LAUSR

Dear Editor Typical Bickerstaff brainstem encephalitis (BBE) is characterized by acutely progressive bilateral ophthalmoparesis and ataxia with disturbance of consciousness demonstrating a monophasic course with good recovery [1]. However, atypical BBE is prone to untoward sequelae [2, 3]. BBE is considered as autoimmune encephalitis; IgG anti-GQ1b antibodies are detected in 66%–75% of BBE [1, 2]. Therefore, therapeutic plasma exchange (TPE) and intravenous immunoglobulin (IVIG) are considered effective [1–3]. The goal of BBE treatment is severity and sequelae reduction. We report a case in which we attempted TPE; however, selective plasma exchange (SePE) was conducted owing to anaphylaxis due to fresh frozen plasma (FFP). A 13-year-old male presented with fever, sore throat, and headache. After 4 days, he complained of light headedness and residual urine. The patient was admitted to our hospital after 9 days (Day 1). On admission, he had lower limb weakness; however, he was alert. A bladder balloon catheter was placed for urinary retention. Cerebrospinal fluid (CSF) protein level was 184 mg/dL, associated with pleocytosis (107 cells/μL). Magnetic resonance imaging (MRI) on Day 2 revealed no brain abnormality. T2-weighted MRI of the spinal cord demonstrated a slight hyperintensity. On Day 3, he was administered intravenous methylprednisolone (1000 mg) for three consecutive days. On Day 4, he suddenly developed external ophthalmoparesis and evident consciousness disturbance. BBE was diagnosed based on the clinical course. On Day 6, no neurological improvement was observed; therefore, he underwent TPE with albumin. All neurological symptoms, except urinary retention, showed prompt improvement. Since fibrinogen (Fib) was low (113 mg/dL), he underwent the second TPE with FFP. Steroids and antiallergic drugs were used for premedication to prevent allergic reactions caused by FFP. Nevertheless, he developed anaphylaxis 1 h following TPE initiation and was compelled to take additional steroids and anti-allergic drugs, thereby discontinuing treatment. Therefore, he underwent the 3rd and 4th TPE with albumin, and the 5th, 6th, and 7th treatment using SePE with albumin using a selective membrane plasma separator Evacure EC-4A10 (Kawasumi Laboratories Inc., Tokyo, Japan), for fibrinogen retention (Figure 1). He was able to complete the treatment without complications, including bleeding. IVIG (400 mg/kg for five consecutive days) was administered on the last day of SePE, and BBE treatment was terminated. No neurological sequelae were observed. Finally, the serum test before initiating all the treatments showed negative IgG anti-GQ1b antibodies, positive IgG anti-GM1 antibody, and IgM/IgG anti-GM2 antibody. The IgG anti-GQ1b antibody positivity rate of probable (atypical) BBE is 38% [2]. Abnormal MRI findings and increased CSF cell numbers increase the likelihood of probable BBE [2]. Thus, there was a possibility that the IgG anti-GQ1b antibody was negative in this case even before the autoantibody result was obtained; thus, not always indicating a benign disorder [2, 3]. No previous report exists on SePE use for BBE. A caveat exists that SePE does not eliminate IgM [4]. However, no report