In 1783 Alexander Monro deduced that the cranium was a "rigid box" filled with a "nearly incompressible brain" and that its total volume tends to remain constant. The doctrine states that any increase in the volume of the cranial contents (e.g. brain, blood or cerebrospinal fluid), will elevate intracranial pressure. Further, if one of these three elements increase in volume, it must occur at the expense of volume of the other two elements. In 1824 George Kellie confirmed many of Monro's early observations.
- A. Monro:
Observations on the structure and function of the nervous system.
Edinburgh, Creech & Johnson 1823, page 5.
- G. Kellie:
An account of the appearances observed in the dissection of two of the three individuals presumed to have perished in the storm of the 3rd, and whose bodie were discovered in the vicinity of Leith on the morning of the 4th November 1821 with some reflections on the pathology of the brain.
The Transactions of the Medico-Chirurgical Society of Edinburgh, 1824, 1: 84-169