Differential Diagnosis
The patient's presentation of severe headache, loss of consciousness, and nuchal rigidity suggests a neurological emergency. The following differential diagnoses are considered:
Single most likely diagnosis
- E) Subarachnoid hemorrhage: The patient's sudden onset of severe headache, loss of consciousness, and nuchal rigidity are classic symptoms of subarachnoid hemorrhage. The CT scan of the head is likely to show blood in the subarachnoid space, confirming this diagnosis.
Other Likely diagnoses
- A) Bacterial meningitis: Although less likely, bacterial meningitis can present with severe headache, nuchal rigidity, and altered mental status. However, the patient's lack of fever and absence of other symptoms such as rash or seizures make this diagnosis less likely.
- D) Sagittal sinus thrombosis: This diagnosis is possible, but less likely, as it typically presents with more gradual onset of symptoms and may be associated with risk factors such as hypercoagulability or dehydration.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- B) Basilar artery thrombosis: Although less likely, basilar artery thrombosis is a life-threatening condition that requires prompt diagnosis and treatment. The patient's symptoms of severe headache and loss of consciousness could be consistent with this diagnosis, and it should not be missed.
- C) Hypertensive encephalopathy: The patient's elevated blood pressure and altered mental status could suggest hypertensive encephalopathy, which is a medical emergency requiring prompt treatment.
Rare diagnoses
- Other rare diagnoses, such as cerebral vasculitis or reversible cerebral vasoconstriction syndrome, could be considered, but are less likely given the patient's presentation and lack of other symptoms.