The crossing of the spinothalamic tract

Area of Science:

• Neuroscience
• Spinal Cord Anatomy
• Pain Perception

Background:

• The anatomical pathways of sensory information, specifically spinothalamic and spinoreticular fibers, have been a subject of debate regarding their crossing pattern within the spinal cord.
• Understanding the precise trajectory of these fibers is crucial for interpreting sensory deficits following spinal cord lesions or surgical interventions.

Purpose of the Study:

• To investigate whether spinothalamic and spinoreticular fibers cross the spinal cord transversely or diagonally.
• To correlate the pattern of sensory loss with fiber trajectories after anterolateral cordotomy and spinal artery thrombosis.

Main Methods:

• Analysis of sensory loss patterns in patients who underwent anterolateral cordotomy.
• Examination of a case involving thrombosis of the anterior spinal artery.
• Correlation of observed sensory deficits with the presumed transection of ascending and crossing spinal cord fibers.

Main Results:

• Anterolateral cordotomy resulted in a distinct pattern of sensory loss: a narrow band of decreased nociception and thermanalgesia at the incision level, with a broader area of total loss.
• This pattern is best explained by the transection of fibers already within the cord and those crossing transversely at the level of the lesion.
• Evidence for transverse crossing of spinothalamic fibers was observed across cervical, thoracic, and lumbar segments in the majority of cases studied.

Conclusions:

• The findings strongly support the hypothesis that spinothalamic fibers cross the spinal cord transversely.
• This transverse crossing pattern accounts for the observed segmental sensory loss following anterolateral cordotomy.
• While a small number of cases deviated, diagonal crossing was considered an unlikely explanation for the observed sensory deficits.