One of Australia's leading clinical neurologists, McLeod is distinguished for his experimental contributions related particularly to our understanding of peripheral neuropathies in both the somatic and visceral nervous systems.
He was the first to demonstrate the convergence of visceral and somatic afferent information onto single cells in the thalamus, thereby providing a physiological basis for the phenomenon of referred pain. In subsequent studies he has related structural changes in nerve fibres to disturbances of conduction determined neurophysiologically, enabling him to establish clearly for the first time the pathology of various neuropathies, such as those occurring in diabetes, alcoholism and acromegaly. Using these and other findings he has made important advances in the diagnosis and management of these common and disabling human disorders.