Male, 23 years of age, previously healthy, with 6-month onset of constitutional symptoms, ataxia, dysmetria and dysarthria. Three months later additional symptoms of polyarthritis, pustular dermatosis, and oral and genital ulcers presented. Diagnosis ruled out infectious aetiologies and confirmed the existence of retinal vasculitis in fluorescein angiography and in magnetic resonance imaging, which showed predominantly mesencephalic inflammatory lesions. Behçet's disease was considered and was treated with methylprednisolone and cyclophosphamide with favourable response. During the course of the disease the patient again presented with ataxia, dysphagia, and dysarthria, accompanied by episodes of intense laughter. His mother reported that the laughter even occurred in situations such as when he was bathing or eating and when his attention was captured. The patient again received methylprednisolone by IV and cyclophosphamide, with subsequent maintenance therapy of azathioprine with partial response. Gait disorders persisted which led to the patient becoming bed-ridden, with dysphasia and a continuation of the inappropriate laughter. Treatment was changed to anti-TNF, but shortly after initiation of treatment the patient died from respiratory infectious complications.

Male, 39 years of age, previously healthy. He presented with a 4-month history of constitutional symptoms of low-grade fever, polyarthritis, oral and genital ulcers. Behçet's disease was diagnosed for which the patient was treated with glucocorticoids and cyclophosphamide. During follow-up, his family members, and the patient himself commented upon changes to his behaviour characterized by the appearance of involuntary and irrepressible laughter, even in serious situations or without any stimuli. The most dramatic event presented during the funeral of his daughter aged 12 where, despite being grief stricken, the patient burst into uncontrollable laughter and preferred to vacate the premises. The patient continued with immunosuppressant treatment based on methotrexate, with remission of symptoms.

Behçet's disease, a chronic multisystemic inflammatory disease, is included in the Chapel Hill classification as vasculitis of blood vessels of varying size.8 An extremely high percentage of patients with this vasculitis, ranging from 5% to 50%, may present with neuropsychiatric symptoms. There are two suggested mechanisms to explain the clinical symptoms: parenchymatose inflammatory lesions (with involvement of the brain stem, mesodiencephalic union, cerebellar and cerebral hemispheres) and the thrombotic phenomenon. Pseudobulbar paralysis syndrome has been previously reported in this disease, but uncontrollable laughter being predominant as a symptom is extremely rare. This finding presented in both patients. In the first case there was mesodiencephalic involvement despite immunosuppressant treatment and evolution was not favourable.

Different disorders have received eponyms from other, non-medical areas. One such known case, the Pickwickian syndrome, was established by Charles Dickens in his novel The Posthumous Papers of the Pickwick Club published in 1837. Might we then speak of the “Joker syndrome” in the case of the inappropriate laughter in our patients with this neuropsychiatric expression related to Behcet's disease?