Clinical
Presentation: This patient is a 23-year-old female who initially presented with weakness and ataxia at an outside hospital before transfer to Strong Memorial Hospital. Her symptoms of malaise, diaphoresis, weakness and sensation of imbalance began 1 week prior to admission.
She was initially diagnosed with bronchitis and was prescribed azithromycin, but returned the following day to the ED with worsening symptoms including nausea, vomiting, unsteadiness of gait, neck stiffness and low-grade fevers.
Other pertinent history includes recurrent oral, genital, anal and nasal ulcers since the age of 13 years, and chronic sore throats. Her genital ulcers worsen during menstruation. She also reported visual blurriness and eye pain, which was diagnosed as uveitis with anterior chamber involvement only. On exam, she revealed 3/5 right-sided weakness and bilateral hyperreflexia.
Imaging Findings: A CT of the head, performed at an outside hospital upon initial presentation, demonstrated multiple ring enhancing lesions in the left cerebellum and pons (not shown).
MRI of the brain, performed at our institution, demonstrated multiple foci of decreased T1-weighted signal, increased T2-weighted signal and ring enhancement on post-contrast T1-weighted images with surrounding edema in the white matter of the left pons, left cerebellar hemisphere, and body of the corpus callosum. The left pontine and cerebellar lesions also demonstrated restricted diffusion.
Follow-up MRI of the head, while the patient was being treated with prednisone two days following the initial MRI, demonstrated persistent lesions in the white matter of the left pons and cerebellar hemisphere. The corpus callosal lesion resolved.
Figure 1: MRI of the brain demonstrates foci of increased T2-weighted signal on an axial FLAIR sequence in the white matter of the left pons and left cerebellar hemisphere.
Figure 2: Axial diffusion weighted image (2A) and apparent diffusion coefficient map (2B) reveals restricted diffusion in the same pontine and cerebellar areas as described in Figure 1.
Figure 3. Axial pre- (3A) and post-gadolinium contrast (3B) T1-weighted images demonstrate ring enhancement of the same pontine and cerebellar lesions. Focal enhancement is also noted in the body of the corpus callosum (3C).
Figure 4. A five day interval follow-up axial T1-weighted post-contrast image demonstrates interval resolution of the corpus callosal lesion. The pontine and cerebellar lesions (not shown) continued to exhibit ring enhancement but were less prominent compared to the initial exam.
Diagnosis: Behcet’s syndrome (clinical diagnosis)
Discussion: Behcet’s syndrome is an inflammatory vascular disease of unknown etiology affecting multiple organs including the central nervous system in a small subgroup. The disease is chronic relapsing. The syndrome may result in oral and genital mucocutaneous ulcers, uveitis, which may eventually result in blindness, skin lesions, arthritis, thrombophlebitis, gastrointestinal lesions, and epididymitis.The disease affects men more than women. Patients typically present in the forth decade.
Neurological involvement is classified into two categories: CNS parenchymal disease secondary to small venous inflammation, and central venous sinus thrombosis (extra-axial neurological Behcet’s syndrome NBS) [1]. The small venous type of NBS is the more prevalent of the two, and has a poorer prognosis [1]. Reported frequency of NBS is approximately five percent [1].
CNS parenchymal disease is asymmetric and affects the brainstem at the mesodiencephalic junction. Lesions often extend along long fiber tracts inferiorly as well as into the diencephalon, sparing the red nucleus [2]. Occasionally, the periventricular and subcortical white matter is involved [2]. Other less common locations include the hypothalamothalamic region, basal ganglia, cerebral hemispheres, cerebellum and spinal cord. Hemispheric lesions almost always occur in conjunction with mesencephalic and diencephalic lesions. In chronic cases, signal abnormalities extend into the cervical spine, possibly reflecting Wallerian degeneration [2].
Behcet’s is a vas culitic process, with perivascular lymphocytic infiltrates surrounding predominantly venules and also small arteries [1,3]. It has been hypothesized that cortical and juxtacortical lesions are secondary to leptomeningeal ischemia due to vasculitic involvement of long cortical arteries [4].
MR imaging findings most often describe multiple small nodular foci of decreased T1-weighted and increased T2-weighted signal, some of which can coalesce into larger lesions, particularly in the basal ganglia [5]. Lesions are often less than 5 mm [3]. T1-weighted images are less sensitive than T2-weighted sequences [5]. In addition, FLAIR images have been shown to detect additional lesions compared to T2-weighted sequences, particularly in asymptomatic patients [3]. Enhancement most often manifests homogeneously, but other patterns include heterogeneous, linear, and ring-type patterns [5]. Although uncommon, focal encephalomalacia can also be detected in the optic nerve and brain stem [5].
Many lesions have been found to decrease in size or resolve altogether in response to steroid therapy [6]. The reversibility of extensive lesions reflect the presence of edema tracking along fiber tracts, rather than ischemia or infarction [7,8]. Case reports of diffusion weighted imaging (DWI) of T2 hyperintense lesions revealed elevated ADC values compared to normal subjects, indicating restricted diffusion and the presence of vasgoenic edema [9,10].
This patient was placed on high dose intravenous prednisone, after which she began to show dramatic clinical improvement. While the pontine and cerebellar lesions persisted on the follow up MR, the callosal lesion resolved.
References:
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