MRI
- Brain edema
MRI typically shows vasogenic (Lamy 2014) posterior (occipital > frontal) brain edema, which is usually reversible. It is referred to as "posterior leukoencephalopathy."
The radiological term "reversible posterior leukoencephalopathy (RPLE)" is now considered obsolete. Nowadays, the picture is referred to as a "posterior reversible encephalopathy syndrome = PRES" (Kasper 2015).
- Intracranial hemorrhage
At times, intracranial hemorrhages (seen as microhemorrhages in approximately 65% [Fischer 2017]) may be observed and/or sites of restricted diffusion, similar to infarction (Okamoto 2017). Microbleeds are best visualized in T2-weighted sequences (Fischer 2017).
- watershed distribution
- vasogenic edema
- Lesions of the subcortical substance (Fischer 2017), which are often symmetrically arranged (Schwab 2015)
- Involvement of frontal and parietal lobes possible (Fischer 2017).
- FLAIR sequences show white matter lesions (Bopp 2021).
However, cases with normal imaging have also been described (Kasper 2015).
Computed tomography
CT is less sensitive than MRI. Patchy hypodensity may be detectable in the affected area on CT (Kasper 2015).
EEG
EEG does not show specific changes (Schwab 2015). There may be:
- slowed delta waves
- rhythmic delta activity
- diffuse theta slowing
- sharp-slow wave activity
- focal or diffuse symmetrical slowing of background activity
- periodic lateralized epileptiform discharges (Fischer 2017).
Angiography
Angiography may reveal vasoconstriction and diffuse or focal vasospasm (Fischer 2017).