Differential Diagnosis
- Single most likely diagnosis
- Subarachnoid hemorrhage: The patient's sudden onset of headache, fever, nausea, and collapse within a short time frame (5 hours) is highly suggestive of a subarachnoid hemorrhage. The normal FBC and elevated CRP could be indicative of an inflammatory response to the hemorrhage, while the elevated creatinine and urea may be secondary to dehydration or acute kidney injury.
- Other Likely diagnoses
- Meningitis: The combination of headache, fever, and collapse could also be indicative of meningitis, particularly if the patient has been exposed to someone with the infection. The elevated CRP supports an infectious or inflammatory process.
- Encephalitis: Similar to meningitis, encephalitis could present with headache, fever, and altered mental status (collapse). The normal FBC does not rule out encephalitis, as it can be normal in the early stages of the disease.
- Intracerebral hemorrhage: Although less likely than subarachnoid hemorrhage given the absence of focal neurological deficits, an intracerebral hemorrhage could still present with sudden onset of headache, nausea, and collapse.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Brain tumor with hemorrhage: Although rare, a brain tumor with hemorrhage could present with sudden onset of symptoms and would require urgent imaging and intervention.
- Cerebral venous sinus thrombosis: This condition can present with headache, fever, and altered mental status, and would require prompt anticoagulation to prevent further complications.
- Sepsis: Although the patient's FBC is normal, sepsis can present with non-specific symptoms such as headache, fever, and collapse, and would require urgent identification and treatment.
- Rare diagnoses
- Cerebral vasculitis: This condition is rare, but could present with headache, fever, and altered mental status. It would require urgent imaging and immunosuppressive therapy.
- Pituitary apoplexy: This condition is rare, but could present with sudden onset of headache, nausea, and collapse, particularly if the patient has a pre-existing pituitary adenoma.