Understanding Spinal Cord Lesions

Cross-Sectional Anatomy of the Spinal Cord

• Anterolateral side:
  • Corticospinal tract: Carries upper motor neurons
  • Anterior horn cells: Carry lower motor neurons
  • Spinothalamic tract: Carries sensation of pain, temperature, and crude touch
• Posterior side (Dorsal columns):
  • Carries sensation of vibration, proprioception, and light touch

Symptoms of Motor Neuron Lesions

• Upper Motor Neuron Symptoms:
  • Hyperreflexia
  • Positive Babinski sign (toes going up)
  • Standing up when choking
  • Weight loss from lifting weights (think of the gym)
• Lower Motor Neuron Symptoms:
  • Passive muscle atrophy (due to lack of movement)
  • Muscle wasting
  • Fasciculations (small, non-purposeful movements)

Clinical Findings for Spinal Cord Lesions

Anterior Cord Syndrome

• Only the posterior cord (dorsal column) is unaffected
• Symptoms are bilateral and start at the level of the lesion
• Involves the corticospinal, anterior horn cells, and spinothalamic tracts

Complete Transection

• Entire spinal cord affected
• Loss of sensation and motor function bilaterally at and below the level of the lesion

Brown-Séquard Syndrome

• Hemisection of the spinal cord
• Ipsilateral symptoms at the level of the lesion:
  • Corticospinal tract symptoms
  • Dorsal column symptoms
• Contralateral symptoms starting two levels below the lesion for the spinothalamic tract:
  • Due to the crossing of the spinothalamic tract two levels above in the spinal cord

Key Concepts

• In anterior cord syndrome, the spinothalamic tract symptoms do not start two levels below because both sides are affected, preventing bypass of the injury.
• Understanding the location and crossing of spinal tracts helps in predicting clinical findings.

Summary

• At the level of the lesion in Brown-Séquard:
  • Ipsilateral: Corticospinal and dorsal column symptoms
  • Contralateral: Spinothalamic symptoms start two levels below
• In anterior cord syndrome:
  • Bilateral symptoms starting at the level of the lesion

Conclusion

• Understanding spinal cord lesions requires knowledge of the anatomy and the crossing of tracts.
• This understanding aids in anticipating the clinical presentation of different lesions.

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