Peripheral nerve disrders

1. Diseases of peripheral nerve

3. • Inflammatory, traumatic, metabolic, toxic,
genetic, neoplastic

4. 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

5. • 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

6. Morphology
• Inflammation of peripheral nerve
• Perivenular & endoneurial infiltration by
lymphocytes, macrophages & few plasma
cells
• Segmental demyelination affecting
peripheral nerve is pri.lesion

7. 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

8. 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

9. • Endoneurial fibrosis & multilayered
thickening of perineural sheaths
• Symmetric polyneuropathy involves pain
fibres, leads to loss of sensation, trophic
ulcers

10. • 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

11. 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 )

12. • Ganglia show neuronal destruction,
mononuclear inflammatory infiltrate
• Regional necrosis & h’ge may be seen

13. Hereditary neuropathies
• Grp of heterogenous, typically
progressive, often disabling syndrome

14. Hereditary motor & sensory neuropathies
• Common
• Caused by mutations in genes whose
products are involved in formation &
maintainence of myelin

15. 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 )

16. 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

18. • AD , slowly progressive, sensorimotor
deficits
Hereditary sensory & autonomic
neuropathies
• Numbness, pain, orthostatic HTN
Familial amyloid polyneuropathies
• Deposition of amyloid within p.nerves

19. 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

20. Morphology
• Axonal neuropathy in distal symmetric
sensorimotor neuropathy
• Other types there is some segmental
demyelination
• Endoneurial arterioles show thickening,
hyalinization

22. Clinical course
• Decreased sensation in distal extremities
• ulcers

23. 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

24. • 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

25. • 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

26. • 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

28. 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

29. • 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