A 76-year-old man was referred with a diagnosis of ‘motor neuron disease’ or ‘polyneuropathy’. For about eight months he had noticed progressive muscle weakness in his right leg associated with pain, initially more intense than at referral, and a numb feeling around the right knee. Two years previously his left hand had become weak and wasted, associated with loss of sensation of the ring finger, the little finger, and the ulnar part of the palm of his hand. He had lost weight (5 kg) unintentionally over the past six months. He had always been very active, but was now no longer able to walk his dog or do some gardening. He was recently diagnosed with diabetes mellitus (DM) for which oral antidiabetics were prescribed. Family history was unremarkable.

Behçet’s syndrome (BS), originally described in 1937 by the Turkish dermatologist Hulusi Behçet, as a distinct disease with oro-genital ulceration and uveitis known as the “triple-symptom complex”, is an idiopathic chronic relapsing multisystem vascular-inflammatory disease of unknown origin. The condition that features primary neurological involvement is termed as neuro-Behçet syndrome (NBS). Based on the clinical and neuroimaging features, primary BS neurological involvement may be divided into two major forms: 1) parenchymal NBS (p-NBS); and, 2) vascular NBS. Cranial neuropathy, dysarthria, ataxia, hemiparesis, and headache are the major symptoms of p-NBS, with headache being the most prevalent (in patients with both p-NBS and neuro-vascular involvement). Lesions revealed by magnetic resonance imaging are most common in the mesodiencephalic junction followed by the pons/medulla oblongata. Vascular involvement (the second most common form of neurological involvement) is associated with a better prognosis than p-NBS, and the clinical manifestations vary by the site and extension of venous thrombosis. During the acute phase of p-NBS, the cerebrospinal fluid shows inflammatory changes in most cases of p-NBS with an increased number of cells, up to a hundred and sometimes more per ml, neutrophils being mostly the predominating cells and modestly elevated protein levels. Patients with BS-CVST do not exhibit any remarkable cerebrospinal fluid finding apart from an increased pressure. Currently, the only drug that have been shown to be effective based on the Class IV evidence is infliximab for the treatment of p-NBS