Page 139 - Registrar Orientation Manual 2016

Reference:
1257
Effective date:
7 July 2015
Expiry date:
6 July 2018
Page:
22 of 35
Title:
Imaging Guidelines
Type:
Clinical Guideline
Version:
02
Authorising initials:
Headache
Not every patient with a headache needs imaging. Imaging is indicated if there are any “Red Flags”. See our Headache Guidelines for further details.
There are also pathways for Headache and Thunderclap Headache in the Australian guidelines. A JAMA 2006;296:1274 review of imaging in headache suggests a POUNDing mnemonic to help
make a diagnosis of migraine and identify those patients who did not need imaging.
The National Community Radiology Access Criteria include these indications for CT in headache:
• New onset >50 years
• Change in pattern of headaches with increase in frequency or severity
• Aggravated by exertion or Valsalva
• Associated with nausea and vomiting
• Systemic illness with cerebral complications or involvement especially malignancy.
CT without contrast is adequate for most of the patients with “Red Flags” who need imaging. Contrast CT may be needed if there is a history of malignancy and/or a possible mass lesion.
MRI is not indicated after CT unless there is a clear clinical indication or an abnormality needing further imaging to guide management. Always consider if this is necessary.
MRI/MRA/MRV or CTA/CTV may be needed in a minority of patients, where dissection or venous thrombosis are realistic possibilities; note that a -ve D-dimer makes thrombosis unlikely.
Further imaging may also be indicated in thunderclap headache despite a negative CT and LP where there is a still very strong pre-test probability or clinical suspicion of haemorrhage.
Clinical Urgency:
? Subarachnoid or subdural with neurology 24 hour CT / 7 days a week
Other probable cause of headache: CT 8am to 10pm / 7 days a week
The ‘Choosing Wisely’ recommendations include:
Don’t do imaging for uncomplicated headache.
Don’t perform neuroimaging studies in patients with stable headaches that meet criteria for migraine.
Head Injury
The ED has a Head Injury Imaging Guideline which uses the ‘Canadian Head CT Rules’. See this for more detail. Only the imaging recommendations are summarised below:
GCS < 8 = Severe Head Injury
• All patients suffering any kind of trauma leading to GCS <8 require a CT head and a CT neck.
GCS 8-12
• All such patients require a CT head.
GCS 13-15 = Minor head injury
Use the ‘Canadian CT Head Rules’ (only validated in adults) to decide on CT
‘Minor Head Injury’ is defined as initial GCS 13-15 in ED with any of the following:
• witnessed loss of consciousness, or
• definite amnesia, or
• witnessed disorientation