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Neuroradiology Case of the Month

June 2001

Clinical Presentation: A 25-year-old male with a remote history of aseptic meningitis presented with new onset of right arm weakness and lower facial droop. The patient also had anal and genital ulcers and relapsing uveitis.

Radiographic findings: Initial T2 weighted magnetic resonance imaging (MRI), ten months prior to current presentation, showed a hyperintense lesion in the left midbrain with enlargement of the left cerebral peduncle (Fig. 1). On diffusion weighted image, this lesion was slightly hyperintense (Fig. 2) and it showed contrast enhancement (Fig. 3).

At this presentation, T2 weighted image shows a large hyperintense lesion in the left midbrain extending into the medial temporal lobe with prominent enlargement of the left cerebral peduncle (Fig 4). The lesion also extends into the left pons inferiorly, the left thalamus and posterior limb of the left internal capsule superiorly, and the left optic tract and optic chiasm region anteriorly. On diffusion weighted image, the lesion is iso-intense compared to the opposite side (Fig. 5). After the administration of contrast material, there is enhancement predominantly in the midbrain and thalamus (Fig. 6).

Diagnosis: Neuro-Behcet's disease (Clinical diagnosis)

Ten months prior to the current presentation

Figure 1	Figure 2	Figure 3
Figure 1-3: T2 weighted image (Fig. 1) showed a hyperintense lesion on the left midbrain with enlargement of the left cerebral peduncle. The lesion was slightly hyperintense on diffusion weighted image (Fig. 2), and there was contrast enhancement (Fig. 3).

Current Presentation

Figure 4	Figure 5	Figure 6
Figures 4-6: Current MRI shows a large T2 hyperintense lesion in the left midbrain extending into the medial temporal lobe with prominent enlargement of the left cerebral peduncle (Fig. 4). The lesion is iso-intense on diffusion weighted image (Fig. 5). After the administration of contrast material, there is more intense enhancement (Fig. 6).

Discussion: Behcet's disease is a multisystem disorder of unknown origin. It was first described in 1937 by Hulusi Behcet, a Turkish dermatologist, and consists of a triad of recurrent aphthous ulcers of the oral and genital mucosa with relapsing uveitis [1]. Since the first description, additional organ involvements have been reported. Skin, central nervous system, kidney, lung, subcutaneous thrombophlebitis, deep vein thrombosis, epididymitis, arterial occlusion and/or aneurysms, arthralgia, arthritis, family history, gastrointestinal features, and AA type amyloidosis are other symptoms or signs seen in Behcet's disease [2]. The pathological lesion is a vasculitis, involving veins, venules, capillaries and, less frequently, arteries [3].

There is a clinical involvement of the central nervous system in 4-49% of cases [3, 4]. There have been several reports describing the MRI appearances of the brain in this condition. The most common neural parenchymal involvement is a mesodiencephalic junction lesion with edema. The next most common location is the pontobulbar area. During an acute/subacute phase, the lesion can be surrounded by a T2 hyperintensity. Most lesions tend to have contrast enhancement [4]. Other abnormalities such as cerebral vein thrombosis, brain stem atrophy and space occupying lesions have also been described [5].

Differential Diagnosis: Differential diagnosis includes other vasculitis, such as systematic lupus erythematosis. Central nervous system involvement due to systematic lupus erythematosis tends to involve arterial territories, and cortical involvement is frequently seen. Perivascular and ovoid lesions suggestive of multiple sclerosis are not expected to be seen in neuro-Behcet's disease. Moreover, leptomeningeal contrast enhancement is a typical finding of sarcoidosis; this finding is also rarely seen in neuro-Behcet's disease. The radiological findings of this disease are quite distinct, which may help differentiate it from other disorders. Lymphoma, Progressive multifocal leukoencephalopathy, Cryptococcoma. Tuberculoma in an immunocompromized patients.

References:

1. Behcet H. Uber residivierende, aphtose, durch ein virus verursachte Geschwure am Mund, am Auge und an den Genitalien. Derm Woschenscr 1937;105:1152-57
2. Akpolat T, Danaci M, Belet U, Erkan ML, Akar H. MR imaging and MR angiography in vascular Behcet's disease. Magn Reson Imaging 2000;18:1089-96.
3. Guma A, Aguilera C, Acebes J, Arruga J, Pons L. Meningeal involvement in Behcet's disease: MRI. Neuroradiology 1998;40:512-5.
4. Kocer N, Islak C, Siva A, Saip S, Akman C, Kantarci O, Hamuryudan V. CNS involvement in neuro-Behcet syndrome: an MR study. AJNR Am J Neuroradiol 1999;20:1015-24.
5. Jager HR, Albrecht T, Curati-Alasonatti WL, Williams EJ, Haskard DO. MRI in neuro-Behcet's syndrome: comparison of conventional spin-echo and FLAIR pulse sequences. Neuroradiology 1999;41:750-8.