- Mainstay of the diagnosis of structural brain disease until the advent of MRI during the late 1980s.
- CT remains an extremely valuable method of investigation, particularly in the acute situation and because of the very high expense of MRI systems.
- Safer technique than MRI in uncooperative, unconscious or intubated patients
- Shouldbeavoidedinpregnancyorpotential pregnancy unless absolutely essentials
- ElectiveCTonfemale:(-)hcGorfirsthalfof menstrual cycle
- CT or MRI : assesswhetherMRIwouldgivemore accurate diagnosis, rapid diagnosis is essential for patient’s safety
- CT was first used at the Atkinson Morley hospital in London in 1972
- Multi-slices CT technology: most important advance in CT imaging
- Diagnostic tool, well-tolerated by patient and widely available
- Results quicker than most blood tests
Disadvantages
- Irradiation to patients
- Risk of inducing cancer 1:10,000
- Low contrast tissue resolution: difference between gray and white matter is not nearly as good as seen in MRI
- Less accurate than MRI in assessment of white matter disease (MS), posterior fossa area
- But less claustrophobic than MRI
Contrast study
- Low risk of significant reaction
- Relativecontraindicationinrenalimpairment; creatinine>150 micmol/l(1.7mg/dl),GFR<40
- Contrast-inducednephropathy:Metformin accumulate and rarely precipitate Metformin- related lactic acidosis (stop Metformin 48 hr after IV contrast)
- Patients
- Reasons for the tests
- What information is expected
- Any alternative imaging or tests
- Consequences of not obtaining CT
- Secondary indications when MRI not available including diplopia, cranial neuropathy, seizures, syncope
Common indications of CT in general practice
- Stroke
- Motorsymptoms
- Speechorlanguagedisturbances
- Sensorysymptoms
- Visualdefect
- Vestibularsymptoms
- Behaviouralorcognitivesymptoms • Seizures
- Hykineticmovementdisorders
- Investigation of choice in patients with :
- Trauma
- Suspected SAH
- Prior to LP
- ICH
- infarct for thrombosis
Common indications of CT in general practice
- Stroke
- Headtrauma
- Headaches
- Unexplained change in mental status and behaviour
- SuspicionofraisedICP
- Dizziness
- Seizures
Exclusion Criteria (must be all NO)
- SBP > 185 or DBP > 110
- Symptoms rapidly improving or minor symptoms
(NIHSS= 0-3), except aphasia or hemianopia - Coma or severe obtundation (or NIHSS > 25 )
- Seizure at onset
- Symptoms of subarachnoid hemorrhage ( sudden onset diffuse headache, stiffness of neck)
- Prior stroke or head trauma within 3 months
Exclusion Criteria (must be all NO)
- Major surgery within 14 days
- Prior intracranial he morrhage
- Active internal bleeding and recent GI or UT or hemorrhage within 21 days
- Arterial puncture at a non compressible site or LP within 21 days
- Recent Myocardial infarction within 3 months
- Patients receiving Heparin within 48 hours and with an elevated APTT
Selected cases for mild head injury
NOT indicated if ALL of the following criteria ABSENT
- Headache
- Vomiting
- Ageover60
- Drugintoxicationoralcoholintoxication
- Short-termmemorydeficits(persistentanterograde amnesia)
- Physicalevidenceoftraumaabovetheclavicles
- Seizures
Exclusion Criteria (must be all NO)
- PT > 15 or INR > 1.7
- Platelet count < 100,000
- Plasma glucose < 50mg/dl or> 400 mg/dl
- Haematocrit <25%
- Pregnant (Note: menstruation is NOT a contraindication)
- Age >80 years old
- CombinationofbothpreviousischaemicstrokeandDM
- Oral anticoagulants use regardless of INR
- Intracranial neoplasm, arteriovenous malformation, or aneurysm
- Recent intracranial or intraspinalsurgery
- Current use of Warfarin direct thrombin inhibitors, or direct factor Xa inhibitors with elevated sensitive laboratory tests (such as PTT, INR, platelet count ECT, TT or appropriate factor Xa activity assays
- Allmoderateandsevereheadinjury
- Allpatients
- Neurological deficit
- Seizures
- Oral anticoagulants or other bleeding diathesis : Warfarin is associated with delayed intracranial bleeding in 6% of patients at 24 hours (may be delayed as long as 1 week after head injury)
High risk indication
- GCSlessthan15at2hoursafterinjury
- Openordepressedskullfracture
- Vomiting(2ormoreepisodes)
- Ageover60
- Basalskullfracturesigns
- Hemotypanum
- Periorbitalbruising(raccoon’seyes)
- Mastoidprocessecchymosis(Battle’ssign)
- CSFleakagefromearornose
Moderate risk indications
- Pre-trauma amnesia lasting longer than 30 minutes
- High risk mechanism of injury
- Pedestrian in motor vehicle accident
- Passenger ejected from vehicle
- Fall from height over 3 feet or 5stairs
Moderate risk indications
- Historyofmalignancy
- Historyofneurosurgeryorcerebralshunt
- Pregnancyorpostpartum
- Headachethatbeginswithexertion
- Alteredmentalstatus
- Seizures
- Signsofmeningealirritation
- Focalneurologicalsigns(vision)
SOL and raised ICP
- Disorientationoftime,placeandperson
- Diplopia
- Sluggishorabsentpupillarylightreaction
- Shallowbreathing
- Seizures
- Lossofconsciousness
- Coma
Moderate risk indications
- Dangers signals in Headache
- Sudden-onset headache ( maximal intensity within minutes of onset)
- Worst headache of life
- Headache dramatically different from past
- Immunocompromised
- New onset of headache after age50
SOL and raised ICP
- Headache
- Nausea
- Vomiting
- Increasedbloodpressure
- Decreasedmentalabilities
- Disorientationoftime,placeandperson
