Head trauma generally is described as mild (Glasgow Coma Score [GCS]
14 to 15), moderate (GCS 9 to 13), or severe (GCS 3 to 8). Mild head
trauma accounts for 80% of the head traumas seen in a general
emergency department. Among affected patients, alcohol and other drugs
are the most common causes of a GCS less than 15.
A classic cerebral concussion is defined as a head injury that results
in a loss of consciousness. Consciousness is preserved in a mild
concussion, but there is a noticeable degree of temporary neurologic
dysfunction that generally manifests as confusion and disorientation.
The lack of physical evidence for head trauma reported for the patient
in the vignette does not rule out a mild concussion as the cause of
his confusion, but it does make this cause less likely.
Epidural (EDH) and subdural hematomas (SDH) are among
the most common indications for operative intervention after moderate
or severe head trauma. Of the two, SDH is the most common and may be
present in as many as 70% of patients suffering intracranial bleeding
after head trauma. SDH represents acute or chronic bleeding from
bridging veins beneath the dura. The severity of symptoms after an SDH
depends on the rapidity with which the hematoma accumulates. An EDH
represents bleeding between the dura and the inner skull table (Figure
C32B). The classic history for EDH is loss of consciousness from a
blow to the head, followed by a lucid interval and subsequent
deterioration. This chain of events usually is due to arterial
bleeding from a damaged middle meningeal artery, resulting in a slowly
expanding, confined hematoma. The presentation of the patient in the
vignette warrants an emergent head CT to rule out these
life-threatening complications of head injury, but alcohol or drugs
remain the most likely cause of his altered level of consciousness.
The patient described in the vignette lacks the classic signs of
basilar skull fracture, such as Battle sign, hemotympanum, or
cerebrospinal fluid rhinorrhea.