Following a sudden impact in an accident, the 34-year-old race car driver becomes unconscious and is admitted to the hospital. A CT scan is performed, and a right space-occupying lesion is noted (Fig. 11-1). What is the most likely diagnosis?
**Core Concept**
The patient is presenting with a sudden loss of consciousness and a space-occupying lesion on CT scan, which suggests a focal injury to the brain. This is likely due to a traumatic brain injury (TBI), which can result from a sudden impact, such as a car accident.
**Why the Correct Answer is Right**
The most common cause of a space-occupying lesion in the context of TBI is a subdural hematoma (SDH). A SDH occurs when blood collects between the dura mater and the arachnoid mater, two of the meningeal layers surrounding the brain. This can happen when a blood vessel in the subdural space is torn, allowing blood to accumulate and compress the surrounding brain tissue. The patient's symptoms, including loss of consciousness, are consistent with a SDH.
**Why Each Wrong Option is Incorrect**
**Option A:** Epidural hematoma (EDH) is a possibility in TBI, but it is typically associated with a more rapid loss of consciousness and a "lucid interval" before the patient becomes unconscious again. EDH is also more likely to occur in the temporo-parietal region.
**Option B:** Cerebral contusion is a possible diagnosis in TBI, but it typically refers to bruising of the brain tissue itself, rather than a space-occupying lesion.
**Option C:** Meningitis is an infection of the meninges, which can cause a range of symptoms including fever, headache, and stiff neck. However, it is not typically associated with a space-occupying lesion on CT scan.
**Clinical Pearl / High-Yield Fact**
The "lucid interval" is a classic clinical finding in patients with an epidural hematoma, where the patient appears to be awake and alert for a short period after the initial injury, before rapidly deteriorating due to increasing intracranial pressure.
**Correct Answer:** C.