TRAUMATIC BRAIN INJURY: IMAGING, OPERATIVE AND NONOPERATIVE CARE, AND COMPLICATIONS

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CHAPTER 25 TRAUMATIC BRAIN INJURY: IMAGING, OPERATIVE AND NONOPERATIVE CARE, AND COMPLICATIONS

Alex B. Valadka, Mark J. Dannenbaum

The previous chapter described pathophysiology and initial management of traumatic brain injury (TBI) patients. This chapter provides an overview of selected aspects of surgical management, nonoperative care, complications, and outcome.

SURGICAL MANAGEMENT

The strength and rigidity of the skull, its covering by the highly vascular scalp, and the need to do something with the overlying hair all combine to make it harder to get to the brain than to most other organs. Consequently, the surgeon must prepare carefully prior to any craniotomy, especially an emergency. Disaster can occur if the original positioning and exposure prove to be inadequate to deal with the known pathology, much less with the unexpected contingencies that seem to arise all too frequently during emergency craniotomies. If additional exposure should suddenly become necessary in the middle of a case, the price that might need to be paid to gain this additional access may include considerable blood loss, brain swelling, or other complications.

Positioning

Most traumatic lesions can be accessed by positioning the patient supine, with the head turned to the contralateral side (i.e., to the right for a left-sided craniotomy). A large roll of sheets or other support placed parasagittally under the ipsilateral shoulder blade and upper chest can also facilitate rotation of the head. Rigid fixation of the head via pins is not needed for most trauma craniotomies. Instead, the hospital’s usual doughnuts, foam head holders, or other devices are typically used. In most trauma cases, the goal is to have the midline of the head more or less parallel to the floor.

In patients with rigid cervical collars, this goal may be achieved by varying the positioning described previously so that the patient is placed in the lateral position. Putting a patient into such a position requires more work from all members of the surgical team, but an experienced crew should be able to secure a patient in this position quickly.

The seemingly infinite variety of anatomical lesions that may be found in head-injured patients makes it necessary for the surgeon to know how to gain access to all parts of the brain and skull. Treatment of occipital, posterior temporal and parietal, and posterior fossa pathology may require that the patient be positioned prone. Injuries to the anterior midline skull base, such as depressed frontal sinus fractures, are usually operated on with the head neutral and the neck slightly extended. A detailed discussion of the variety of positionings and approaches that are used in neurosurgery is beyond the scope of this book. The essential message is that flexibility and familiarity with different surgical approaches are key parts of the management of head and brain injury.

Bone Flap

Another general principle of surgery for TBI is to create a large bone flap. This principle is especially true for an acute subdural hematoma (SDH). The blood in these lesions often layers out over much of the cerebral hemisphere. Trying to remove a clot from far under the edges of a small bony opening is often frustrating for the surgeon and may be dangerous for the patient. Furthermore, the intradural bleeding that often accompanies SDHs may arise almost anywhere: from draining veins that enter the superior sagittal sinus near the midline, from the floor of the anterior or middle cranial fossa, from inferior or medial to the frontal pole, or from the transverse sinus, to name just a few common areas. A large bone flap is the best way to ensure that as many potential bleeding sites as possible have been made accessible.

Most trauma incisions begin at the posterior root of the zygoma, just anterior to the tragus. They then curve posteriorly, above and behind the ear. In trauma cases, this posterior extension should extend as far as possible. The incision then curves medially and superiorly. It is wise to take the skin incision to the midline to permit access to the superior sagittal sinus in the event that troublesome bleeding arises from the midline.

Although the scalp flap extends near or to the midline, it is wise to keep the medial edge of the bone flap several centimeters off the midline. Attempts to remove bone on or near the midline may produce brisk epidural bleeding from arachnoid granulations or severe dural bleeding from dural venous lakes. Such bleeding is usually controllable with gentle pressure, but these maneuvers delay and distract attention from the goal of rapid evacuation of the SDH. Similarly, recurrence of this bleeding may go unnoticed while the surgeon is preoccupied with evacuation of the clot. If brisk bleeding originates from underneath the medial edge of the craniotomy opening, the best treatment may be tamponade with absorbable hemostatic agents and placement of numerous closely spaced dural tack-up sutures.

The size of the opening needed to evacuate an epidural hematoma (EDH) may often be smaller than that for a SDH because the tight adherence of the dura to the overlying skull constrains the spread of these lesions. For this reason, EDHs often appear to be “short and fat” on computed tomography (CT) scans, but SDHs often spread out and appear to be “long and thin” because of the absence of barriers to their spread over the surface of the hemisphere. Care must still be taken, however, not to make the bony opening too small when attempting evacuation of an EDH.

Intraparenchymal lesions like hematomas and contusions are often amenable to evacuation via smaller openings. In fact, even large lesions can be evacuated through very small openings in the cerebral cortex. Careful retraction of the cortical edges is made easier because of the cavity that is left behind as the clot is removed.

Brain Swelling

Rapid brain swelling is a major concern after evacuation of an acute SDH. The speed with which this phenomenon occurs suggests that defective autoregulation may play an important role. A popular current practice is simply to leave the native dura open (but loosely cover the brain with a dural graft) and not replace the bone flap. Some neurosurgeons strongly advocate this practice, and it does seem to be effective in lowering intracranial pressure (ICP), but its effects on outcome remain unclear. Publications going back several decades report that a persistent vegetative state was commonly seen in survivors.1 Other concerns are that decompressive craniectomies may be performed too frequently or for poor or inadequate indications. Often, the bony opening that is left behind is too small, causing the swollen brain to strangulate and die, with the resulting edema tracking back intracranially and further aggravating intracranial hypertension.

Although the surgeon sometimes has no choice but to leave the bone flap off, a better strategy is to undertake several steps to minimize the likelihood of being placed in such a situation. Instead of a wide dural opening, slits may be made in the dura in the four different quadrants of the exposure, and the clot carefully aspirated through these slits. Slow, controlled evacuation of the hematoma may prevent sudden massive brain swelling more than immediate removal of the entire clot. If it appears that most of the hematoma has been removed, and if there is no evidence of ongoing intradural bleeding, the slits can be closed quickly if the brain begins to swell. However, if continued intradural bleeding persists, a wider dural opening must be created by connecting two or more of the slits in order to identify and control the source of the bleeding. Such a maneuver must be performed as rapidly as possible so that dural closure can be achieved before the brain begins to swell.

Implicit in the previous discussion is the need to close the dura before brain swelling makes this impossible. As mentioned previously, this goal may seem antiquated in light of the current popularity of simply not replacing the bone flap. However, the authors have rarely encountered problems using this strategy, even when a retractor had to be used to gently depress swelling brain while the dural edges were forcibly pulled together with forceps so that they could be sutured together. This experience is consistent with laboratory data suggesting that decompressive craniectomy may actually promote cerebral edema.2

Epidural Hematomas

Surgery for EDHs is usually more straightforward. Occasionally, the surgeon may feel the need to make a small opening in the dura to verify that no subdural blood is present. It is common to see a thin layer of subdural blood when this maneuver is carried out, but this can usually be irrigated away without too much difficulty. Another common problem in the epidural space is persistent bleeding, either from dural veins or the dural venous sinuses or from underneath the bony edges of the craniotomy. If epidural venous bleeding cannot be stopped with cautery, gentle pressure with any of the various commercially available neurosurgical hemostatic agents is usually effective. In most cases, leaving these bioabsorbable materials in place is better than attempting to remove them. Of note, bleeding from the middle meningeal artery is not encountered as frequently as some books suggest, but when seen, it is usually possible to cauterize the bleeding artery directly.

Intraparenchymal Lesions

Evacuation of intraparenchymal hematomas and contusions can often be performed via a small corticectomy. Fortunately, as soon as one of these lesions is evacuated, the brain becomes much more relaxed. The main difficulties in these cases are ensuring complete lesion evacuation and verifying hemostasis. These goals may be difficult if the hematoma cavity is large. Occasionally, for large contusions or hematomas, a second corticectomy may facilitate lesion evacuation and hemostasis of parts of the lesion that would be inaccessible via the original cortical opening.

Intracranial Pressure Monitoring

The question of whether these patients require postoperative ICP monitoring is often difficult to answer. In general, if a patient is not expected to “wake up” after surgery, that is, not expected to obey commands and/or to have a Glasgow Coma Scale score greater than 8, insertion of a monitor should be strongly considered. Ventriculostomies are preferred because they permit therapeutic drainage of cerebrospinal fluid (CSF) in the event that ICP becomes elevated. Insertion of these devices during the initial craniotomy is usually possible, but some surgeons prefer to wait until the craniotomy has been closed and then insert the ventriculostomy in the operating room (OR) or in the intensive care unit (ICU). If the ventricles cannot be cannulated, a parenchymal monitor may be used.

Coagulopathy

If patients appear to be coagulopathic, the blood bank should be given early notification that platelets and fresh frozen plasma are urgently needed in the OR. Severe diffuse oozing may require the use of recombinant factor VIIa. Laboratory studies can be used during surgery to track the effects of these interventions on coagulation studies and platelet counts, but an easier way to gauge the status of hemostasis is simply to check whether blood that trickles down into the dependent parts of the surgical field is able to form a solid clot.

Summary

In summary, the surgeon can often avoid trouble by thinking ahead about possible setbacks and their avoidance. Planning the exposure to permit adequate clot evacuation is crucial. Elevating the head of the bed slightly may minimize venous bleeding. Major bleeding should be anticipated if depressed fractures overlying major dural venous sinuses are elevated. A controlled dural opening during evacuation of an acute SDH may be helpful for minimizing massive brain swelling.

NONOPERATIVE MANAGEMENT

Location of Care

The complexity of TBI management and the tremendous impact of TBI on long-term outcome suggest that brain-injured patients should initially be admitted to an ICU with physicians and nurses experienced in the care of TBI patients. This specialized experience in TBI may be more important than expertise only in general trauma or critical care. During the first few days after injury, TBI patients may require blood pressure monitoring, frequent checking of hemoglobin concentrations, complex ventilator management, and other interventions that are standard for patients without a brain injury, but in addition to these basic measures, careful assessment and management of the brain injury and integration of systemic management practices with brain-specific therapies must also occur. Although many general ICUs or trauma ICUs are not comfortable with the nuances of TBI management, most neurosurgical ICUs are quite capable of managing patients with major systemic illnesses.

If a TBI patient improves or remains neurologically stable for a few days, he or she can then be transferred to another ICU, to an intermediate care unit, or to a regular care ward. This approach differs from the commonly advocated view that patients should initially be admitted to a standard trauma unit instead of to a neurosurgical ICU. In many standard surgical ICUs, however, management is based on a patient’s systemic parameters, which may not necessarily be optimal for the brain injury. In the real world, these discrepancies are handled differently at each institution according to whatever arrangements have been made among the different parties who care for these patients.

Secondary Insults

The prehospital emphasis on prevention and early treatment of secondary cerebral insults continues during the ICU management of these patients and, in fact, forms the foundation of their management. Special attention should be paid to basic metabolic and physiologic parameters, including blood pressure, oxygenation, hemoglobin concentration, and serum sodium concentration. Surgery for associated injuries that do not absolutely require immediate treatment, such as facial fractures, hand or foot injuries, and even most long-bone fractures, is best deferred while the injured brain is still vulnerable to possible intraoperative metabolic disturbances.

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