outline the indicators and signs of sight loss
Dissociated sensory loss is a pattern of neurological damage caused by a lesion to a single tract in the spinal cord which involves selective loss of fine touch and proprioception without loss of pain and temperature, [ or vice-versa.
Understanding the reason this is possible requires a brief discussion of the anatomy involved.
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). 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).
Loss of fine touch and proprioception are due to damage to the dorsal columns, which do not cross the cord until the brainstem, and so travel up the column on the same side to the one they innervate (i.e. they ascend ipsilaterally).
This means that a lesion of the dorsal columns will cause loss of touch and proprioception below the lesion and on the same side as it, while a lesion of the spinothalamic tracts will cause loss of pain and temperature below the lesion and on the opposite side to it. ]
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