Peripheral nerve disrders

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Peripheral nerve disrders

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Peripheral nerve disrders

  1. 1. Diseases of peripheral nerve
  2. 2. • Inflammatory, traumatic, metabolic, toxic, genetic, neoplastic
  3. 3. Inflammatory neuropathies • Inflammatory cell infiltrates into peripheral nerves, roots & autonomic ganglia Immune mediated neuropathies G. B. syndrome ( acute inflammatory demyelinating polyradiculoneuropathy ) • Most common, life threatening
  4. 4. • Weakness in distal limbs, rapidly advancing to proximal muscle ( asc paralysis) • Inflammation & demyelination of peripheral nerves & spinal nerve roots Pathogenesis • Preceded by acute infleunza like illness, viral • Immunologically mediated disease
  5. 5. Morphology • Inflammation of peripheral nerve • Perivenular & endoneurial infiltration by lymphocytes, macrophages & few plasma cells • Segmental demyelination affecting peripheral nerve is pri.lesion
  6. 6. Clinical course • Dominated by asc paralysis • Deep tendon reflexes disappear early • Nerve conduction velocity slowed bcoz of multifocal destruction of myelin segments involving axons within nerve, increase in CSF protein due to inflammation
  7. 7. Infectious polyneuropathies Leprosy • Lepromatous leprosy – schwann cells invaded by M.leprae which proliferates & infects other cells • Evidence of segmental demyelination & remyelination & loss of both myelinated & unmyelinated axons
  8. 8. • Endoneurial fibrosis & multilayered thickening of perineural sheaths • Symmetric polyneuropathy involves pain fibres, leads to loss of sensation, trophic ulcers
  9. 9. • Tuberculoid leprosy – active CMI with nodular granulomatous inflammation • Inflammation injures cutaneous nerves in the vicinity, axons, schwann cells & myelin are lost • Fibrosis of perineurium & endoneurium
  10. 10. Varicella zoster virus • Common viral infection • Latent infection of neuron in sensory ganglia of spinal cord & brain stem follows chickenpox • Painful vesicular skin eruptions in distribution of sensory dermatomes ( thoracic/trigeminal )
  11. 11. • Ganglia show neuronal destruction, mononuclear inflammatory infiltrate • Regional necrosis & h’ge may be seen
  12. 12. Hereditary neuropathies • Grp of heterogenous, typically progressive, often disabling syndrome
  13. 13. Hereditary motor & sensory neuropathies • Common • Caused by mutations in genes whose products are involved in formation & maintainence of myelin
  14. 14. Type I ( HMSN I ) • Childhood • Progressive muscular atrophy of calf • Duplication of large region of chromosome 17p11 – p12 -> segmental trisomy, which includes gene for peripheral myelin protein 22 (PMP22 )
  15. 15. Morphology • Histology shows consequences of repetitive demyelination & remyelination with multiple onion bulbs more in distal nerves • Schwann cell hyperplasia surrounding individual axons -> enlargement of individual p.nerves -> hypertrophic neuropathy
  16. 16. • AD , slowly progressive, sensorimotor deficits Hereditary sensory & autonomic neuropathies • Numbness, pain, orthostatic HTN Familial amyloid polyneuropathies • Deposition of amyloid within p.nerves
  17. 17. Acquired metabolic & toxic neuropathies Peripheral neuropathy in adult onset DM • Depends on duration of disease 1. Distal symmetric sensory/sensory motor neuropathy 2. Autonomic neuropathy 3. Focal/multifocal asymmetric neuropathy
  18. 18. Morphology • Axonal neuropathy in distal symmetric sensorimotor neuropathy • Other types there is some segmental demyelination • Endoneurial arterioles show thickening, hyalinization
  19. 19. Clinical course • Decreased sensation in distal extremities • ulcers
  20. 20. Metabolic & nutritional peripheral neuropathies • In renal failure – distal symmetric neuropathy, muscle cramps, decreased deep tendon reflexes, axonal degeneration • Chr liver disease, chr resp insufficiency, thyroid dysfunction • Thiamine deficiency -> axonal degeneration – Beri Beri
  21. 21. • Excessive consumption of alcohol -> axonal neuropathy Neuropathies ass with malignancy • Direct infiltration/ compression of p nerves by tumor -> mononeuropathy • Eg brachial plexopathy – lung tumor • Diffuse symmetric neuropathy in distant CA due to paraneoplastic syndromes
  22. 22. • Numbness, paraesthesia Toxic neuropathies • After exposure to industrial/environmental chemicals, toxins, drugs – lead, arsenic Traumatic neuropathies • Nerves injured during course of trauma • Lacerations from cutting injuries, avulsions – tension applied to peripheral nerve
  23. 23. • Regeneration slow, regrowth complicated by discontinuity between proximal & distal portions of nerve sheath/ misalignment of individual fascicles • Axons in absence of distal segment continue to grow resulting in mass of tangled axonal process -> traumatic neuroma
  24. 24. Compression neuropathy - occurs when p nerve is compressed Carpal tunnel syndrome • Compression of median nerve at the level of wrist within compartment limited by transverse carpal ligament • Women, bilateral • Pregnancy, inflammatory arthritis, hypothyroidism, acromegaly, DM
  25. 25. • Numbness, paraesthesia of tips of thumb & 1st two digits Other • Involvement of ulnar nerve at the level of elbow • Peroneal nerve – level of knee • Radial nerve in the underarm – sleeping with arm improperly positioned – sat night palsy

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