Page 137 - Registrar Orientation Manual 2016

Reference:
1257
Effective date:
7 July 2015
Expiry date:
6 July 2018
Page:
20 of 35
Title:
Imaging Guidelines
Type:
Clinical Guideline
Version:
02
Authorising initials:
• history of cancer (especially in sites and types that metastasize to the brain)
• use of anticoagulants or history of bleeding disorder
• history of urinary incontinence and gait disorder early in the course of dementia
• any new localizing sign (e.g. hemiparesis or a Babinski reflex)
• unusual or atypical cognitive symptoms or presentation (e.g. progressive aphasia)
• gait disturbance
Clinical Urgency: Urgent CT is rarely indicated in suspected dementia unless there are red flags.
The ‘Choosing Wisely’ recommendations include:
Don’t use PET imaging in the evaluation of patients with dementia unless the patient has been assessed by a specialist in this field.
Dizziness and Vertigo
The Australian imaging guidelines have a Vertigo Imaging Pathway and General Medicine have also
developed Dizziness and Vertigo guidelines.
It is usually possible to differentiate between peripheral and central causes of dizziness and vertigo.
Patients with a likely peripheral cause do not need imaging.
Isolated dizziness without any other neurological features is very rarely due to a central cause and imaging is only indicated if there are neurological findings or in an older patient if the cause is uncertain and they have vascular risk factors.
Ideally MRI is performed to image the posterior circulation but, because of limited availability, CT is usually done and, in most cases, is adequate. MRI may still be required in selected patients.
Clinical urgency:
If stroke is suspected and there are neurological findings:
If a candidate for thrombolysis:
If on anticoagulants and progressing: Other strokes or suspected strokes*:
Immediate CT whatever the time 24 hour CT / 7 days a week
CT 8am to 10pm / 7 days a week
MRI will not usually be performed out of hours for dizziness and vertigo.
ENT
The ‘Choosing Wisely’ recommendations include:
Don’t order CT of the head for sudden hearing loss.
Don’t order imaging studies in patients with non-pulsatile bilateral tinnitus, symmetric hearing loss and an otherwise normal history and physical examination.
Don’t order sinus computed tomography (CT) for uncomplicated acute rhinosinusitis or symptoms limited to a primary diagnosis of allergic rhinitis alone.
Epilepsy (and Seizures)
The Australian imaging guidelines also include an imaging pathway for Seizure. The General Medicine and Neurology Seizure Guidelines have more details.
In patients without red flags (see below) there is no urgency to image and it may be more appropriate to get an outpatient MRI rather than a CT. However, in older patients with a new onset of seizures a pragmatic approach is to do a CT (but not overnight) before discharge from ED or the ward.
If CT shows a structural lesion not requiring further imaging, MRI may not be needed. Nor is MRI usually needed in older patients after a single seizure if the CT and neurological examination are normal as it is unlikely to change management. Seek SMO advice.