A 68-year-old man presents with sudden right-sided hemiplegia and global aphasia 3 hours after onset. Non-contrast CT head shows a hyperdense vessel in the region of the left sylvian fissure with early hypoattenuation of the left insular cortex. The hyperdense vessel seen on this CT corresponds to:
- A Thrombus within the proximal middle cerebral artery ✓
- B Acute haemorrhage into the sylvian cistern from a ruptured aneurysm
- C Calcified atheromatous plaque of the distal internal carotid artery
- D Contrast reflux from a prior angiographic study
Correct answer: A. Thrombus within the proximal middle cerebral artery
Explanation
The hyperdense middle cerebral artery sign represents fresh thrombus within the first segment of the MCA and is visible when attenuation exceeds about 40 Hounsfield units. It is one of the earliest CT signs of large vessel occlusion ischaemic stroke and predicts a larger infarct core and worse outcome. Subarachnoid blood fills the cistern diffusely rather than casting a tubular vessel, and calcified plaque is far denser, typically above 100 Hounsfield units.
Reference: Osborn's Brain: Imaging, Pathology, and Anatomy, 2nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.