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The lecture has been given on Feb. & Mar. 26th, 2011 by Dr. Bakhtyar.
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Peripheral nerve injuries
Structure of the nerve
Axon
myeline sheath
Schwann cell layer
Endoneurium
Perineurium
Epineurium
Pathology
The nerve is injured by:
Ischaemia
Compression
Traction
Laceration
burning
Types of injury
•Transient ischaemia
•Neurapraxia
•Axonotmesis
•Neurotmesis
Axonotmesis
• Segmental interruption of the axons
• Loss of conduction
• But the neural tubes are intact
• Seen in closed fractures and dislocations
• Distal to the lesion → Wallerian degeneration
• Axonal regeneration occurs by formation of the new axonal processes which grow at a speed of 1-2 mm per t
Neurotmesis
Division of the nerve trunk
Occurs in open wounds
Neural tubes are destroyed
A Neuroma is formed( regenerating fibers + Schwann cells + fibroblasts)
Function may be adequate but is never normal even after surgical repair.
Diagnosis
Symptoms: (1) Numbness (2) Tingling (3) Weakness
Signs: (1) Abnormal posture ( wrist drop) (2) Atrophy of the muscles (3) Change in sensibility
Tinels sign: shows progression in nerve recovery
Electrodiagnostic tests (1) level of injury (2) Severity (3) progress of nerve recovery
Principles of treatment
Closed injuries : If no muscle power restoration at the expected time, exploration
Open injuries : Primary repair OR graft
Missed cases : Delayed repair except when:
The patient has adapted to the functional loss.
High lesions when reinnervation is unlikely within the critical 2-year period.
Pure motor loss, which can be treated by tendon transfer.
Excessive scarring
Intractable joint stiffness.
In the HAND always try to repair to regain at least protective sensation
Care of paralyzed part
•Skin must be protected from friction damage and burn.
•The joints are moved in full range of motion twice daily.
•Dynamic splint
Obstetric brachial plexus injuries
Caused by excessive traction on the brachial plexus during childbirth.C5+C6+C7+C8+T1
Clinical features:•Difficult delivery•Flail arm.
•Further examination reveals one of the following: (A) Erb’s palsy (B) klumpke’s palsy
Erb’s palsy:
Injury of C5+ C6
The arm is held to the side, internally rotated, and pronated.
(i.e paralysis of the abductors and external rotators of the shoulder + the supinators)
Klumpke’s palsy:
Less common
The arm is flail and pale
All muscles of the fingers are paralyzed
± Ipsilateral Horner’s syndrome
Treatment:
If there is no biceps recovery by 3 months, surgery is performed:
If the roots are not avulsed: Nerve graft
If the roots are avulsed : Nerve transfer
If severe internal rotation : Subscapularis release ± tendon transfer OR Rotation osteotomy of the humerus
Physiotherapy in all cases
Prognosis in Klumpke’s palsy is poor.
Axillary nerve injury (C5)
Supplies (1) Deltoid (2) Skin over the lower ½ of the deltoid.
Injured in (1) Shoulder dislocation (2) # of humeral neck
Clinically (1) Loss of abduction (2) Numbness over the deltoid.
Treatment:
Spontaneous recovery during 8 weeks. If not:
Exploration + repair OR graft. If failed:
Tendon transfer OR Shoulder arthrodesis. .