A case of reversible isolated cognition impairment in meningoencephalitis without abnormal MRI findings

Abstract

AbstractBackgroundWe report a case of meningoencephalitis with reversible isolated cognition impairment without abnormal MRI findings.MethodA 75‐year‐old man presented with confusion including bizarre behavior 2 days ago. Before visiting the hospital, his son found the patient naked and under the blanket saying it was cold. Fever didn’t occur. Mental status was alert without awareness. On neurologic examination, mutism was found. Muscle power on both upper and lower limbs was normal. Routine laboratory test showed that leukocytes count was normal but eosinophils were increased to 14.0%. Initial brain MRI including DWI and contrast enhanced image revealed no enhanced structural lesions. Initial K‐MMSE score was 4 points while the previous K‐MMSE score 3‐months‐ago was 25 points. There was no epileptic form discharge in EEG. CSF study demonstrated that WBC count was 18/L. protein was 42.6mg/dL, and glucose was 103mg/dL. CSF opening pressure was 5cmH2O. Culture study including gram stain, AFB stain, PAS stain showed no growth of aerobe, anaerobe, fungus and hyphae. Mycobacterium tuberculosis PCR and HSV PCR were negative. ADA was under 3 IU/I. Serum paraneoplastic antibodies were all negative.ResultThe patient showed only isolated cognition impairment without fever and there was no evidence of meningoencephalitis on the contrast enhanced MRI. Although the patient revealed CNS infection with unknown cause in CSF profile, it has some possibilities; 1) Aseptic meningoencephalitis with viral infection, 2) Bacterial meningoencephalitis with early stage, 3) Parasitic meningoencephalitis, 4) Autoimmune meningoencephalitis. Because of the negative findings in autoimmune antibody test, autoimmune meningoencephalitis was less likely. After treatment with acyclovir 0.6g for 7days, ceftriaxone 4g, vancomycin 2.5g and Ampicillin 8g for 10 days, confusion and mutism were improved with K‐MMSE 18 points.ConclusionMany reports have been published on meningoencephalitis accompanied by fever, altered mentality, seizure, muscle weakness and abnormal MRI findings respectively. However there have been few cases of meningoencephalitis with isolated cognition impairment and normal MRI simultaneously. If it is a change of consciousness and cognition impairment caused by meningoencephalitis, it can be reversible with proper treatment. Therefore, if only sudden onset isolated CNS symptom with normal brain MR finding, it is essential to check CSF profile.