Locked-in syndrome in a patient with acute obstructive hydrocephalus, caused by large unruptured aneurysm of the basilar artery (BA).

We describe a case of acute obstructive hydrocephalus as a consequence of compression of the brainstem by a large aneurysm of the basilar artery (BA) in a 62-year-old male. After the insertion of the ventriculoperitoneal shunt (VPS), we encountered the "locked-in syndrome" clinical condition. "Locked-in syndrome" is a clinical state characterized by quadriplegia and anarthria with preserved consciousness, most commonly caused by ischemia in the ventral part of pons.