LMN Lesions

  1. Peripheral Nerve Dysfunction can be described using severeal terms
    • Neuropathy is the term used to describe an injury affecting the peripheral nerve due to infection, a toxin, or a metabolic disorder.
    • Polyneuropathy refers to widespread bilateral insults to the peripheral nerve. The axon continues to die back as long as the toxin or metabolic problem remains and then the axon regenerates
  2. Signs and Symptoms of Peripheral Nerve Dysfunction
    • muscle atrophy
    • glove/stocking sensory and motor loss
    • tingling in toes, fingers
    • decreasedd forearm, ankle reflexes
    • decreased nerve conduction velocity (NCV)
    • Regeneration occurs at the rate of approximately 1-2 mm per day if the axon hillock is still intact
  3. Metabolic neuropathies are
    • those nerve deficits taht develop secondary to systemic disease w/ a metabolic origin.
    • Common disease include:
    • Diabetes Mellitus (most common)
    • Hypoglycemia
    • Uremia (second most common)
    • Hypothyroidism
    • Hepatic failure
    • Polychthemia
  4. Traumatic lesions can be milde to very severe depending on the type of injury and amount of tissue damage from the trauma. Cassified in 3 ways:
    • Class 1: mild/moderate compression of nerve; recovery takes 3 months
    • Class 2: caused by closed-crush or percussion injuries; recover- several months to years (proximal to distal)
    • Class 3: caused by staby wounds, bullet wounds, or severe stretch injury (bracheal plexus); involve total motor, sensory and autonomic dysfunction (caused by MVA)
  5. 2 types of brachial plexus injuries that can occur from multiple causes
    • Upper (C5-C6)-Erb's Palsy
    • Lower (C8, T1)-Klumpke's Palsy
  6. Upper (C5-C6)-Erb's Palsy
    This type of brachial plexus injury results in paralysis of the deltoid, biceps, brachioradialis, supraspinatus, infraspinatus, and subscapularis muscles. This results in areflexia of the biceps and brachioradials reflexes, sensory loss in the lateral shoulder and upper arm and radial side of the forearm. In infants, this is caused by breech presentation or overstretching of the neck. Recovery is poor-only 1/3 of Erb's palsy patients regain full motion.
  7. Lower (C8, T1) Klumpke's Palsy
    Injury results in paralysis of the hand intrinsics resulting in a claw hand weak wrist flexors and sensory loss of the medial forearm/hand/ and the lateral 2 fingers. Recocvery from Klumpke's Palsy is usually better.
  8. Radial nerve injury results in
    • paralysis of the:
    • brachioradialis
    • extensor carpi radialis longus and brevis
    • supinator
    • extensor digitorum
    • extensor digiti minimi
    • abductor pollicis longus
    • extensor pollicis longus and brevis
    • extensor indices
    • wrist drop
  9. Median Nerve Injury
    • Sensory loss on the lateral aspect of the palm and the palmar aspect of the first three digits
    • An injury to the median nerve is considered the most serious single nerve injury as the thumb and index finger are non-functional and leads to "ape" hand.
  10. Ulnar Nerve Injury
    Claw Hand
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LMN Lesions
LMN Lesions