Tonsil of cerebellum
Tonsilla cerebelli
- Latin synonym: Lobulus IX hemisphaerii cerebelli
- Synonym: Lobule IX of cerebellar hemisphere
Definition
The tonsil of cerebellum is a rounded lobule which is situated on the undersurface of each hemisphere of cerebellum. Tonsils are part of the middle/posterior lobe of cerebellar hemisphere. The two cerebellar tonsils are continuous in the midline with the uvula or lobule IX of the vermis. Tonsil of cerebellum is separated anteriorly from the flocculus by the posterolateral or flocculonodular fissure.
Cerebellar tonsils have huge clinical significance in case of an increased intracranial pressure–for example, due to an intracranial hemorrhage–in which the tonsils can herniate out of the foramen magnum along with the neighboring lower medulla oblongata. In these circumstances, it is extremely dangerous to perform a lumbar puncture, as a sudden withdrawal of cerebrospinal fluid could further lowers down the pressure, thus augmenting the herniation effect. If this happens, cerebellar tonsils can compress and damage the cardiorespiratory neuronal centers inside the medulla oblongata, leading to cardiorespiratory arrest and death. This phenomenon is called coning or tonsillar herniation.
References
Text written by Muhammad A. Javaid, MD, PhD © 2022 IMAIOS.
Standring, S. and Gray, H. (2016). ‘Chapter 22: Cerebellum’ in Gray’s anatomy The anatomical Basis of Clinical Practice. (41st ed.) New York: Elsevier, pp. 331-335.
Snell, R.S. (2010). ‘Chapter 5: The Brainstem’, in Clinical Neuroanatomy. (7th ed.) Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, pp. 217.
Patricia, K.Y. Kan., Mandy, H.M. Chu., Emily, G.Y. Koo. and Matthew, T.V. Chan. (2016). ‘Chapter 1: Brain Herniation’ in Complications in Neuroanesthesia. Academic Press, Editor(s): Hemanshu Prabhakar, pp. 3-13. https://doi.org/10.1016/B978-0-12-804075-1.00001-8
