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Hemisection of the spinal cord results in the distinctive syndrome of
ipsilateral paralysis and
contralateral pain and temperature loss below
the level of the lesion, known as the Brown-Séquard syndrome. Although often not
as prominent clinically, ipsilateral vibration and proprioceptive loss also occurs
(on the same side as the motor symptoms). In the complete syndrome, the
ipsilateral anterior horn cells and dorsal roots are also affected at the level
of the transection (see Figure below). Thus, a complete hemisection of the right side of
the spinal cord results in paralysis with increased reflexes (after the acute
phase) and loss of joint position and vibration sense on the right side below
the level of the lesion and loss of pain and temperature sense on the left side.
If the lesion happens to occur at the level of the lumbar or cervical plexuses,
lower motor neuron involvement at that level may be more easily observed with
loss of segmental reflexes and, later, wasting and other signs of denervation in
the muscles of the affected root level's distribution. Likewise, with a
right-sided spinal cord hemisection, an isolated area of complete sensory loss
to both dorsal column and spinothalamic tract modalities is seen on the right in
the dermatome(s) at or just below the level of the hemisection. This occurs as a
result of interruption of all sensory neurons entering the cord on the right
side at the affected level. |
