Timothy C. Hain, MD • Page last modified: March 5, 2021

The medulloblastoma is the most common malignant tumor in the posterior fossa in children. It arises from the nodulus of the cerebellum, and for this reason, greatly affects coordination and balance.


The most common presentation (as is true in nearly all posterior fossa tumors), is nausea vomiting and headache. Vomiting is worst in the morning.

Truncal ataxia, nystagmus, and double vision are common later developments. The nystagmus may be a very strong positional nystagmus, as this tumor arises in the vestibulocerebellum. These patients do not process vestibular signals related to tilt normally (Hain et al, 1988).

Symptoms are usually present prior to diagnosis for only 6-7 weeks. This is very different from the case in cerebellar astrocytomas, in which symptoms are generally present for much longer periods of time.



The diagnosis is made via MRI scan.

This is an MRI scan of a patient who had her medulloblastoma removed. There is a large hole in the center of the cerebellum.


Hain TC, Zee DS, Maria B: Tilt-suppression of the vestibulo-ocular reflex in patients with cerebellar lesions. Acta Otolaryngology. (Stockh), 105:13-20, 1988.