Acute confusional states or amentia were described by Meynert in 1881. These are characterized by a clouding of consciousness with multiform manifestations of excitement both sensory and motor. Amentia is one of the sequelae of infectious diseases. It takes the form of a subacute development of a dreamlike confusion with hallucinations, illusions and motor excitement lasting usually for several months. It is very closely related to collapse delirium and the hallucinatory insanity of Hoche, Fürstner and others. The early symptoms are sleeplessness and unrest. The patients become anxious, forgetful, develop a fear of death, and cannot control their thoughts, complaining of dulness and confusion of mind. A difficult comprehension of external impressions develops. They may be attentive and seriously troubled at not being able properly to grasp their surroundings. A decided uncertainty and restlessness results. Everything seems changed or false. There is at first a feeling of inadequacy and a profound disturbance of thought which develops into a well defined confusional condition. A dreamlike state follows, sometimes with a tendency to fabrications. Rhymes, phrases and words may be repeated frequently. There is a tendency towards distractibility and flight of ideas with vague thoughts of persecution. Hallucinations sometimes become apparent, and illusions appear. The mood is usually one of irritable anxiety, suspicion and mistrust, seldom with complete dulness. Occasional outbursts of anger take place. A restless behavior is noted as a rule. Sometimes suicidal tendencies occur and mild stuporous states follow.