1. Is there evidence of peripheral nervous system (peripheral nerve, spinal nerve, or dorsal/ventral root) involvement in this case, and, if so, what is the level(s) of that involvement?
No
2. Are the patient’s right lower limb motor and reflex examinations suggestive of an upper motor neuron or lower motor neuron process?
Upper motor neuron
3. Is there evidence of spinal cord involvement in this case and, if so, at what level?
No. A spinal cord lesion would have to be located on the right side of the thoracic or upper lumbar cord, involving the right lateral corticospinal tract and the right fasciculus gracilis. However, the left spinothalamic tract would be involved to produce the right lower limb pain deficits; so it is unlikely that this is a spinal cord process.
4. Could this patient’s signs and symptoms be localized to any other place in the central nervous system? If so, what is the precise localization of her neurologic lesion, including the side of involvement? Indicate the specific structure(s) involved by this lesion.
Yes. An isolated right lower limb weakness and sensory deficit could be caused by a lesion involving the left paracentral lobule. Such a lesion would interrupt the origin of the corticospinal fibers to the contralateral lower limb and the termination of the somatic sensory pathways from the contralateral lower limb (review the “motor homunculus” on the primary motor cortex [area 4] and the “sensory homunculus” on the primary somatic sensory cortex [areas 3, 1, 2]).
5. In general, what type of pathologic process do you think is involved in this case, and what would be included in the differential diagnosis?
Neoplastic – Left parasagittal meningioma (Differential Diagnosis: chronic infectious process such as an abscess, tuberculoma, cryptococcoma, etc.)
6. What diagnostic procedure(s) would you undertake at this point?
