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To scan or not to scan
Scan everyone• Safe?• Reassuring?
Selective scanning• How selective?
Scan no-one• Not recommended!
Where is the disease?
SYMPTOMS
PATHOLOGYABNORMAL TESTS
BASH guidelines 2007
“Investigations, including neuroimaging, do not contribute to the diagnosis of migraine or tension-type headache. Some experts, but not all, request
brain MRI in patients newly diagnosed with cluster headache. There are no data on the rate of abnormal findings. Otherwise, investigations are
indicated only when history or examination suggest headache is secondary to some other
condition.”
IHS classification 2004Primary headache…
• Is not attributed to another cause; i.e.• History and physical examination do not suggest
any of the disorders listed in groups 5-12 (i.e. secondary headache), or history and/or physical and/or neurological examinations do suggest such disorder but it is ruled out by appropriate investigations, or such disorder is present but attacks do not occur in close temporal relationship to the disorder
Demography of headache
• 95% have headache in their lifetime
• 75% have headache in any year
• 20% of women have migraine
• 4% have headache on most days
Serious cause for headache
• Primary care
• Neurology clinic
• Accident & emergency
0.1%
1%
10%
Three casesAll normal to examine
• Male 80. 3/12 R facial pain. Longstanding headache.
• Female 47. 30 yr episodic headache better off COC, worse 4yr, continuous 1yr.
• Female 74. Few months right craniofacial pain, partial response NSAID.
Unenhanced CT overlooks important secondary headaches
• Early tumours• Early stroke• Giant cell arteritis• Venous sinus thrombosis • Subarachnoid haemorrhage• Subdural haematoma • Tonsillar ectopia• Colloid cyst• Parameningeal suppuration• Medication overuse headache
Imaging urgent: red flagstumour risk>1%
• Papilloedema
• Significant change consciousness, memory, confusion, coordination
• New epileptic seizure
• New cluster headache
• Cancer elsewhere
Imaging low threshold: orange flagstumour risk 0.1-1%
• New headache undiagnosed >8weeks
• Significant neurological findings
• Headache worse exertion/Valsalva
• Headache with vomiting
• Changed or crescendo headache
• New headache pt over 50 yrs
• Headache waking from sleep
Imaging yellow flagstumour risk 0.01-0.1%
• Migraine or TTH
• Weakness or motor loss
• Memory loss
• Personality change
Incidentalomas
• Age 20– n= 2389– ¼ not strictly normal– ¾ of these = normal variants
• Age 45-97– n=2000– ⅛ significant abnormality
One of these six has no headache…which one is it?
MRI result may be harmful...
• Female age 38• Migraine with aura• Medication overuse• MRI arranged in
primary care
Two recent cases…
Headache imaging 1994-2001 (n=2488)
0
10
20
30
40
50
60
1 2 3 4 5 6 7 8
Year
%
MR & CT
MR
CT
Headache imaging 1994-2008 (n=4971)
0
10
20
30
40
50
60
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
Year
%
%CT & MRI
% MRI
%CT
IncidentalomasMorris et al BMJ 2009;339:547-550
• Systematic review and meta-analysis of MRI brain scans of 19,559 ‘normal’ subjects
• Neoplastic, structural vascular, inflammatory lesions, cysts, other structural lesions. Excluded: ‘white matter hyperintensities’, silent infarcts, microbleeds
Lesion Prevalence % ‘NNS’
Neoplasms
Meningioma 0.29 (0.13-0.51) 345
Pit. Adenoma 0.15 (0.09-0.22) 667
Low grade glioma 0.05 (0.02-0.09) 2000
TOTAL 0.7 (0.47-0.98) 143
Other 2.0 (1.13-3.10) 50
TOTAL 2.7 37
Imaging for headache
• A&E: – low threshold– CT > MRI– Don’t forget LP, ESR(CRP)
• Office practice:– higher threshold– MRI > CT
Imaging for all
• Covers your back
• Improves provider income
• May temporarily reduce most patients’ anxiety
• Emotion based
• Expensive
• Scan only as good as the report
• Longer waits disadvantage those in urgent need
• Creates precedent
• Diminishes non-imaged diagnoses
• Causes harm to minority
Selective imaging
• Evidence based• Economical• Places clinical
diagnosis first• Allows prioritisation
• Incomplete precision• Litigation risk• Reduces provider
income
Headache imaging: conclusions
• Suggest selective imaging policy
• Acute presentation: CT (NB LP, ESR)
• Non-acute: MRI
• First scan: – Patient (emotion) led
• Subsequent scan:– Doctor (evidence) led