1. Are the findings in the left upper limb and right lower limb suggestive of an upper motor neuron or lower motor neuron process?
Upper motor neuron
2. If all signs and symptoms in this case are due to a single localized lesion, there is only one place in the central nervous system that this lesion can be placed. Where is that location, at what level in the central nervous system is it, and what structures are involved by the pathologic process?
Left pyramidal decussation, in the lowermost section of the medulla (i.e., the transition from medulla to spinal cord). The lesion would involve the left lateral corticospinal tract at its origin, after the fibers to the left upper limb have crossed, but before the fibers to the left lower limb have crossed. The lesion would also involve the left pyramidal tract before the fibers to the right lower limb have crossed, but after those to the right upper limb have crossed.
3. The clinical findings in this case represent a rare but classic neurologic syndrome. What is the name of this syndrome?
Cruciate (alternating) hemiplegia.
4. In general, what type of pathologic process do you think was involved in this case?
Vascular – probably due to a microembolus to the left lower medulla via a branch of the anterior spinal artery
5. What diagnostic procedure(s) would you undertake at this point?
Click here for images
