The reflex examination is important for several reasons. Reflex changes may be the earliest and most subtle indication of a disturbance in neurologic function. The testing of reflexes is the most objective part of the neurologic examination. Reflexes are under voluntary control to a lesser extent than most other parts of the neurologic examination, and reflex abnormalities are difficult to simulate. They are not as dependent on the attention, cooperation, or intelligence of the patient, and can be evaluated in patients who cannot or will not cooperate with other parts of the examination. In such circumstances, the integrity of the motor and sensory systems can sometimes be appraised more adequately by the reflex examination than by other means. Although the reflex examination is an essential component, it is only one part of the neurologic examination, and must be evaluated in the context of the other findings.

A reflex is an involuntary response to a sensory stimulus. Afferent impulses arising in a sensory organ produce a response in an effector organ. There are segmental and suprasegmental components. The segmental component is a local reflex center in the spinal cord or brainstem and its afferent and efferent connections. The suprasegmental component is made up of the descending central pathways that control, modulate, and regulate the segmental activity. Disease of the suprasegmental pathways may increase the activity of some reflexes, decrease the activity of others, and cause reflexes to appear that are not normally seen. A reflex response may be motor, sensory, or autonomic.