Medical device diagnostics should be performed on a patient with suspected apoplexy within half an hour of arrival at the hospital so that treatment can be started within one hour. The following medical-device diagnostic procedures should be used immediately:
- Computed tomography (CT) – cross-sectional imaging (radiographs from different directions with computer-based analysis) [hypodense area; ischemic stroke; hyperdense area: intracerebral hemorrhage (ICB; cerebral hemorrhage)] or
- Magnetic resonance imaging of the skull (cranial MRI, cranial MRI, or cMRI); or
- CT angiography or MR angiography – to identify patients who are candidates for lysis (drug therapy used to dissolve blood clots) or thrombectomy (surgical removal of a blood clot (thrombus) from a blood vessel)
Signs of infarction on CT
Early signs
- Parenchyma space-occupying hypodense
- Cerebral furrows stroked
- Brain edema (swelling of the brain)
Late signs
- Parenchyma spatially hypodense
- Fogging effect (2nd-3rd week after infarction) – infarct area hirnisodens.
- Contrast agent uptake circa from the fourth day.
Signs of infarction on MRI
Early signs
- T1: decreased differentiability between the white and gray matter.
- T1: elapsed sulci
- T2: hyperintense
Late characters
- Corresponds to CT
- T2: hypointensity possible
Further notes
- CT or MR angiography may reveal vascular occlusion.
- Which of the procedures is used depends on whether and how quickly MRI is available. In general, MRI is superior to CT in visualizing infarct changes.
- If a lacunar infarction is suspected, MRI should be sought if possible.Note: Lacunar strokes are small subcortical ischemia (reduced blood flow “below the cerebral cortex (cortex)”); pathophysiologically, a microangiopathy (disease of small blood vessels, usually a particular manifestation of atherosclerosis) may also be present small emboli (partial or complete sudden occlusion of a blood vessel by material washed in with the blood).
- Special evaluation of cMRI, which indicates disruption of the blood–brain barrier, could predict cerebral hemorrhage as a possible complication of lysis therapy (“dissolution of the blood clot”).
- Hemorrhagic infarction (stroke due to cerebral hemorrhage) is immediately apparent.
- Already two hours after the event, CT infarct signs of an ischemic insult (stroke due to reduced blood flow) can be detected.
Diagnostic procedures after the event
Diagnostic procedures that should be performed within the first day after the event:
- Duplex and Doppler sonography – sonography of the carotid artery to detect structural changes such as stenosis (narrowing of the vessel) or plaques (abnormal deposits on the blood vessels)
- Electrocardiogram (ECG; recording of the electrical activity of the heart muscle) – to detect arrhythmias (esp. atrial fibrillation); part of the standard diagnostic workup for apoplexy (formerly 24 h; now at least 72 h; ≥ 7 days if elevated BNP or NT-proBNP levels are present or if many extrasystoles occur)
- By 72 h long-term ECG, approximately 4.3% cases of AF are newly detected; by 24 h monitoring, only 2.6
- One meta-analysis (50 studies) arrived at an overall detection rate of approximately 24%:
- Initial resting ECG on admission: 7.7% of all patients showed VCF whose history did not include evidence of atrial fibrillation
- Monitoring during inpatient stay (phase II): 5.1% of patients showed VHF for the first time
- Outpatient Holter ECG recordings after discharge (phase III): 10.7% of patients showed VHF for the first time
- Second outpatient phase with telemetry monitoring or monitoring by external or implanted event recorders (phase IV): 16.9% of patients now showed VHF for the first time
- Echocardiography (echo; cardiac ultrasound) – for the detection of thrombi (blood clots)
Embolic Stroke of Undetermined Source (ESUS; cryptogenic apoplexy)
Standardized Diagnostics for ESUS
- Extracranial and intracranial vascular imaging (catheter angiography, MR or CT angiography, cervical plus transcranial Doppler sonography to identify vascular changes )
- Electrocardiogram (12-lead ECG; recording of electrical activity of the heart muscle).
- Transthoracic echocardiography (TTE; echocardiography in which the transducer is placed on the outside of the chest (thorax) and the sound waves pass through the thoracic wall)
- ECG monitoring ≥ 24 h with automated rhythm detection.
Criteria for the diagnosis of ESUS
- Presentation of a stroke by CT or MRI that is not considered a lacunar stroke* .
- No extra- or intracranial arteriosclerosis with ≥ 50% stenosis in vessels supplying the area of ischemia
- No known cardioembolic risk factors (eg, VHF; myocardial infarction within the past 4 weeks; artificial heart valves)
- No other specific cause of stroke (eg, arteritis, dissection, migraine/vasospasm, substance abuse)
* subcortical infarct ≤ 1.5 cm (≤ 2 cm in diffusion-weighted MRI images) in the distribution area of small penetrating cerebral arteries.
Long-term monitoring of patients with cryptogenic stroke
Long-term monitoring of patients after a stroke of unknown cause (cryptogenic stroke) using a subcutaneously implanted event recorder (ICM, Insertible Cardiac Monitor) provides evidence of underlying atrial fibrillation in many cases. In the CRYSTAL AF (Cryptogenic Stroke and Underlying Atrial Fibrillation) clinical trial, this was used to detect atrial fibrillation in approximately 1 in 10 patients within 1 year.
Predictors of Apoplexy
Appropriate medical device diagnostic procedures follow:
- Ankle-brachial index [highest predictive value/predictive value].
- Cardio-CT (cardiac computed tomography) – determination of the extent of calcification of coronary arteries (arteries that surround the heart in a wreath shape and supply blood to the heart muscle).
- Intima-media measurement [smallest predictive value].
