Parkinson’s Disease (PD) Neurological II Practice Exam

Pathological reflexes arise when the brain’s inhibitory control over spinal reflexes is lost due to damage to the upper motor neurons. The corticospinal tract is the main upper motor neuron pathway that modulates voluntary movement and reflex arcs. When this pathway is disrupted, you get the upper motor neuron syndrome: increased tone, hyperreflexia, and the emergence of primitive or pathological reflexes such as the Babinski sign. These signs indicate a lesion above the level of the final common pathway, i.e., in the corticospinal tract. In contrast, lower motor neuron lesions produce flaccidity and decreased reflexes, cerebellar lesions cause coordination problems, and peripheral neuropathies affect nerves outside the CNS without producing the classic UMN pathological reflex signs.