Point 22
Intro
As far as I know there are no clinical case studies involving a lesion limited to the red nucleus. You already know that many of the fibers of the brachium conjunctivum run through and around the ruber on their way to VA and VL of the thalamus (have they crossed yet?). Therefore a lesion in the ruber will not only destroy rubrospinal neurons but also cerebellothalamic axons destined for VA and VL. Since the fibers in the brachium conjunctivum have already crossed, their interruption will result in a contralateral motor deficit (remember VA, VL to ipsi motor cortex and then the crossed corticospinal system). A contralateral motor deficit would also result from a lesion of the rubrospinal neurons, whose axons innervate the contralateral spinal cord gray. Thus it is difficult to know just what particular motor deficit(s) are associated with damage to the ruber versus damage to the cerebellothalamic fibers. It has been reported that large lesions of the midbrain tegmentum involving the red nucleus (called the tegmental syndrome) result in hemichorea, which is a tremor or involuntary movement of the contralateral limbs. Since we don't know that this problem is due to involvement of only the rubrospinal system, I feel it is best to consider a lesion of the ruber to result in MOTOR PROBLEMS OF THE CONTRALATERAL LIMBS for our problem solving exercises.