2. Case presentation
In November 2020, a 54-year-old man presented with manifestations of unsteady gait and dysarthria, with mild dizziness and cognitive decline. The patient’s past history was unremarkable. Neurological examination revealed free movement of both eyes, slurred speech, broad footbed, unstable posture, leaning to the right when walking, hyperreflexia in the limbs, no focal sensory disturbances, and no focal muscle atrophy. Magnetic Resonance Imaging(MRI) examination showed multiple abnormal signal shadows in bilateral fronto-parietal cortex, hind limb of internal capsule, midbrain, and right cerebellum, which suggested poisoning or metabolic encephalopathy (Fig.1(A-D)). Magnetic Resonance Angiography(MRA) reported normal blood vessels. Routine blood, liver function tests, renal function tests and serum electrolytes were normal. Serum antinuclear antibody (ANA) and cytoplasmic antineutrophil cytoplasmic antibody (c-ANCA) levels were normal. β2_microglobulin (β2_MG): 2.321 mg/L. Cerebrospinal fluid (CSF) examination revealed 2 cells, increased protein levels of 616 mg/dL (normal range: 150-450 mg/dL), and normal glucose levels of 3.07 mmol/L (normal range: 2.5-4.4 mmol/L). CSF fungal and Gram stain tests were negative, and no oligoclonal bands were detected. Serology was negative for typhoid fever, leptospirosis, dengue, Japanese encephalitis and toxoplasmosis. Chest tomography (CT) showed diffuse inflammation in both lungs, predominantly interstitial pneumonia.
He received 20 mg of dexamethasone intravenously for 7 days, gradually transitioning to oral prednisone. During corticosteroid treatment, the patient’s neurological symptoms improved significantly. One month later, the lesions detected by head MRI were less than before. Oral corticosteroids were discontinued after 3 months.
However, in April 2021, the patient experienced gait instability and dysarthria again. Physical examination revealed a positive Barthel sign. The enhanced scan of MRI showed multiple patchy enhancement signals in the cerebellum and pons, Contrast-enhanced MRI scans show multiple patchy enhanced signals in the cerebellum and pons, resembling peppercorns Fig.1(E). DWI showed cerebellar softening foci (Fig.1(F)). We restarted dexamethasone 20 mg intravenous infusion for 7 days. During the treatment, the patient developed intractable hiccups, and with the reduction of hormone dose and the application of baclofen, the patient’s hiccups gradually eased. The patient’s dysarthria improved, but gait instability remained.
Considering the complexity of the lesions, we further refined PET/CT to reveal abnormal glucose metabolism in bilateral cerebellar hemispheres (Fig.1(G)). However, during hospitalization, the patient suddenly developed a right cerebellar hemorrhage and fell into a coma (Fig.1(H)). Surgery was performed in the emergency department. Pathological examination revealed infiltration of perivascular lymphocytes and neutrophils. Immunohistochemistry showed perivascular infiltrate primarily composed of CD3+ T cells, scattered CD20+ B cells, and no signs of malignancy, consistent with perivascular inflammation (Fig.2). After the operation, the patient woke up quickly and gradually carried out rehabilitation training, and the symptoms of the nervous system remained stable. Therefore, we never initiated immunosuppressive therapy.