While the indication of decompressive craniotomy has become much harder now that everyone has been shown to profit, the prognostication of herniation in probably malignant MCA stroke has always been difficult.
The topic of yesterdays was the ultrasonographic depiction of third ventricle midline shift (mainly used in german centers where ultrasound wizards reside). But there are several steps involved before you can understand what you do there:
- Depending on the location of the stroke either uncal, posterior transtentorial or anterior-posterior shift can occur – only half of them lead to lateral mass shift.
- Clinical deterioration not only can come from lateral shift (as determined by the midline shift), but from rostrocaudal shift, compression of the ACA or PCA.
- Lateral shift can occur at the level of the mesencephalon, the diencephalon or above, thus leading to divergence of CT determination of septal shift and ultrasound determination of third ventricle shift.
Still, if you can spare half of the CTs of an intubated and sedated patient, it should be worth it – so try ultrasound and gain experience.