A pathology of the animal spirits -- the clinical neurology of Thomas Willis (1621-1675) part I -- background, and disorders of intrinsically normal animal spirits.

Thomas Willis (1621-1675), author of the classical work Cerebri Anatome (1664), was arguably the father of the modern era of neurology. As compared with his neuroanatomy, relatively little attention has been paid to Willis' clinical neurology, as described in his Pathologiae Cerebri (1667) and De Anima Brutorum (1672), where he gave a structured account of disease of the nervous system as it was known in his day. His account was largely derived from personal observations and not from traditional authorities and was based around his concept of the animal spirits, a fictitious entity in many ways analogous to the present day idea of the nerve impulse. This concept allowed him to develop a pathology of the animal spirits which embraced the whole content of the clinical neurology and psychiatry of his times. The anatomical and physiological background to Willis' concepts of animal spirit dysfunction, and those disorders he regarded as due to disturbed function of intrinsically normal animal spirits (mainly headache, disorders of consciousness, apoplexy and palsy) are dealt with in the present paper. The disorders he attributed to inherently abnormal animal spirits are considered in a second part of the paper.