Peripheral nervous system


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Lower Limbs


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Summary of Common Conditions Seen in OSCEs


List of Common Cases








































Lower limb Upper limb
Foot drop Carpal tunnel syndrome
Post stroke Ulnar nerve palsy
Cerebellar degeneration Wrist drop
Sensory neuropathy Axillary nerve palsy
Radiculopathy secondary to spinal pathology Volkmann’s contracture
Cerebral palsy Cervical rib
Muscular dystrophy Cerebellar degeneration
Pes cavus Tremor – Parkinson’s disease, essential tremor
Old cauda equina syndrome Post stroke
Old polio Motor neurone disease
Brown–Sequard syndrome Erb’s or Klumpke’s palsy

Common Patterns of Weakness, and Common Causes for Them

























Pattern of weakness Common causes
Proximal muscle weakness Myopathy
Distal weakness Inherited myopathies
Hemiparesis Cerebral pathology
Paraparesis Thoracic or lumbar cord lesion
Cauda equina syndrome
Tetraparesis Cervical cord lesion
Monoparesis Plexus lesion

Summary of Common Conditions and Findings in the Peripheral Nervous System


























Upper motor neurone (UMN) conditions Lower motor neurone (LMN) conditions Combined UMN and LMN lesions
Stroke:

  • Unilateral hemiplegia
  • Patient is commonly elderly
 Peripheral neuropathy: secondary to:

  • Common causes:


    • Diabetes (most common)
    • Alcohol
    • Vitamin B/B12 deficiency
    • Excess toxins (e.g. from liver or renal failure)
    • Malignancy
    • Inflammatory disease (such as vasculitis)

  • Rarer causes:


    • HIV
    • Guillain–Barré syndrome
    • Chronic inflammatory demyelinating polyneuropathy
    • Lead poisoning
 Motor neurone disease:

  • Elderly
  • Dysarthria
  • Fasciculations
  • Weakness
  • Hypertonia
Multiple sclerosis:

  • UMN signs
  • Cerebellar signs
  • Often a young woman in a wheelchair
 Nerve root lesion:

  • Specific dermatome/myotomal signs
  • Sensory level
 Subacute combined degeneration of spinal cord:

  • Features of pernicious anaemia or vitamin B12 deficiency
Spinal cord lesion/damage:

  • Spastic paraplegia
 Proximal myopathy:

  • Secondary to endocrine causes (Cushing’s disease, Addison’s disease)
  • Polymyalgia rheumatica
 Friedreich’s ataxia:

  • Upgoing plantars and weak ankle reflexes
  • Kyphoscoliosis
  • Pes cavus
  • High-arched palate

Hereditary neuropathies:

  • e.g. Charcot–Marie–Tooth disease

Mononeuritis multiplex:

  • Secondary to anything that damages the nerve intrinsically, e.g. diabetes, excess toxins

UMN vs LMN Signs




























UMN (brain and spinal cord) LMN (distal to anterior horn cells)
Inspection Spastic gait Muscle wasting
Fasciculations
Tone Increased tone (spastic – pyramidal, or rigid – extrapyramidal) Reduced/normal tone
Power Weakness Weakness
Reflexes Brisk reflexes Hyporeflexia
Plantars Upgoing plantars Downgoing plantars

Gait in Examination of the Peripheral Nervous System





































Type of gait Findings
Spastic gait Both legs affected
Hemiplegic gait Circumduction, usually post stroke
Waddling gait Proximal myopathy
Festinant gait with freezing and no arm movements Parkinson’s disease
Broad-based ataxic gait Cerebellar dysfunction
Antalgic gait Joint or back pain in which the patient takes their weight off the affected side
High-stepping gait Sensory neuropathy, and in foot drop
Scissor gait Cerebral palsy and multiple sclerosis
Stamping gait Sensory neuropathy
Apraxic gait Diffuse cerebral disease and dementia

Hints and Tips for the Exam


Before going any further, it is important to remove from your mind the myth that neurology is difficult, and ingrain some structures that will simplify your examination findings and help you come to the right conclusions.


First of all, always ask yourself the following two questions when encountering neurological cases:



1. Where is the lesion?
If the findings relate to an UMN, the lesion is affecting the brain or the spinal cord. If it is an LMN lesion, it is affecting the peripheral nerves.

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May 17, 2017 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Peripheral nervous system

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