Loss of pain and temperature are due to damage to the lateral spinothalamic tracts, which cross the central part of the cord close to the level where they enter it and travel up the spinal column on the opposite side to the one they innervate ( i . e . they " ascend contralaterally " ).
42.
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 ).
43.
In the central nervous system they can detect damage to the spinothalamic tract, lateral brain stem, and fibers carrying pain and temperature signals from the thalamus to the A delta ) fibers to the spinal cord, and LEPs can be used to determine whether a neuropathy is located in these small fibers as opposed to larger ( touch, vibration ) fibers.
44.
Spinothalamic Tract ( STT ) cells that project from laminae I and V in the lumbrosacral area of the spinal cord project to the VPL in the VB . STT cells located in the cervical area of the spinal cord are the densest and project from the neck of the dorsal horn to the VPL of the VB . Most projections to the VB are contralateral while only a few projections to the VB are ipsilateral.
