Question 2#

The lesion that can cause mass effect and rapidly kill the patient is:

A. Inferior fossa lesions
B. Posterior fossa lesions
C. Progressive obtundation
D. Bradycardial lesions

Correct Answer is B


The posterior fossa (brain stem and cerebellum) requires special consideration because the volume of the posterior fossa within the cranial vault is small. Posterior fossa lesions such as tumors, hemorrhage, or stroke can cause mass effect that can rapidly kill the patient in two ways. Occlusion of the fourth ventricle can lead to acute obstructive hydrocephalus, raised intracranial pressure (ICP), herniation, and eventually death. This mass effect can also lead directly to brain stem compression (Fig. below). Symptoms of brain stem compression include hypertension, agitation, and progressive obtundation, followed rapidly by brain death. A patient exhibiting any of these symptoms needs an emergent neurosurgical evaluation for possible ventriculostomy or suboccipital craniectomy (removal of the bone covering the cerebellum). This situation is especially critical, as expeditious decompression can lead to significant functional recovery.

Maturing cerebellar stroke seen as a hypodense area in the right cerebellar hemisphere (arrowhead) on head computed tomography (CT) in a patient with rapidly progressing obtundation 2 days after the initial onset of symptoms. Swelling of the infarcted tissue causes posterior fossa mass effect. The fourth ventricle is obliterated and not visible, and the brain stem is being compressed.