Burr holes in the Emergency Department setting are uncommonly performed for diagnostic and therapeutic purposes. Diagnosis and treatment of increased intracranial pressure (ICP) in a timely fashion can be a lifesaving measure. Increased ICP can be the result of congenital anomalies, hemorrhage, infection, trauma, and tumors. There has been less need to make exploratory burr holes in head-injured patients since CT scanning has become widely available.
Burr holes can be lifesaving on rare occasions when the patient is worsening neurologically or has blown a pupil and CT scan is unavailable. Suspect a space-occupying lesion when there is clinical evidence of tentorial herniation or upper brain stem dysfunction. This includes pupillary dilation with a decreased or absent light reflex, progressive deterioration in the patient's level of consciousness, and/or hemiparesis including posturing (decerebrate/decorticate) or flaccidity. The placement of a temporal burr hole on the side of the mydriatic pupil to decompress an epidural or subdural hematoma can be lifesaving. Up to 70% of patients with evidence of brain stem dysfunction soon after head trauma have significant intracranial mass lesions, most of which are extra-axial blood collections.1
A significant proportion of patients with fatal head injuries die before reaching the hospital. The cause of death is usually a result of an expanding intracranial hemorrhage, extensive basilar skull fractures with associated injury to the venous sinuses, intracranial carotid artery lacerations, and/or major cortical blood vessel lacerations. Skull fractures are present in up to 90% of adults who develop a traumatic intracranial hematoma. Children are less likely to suffer a skull fracture after head trauma than adults.
The middle meningeal artery is a branch of the maxillary artery and enters the cranium via the foramen spinosum. It is usually located between the periosteal and meningeal layers of the dura mater. Shortly after entering the skull, it divides into anterior and posterior branches. The larger branches of the middle meningeal artery lie within the dura and are accompanied by veins. Their superficial location in the dura produces grooves on the interior of the cranium. This location makes them vulnerable to injury, especially from fractures of the temporal bone. The bony vault of the skull is fairly thick, approximately 5 mm in thickness, and shows considerable individual and regional variation. The temporal bone, in particular the squamous temporal bone, is much thinner than other areas of the skull. This makes it more vulnerable to a fracture with an associated injury to the underlying middle meningeal vessels.
Posttraumatic epidural hematomas usually develop in the temporal or temporoparietal location as a result of an injury to the middle meningeal vessels (Figures 116-1A & B). More than 50% of all epidural hematomas result from an injury to the middle meningeal artery itself. Epidural hematomas occur laterally over the cerebral hemispheres with the epicenter at the pterion in approximately 70% of patients (Figure 116-2). The remaining epidural hematomas are distributed in ...