features of regional disruption within a segment

Last reviewed 01/2018

Segmental spinal cord compression features will depend upon the position of the lesion and its extent.

The posterior columns lie dorsally and mediate joint position and vibration sense - a 'purely' posterior column spinal cord lesion rarely affects the bladder. Fibres decussate in the medulla, hence effects are ipsilateral to lesion.

The pyramidal or cortico-spinal tracts lie laterally and mediate ascending sensory and descending motor affects. Fibres cross in the lower medulla, hence effects are ipsilateral to any lesion.

The lateral spino-thalamic tracts mediate pain and temperature. Fibres decussate in the spinal cord, hence effects may be contralateral to the lesion.

The Brown Sequard syndrome is a complete hemicord lesion.

Intra-medullary lesions cause a characteristic pattern of deficiency - the second sensory neuron crossing to the lateral spinothalamic tract tends to be affected first, so that pain and temperature impairment occurs early. With expansion, there are lower motor neurone signs resulting from involvement of anterior horn cells, then upper motor neurone signs below the level of the lesion from corticospinal involvement. Joint position and vibration sense are altered as the lesion spreads posteriorly.

'Sacral sparing' may occur as the sacral fibres lie peripherally in the lateral spinothalamic tract. In the cervical region, pain and temperature impairment extends downwards in a 'cape' like distribution.

Bladder involvement is late. Sympathetic involvement in the cervical cord may produce a unilateral or a bilateral Horner's syndrome.