Intracranial cavity volumes: a new method and its potential applications.

Variations of brain weights and volumes often reflect pathological states. However, these parameters are more meaningful when related to intracranial volume. The most useful derived parameter is the difference between intracranial volume and brain volume expressed as a percentage (potential intracranial space). In patients with cerebral atrophy the potential intracranial space will be large, whereas in patients with space occupying lesions or brain swelling the potential intracranial space will shift towards 0%. Previously described techniques to determine intracranial volume have been unsatisfactory for routine application in the autopsy room. The technique described herein is based on the production of a permanent polyurethane cast of the cranial cavity. The casts can be formed in about 20 min with little modification of standard autopsy technique. Duplicate casts were made in twenty-seven unselected cases and in all cases there was less than 2% error in duplicate cast volumes. The cast provides a permanent record of the size and shape of the cranial cavity and can be used to determine intracranial volume or other intracranial dimension. The usefulness of the derived parameter, potential intracranial space, is evident in some of the cases studied.