Ok, the main question is: In syringomyelia, are the involved dermatomes the ones at the level of the lesion or 1-2 dermatomes below the lesion? The reason I am asking is:
When the lateral spinothalamic tract is affected, then the dermatomes affected are always 1-2 dermatomes below the lesion.
Explanation: "Note that a lesion of the lateral spinothalamic tract at a given level will not result in sensory loss for the dermatome of the same level; this is due to the fibers of the tract of Lissauer which transmit the neuron one or two levels above the affected segment (thus bypassing the segmental lesion on the contralateral side).(It contains centrally projecting axons carrying discriminative pain and temperature information (location, intensity and quality), which enter the spinal column ascend or descend one or two spinal segments in this tract before penetrating the grey matter of the dorsal horn where they synapse on second-order neurons. The axons of these second-order neurons cross the midline and ascend in the anterolateral quadrant of the contralateral half of the spinal cord, where they join the spinothalamic tract.)
So it would make perfectly sense that the affected dermatomes in syringomyelia are 1-2 sections below the lesion. YET I keep reading in books and UWorld that the dermatomes of the affected segments are affected.
Can anyone explain this to me ?
When the lateral spinothalamic tract is affected, then the dermatomes affected are always 1-2 dermatomes below the lesion.
Explanation: "Note that a lesion of the lateral spinothalamic tract at a given level will not result in sensory loss for the dermatome of the same level; this is due to the fibers of the tract of Lissauer which transmit the neuron one or two levels above the affected segment (thus bypassing the segmental lesion on the contralateral side).(It contains centrally projecting axons carrying discriminative pain and temperature information (location, intensity and quality), which enter the spinal column ascend or descend one or two spinal segments in this tract before penetrating the grey matter of the dorsal horn where they synapse on second-order neurons. The axons of these second-order neurons cross the midline and ascend in the anterolateral quadrant of the contralateral half of the spinal cord, where they join the spinothalamic tract.)
So it would make perfectly sense that the affected dermatomes in syringomyelia are 1-2 sections below the lesion. YET I keep reading in books and UWorld that the dermatomes of the affected segments are affected.
Can anyone explain this to me ?
