Ce cas décrit l’évolution vers un trouble psychotique déficitaire d’un patient de 38 ans, sans antécédents psychiatriques, après une ischémie cérébrale au niveau mésencéphalo-thalamique bilatéralement, à prédominance gauche. Les symptômes psychotiques positifs initiaux (délire, hallucinations acoustico-verbales) ont laissé progressivement la place à des symptômes négatifs, qui sont devenus prédominants après quelques mois. Le diagnostic retenu après un suivi psychiatrique de 14 mois a été : trouble psychotique avec idées délirantes, dû à une ischémie cérébrale (DSM IV). L’intérêt du développement d’une échelle spécifique pour des troubles psychotiques survenus après une ischémie cérébrale est suscité à partir des descriptions cliniques isolées, d’autant plus qu’une échelle spécifique pour des troubles dépressifs post-ischémiques a déjà été développée. La nécessité d’un examen psychiatrique et des réévaluations systématiques dans le décours des ischémies cérébrales thalamiques nous semble importante à retenir, tant au niveau du diagnostic différentiel qu’au niveau d’une prise en charge psychiatrique précoce, plus efficace.

A 38-year old male patient with no history of psychiatric illness developed a progressive psychotic disorder after bilateral (predominantly left) mesencephalo-thalamic cerebral ischaemia. The reason of the emergency hospitalization was the sudden onset of a confusional state, culminating in a fluctuating comatose status. The neurological examination found mild right hemiparesia, praxic disorders and reactive left mydriasis with paresia of the downward vertical stare, leading to the hospitalisation in the neurology department for suspicion of a cerebral vascular ischaemic accident. The psychiatric symptoms started with acoustic-verbal hallucinations, poorly structured paranoid delusions, progressively developed over two weeks, followed by behavioural disorders with psychomotor agitation and heteroaggressivity. The patient was transferred to the psychiatric department, because of the heteroaggressive risk and lack of morbid consciousness, in spite of recovering from the confusional status. An intensive psychiatric management was proposed, combining a psychotherapeutic approach with 4 mg of risperidone and adjustable doses of benzodiazepine according to the psychomotor agitation. During the next days, there was a net recovery of the behavioural disorders, in spite of the persistence of the ideas of persecution. All the neurological symptoms also decreased. An anomaly of the polygon of Willis was found on a cerebral arteriography (the posterior cerebral arteries had a foetal origin, dependent on carotidal axes and not on the vertebro-basilar system). The main emboligen risk factor was the presence of a permeable foramen ovale, discovered during a transoesophageal echography. The patient underwent a surgical correction of the permeable foramen ovale. The psychiatric hospitalization for three months was continued by ambulatory follow-up. The initial positive symptoms (delusions, acoustic-verbal hallucinations) progressively diminished while negative symptoms became predominant after few months. One year after the first hospitalization the patient presented a second psychotic decompensation, with delusions of persecution, jealousy and behavioural disorders with heteroaggressivity, that required an emergency psychiatric hospitalization. The wife of the patient decided to divorce, because she was « frightened by the threats of death » from her husband. A neurological assessment during the second hospitalization in psychiatry did not find new ischaemic lesions after the cardiac surgery for the permeable foramen ovale, nor relevant changes in cerebral perfusion. The final diagnosis after the psychiatric follow-up of 14 months was : psychotic disorder with delusional ideas, due to cerebral ischaemia (DSM IV). There are relatively few data in the literature regarding persistent psychotic disorders in the context of ischaemic mesencephalo-thalamic lesions. However, several authors support the hypothesis of a possible disconnection of the thalamic nuclei, the frontal lobes and limbic system as a risk factor or a triggering factor for psychotic disorders in cerebral ischaemia. Observations concerning the occurrence of psychotic disorders following cerebral – especially localised – ischaemia may help to better understand the neuro-physiological mechanisms triggering or accompanying the psychiatric symptomatology. The role of functional cerebral imagery in the detection of possible structural lesions related to clinical observations must be emphasised. The slow progression (over a year) to psychotic disorder with predominantly negative symptoms emphasized the importance for long-term prospective studies. Isolated clinical observations arouse the interest for a specific scale for psychotic disorders occurring after cerebral ischaemia, similar to existing specific scale for post-ischaemic depressive disorders. The necessity of systematic psychiatric examination and re-evaluations in thalamic cerebral ischaemia is to be highlighted, both for the differential diagnosis and for the early psychiatric care.