This study is to present a psychopathological analysis of complex hallucinatory symptoms--without consciousness breaking up in confusional state--occurring in patients with acute Guillain-Barré's syndrome diagnosis requiring neurological intensive care. Finally the patients experience an unitary and closed situation "close to dream without being dream". This experience is corresponding to the semeiology of the "oneiroid experience" (Mayer-Gross, 1924). The "oneiroid experience" appears to be of syndromic nature independent of any etiological and/or nosological classification. But its conceptualization does probably need widening: the oneiroid world appears to be a creation of a primitive function which inserts us in the world before any science or verification.