Scan Findings in Patients With Headaches

CT scan findings in patients with headaches are outlined below. A CT scan is not indicated in patients with extra-cranial pathologies.

SAH

SAH is 98% sensitive within 12 hours.

Blood localised to the basal cisterns or in the Sylvian or interhemispheric fissures suggests rupture of an aneurysm.

Blood overlying the cerebral convexities, or within the superficial brain parenchyma, suggests rupture of an AV malformation.

Note: One in 50 patients with SAH scanned within 12 hours will have a ‘false negative’ result. An LP is therefore required in patients with suspected SAH whose CT scan appears normal.

CAD & VAD

In carotid/vertebral artery dissection, a plain CT head is often normal.  Imaging of the vasculature is required.  CT or MRI angiography can be used, although a CT angiogram is often more easily accessible, particularly out of hours.  You should discuss with the duty radiologist about your local policy.

CVST

In cerebral venous thrombosis, the CT may show:

• Small ventricles
• Hyper-density of the thrombosed sinuses
• Small haemorrhages secondary to venous congestion

A CT head may be normal and a CT venogram or contrast MRI are required for definitive diagnosis.

Brain tumour

MRI is the investigation of choice. CT with contrast is probably the best ED option. Note that The radiological differentiation between tumours (primary and secondary) and intra-cerebral abscess can be very difficult, and requires both radiological expertise and correlation with the other clinical features of the patient.

Intra-cerebral abscess

CT scan with contrast shows:

• A hypodense lesion
• Peripheral ring enhancement
• A further hypodense surrounding area of brain oedema

Note: that the radiological differentiation between tumours (primary and secondary) and intra-cerebral abscess can be very difficult, and requires both radiological expertise and correlation with the other clinical features of the patient.

Idiopathic Intracranial Hypertension

A CT scan is indicated on first presentation to exclude SAH/structural lesion. If negative, an LP with measurement of the opening pressure is essential.

Pituitary apoplexy

A brain CT without contrast shows intra-sellar haemorrhage.