A 15-year-old boy is struck by a baseball in the side of the head. He briefly looses consciousness but quickly returns to a lucid state. Which of the following statement(s) is/are true concerning his subsequent course.
- The initial neurologic finding may be dilatation of the ipsilateral pupil
- If the patient has a normal neurologic examination at the time of emergency room assessment, he can be discharged safely to home
- A head computed tomography (CT) scan should be performed regardless of the current neurologic examination
- The likely mechanism of injury arises from a tear of a branch of the middle meningeal artery as it courses through a grove in the skull at the area of impact
- If, after an initial lucid interval, a rapid progression to coma with fixed and dilated pupils and decerebration occurs, the most likely CT finding would be a subdural hematoma
Medicine
a. The initial neurologic finding may be dilatation of the ipsilateral pupil
c. A head computed tomography (CT) scan should be performed regardless of the current neurologic examination
d. The likely mechanism of injury arises from a tear of a branch of the middle meningeal artery as it courses through
Hemorrhage between the inner table of the skull and the dura mater most commonly arises from a tear of the middle meningeal artery or one of its branches that course through a grove in the lateral skull. Arterial bleeding strips the dura from the undersurface of the bone and produces still more bleeding because the small bridging veins from the dura to the skull are torn. The result is an epidural hematoma which may rapidly increase in size and compress the cerebral cortex. An epidural hematoma classically follows a blow to the head which causes a brief period of unconsciousness. After the patient regains consciousness, there may be a lucid interval during which there are no abnormal neurologic symptoms or signs. As the hematoma enlarges, hemispheric compression occurs. With time the medial portion of the temporal lobe is forced over the edge of the tentorium causing compression of the oculomotor nerve and subsequent dilatation of the ipsilateral pupil. Similarly, compression of the ipsilateral cerebral peduncle causes contralateral hemiparesis, which progresses to decerebrate posturing. Coma, fixed and dilated pupils, and decerebration is the classic triad suggestive of transtentorial herniation. Epidural hematomas are curable lesions, but the mortality rate remains high because the severity of the injury is often not recognized early. A patient may be seen during a lucid interval and discharged. Later, the patient becomes unconscious because of progressive brain compression by the expanding hematoma. Because of the danger of misdiagnosis, any patient with a history of a blow to the head leading to a period of unconsciousness should have a CT scan.
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