Peripheral Never Injuries Dr. Arun
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Transcript of Peripheral Never Injuries Dr. Arun
Dr. Arun MoreOrthopedics Lecturer
MTH Pokhara
PERIPHERAL NERVE INJURIES
Peripheral nerve injuries
Anatomy Mechanism Assessment Management Discussion
Peripheral nerve structure and function
Composed of Nerve fibres Blood vessels Connective tissue
Outer most Epineural sheath encloses fascicles with surrounding alveolar tissue called Epineurium
Fascicles are nerve bundles covered with connective tissue called Perineurim
Vary in diameter of 2-25 micrometer
Biological response to nerve injury
Nerve degeneration
Part of neuron distal to the point of injury undergoes secondary or wallerian degeneration
Proximal part undergoes primary or retrograde degeneration for a single node
Biological response to nerve injury
Nerve regeneration Axonal stump from proximal segment begins to
grow distally If endoneureal tube with its contained schwann
cell is intact the axonal sprouting occurs Rate of recovery 1mm/day Muscles nearest to the site of injury recovers
first Followed by others as the nerve reinnervates
muscles from proximal to distal so called motor march
If the endoneurial tube is interrupted, the sprouts may migrate aimlessly throught the damaged area to form a neuroma
Classification
Neuropraxia
the mildest form, reversible conduction
block loss of function, which persists for
hours
or days direct mechanical compression,
ischemia,
mild burn trauma or stretch
Axontmetic
axon continuity is disrupted fascicular integrity is maintained Wallerian degeneration occurs
Neurotmesis
laceration from sharp or blunt forces
the only important consideration is
the timing of repair acute repair or more bluntly
lacerated
nerves are repaired 3-4 weeks
Etiology
Mechanical injury Saturday-night paralysis ,Tourniquet paralysis
Crush and percussion injury fractures, hematomas, compartment syndrome
Laceration injury – blunt, penetrating injury
Stretch injury - brachial plexus High-velocity trauma - RTA , gunshot wounds Iatrogenic injury
Fibrillation potentials andpositive sharp waves
Acute Denervation
Long duration, small amplitude polyphasic motor unit potentials
Regeneration
Clinical Signs Motor function
Tinel’s sign
positive-sensory function
negative(after 4-6weeks)-total interruption
Sweating-sympathetic fiber
Sensory function
Diagnosis
Chronic Injuries of Peripheral Nerves by Entrapment
Pain Paresthesia Loss of function
Clinical diagnosis of nerve injuries: Highet Scale: 0 – total paralysis. 1- muscle flicker. 2-muscle contraction. 3- muscle contraction against gravity. 4- muscle contraction against gravity and
resistance. 5-normal muscle contraction .
Tinel sign :A positive Tinel sign is presumptive
evidence that regenerating axonal sprouts that have not obtained complete myelinization are progressing along the endoneurial tube.
@- neuropraxia(sunderland1) -------negative Tinel sign.
@- axonotmesis (sunderland2,3) -------positive Tinel sign.
(sunderland4-------- negative Tinel sign )
@- neurotmesis (sunderland 5) ------- negative Tinel sign.
Other diagnostic test:Sweat test.,skin resistance test, electrical
stimulation
Electrophysiological Tests
EMG SNAP SSEP Intraoperative NAP
Diagnosis
EMG SNAP
SSEP
Intraoperative NAP
Diagram of EMG tracing depicting normal insertion activity, which also may be present immediately after denervation.
A, Diagram of EMG tracing demonstrating positive sharp wave consistent with denervation 10 to 14 days after injury. Rhythm is regular, amplitude is 100 to 400 uV, duration is 5 to 150 msec, and rate is 2 to 40 Hz.
B, Diagram of EMG tracing demonstrating spontaneous denervation fibrillation potentials present within 14 to 18 days after injury. Rhythm is regular, amplitude is 50 to 1000 uV, duration is 0.5 to 2 msec, and rate is 2 to 30 Hz.
GENERAL CONSIDERATIONS OF TREATMENT.
FACTORS THAT INFLUENCE REGENERATION AFTER NEURORRHAPHY :
1-Age2-Gap Between Nerve Ends3-Delay Between Time of Injury and Repair4-Level of Injury
5-Condition of Nerve Ends
Conservative Tx Indications
not long history
mild-moderate, intermittent
reversible cause
pregnancy, oral contraceptive, endocrine abnormalities(DM…), type writer
Method
nonsteroidal anti-inflammatory drugs
splint
Treatment
Surgical Indications
Failed conservative tx Typical clinical finding
with electrodiagnostic data
Severe
sensory loss
muscle atrophy
motor weakness
Treatment
TECHNIQUE OF NERVE REPAIR:
Endoneurolysis (Internal Neurolysis
Partial NeurorrhaphyNeurorrhaphy and Nerve Grafting
Methods of Closing Gaps Between Nerve Ends:
Mobilization
Positioning of Extremity
Transposition
Bone Resection
Nerve Stretching and Bulb Suture
Nerve Grafting
Techniques of Neurorrhaphy:
Epineurial Neurorrhaphy
Perineurial (Fascicular) Neurorrhaphy
Interfascicular Nerve Grafting
Injured Peripheral Nerve
Evaluation of Closed Injury
Conclusions1. Immediate primary repair in sharp injuries with
suspected transsection of nerve
Immediate repair is especially important for brachial plexus and sciatic nerve transsections because delay leads not only to retraction but also to severe scaring
Bluntly transsected nerve best repaired after a delay of several weeks.
2. A focally injured nerve should be explored if no functional return within 8-10 weeks
3. Decision - making as to whether neurolysis or resection & repair in a lesion in gross continuity based on intraoperative electrophysiological evaluation
4. Split repair with usually graft - lesion in continuity 가 partial function or undergoing partial regeneration
5. Careful patient selection for operation
- plexus involved
6. Nerve anastomosis failure
① inadequate resectin of scarred nerve ends
② nerve suture distration
7. A good end result requiring rehabilitation from onset of treatment. Prevention of disuse, relief of pain, predicting probable end results of operative procedures.
Conclusions
Entrapment of Thoracic Outlet
• Etio - Cervial rib or anomalous transverse
process of C7
- Fibromuscular bands or scalene muscle abnomality
• Inv.- X-ray
- NCV & EMG
- Angiography – vascular anomaly
• Tx : Supraclavicular approach
- Best op. management
scalene anterior and medius M.
Carpal Tunnel Syndrome
thenal atrophy
Entrapment of Radial Nerve
Entrapment of Ulnar Nerve- Cubital tunnel - Guyon’s canal
Motor Deficit of Ulnar Nerve
• Bediction posture : clawing of ring
& small finger
• Froment’s sign : weakness of adductor pollicis, there will
be flexion of the interphalangeal joint of the thumb because of substitution
of the median innervated flexior pollicus longus for a weak adductor pollicis
Meralgia Paresthesia
Lateral femoral
cutaneous nerve
injury (L1-2)
Tarsal Tunnel Syndrome
Etiology of peripheral nerve injuries: - Metabolic or collagen diseases - Malignancies -Endogenous or exogenous toxins -Thermal -Chemical -Mechanical trauma
Diagnostic tests:Electrodiagnostic studies provide the clinician with a
base of knowledge as follows:: 1-Documentation of injury Location of insult 2 -3-Severity of injury 4-Recovery pattern 5-Prognosis 6-Objective data for impairment documentation 7-Pathology 8-Selection of optimal muscles for tendon transfer 9-
procedures
Operations Neurolysis : internal/external Nerve repair
end-to-end repair : epineural/fascicular
autologous graft : sural N. Neurotization
intercostal N./accessory N./cervical plexus
within 1 year Muscle and tendon transfer
Operations Neurolysis : internal/external Nerve repair
end-to-end repair : epineural/fascicular
autologous graft : sural N. Neurotization
intercostal N./accessory N./cervical plexus
within 1 year Muscle and tendon transfer
Epineural Repair
Nerve Graft
# leading cause of failure of nerve graft • Inadequate resection • Distraction of repair site
Pathophysiology of Entrapment Direct compression
segmental demyelination
wallerian degeneration(distal) Ischemia
swelling of nerve
microcompartment SD