Brown-Sequard Syndrome Lecture Notes

Overview

• Brown-Sequard Syndrome is a condition resulting from the hemisection (damage to one half) of the spinal cord.
  • First described by Charles-Edouard Brown-Sequard.
  • Causes loss of sensations (pain, temperature, touch) and muscle function paralysis.

Anatomy of the Spinal Cord

• Structure: White matter outside, gray matter inside (butterfly shape).
  • Dorsal horns: Contain sensory neuron cell bodies.
  • Ventral horns: Contain motor neuron cell bodies.
• White matter tracts:
  • Spinothalamic tract: Ascends, carries pain and temperature (lateral) and crude touch (anterior).
  • Dorsal column tracts:
    • Fasciculus gracilis: Lower trunk/legs sensory info.
    • Fasciculus cuneatus: Upper trunk/arms sensory info.
  • Corticospinal tract: Descends, carries motor info for voluntary movement.

Neuronal Pathways

• Three neurons relay to the brain:
  • 1st order neuron: Pseudounipolar, from periphery to dorsal root ganglion.
  • 2nd order neuron: Ascends spinal segments, crosses to opposite side.
  • 3rd order neuron: From thalamus to sensory cortex.
• Motor signal pathway:
  • Upper motor neurons descend via corticospinal tract, synapse with lower motor neurons.

Mechanism of Brown-Sequard Syndrome

• Causes:
  • Trauma (e.g., fracture, gunshot, stab wound) or non-traumatic (e.g., tumor).
• Effects of a Right Hemisection:
  • Corticospinal tract damage: Ipsilateral hemiplegia and spastic paralysis.
  • Dorsal column damage: Loss of fine touch, pressure, vibration, proprioception on right side.
  • Spinothalamic tract damage:
    • Loss of pain/temperature sensation on left side, below lesion.
    • Complete sensation loss at lesion level on right.
  • Horner’s syndrome: Possible if hemisection above T1, affects the face (miosis, ptosis, anhidrosis).

Diagnosis and Treatment

• Clinical Presentation:
  • Often incomplete hemisection with varied sensory/motor loss.
  • Example: Left side loss of pain/temp, normal motor/fine touch indicates right spinothalamic tract damage.
• Imaging: MRI to confirm spinal cord lesions.
• Treatment: Supportive with rehabilitation, corticosteroids for swelling.

Recap

• Brown-Sequard syndrome involves damage to the spinal cord resulting in motor and sensory dysfunctions on respective sides of the injury.
  • Paralysis/proprioception loss on side of injury.
  • Pain/temperature sensation loss on opposite side.