Monro-Kellie Doctrine

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The Monro-Kellie doctrine , also known as the Monro-Kellie hypothesis , states that the sum of the three components: brain tissue , blood and cerebrospinal fluid within the cranial cavity must always remain the same in order to keep the intracranial pressure constant.


The doctrine formulated as early as the 19th century is based on the fact that the cranial cavity is a rigid cavity with a defined volume ( rigid box ). It says that the sum of the three components:

  • Brain tissue (about 80 percent)
  • Blood (about 12 percent)
  • CSF (about 8 percent)

must always remain the same within the cranial cavity in order to keep the intracranial pressure constant. The available intracranial volume is around 1600 ml.

If one of the three components increases, the pressure can be kept as constant as possible by decreasing another component, for example through CSF absorption . This possibility of compensation is quickly exhausted, however, and the intracranial pressure then rises steeply with further small increases in volume.

As the intracranial pressure increases, the cerebral perfusion pressure (CPP), which is the difference between the mean arterial pressure and the intracranial pressure , can decrease. If this falls below a value of 50 mmHg for several minutes , the blood supply to the brain is reduced and irreversible damage occurs after a short time.

Example of the Monro-Kellie Doctrine

When the volume of the liquor increases, e.g. B. as a result of a chronic disturbance of the liquor outflow , there is an expansion of the liquor spaces ( hydrocephalus occlusus ) with shrinkage of the brain tissue ( brain atrophy ).


In 1783, the Scottish anatomist Alexander Monro II (1733–1817) was the first to describe the human skull as a rigid box (“rigid container”), which is filled with the almost unimpressible brain. George Kellie confirmed this approach in 1824, which later became known as the Monro-Kellie Doctrine .


  • MR Gaab: The registration of intracranial pressure. Basics, techniques, results and possibilities. In: Fortschr Med. 102/1984, pp. 957-962.
  • MR Gaab: Intracranial pressure increase: therapeutic options. In: Anesthesiology Intensivmed Emergency Med Painth. 34/1999, pp. 71-78.
  • AJ Popp et al. a .: Pathophysiologic of traumatic brain injury. In: Neurosurgery. McGraw-Hill, 1996, pp. 2623-2637.
  • F. Servadei et al. a .: Analysis of 37 patients with evolving intracranial lesions in the first 12 hours after trauma: Value of ICP-monitoring. In: Intracranial Pressure IX. Springer, 1994, pp. 335-338.
  • DG Silverberg: Intracranial pressure monitoring. In: Neurosurgery. McGraw-Hill, pp. 185-190.
  • DW Taylor: The Manuscript Lecture-Notes of Alexander Monro, Secundus (1733-1817). In: Medical History. 22/1978, pp. 174-186. PMC 1082216 (free full text)
  • B. Mokri: The Monro-Kellie hypothesis: Applications in CSF volume depletion. In: Neurology. 56/2001, pp. 1746-1748.

Individual evidence

  1. Czosnyka M: Cerebrospinal fluid dynamics . In: Physiol. Meas. . 25, 2004, pp. R51-R76. doi : 10.1088 / 0967-3334 / 25/5 / R01 .
  2. a b G. Brinksmeier: Experimental measurement of spatially different pressure development on an artificial head with supratentorial masses , dissertation, University of Münster, 2003 (PDF file; 3.85 MB)
  3. Alexander Monro: Observations on the structure and function of the nervous system. Creech & Johnson, Edinburgh 1823, p. 5.
  4. Monro-Kellie doctrine. Retrieved August 8, 2007
  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. In: The Transactions of the Medico-Surgical Society of Edinburgh. 1/1824, pp. 84-169.
This text is based in whole or in part on the Monro-Kellie Doctrine entry in the Flexikon , a wiki from DocCheck . The takeover took place on August 8, 2007 under the then valid GNU license for free documentation .