Clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with febrile urinary tract infection

Abstract

Common pathogens of clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) are viruses, such as influenza virus. However, bacteria are rare pathogens for MERS. We report the first patient with MERS associated with febrile urinary tract infection. A 16-year-old lupus patient was admitted to our hospital. She had fever, headache, vomiting, and right back pain. Urinary analysis showed leukocyturia, and urinary culture identified Klebsiella pneumoniae. Cerebrospinal fluid examination and brain single-photon emission computed tomography showed no abnormalities. Therefore, she was diagnosed with febrile urinary tract infection. For further examinations, 99mTc-dimercaptosuccinic acid renal scintigraphy showed right cortical defects, and a voiding cystourethrogram demonstrated right vesicoureteral reflux (grade II). Therefore, she was diagnosed with right pyelonephritis. Although treatment with antibiotics administered intravenously improved the fever, laboratory findings, and right back pain, she had prolonged headaches, nausea, and vomiting. T2-weighted, diffusion-weighted, and fluid attenuated inversion recovery images in brain magnetic resonance imaging showed high intensity lesions in the splenium of the corpus callosum, which completely disappeared 1 week later. These results were compatible with MERS. To the best of our knowledge, our patient is the first patient who showed clinical features of MERS associated with febrile urinary tract infection. Conclusion: In patients with pyelonephritis and an atypical clinical course, such as prolonged headache, nausea, vomiting, and neurological disorders, the possibility of MERS should be considered.

Mild encephalitis/encephalopathy with reversible splenial lesion (MERS) associated with Streptococcus pneumoniae Bacteraemia

“…Additionally, local infiltration by inflammatory cells could lead to reduced diffusion on MRI. Similar to our case, pleocytosis, a sign of inflammation in the central nervous system, is reported in patients with MERS [4]. Genetic factors may also play a role because patients with MERS have been most commonly seen in Southeast Asia.…”

“…Similarly, the patient in this case had hyponatremia, but S. pneumoniae was considered to be the causative agent because of the patient's fever, respiratory infection findings and positive blood culture. Axonal damage, oxidative stress and activation of the immune system are considered to be associated with pathogenesis of MERS [4]. Additionally, local infiltration by inflammatory cells could lead to reduced diffusion on MRI.…”

“…The most common neurological symptoms are behavioral changes, altered consciousness, and seizures [3]. Most patients with MERS clinically recover within 1 month [4]. The major causative agents of MERS are viruses, especially influenza types A and B [4].…”

“…Most patients with MERS clinically recover within 1 month [4]. The major causative agents of MERS are viruses, especially influenza types A and B [4]. Bacterial infection-related MERS has also been reported in a few patients.…”

Ipilimumab-Induced Encephalopathy with a Reversible Splenial Lesion

“…PRES is closely related to MERS, with similar transient diffusion restriction seen on brain MRI preferentially affecting the parietal and occipital lobes thought secondary to decreased sympathetic innervation of the posterior circulation (16). Although the pathogenesis of these syndromes overlaps, PRES is predominantly a vasogenic process with hypertension as the most common cause, and MERS is predominantly related to immune activation (9,10,16).…”