Effect of Craniotomy on Temporalis Function

Overview

The scientific objectives of this study are to systematically study the problems that are created by incising the attachment of the temporalis muscle in a randomized group of patients, and to determine whether another approach that does not detach the temporalis muscle results in less post-operative morbidity. Cutting through the attachment of the temporalis muscle to the skull is a widely-accepted procedure used to gain access to the skull prior to the drilling used for a pterional craniotomy (one of the most frequent types of surgeries used in neurosurgical practice). Despite the frequent use of this maneuver and the known sequelae of temporalis mobilization (e.g. post-operative myofascial pain, temporalis weakness, and pain with mastication), very little is known about the true incidence of these post-operative symptoms. Furthermore, there is very little objective evidence at the present time to support the claim that the incidence and severity of these post-operative phenomena can be decreased with use of an osteoplastic craniotomy (a procedure where the temporalis is left attached to the bony calvarium). The investigators would like to evaluate whether this slightly more time-consuming and technically demanding approach is less morbid in this respect than the contemporary pterional approach. Special note is made that the osteoplastic approach has been used in standard neurosurgical practice for quite some time.

In contemporary neurosurgery, when performing a pterional craniotomy, neurosurgeons have been taught to cut through and detach the temporalis before drilling the skull to "turn a bone flap". While there are ways to turn a bone flap with the temporalis still attached (i.e., an "osteoplastic craniotomy"), this is thought to be slightly more time-consuming and is used less often in many centers. Additionally, there is a common misconception that osteoplastic craniotomy does not allow an equivalent view, although recent evidence suggests that the surgical exposure in the two approaches is no different. Aside from the extra time involved, we do not feel that leaving the temporalis attached to the bony calvarium disadvantages the patient in any fashion (and-in fact-may result in less post-operative morbidity). We are interested in this project because there is actually very little objective data regarding the morbidity people experience when the temporalis muscle is cut and mobilized prior to drilling the skull. If, in this study, we find that the group randomized to traditional pterional craniotomy experiences significantly more morbidity than the group randomized to osteoplastic craniotomy, this may justify conversion to an osteoplastic craniotomy in many or all instances. We wish to quantify the morbidity that is associated with the specific methods used to detach the temporalis muscle from the skull. Many variables regarding the way the temporalis is detached will be recorded and assessed in the group randomized to traditional pterional craniotomy. Additionally, many methods will be used to measure post-operative temporalis atrophy and/or dysfunction in the two randomized groups. After post-operative morbidity has been quantified, we plan to compare the traditional pterional group to the osteoplastic group and assess for significance.