2. Case report
A 43-year-old, otherwise healthy woman visited our emergency room with
high fever and a sore throat. She was discharged initially after symptom
control, but after three days re-visited with an altered, drowsy mental
status (Glasgow coma scale, 4). The body temperature was 38℃. The
initial laboratory tests showed mild leukocytosis with slightly elevated
C-reactive protein. A lumbar puncture was performed and cerebrospinal
fluid (CSF) analysis showed minimal pleocytosis (white blood cells,
3cells/mm3) with slightly elevated protein
concentration of 46 mg/dL. The brain MRI (T2-weighted and
fluid-attenuated inversion recovery) displayed diffuse swelling in the
bilateral cerebral regions involving the bilateral pons (Fig. 1). We
immediately administered intravenous (IV) ceftriaxone, vancomycin,
acyclovir, and dexamethasone. On hospital day 3, IV immunoglobulin was
also administered since autoimmune encephalitis such as NMDA
encephalitis could not be ruled out. On hospital day 4, the patient’s
mental status recovered, but diplopia remained. The specific serological
IgM test via EIA (DIESSE Diagnostica, Italy) for M .pneumoniae was positive (1.5 [cutoff value: 0.9]) and that
for IgG was negative. The antibiotics regimen was changed to
clarithromycin due to infection with M . pneumoniae .
Routine CSF gram stain and bacterial cultures, and polymerase chain
reaction tests (PCR) showed negative results for herpes simplex,
varicella zoster, cytomegalovirus, Epstein-Barr virus, and
Mycobacterium. The tests for autoimmune antibodies (anti-NMDAR, -LGI1,
-CASPR2, -AMPA1, -AMPA2, -GABAB-R, -Hu, -Yo, -Ri, -Ma2, -CV2/CRMP5, and
-amphiphysin) in the CSF and serum were negative. Also, serum anti GQ1b,
GM1 and GD1b IgM antibodies were negative. On hospital day 10, serum IgM
value for M. pneumoniae increased by up to 2.1-and the IgG test
still was negative. After one month, the patient fully recovered from
the neurological deficits and a follow-up brain MRI was completely
improved.
Written informed consent was obtained from the patient for publication
of the case and any accompanying images.