Corticospinal tracts — MCQs

A 52-year-old man with multiple sclerosis presents with progressive bilateral leg weakness and spasticity over 3 years, now requiring a wheelchair. MRI shows demyelinating plaques in the cervical and thoracic spinal cord lateral columns bilaterally, corona radiata, and periventricular white matter. He has no sensory level but has impaired vibration sense in the feet. Upper extremities are minimally affected. Evaluate which anatomical principle best explains the leg-predominant motor disability despite multiple CNS lesions.

A 25-year-old woman presents after a motor vehicle accident with complete paralysis below T10. Initial examination shows flaccid paralysis, absent reflexes, and loss of all sensation below T10. Five weeks later, she develops spastic paralysis, hyperreflexia, clonus, and Babinski signs bilaterally below the lesion, but remains unable to move her legs voluntarily. Bladder function shows detrusor hyperreflexia. Evaluate the pathophysiological changes in the corticospinal system that explain this evolution.

A 42-year-old man with known cerebral arteriovenous malformation undergoes embolization. Post-procedure, he develops weakness of his right lower extremity (2/5) with preserved right upper extremity strength (5/5). He also has urinary incontinence and personality changes with apathy. MRI shows ischemic changes in the left medial frontal lobe. Evaluate the relationship between the ischemic location and the specific pattern of motor and associated deficits.

A 67-year-old man with uncontrolled hypertension presents with sudden right hemiplegia, right facial weakness, and leftward eye deviation. He is alert but has right-sided weakness (1/5 in arm and leg). CT shows a hemorrhage in the left corona radiata and internal capsule. Three days later, he develops increased weakness. Repeat CT shows hemorrhage expansion into the ventricles. Analyze the anatomical progression affecting the corticospinal system.

A 34-year-old woman presents with progressive weakness that began in her right hand and has spread to involve her right arm and leg over 18 months. She now has weakness in the left hand. Examination shows fasciculations, muscle atrophy, hyperreflexia, and both upper and lower motor neuron signs without sensory deficits. EMG shows widespread denervation. Analyze the anatomical levels of corticospinal tract involvement that best explain both upper and lower motor neuron signs.