[Henry Head and the Genealogy of the "Thumb Localizing Test"]

Henry Head (1861-1940) is not well-known in Japan today, yet his achievements were so great that he was nominated four times for the Nobel Prize in Physiology or Medicine, starting with the first award (1901). He is regarded as one of the great founders of clinical neurology. I have encountered his work three times in the literature. The first time was when research on the "thumb localizing test" began. In a joint publication with Gordon Holmes, Head proposed a test to demonstrate defective recognition of posture. They described it as follows: "The patient's eyes are closed, and the affected limb is placed in a position different from its initial one. The patient is then instructed to touch a specific part of the affected limb, such as the index finger, with his normal hand." Subsequently, some investigators described similar tests; however, they did not gain popularity, perhaps due to the difficulty in interpretation. We have examined a large number of cases and established its value as a screening tool for detecting disorders of the posterior column-medial lemniscus system. My second encounter with his work was in their dermatome studies, and the third was in their research on body schema, particularly the report of a case involving phantom limb sensation.