What type of sensory loss occurs below the level of a syringobulbia lesion?

In the case of a syringobulbia lesion, which is generally characterized by the development of a fluid-filled cavity within the spinal cord, the impact on sensory pathways is significant. Syringobulbia primarily affects the brainstem and upper spinal cord, leading to specific types of sensory and motor deficits depending on the location and extent of the lesion.

Dissociated sensory loss is experienced due to the involvement of different types of sensory fibers — specifically, pain and temperature sensations can be disrupted while proprioception and light touch may remain intact. This phenomenon occurs because the fibers that carry pain and temperature sensations decussate (cross over) at different levels than those that carry proprioception and light touch.

While lower motor neuron (LMN) and upper motor neuron (UMN) signs can be associated with different neurological conditions, syringobulbia typically leads to both types of motor signs due to the disruption of pathways: the corticospinal tracts, which are responsible for upper motor neuron functions, and anterior horn cells or lower motor neuron pathways, which lead to muscle function. Syringobulbia can cause LMN signs by affecting the anterior horn cells directly, and UMN signs due to the disruption of the corticospinal pathways