Teaching Case

A 35 year old man with Behcet's disease admitted to our hospital with high fever and tendency to sleep. Cranial MRI revealed bilateral basal ganglionic, talamic and brain stem lesions.

A 35 year old man presented with 1.5 months of fever which increased to 39°C, progressively increasing tendency to sleep and had hallucinations in the last 1 week accompanying sphincter disturbance. He had a diagnosis of Behcet’s disease for one year and has been using colchicine irregularly. In physical examination he had a limited cooperation an anisocoria with positive light reflexes. Babinski test was bilaterally positive. No neck stiffness was found. To exclude encephalitis, lumbar puncture was done. Glucose and protein values and pressure of cerebrospinal fluid were in normal limits. There were 60/mm³ leucocytes. Cranial CT examination showed bilateral symmetric hypodense areas in the basal ganglia and thalamus (Fig 1). MR examination revealed increase in signal intensity in globus pallidi, posterior limbs of internal capsule, anterior part of thalamus and cerebral peduncles with sparing red nucleus in T2-weighted and FLAIR images (Fig 2,3). In diffusion weighted (b=1000 s/mm²) images, there were symmetric lesions in the basal ganglia showing vasogenic oedema as a reflection of the inflammatory process (Fig 4). The diagnosis of neurobehcet was made on the basis of clinical and radiological findings.

Behcet's disease (BD) is a multi-system disorder of unknown aetiology. It frequently involves the nervous system, in which case it is referred to as Neuro-Behcet’s disease (NBD). It usually occurs 1-10 year after the first symptom of BD has occurred. In 3% of the cases the disease starts with a neurological symptom.
Neurological involvement in BD is classified into parenchymal and non-parenchymal group. Parenchymal NBD is more common and presents with attack of hemiparesis, cognitive changes, sphincter disturbance and possible fever in men in the 3rd decade. This form of involvement have predilection to brainstem, thalamic and basal ganglia region. Junction of the midbrain and thalamus (meso-diencephalic junction) is characteristically involved. Cerebral peduncles are involved in the midbrain with sparing of red nuclei. Pontobulber region may also be affected. The disease commonly involves basal ganglia and internal capsule region in one third of the cases. Especially globus pallidus and posterior limb of the internal capsule are characteristically involved and lesions in basal ganglia may extend along corticospinal tracts to cervical cord. In the subacute stage of NBD subcortical hemispheric lesions may appear. Involvement of cerebellum, cranial nerves and spinal cord occurs less commonly. Gliosis and atrophy may occur with striking involvement of the brain stem in the chronic stage of the NBD. Parenchymal lesions of NBD have high signal intensity in T2 weighted images suggesting the presence of demyelination, gliosis or transient inflammation. Hypointense lesions in T1 weighted images may be seen in the chronic stage. Some lesion show contrast enhancement in the acute or subacute stage of NBD representing breakdown in the blood-brain barrier.
Non-parenchymal NBD affects major intracranial vessels with frequent involvement of the venous sinuses, cerebral veins and less commonly intracranial arteries. Venous sinus thrombosis is the most common vascular manifestation of the disease followed by deep and cortical cerebral vein thrombosis. Arterial involvement is seen as aneurysm or thrombosis of large cerebral arteries. Patients usually present with acute stroke due to venous infarcts or symptoms of raised intracranial pressure (headache, papilledema, focal neurologic deficit, seizure) due to venous sinus thrombosis.
Differential diagnosis involves multiple sclerosis, systemic lupus erythematosus, sarcoidosis and some viral, pyogenic or fungal infections.