Neurology · MU Sofia

40. Polyneuropathy: classification, clinical features, examination methods, differential diagnosis

Covers polyneuropathy as a diffuse, mostly symmetrical peripheral nerve disorder, starting in the distal limbs. It sets out classifications by distribution, by pathology (axonal versus demyelinating) and by aetiology, including metabolic, toxic, nutritional, infectious, autoimmune and hereditary causes. Sensory, motor, reflex and autonomic features are described, followed by motor and sensory examination methods and differential diagnosis against radiculopathy, myopathy, motor neuron disease, spinal cord disease and mononeuropathy.

Inside: 1 section · 1 labelled picture · 15 flashcards · 2 min

Topic 40 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 285 words (2 min of reading), with 15 flashcards.

In this note

  1. Polyneuropathy - classification, clinical features, examination methods, differential diagnosis

Polyneuropathy - classification, clinical features, examination methods, differential diagnosis

Definition:Polyneuropathy is a diffuse, usually symmetrical disorder of multiple peripheral nerves, typically affecting distal limbs first (“length-dependent neuropathy”).

Classification

A. By Distribution

  • Symmetrical distal (most common) → “stocking-glove”
  • Asymmetrical (mononeuritis multiplex)
  • Pure motor / pure sensory / mixed
  • Autonomic polyneuropathy

B. By Pathology

1. Axonal neuropathy (most common): Primary axon damage. Distal degeneration

2. Demyelinating neuropathy: Myelin sheath damage. Slowed conduction

C. By Etiology

1.Metabolic: diabetes mellitus (most common)

2.Toxic: alcohol, drugs, heavy metals

3.Nutritional: B1, B6, B12 deficiency

4.Infectious: HIV, Lyme disease

5.Autoimmune: GBS, CIDP

6.Hereditary: Charcot-Marie-Tooth disease

Clinical Features

A. Sensory Symptoms (earliest): Numbness, tingling, burning pain. “Stocking-glove” distribution. Loss of vibration and proprioception

B. Motor Symptoms: Distal weakness (feet → hands). Foot drop (common early sign). Muscle atrophy (distal > proximal). Fatigability

C. Reflexes: Reduced or absent deep tendon reflexes (early Achilles reflex loss)

D. Autonomic Symptoms (if involved): Orthostatic hypotension. Sweating abnormalities. Erectile dysfunction. Gastrointestinal dysmotility

Clinical Patterns

  • Length-dependent pattern (classic): Feet → legs → hands → arms
  • Mononeuritis multiplex: Asymmetrical involvement of multiple nerves. “Patchy deficits”

Examination Methods

A. Motor Examination

  • Distal muscle strength (foot dorsiflexion, toe extension)
  • Muscle atrophy (especially intrinsic foot muscles)
  • Gait: steppage gait (foot drop)

B. Sensory Examination

  • Pain and temperature (spinothalamic)
  • Vibration (tuning fork)
  • Proprioception (joint position sense)

C. Reflexes: Achilles reflex (earliest reduced). Patellar reflex later

D. Autonomic Testing (if needed): Orthostatic blood pressure. Skin temperature/sweating. Heart rate variability

Differential Diagnosis

A. Radiculopathy: Dermatomal distribution. Asymmetrical. Back pain common

B. Myopathy: Proximal weakness. No sensory loss. Reflexes preserved until late

C. Motor Neuron Disease: UMN + LMN signs. No sensory loss. Fasciculations prominent

D. Spinal cord disease: Sensory level present. Upper motor neuron signs below lesion

E. Mononeuropathy: Single nerve distribution. Asymmetrical focal deficit

Read the full note free

The whole note is free with an AceMed account, with its 15 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note