What symptom is most characteristic of Brown Sequard syndrome?

Brown Sequard syndrome is characterized by a hemisection of the spinal cord, resulting in a unique pattern of neurological deficits. This syndrome typically presents with a combination of motor and sensory loss that is ipsilateral and contralateral, depending on the type of nerve fibers affected.

The correct answer, which highlights "ipsilateral pyramidal weakness," reflects the impact on the corticospinal tract, which crosses over at the junction of the medulla and spinal cord. When there is a lesion on one side of the spinal cord (as in Brown Sequard syndrome), motor fibers descending from the cerebral cortex to the body are affected on the same side, causing weakness or paralysis of the muscles on that side. This is known as ipsilateral pyramidal weakness due to the involvement of upper motor neurons.

The other symptom choices represent other aspects of neurological function. For example, contralateral loss of touch sensation pertains to the pathways that carry proprioceptive and fine touch information, which cross over in the brainstem, leading to sensory loss on the opposite side of the lesion. Ipsilateral flaccid paralysis indicates lower motor neuron involvement, which would not typically occur with Brown Sequard syndrome as this affects upper motor neurons. Loss of bladder control may occur in many