The range of clinical findings, symptoms & signs of craniocerebral trauma and neurologic deficits following craniocerebral trauma is wide and depending on the location, mechanism, and severity of injury. Many confounding factors can also mask neurologic deficits, making accurate assessment difficult. Finally, the neurologic examination can change drastically—a situation that warrants frequent and careful neurologic assessments.
The initial general trauma assessment should focus on the ABCs, and steps should be taken to stabilize the patient hemodynamically. An initial trauma neurologic examination is done, focusing on the mental status, cranial nerve reflexes, and motor function—thus, a quick assessment of the brain, brain stem, and spinal cord can be done.
Glasgow Coma Scale
Mental status is best assessed using the Glasgow Coma Scale, developed by Teasdale and Jennette in 1976. It is the most used neurotrauma scale, is easy to use, and has excellent interexaminer concordance.
Graded from 1 to 4, this component assesses the level of stimulus required for a patient to open his eyes. Eye-opening to ambient stimulus is graded as a 4; eye-opening to directed verbal stimulus, a 3; eye-opening to pain, a 2; and no eye-opening at all is graded a 1.
This parameter grades the level or complexity of spontaneous verbal output on a scale of 1–5. Normal speech with normal content is graded a 5; normal speech with inappropriate content receives a 4; words without sentence structure is graded a 3; sound without word structure is a 2, and absence of verbal output is graded as a 1.
The most sensitive indicator of neurologic dysfunction and best predictor of outcome, motor response is graded from 1 to 6. The highest grade (6) is given to patients who follow verbal commands. All other grades are scored in response to painful stimulus. Patients who localize pain receive a 5; those who withdraw from it are graded as a 4; flexor posturing grades as a 3; and extensor posturing (decerebrate posturing) as a 2. No response to painful stimulus receives a 1.
All three components are added up to give a composite score. Coma is technically considered at a grade of 8 or less—this is considered a severe injury. Moderate injuries are generally considered at a GCS score of 9–12 and mild from 13–15.
The detail and extent of cranial nerve examination depends on the level of consciousness. Awake, cooperative patients presumably can follow commands, allowing full examination of cranial nerve function. Comatose patients, however, can only elicit cranial nerve reflexes. The most simple and directed cranial nerve examination focuses on three reflexes—the pupillary reflex, the corneal reflex, and the gag reflex. The first assesses pupillary response to light, carrying afferent information via cranial nerve (CN) II (optic nerve) and efferent information via CN III (occulomotor). The corneal reflex carries afferent information via CN V (ophthalmic portion of the trigeminal nerve) and efferent information via CN VII (facial). Finally, the gag reflex afferent and efferent signals are carried via the glossopharyngeal (IX) and vagus nerves (X), respectively. With these three reflexes, the entire brain stem can be quickly assessed as the pupillary reflex is localized in the midbrain, the corneal reflex in the pons, and the gag reflex in the medulla. The presence of a unilaterally dilated or fixed pupil in the comatose patient is of considerable concern as it often indicates transtentorial herniation of the ipsilateral temporal uncus due to supratentorial intracranial hypertension. The loss of the corneal or gag reflex is of much more concern as it indicates severe brain stem injury.
Other cranial reflexes include the occulovestibular reflex (caloric reflex) and occulocephalic reflex (doll’s eye), though these are not usually assessed in the trauma bay, as they are impractical in the case of the former and unsafe in the latter (due to the potential presence of a cervical injury).
The initial motor examination should be limited to a qualitative assessment of movement of all four extremities. It is often impossible to formally examine motor strength due to resuscitation efforts and pelvic or long-bone fractures. It is enough to establish the presence of a paresis or plegia and which limbs are affected. More detailed examination can wait until the initial resuscitation has stabilized the patient. The awake, cooperative, hemodynamically stable patient can be examined more formally and at leisure. A rectal examination assessing tone is mandatory in the acute period.
Assessment of sensation, deep tendon reflexes, and coordination is completely useless in the comatose patient and can generally be performed along with the more formal motor examination in the awake, cooperative patient.
Hypotension in the presence of tachycardia most frequently indicates hypovolemia, though this picture can also be due to a high to mid thoracic spinal cord injury. Hypotension with a normal or low pulse can indicate a cervical injury or primary cardiac pathology such as sick sinus syndrome or junctional rhythm. Hypertension and bradycardia (Cushing’s reflex) in the comatose patient usually indicates the presence of intracranial hypertension. This can manifest in subtle ways. Even trends toward hypertension and bradycardia can be harbingers of intracranial hypertension. As such, the neurosurgeon must be alert to gradually increasing blood pressure with downwards drift in heart rate even if the patient remains nominally normotensive and tachycardiac.
This section will focus exclusively on the radiographic evaluation of craniocerebral trauma. The radiographic evaluation of craniocerebral trauma has changed dramatically. No longer are plain skull films, pneumoencephalography, or cerebral angiography mainstays of trauma evaluation. Head CT has for all practical purposes supplanted them. It is fast, easy, readily available in any trauma center, and exceedingly sensitive to intracranial blood or air and bony (skull) injury. Most modern CT scanners can obtain a complete head CT with 5-mm-thick sections in 2 minutes, and the images are of excellent quality and resolution.
Cerebral angiography is used occasionally if vascular injury is suspected.
If the patient is stable, MRI can be used to establish the severity of any intracranial pathologic process not clearly visualized on CT. This is often in the posterior fossa, where bone can cause significant artifact on CT images, potentially obscuring cerebellar or brain stem pathology. MRA is a viable alternative to conventional angiography in the hemodynamically and neurologically stable patient. The biggest disadvantages of MRI and MRA is that studies take considerably longer than CT scans and they cannot be performed in patient with implanted metallic objects such as cardiac pacers, some intracranial pressure monitors, and some older aneurysm clips.