Neuropathy, Peripheral

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Basics

Description

  • A functional or structural disorder of the peripheral nervous system (PNS), affecting any combination of motor, sensory, or autonomic nerves
  • Peripheral motor involvement causes muscle atrophy, weakness, cramps, and fasciculations.
  • Disorders of sensory nerves produce negative phenomena (loss of sensibility, lack of balance) or heightened phenomena (tingling or pain). Large sensory fiber dysfunction impairs touch and vibration sensation, whereas small fiber sensory neuropathy (SFSN) affects pin and thermal sensation and causes neuropathic pain.
  • The autonomic nervous system (ANS) includes the sympathetic and parasympathetic systems. ANS dysfunction causes cardiovascular, gastrointestinal, and sudomotor symptoms.
  • The PNS can be affected from the cell body (sensory ganglionopathy or motor neuronopathy), root (radiculopathy), or plexus (plexopathy) to the nerve (demyelinating or axonal neuropathy).

Epidemiology

Prevalence
Approximately 8% of people >55 years old are affected by distal symmetric PN. Diabetic sensorimotor polyneuropathy affects 2/3 of diabetic patients.

Etiology and Pathophysiology

PN occurs due to demyelination or axonal degeneration.

  • The most common cause of acquired PN is diabetes mellitus.
  • 30% are idiopathic.
  • Other categories of acquired PN with illustrative examples are the following:
    • Vascular: ischemia, vasculitis
    • Infectious: HIV, hepatitis C, cryoglobulinemia, Lyme disease
    • Traumatic: compression, crush, stretch, or transection
    • Autoimmune: rheumatoid arthritis, Sjögren, etc.
    • Metabolic: renal failure, hypothyroidism, vitamin B12 deficiency, celiac disease, porphyria
    • Iatrogenic/toxic: chemotherapy, platinum, taxanes, metronidazole, colchicine, infliximab, lead, alcoholism
    • Neoplastic/paraneoplastic: paraproteinemia, Waldenström macroglobulinemia, multiple myeloma, amyloidosis, neurofibromatosis
  • Acquired polyneuropathies typically present with distal onset of symptoms.
Genetics
  • Approximately 50% of undiagnosed PN is hereditary.
  • Charcot-Marie-Tooth (CMT) neuropathies: the most common hereditary PN
    • CMT1A (duplication of the PMP22 gene) is the most common CMT.
    • A PMP22 deletion causes hereditary neuropathy with liability to pressure palsy (HNPP).

Risk Factors

Systemic disorders predispose to PN such as diabetes and alcoholism

General Prevention

Healthy nutrition and avoidance of alcoholism and of pressure at nerve entrapment sites

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Basics

Description

  • A functional or structural disorder of the peripheral nervous system (PNS), affecting any combination of motor, sensory, or autonomic nerves
  • Peripheral motor involvement causes muscle atrophy, weakness, cramps, and fasciculations.
  • Disorders of sensory nerves produce negative phenomena (loss of sensibility, lack of balance) or heightened phenomena (tingling or pain). Large sensory fiber dysfunction impairs touch and vibration sensation, whereas small fiber sensory neuropathy (SFSN) affects pin and thermal sensation and causes neuropathic pain.
  • The autonomic nervous system (ANS) includes the sympathetic and parasympathetic systems. ANS dysfunction causes cardiovascular, gastrointestinal, and sudomotor symptoms.
  • The PNS can be affected from the cell body (sensory ganglionopathy or motor neuronopathy), root (radiculopathy), or plexus (plexopathy) to the nerve (demyelinating or axonal neuropathy).

Epidemiology

Prevalence
Approximately 8% of people >55 years old are affected by distal symmetric PN. Diabetic sensorimotor polyneuropathy affects 2/3 of diabetic patients.

Etiology and Pathophysiology

PN occurs due to demyelination or axonal degeneration.

  • The most common cause of acquired PN is diabetes mellitus.
  • 30% are idiopathic.
  • Other categories of acquired PN with illustrative examples are the following:
    • Vascular: ischemia, vasculitis
    • Infectious: HIV, hepatitis C, cryoglobulinemia, Lyme disease
    • Traumatic: compression, crush, stretch, or transection
    • Autoimmune: rheumatoid arthritis, Sjögren, etc.
    • Metabolic: renal failure, hypothyroidism, vitamin B12 deficiency, celiac disease, porphyria
    • Iatrogenic/toxic: chemotherapy, platinum, taxanes, metronidazole, colchicine, infliximab, lead, alcoholism
    • Neoplastic/paraneoplastic: paraproteinemia, Waldenström macroglobulinemia, multiple myeloma, amyloidosis, neurofibromatosis
  • Acquired polyneuropathies typically present with distal onset of symptoms.
Genetics
  • Approximately 50% of undiagnosed PN is hereditary.
  • Charcot-Marie-Tooth (CMT) neuropathies: the most common hereditary PN
    • CMT1A (duplication of the PMP22 gene) is the most common CMT.
    • A PMP22 deletion causes hereditary neuropathy with liability to pressure palsy (HNPP).

Risk Factors

Systemic disorders predispose to PN such as diabetes and alcoholism

General Prevention

Healthy nutrition and avoidance of alcoholism and of pressure at nerve entrapment sites

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