Which of the following is the most appropriate next investigation to confirm this patient’s diagnosis?
This patient presents to the Emergency Department with altered mental status. This presenting symptom can be due to a large variety of etiologies, including hypoglycemia, sepsis, toxic ingestions, electrolyte abnormalities, stroke, and more. The management and evaluation of a patient with altered mental status depends on the primary assessment of the patient (“ABCs”, or Airway, Breathing, Circulation) to identify any acute life-threatening conditions that need to be managed emergently, the history, and the physical examination. One mnemonic that may help in remembering the many causes of altered mental status is “AEIOUTIPS”. The table below outlines this mnemonic.
The information provided indicates that the patient’s headache was maximal at onset, severe, associated with vomiting, and led to a deteriorating mental status ultimately requiring intubation. This history is very concerning for intracranial bleeding, especially subarachnoid hemorrhage (SAH). The majority of atraumatic SAHs are caused by the rupture of a saccular aneurysm. This causes the leakage of blood into the subarachnoid space. Symptoms of a SAH are sudden onset headache that is maximal intensity at onset (“thunderclap headache”), syncope, vomiting, seizures, and any neurological deficits. Risk factors for SAH are age over 50years-old, family history of SAH, alcohol abuse, tobacco smoking, Marfan Syndrome, Ehlers-Danlos Syndrome, and Polycystic Kidney Disease. Diagnosis of SAH takes into account the patient’s history, physical exam, and risk factors.
Patients that arrive in the Emergency Department under 6hours since symptom onset should initially get a noncontrast CT scan of the head (Choice D). When a noncontrast head CT is performed in this time window, its sensitivity reaches 98-100%. Noncontrast head CTs performed within the first 24hrs since headache onset have a sensitivity of about 90%. Patients with signs and symptoms concerning for SAH who have a negative CT head should get a lumbar puncture (Choice A) to evaluate for xanthochromia. This is especially important if the patient’s symptoms have been for over 6 hours. A 12-lead EKG (Choice B) can show ST and T wave changes, but an EKG alone cannot be used to make a diagnosis of SAH. A brain MRI (Choice C) can make the diagnosis of SAH, but a CT scan would be preferred due to greater CT scan accessibility, cost, and the shorter time of this imaging test. The best next investigation would be a noncontrast CT of the head (Choice D).
Correct Answer: D
- Alvarez, A & Sekhon, N. (2019). Altered Mental Status. Society of Academic Emergency Medicine. Retrieved from https://www.saem.org/cdem/education/online-education/m4-curriculum/group-m4-approach-to/approach-to-altered-mental-status
- Nickson, N. (2020). Subarachnoid Haemorrhage (SAH). Life in the Fast Lane. Retrieved from https://litfl.com/subarachnoid-haemorrhage-sah/
- Salim Rezaie, “REBEL Cast Episode 21: Sensitivity of Early Brain CT to Exclude Aneurysmal Subarachnoid Hemorrhage”, REBEL EM blog, February 11, 2016. Available at: https://rebelem.com/sensitivity-of-early-brain-ct-to-exclude-aneurysmal-subarachnoid-hemorrhage/