A rapid neurologic survey can then be made, with attention to the depth of coma, size of the pupils and their reaction to light, ocular movements, corneal reflexes, facial movements during grimace, swallowing, vocalization, gag reflexes, muscle tone and movements of the limbs, predominant postures, reactions to pinch, and reflexes.
Bogginess of the temporal or postauricular area (Battle sign), bleeding from the nose or ear, and extensive conjunctival edema and hemorrhage are useful signs of an underlying basal skull fracture. However, it should be remembered that rupture of an eardrum or a blow to the nose may also cause bleeding from these parts. Fracture of the orbital bones may displace the eye, with resulting strabismus; fracture of the jaw results in malocclusion and discomfort on attempting to open the mouth. If urine is retained and the bladder is distended, a catheter should be inserted and kept there. Temperature, pulse, respiration, blood pressure, arterial oxygen saturation, and state of consciousness should be checked and charted every hour. The Glasgow Coma Scale, mentioned earlier, has provided a practical means by which the state of impaired consciousness can be evaluated at frequent intervals (see Table 34-1), but it should not be considered a substitute for a more complete neurologic examination.
CT and MRI scanning of the cranium have assumed central importance at this juncture. A sizable epidural, subdural, or intracerebral blood clot is an indication for immediate surgery. The presence of contusions, brain edema, and displacement of central structures calls for measures to monitor progression of these lesions and to control ICP. These measures are best carried out in a critical care unit.
Management of Raised Intracranial Pressure
There has been a presumption, not unreasonable, that high levels of ICP are deleterious after head injury, much as it is in other processes that involve an intracranial mass. At issue has been the precise pressure at which damage occurs, whether lowering ICP improves outcome, which treatments are best, and the role of monitoring in guiding treatment. Certainly there are many biologic processes in neurons and astrocytes that greatly influence outcome after traumatic brain injury, many set in motion at the time of impact and not referable to raised ICP. At times, these overwhelm the changes induced by ICP but they are not particularly remediable, producing an emphasis on reducing ICP as a means of preventing secondary brain damage. An approach to ICP treatment is given here and also addressed in Chap. 16 on coma and Chap. 30 on brain tumors.
ICP monitoring In cases of moderate and severe head injury it has been the practice on most ICU services to insert one of several available devices that continuously record ICP. The rationale is ostensibly to gain control over a remediable cause of secondary brain damage, particularly if the patient’s neurologic examination is reduced to a few sentinel signs such as pupillary enlargement or because sedating medications have obscured the examination. The ventricular catheter has been considered a “gold standard” of pressure measurements as it is directly coupled to the CSF compartment, which should best reflect the summated pressures within the cranium. It has the additional advantage of affording therapeutic drainage of CSF in order to reduce ICP. In comatose patients, monitoring of ICP could avoid excessive fluid administration, refine the amount of osmotic agent and hypertonic saline used to reduce pressure, and establishes the ideal level of hyperventilation. In these respects, monitoring can be helpful by guiding treatment and avoiding detrimental effects on ICP of treatments for head trauma.