration, response is obtained to faradic stimulation up to 18-72 hours. After 2-3 days, distal segment is fragmented and the myelin sheath starts degenerating. By seven days, macrophages clear the axon or debris and are completed within 15-30 days. Schwann cells undergo mitosis from seventh day onwards and start filling the areas previously occupied by axon and its myelin sheath. Primary retrograde degeneration proceeds for at least one internodes or more. Histological, its indentical to wallerian degeneration. More proximal the site of injury , more pronounced will be the changes.

NERVE REGENERATION

Axonal sprouting starts from 24 hours after injury. Unmyelinated initially but later on it  myelinated. Now if the endoneurium is int sprouts will readily pass along their former courses and after regeneration may innervate their previous end organs. If the endoneurium is interrupted, then the sprouting axons may migrate aimlessly throughout the damaged area into the epineurial, perineurial regions forming a stump neuroma or neuroma in continuity or they may enter into the other empty endoneural tubes or newly formed endoneural tubes only to terminate in myotomal or dermatomal areas of their own. Hence, recovery is difficult if entire axon is transected and filled with scar tissue.

TYPES OF NERVE INJURIES

Primary: This is due to injury of a peripheral nerve resulting from the same trauma that has injured a bone or joint.

Secondary: This is due to involvement of the nerve in infection, scar, callus, etc.

CLINICAL DIAGNOSIS

It is difficult to evaluate a nerve injury immediately after a severe trauma. The diagnostic approach towards a peripheral nerve injury should essentially consists of the following steps:

Listen: Carefully listen to what the patient has got to tell you about the history of the injury. Many a times mere listening can help clinch you the diagnosis. Here are  some samples:

History                                          

• I’m suffering from leprosy
• I took an injection in the arm or buttocks
• I traveled in a bus overnight
• 1 cut my wrist by a glass piece.
• I suffered from arm bone fracture
• I broke my elbow in a fall
• I have suffered a hip dislocation due to dashboard injury

Look: This is the second step in the diagnosis of PNI. After listening to the story, look for the typical tell tale evidences. Each nerve injury is associated with a particular attitude.

Feel and touch: This helps you to detect damage to the sensory component of a nerve. The affected skin could be cold or clammy. Patient may not be able to feel the temperature touch, vibrations, pressure in the affected areas. Loss of sweating is an ominous sign.

Move: Instruct the patient to move the limb and joints distal to the site of injury. Inability to do so totally reveals complete nerve damage, slight movements possible suggests less than complete damage to the Beware of the trick movements a patient may resort to overcome the loss of a particular muscle function. This is a diagnostic “pitfall” one should carefully avoid.

Knock: Using a knee hammer, knock over the knee, ankle, elbow, etc. to elicit the appropriate reflexes. They are normally absent in peripheral nerve injuries.

Measure: With a measuring tape, measure the muscle girth of the limbs for wasting.

Investigate: After following this various clinical steps, certain investigations needs to be done to confirm the diagnosis and plan the appropriate line of treatment.

Typical Deformities:

• Wrist drop -  Radial nerve injury.
• Claw hand -  Ulnar nerve injury.
• Foot drop -  Lateral poplifeal nerve injury,
• Ape thumb – Median nerve injury.
• Winging of  scapula -  Thoracodorsal nerve injury.
• Pointing index – Median nerve injury.             ‘   _
• Policeman tip – Brachia! plexus injury.

DIAGNOSTIC TESTS

Electromyography:

Electromyography (EMG) helps to record the electrical activity of a muscle at rest and during activity .

Intact muscle: There is no electrical activity in an intact muscle at rest. During a weak contraction, the electrodes record a single action potential. In powerful muscle contractions, these motor action potentials superimpose to give an interference pattern.

Injured or denervated muscle: These muscles show electrical activity at rest. These are primitive responses which is normally suppressed by the stronger nerve action potentials. These denervation potentials normally appear by 1-2 weeks after injury.  If they have not appeared by 15-20 days after muscle denervation, it indicates a good prognostic sign.

Uses and limitations of EMG:  Electromyograph, helps to detect the presence or absence of nerve inury if present whether it is complete or incomplete and whether any regeneration is taking place or not. EMG does not give the level of injury or the degree of injury accurately.

Sweat Test (Starch Test): Presence of sweating within autonomous zone suggests that complete interruption of the nerve has not occurred.

Skin Resistance Test: It is another method of evaluating autonomic interruption by using Richter’s thermometer.

Electrical Stimulation: Faradic stimulation :is of little value (because even normally innervated muscles may fail to respond).

Galvanic stimulation: Recording of chronaxie and strength duration curve by galvanic stimulation is more helpful in evaluating nerve injuries.

MANAGEMENT

General Principles:

Resuscitation is carried out first, if the patient is in shock. General condition is improved by the emergency management measures. A thorough debridement of the wound is carried out; and if the wound is clean, direct suturing of the perineurium or epineurium or epiperineurium of both the cut ends carries out primary repair of the nerve. If the wound is contaminated, nerve is repaired after 3-6 weeks. In closed fractures with peripheral nerve injuries, conservative management is the treatment of choice. Careful assessment of the recovery is made and early surgical exploration is done if the recovery is not satisfactory.

Conservative Management:

This consists of the following essential  steps:

Splinting of the limbs.  Different splints are required to immobilize the limbs in various nerve injuries.

*   Upper limb

• Brachial plexus injury-aeroplane splint.
• Axillary  nerve injury-shoulder  abduction splint.
• Radial nerve injury–cock-up splint.

*    Lower limb..

• Common  peroneal  nerve injury-foot drop splint .
• Passive movements of all joints are done to prevent contractures.

Physiotherapy:  Massage, exercises, stimulation, etc.

Care of the skin, etc.

Operative Management

This consists of various types of nerve repair , tendon transfers, arthrodesis, etc.

TYPES OF NERVE REPAIR

Primary Repair : is done within 6-8 hours after injury and if the wound is clean cut.

Delayed Primary Repair : is done between 7 and 18 days after injury and if the wound is contaminated.

Secondary Repair : is carried out 18 days after injury, if the injury is seen late, failure of conservative treatment, incomplete injury, etc.

TECHNIQUES

Endoneurolysis: It is freeing of the nerve entrapped within the scar tissue either external scar (external neurologsis) or within nerve (internal neurolysis).

Partial Neurorrhaphy: This is advisable if one-half of a large nerve is disrupted, e.g. sciatic nerve injury.

Neurorrhaphy and Nerve Grafting:  if there is a gap after injury.

Methods of closing the gaps between the nerve ends if the nerves cannot be approximated end to end.

• Mobilization of the nerves by sectioning its cutaneous branches  and freeing it from  the fibrous tissue around.
• Positioning of the extremities in functional position.
• Transposition of the nerves, e.g. ulnar net transposition.
• Bone resection.
• Nerve grafting by using sural nerve.
• Nerve crossing.

By these above  methods,  the  cut  ends  of  the nerves can be brought together and sutured by a one of  the techniques mentioned  above.

Tendon transfers are contemplated after 18 months injury when there is no recovery after various net repair techniques or if the patient presents late.

Arthrodesis is considered if no tendons are available for transfers and if there is no hope of recovery.

TREATMENT OF NERVE INJURY

It is critically important that a person with a nerve injury receive medical care as soon as possible. Without timely, appropriate medical care (within nine to 12 months of the injury, preferably earlier), the injured nerves may no longer be repairable.

• Peripheral nerves have a remarkable ability to regenerate themselves.
• Patients with nerve injuries may be treated at physioline at any stage: at the time of the injury, later, for evaluation and treatment, or for secondary treatment, where people have not recovered adequate function after previous treatment.
• The management of a peripheral nerve injury varies depending on the cause, type and degree of the nerve injury.
• Physiotherapy is very important to promote the recovery of peripheral nerve injuries regardless of whether surgery is required.
• Physical therapy is started in the early stages following nerve injury to maintain passive range of motion in the affected joints and to maintain muscle strength in the unaffected muscles.
• Physioline provides specialized treatment programmes  and bracing or splinting.
• increase muscle strength
• increase sensation
• manage neuropathic pain
• maintain range muscle length / joint range of movement
• maintain nerve integrity