Cerebellar acronyms – SCA, PICA, AICA

Every man needs air and the cerebellum does so too. Isn’t it fascinating that such a small organ gets 3 so very different vessels?

In principle, every cerebellar stroke can occur together with a brainstem stroke, because the vessels supply part of the brainstem (the lateral mainly) as well. Yet there are some differences:

  • SCA strokes are mostly embolic, as in top-of-the-basilar-syndrome, only rarely accompanied by brainstem strokes (either very bad – think of locked-in, or somewhat bad – lateral pontine/mesencephalic stroke), but often occuring silently in cardioembolic media or other strokes. May produce isolated dysarthria (pseudolacune) or just lateropulsion.
  • AICA strokes are often due to local thrombosis in the basilar artery and as such ominous. They practically always occur with brainstem strokes (lateral caudal pontine) and happen in the medial cerebellar peduncle, 2/3 affect the flocculus, 3/4 the cerebellar hemisphere (usually small). About a third of ACIA strokes is complete and of course they may occur with other cerebellar strokes. Isolated, it is pseudolabyrinthitis. Coma in a fifth of patients.
  • PICA strokes are more commonly known, not the least because they occur with Wallenberg’s (in a third of the cases) and can lead to Pseudoneuritis. Yet most of the Wallenbergs are vertebral artery problems rather than PICAs. If you have a Wallenberg, you have a PICA. Interestingly – and this I didn’t know until I read the bible (see below), partial PICA strokes rarely become malignant, since they affect the medial branch mainly and this doesn’t lead to much edema. PICA strokes are equally divided in macroangiopathic and embolic strokes.



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