Psychosis in a case with myasthenia gravis and thymoma

A single case of a 45 year-old patient with myasthenia Gravis, thymoma and psychotic symptomatology is being described. The psychiatric symptomatology included delusions of persecution and reference, hallucinations (auditory, visual, olfactory, gustatory) and emotional disturbances (fear, agitation, desperation). He was admitted to the Psychiatric Hospital of Thessaloniki for treatment of his psychiatric condition. Examination with E.E.G., E.M.G. and evoked potentials was applied. The clinical Psychiatric Picture improved rapidly with a classical neuroleptic.

The appearance of psychiatric symptomatology 18 years after the diagnosis of M.G is being discussed as well as the relationship among thymoma, myasthenia and psychosis. A very small number of patients with myasthenia Gravis and thymoma who developed psychosis has been reported in literature. There is the impression that both the neurological symptoms related to myasthenia Gravis and the accompanying psychiatric symptoms are a cluster of symptoms (i.e. a syndrome) which have a common immunological basis, that might be called autoimmune paraneoplastic syndrome. The clinical picture and the onset of psychosis are due to the central cholinergic dysfunction in myasthenia Gravis. It's possible that the cause of psychosis is organic and also related to thymoma, which can provoke myotonic disorders, erythroblastic anomalies, Sjorjen's syndrome, Cushing's disease and carcinoid syndrome.

The onset of psychiatric symptomatology on our patient could be regarded as organic based, without overlooking the fact that myasthenia Gravis plays a significant role as a chronic severe stressful life event, which can sometimes become threatening for the patients' life. The periodic psychiatric evaluation of these patients is very useful because of their vulnerability to the development of psychiatric symptomatology.

Key words: psychosis, myasthenia Gravis, thymoma.