S-65 Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey. Nilüfer Yesilot, MD; Mehdi Shehu, MD; Oget Oktem-Tanor, PhD; Piraye Sedaroglu, MD; Gülsen Akman-Demir, MD. * These authors contributed equally and- share first authorship. Please address correspondence to: Gulsen Akman-Demir, Istanbul Faculty of Medicine Department of Neurology, Çapa 34390 Istanbul, Turkey. E-mail: akmandem@istanbul.edu.tr Received on April 4, 2005; accepted in revised form on September 30, 2005. Clin Exp Rheumatol 2006; 24 (Suppl. 42): S65-S70. © Copyright CLINICAL AND EXPERIMEN- TAL RHEUMATOLOGY 2006. Key words: Behçet’s disease, neuro- logical involvement, subclinical (‘silent’) neurological involvement. ABSTRACT Objective. The aim of this study was to determine the long term clinical course and prognosis of subclinical (‘silent’) neurological involvement in Behçet’s disease (BD). Methods. We included patients with BD who did not have any neurological complaints other than headache, dizi- ness or other non-specific complaints, that showed abnormal neurological findings (Silent Group). We compared these patients with the patients with overt parenchymal neuro-Behçet’s dis- ease (Overt Group). Cases with at least 8 years of follow-up were included. Results. There were 22 patients in the Silent Group (15M, 7F), with a mean follow-up of 12.8 ± 4 years. Magnetic resonance imaging was abnormal in 8 of 21 patients, while neuropsychologi- cal testing revealed mild abnormalities in 15 of 20 patients. During the follow up period, 3 patients of the Silent Group had 4 overt neurological at- tacks. In the last visit, 21 patients were independent, while one that had previ- ously developed overt neurological attack was deceased. The Overt Group consisted of 51 patients (45M, 6F). In the Overt Group the ratio of males was higher, nearing a marginal significance (p = 0.051); whereas age at onset of BD, and frequency of other organ man- ifestations of BD were not different. In the Overt Group at the final visit, 19 patients were independent (37%), while the remaining were either depen- dent to others, or deceased, which was significantly higher when compared to the Silent Group (p = 0.005). Conclusion. Silent neurological in- volvement in BD seems to represent a milder form of the disease, since the mortality and disability rate in this group is significantly low. Introduction Behçet’s disease (BD), first described in 1937 as a disease characterized by recurrent uveitis, oral aphts and genital ulcers (1), is a multisystemic inflam- matory disorder with unknown etiolo- gy. It is more common among males, and this male predominance becomes further pronounced when there is any serious organ involvement (2, 3). Neurological manifestations may occur in about 5% of BD patients (4), which is generally confined to central nervous system (CNS). Mainly two patterns of CNS involvement may be seen. Par- enchymal CNS involvement is the more common form usually involving brainstem, or occasionally spinal cord. Although motor and cognitive signs predominate the clinical picture, brain- stem signs, sphyncteric dysfunction, pyramidocerebellar syndrome and sen- sory findings may also be found (5). Onset is usually with a subacutely evolving attack followed by remission with or without sequelae. After the attack(s) some of the cases show a slow progression (secondary progressive course). In a minority of the cases, there is an insidious onset without any clear-cut attack, showing a slow but continuous progression (primary pro- gressive course) (5-7). An attack of parenchymal involvement is usually accompanied by cerebrospinal fluid (CSF) pleocytosis, and shows a typical magnetic resonance imaging (MRI) finding with a brainstem lesion extend- ing to diencephalic structures, or to basal ganglia region (8). The large le- sion seen during an attack tends to become smaller or may disappear dur- ing follow-up (8). Although less fre- quently, subcortical and periventricular white matter lesions may also be seen (9). On the other hand, non-parenchy- mal CNS involvement mainly repre- sents CNS findings due to major vascu- lar involvement. More commonly, in- creased intracranial pressure is encoun- tered due to venous sinus thrombosis. In this setting cranial MRI usually does not reveal any parenchymal abnormali- ties, and CSF is usually normal other than high pressure. Less frequently, Silent neurological involvement in Behçet’s disease N. Yesilot*, M. Shehu*, O. Oktem-Tanor, P. Serdaroglu, G.Akman-Demir