A thunderclap headache

The non-contrast CT scan (Fig. 1 of Images in Neuroscience: Question) shows subarachnoid haemorrhage (SAH) within a right frontal lobe sulcus. While the arterial phase image (Fig. 2 of Images in Neuroscience: Question) of the digital subtraction angiography is normal, the early and late venous phase images (Fig. 3a and b of Images in Neuroscience: Question) demonstrate a persistent linear filling defect within the Vein of Trolard confirming thrombus. MRI to assess cerebral parenchyma shows a tubular structure showing high signal on T1-weighted imaging (Fig. 4a of Images in Neuroscience: Question) confined within the pre-central sulcus, indicating thrombus within a vessel or SAH. There is high signal on fluid attenuated inversion recovery MRI and blooming artefact on gradient echo imaging around the previously described tubular structure extending further along the sulcus (Fig. 4b and c of Images in Neuroscience: Question). Together with the CT scan findings and the venogram images, the MRI findings confirm Vein of Trolard thrombosis with adjacent SAH. Thunderclap headache is classically described as severe headache, which takes less than a minute or a few minutes from its onset to peak. The differential diagnosis for thunderclap headache includes SAH, cerebral venous sinus thrombosis, idiopathic benign recurrent headache disorder, arterial dissection, pituitary apoplexy, spontaneous intracranial hypotension, and hypertensive encephalopathy. Cerebral venous thrombosis confined to a cortical vein without involvement of the venous sinuses is rare. In our patient, this was associated with SAH. This phenomenon of SAH secondary to isolated cortical venous thrombosis has been described in a few