Erb's explanation for the tendon reflexes. Links between science and the clinic.
OBJECTIVE: To determine whether 19th-century experimental neurophysiological concepts directly influenced Erb's initial explanation for the deep tendon reflexes (DTRs). BACKGROUND: There is extensive literature on the discovery of the clinical utility of the DTRs on the one hand and on the development of 19th-century experimental neurophysiological concepts and early scientific concepts of reflexology on the other. While it seems logical to assume that Erb's 1875 discovery of the clinical utility of the DTRs and his initial interpretation of the physiological meaning of heightened DTRs were grounded in some of these scientific concepts, the important link between the clinical and scientific realm has not, to our knowledge, been the subject of previous analysis. METHODS: Review of the 19th-century neurophysiological literature and translation of seminal manuscripts written by Erb in the years 1875 and 1876. RESULTS: The concepts of spinal inhibition and reflex action arose from 19th-century neurophysiological experimentation. Erb first described the term Patel-larsehnenreflex (patellar tendon reflex) in 1875, and his publications reveal clear insight into several fundamental scientific concepts, including spinal inhibition, the reflex arc, distinct motor and sensory neurons, and an excitomotor system in the spinal gray matter. CONCLUSION: While Erb's initial description and interpretation of the DTRs may be regarded as a fortuitous discovery by a keen clinical observer, on another level his observations were not made in isolation, but were based on his knowledge of the physiological work of the preceding decades.