Diagnostic usefulness of intraoperative ultrasonography for unexpected severe brain swelling in ultra-early surgery for ruptured intracranial aneurysms.

BACKGROUND

In ultra-early aneurysm surgery, the few hours from admission to aneurysm clipping present the greatest risk for an in-hospital recurrent hemorrhage, the development of acute hydrocephalus, and severe brain edema. Thus, severe brain swelling encountered after dural opening in a craniotomy can sometimes not be explained by a preoperative computed tomography (CT) scan. Therefore, neurosurgeons need a diagnostic tool to determine the exact cause of the brain swelling to apply appropriate intraoperative management. Accordingly, the authors propose a designated optimal ultrasound window for evaluating brain swelling during a pterional craniotomy, and assess its diagnostic usefulness and clinical impact.

METHODS

Intraoperative ultrasonography was performed during pterional craniotomies to identify the causes of severe brain swelling in 23 out of 185 patients treated using a policy of ultra-early treatment after a subarachnoid hemorrhage. Paine's point was used as the sonographic window to provide axial images showing the anterior interhemispheric fissure, lentiform nucleus, insular cortex, sylvian fissure, and ventricular system.

RESULTS

The intraoperative ultrasonography revealed significant changes from the preoperative CT findings in 9 (39.1 %) of the 23 patients. These changes included the occurrence of an intracerebral hemorrhage (ICH, n = 2) related to aneurysm rebleeding with aggravated hydrocephalus and the development (n = 5) or aggravation (n = 2) of acute hydrocephalus without rebleeding. Meanwhile, for 14 (60.9 %) of the 23 patients, the ultrasonography showed no intracranial changes. For the total 23 patients with severe brain swelling, the intraoperative management included aspiration of an ICH (n = 3), a ventriculostomy (n = 16), and medical management (n = 8) with additional mannitol and/or mild hyperventilation.

CONCLUSIONS

When severe brain swelling is encountered during a pterional craniotomy for clipping a ruptured aneurysm, an intraoperative ultrasonography technique using Paine's point as a sonographic window provides useful and reliable diagnostic information on the causes of the brain swelling, enabling the neurosurgeon to select appropriate intraoperative management.