Reader response: Pearls & Oy-sters: Isolated oculomotor nerve palsy due to pituitary apoplexy missed on CT scan

We read with interest the case presented by Marzoughi et al.1 describing a patient with pituitary apoplexy and isolated oculomotor nerve palsy. This case demonstrated that pituitary apoplexy was an important differential diagnosis for acute headache and cranial nerve palsies, with which we totally agree. Meanwhile, there are several tips we think would be helpful to pile on. First, for patients with acute headache and cranial nerve palsy, a negative CT scan cannot rule out the possibility of subarachnoid hemorrhage (SAH). Previous studies confirmed the superiority in detecting SAH by susceptibility-weighted imaging (SWI) than CT.2 In addition, uniform and consistent blood from lumbar puncture can help with the diagnosis.3 Second, previous studies reported that a negative CT angiography (CTA) or even digital subtraction angiography (DSA) cannot rule out the possibility of intracranial aneurysm.4 Besides, the guidelines recommended that for SAH patients with negative DSA, a repeated DSA was still recommended.5 Back to this case, if the CT/MRI did not show the abnormality in pituitary, it is still possible for the patient to have SAH and intracranial aneurysm, even with negative CT/CTA/MRI.