JOURNAL OF BIOLOGICAL REGULATORS & HOMEOSTATIC AGENTS

Vol. 34, no. 3, xx-xx (2020)

ABNORMAL PREDOMINANTLY FRONTAL HIGH VOLTAGE AND SLOW EEG
FINDINGS WITH ACUTE ENCEPHALOPATHY ASSOCIATED WITH ACUTE FOCALBACTERIAL NEPHRITIS
G. IMATAKA, Y. FUJITA, Y. KANO and S.I. YOSHIHARA
Department of Pediatrics, Dokkyo Medical University, Shimotsuga, Tochigi, JapanF
O

Received April 3, 2020 – Accepted May 14, 2020
To the Editor,
Acute focal bacterial nephritis (AFBN), an inflammatory lesion of the renal parenchyma caused
by localized bacterial infection of the kidney, wasfirst described by Rosenfield in 1979 (1). The AFBN
stage is considered to be the transition from acuterenal pelvic nephritis to renal abscess (1). In recentyears, a few researchers reported cases of AFBN associated with central nervous system symptoms (2-5).
Here, in this paper, we report a rare case of a AFBN
that was associated with fever and impaired consciousness. This case was initially diagnosed as acuteencephalopathy based on the high-voltage amplitude
and slow wave pattern observed on electroencephalogram (EEG).
The case was a 12-year-old male patient who visited a clinic complaining of fever and fatigue. The
clinic associated the symptoms to common cold andthe patient was returned home. The patient gradually developed speech difficulties which eventually affected his communication ability. The next morning,
after a walk around his house he experienced severe
vomiting and a few hours later, he stopped responding to his parents and was not able to recognize themembers of his family. At this level, his consciousness gradually deteriorated, and he was transported
to our university hospital by an ambulance. After ad-

mission and hospitalization, he exhibited a disturbed
level of consciousness and acted irrationally andstarted shouting while walking around the hospital
general ward. His body temperature was 40°C, andphysical examination did not reveal any physical abnormality on his body. His deep tendon reflexes werenormal, with no difference between the right and left
sides. We instructed him to perform finger-to-nose
test, Romberg test and dancing toe walking test; but
he could not comprehend any of the test instructions. The blood test results were 15,800×109/μl forwhite blood cells (WBC) and 5.72 mg/dL for C-Reactive protein (CRP), suggesting some focal bacterial infection. His urine test results revealed normal
values for protein, glucose, red blood cells, WBC,and β2-microgloburin. Cerebral spinal fluid collection with lumbar test showed normal findings withno increase in the cell count, protein level, glucose
and IgG index. Following this, the patient exhibited
violent movement along with impaired consciousness. Thus, we performed an EEG examination andrecorded high voltage and slow delta wave activities
predominantly for both frontal areas (Fig. 1 A, B).
Brain magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) results showed noabnormalities. Based on symptoms and EEG results,
we diagnosed him as a case of acute encephalopa-O
RP

Key words: AFBN; acute encephalopathy; electroencephalogram; DWI; MRICorresponding Author:
George Imataka M.D., Ph.D., B.Phil. LL.B., PGDBM
Department of Pediatrics, Dokkyo Medical University
880 Kitakobayashi, MIbu, Shimotsuga, Tochigi 321-0293 Japan
Tel.: +81-282-86-1111 (PHS: 7390)
133e-mail: geo@dokkyomed.ac.jp0393-974X (2020)

Copyright © by BIOLIFE, s.a.s.
This publication and/or article is for individual use only and may not be further
reproduced without written permission from the copyright holder.
Unauthorized reproduction may result in financial and other penalties
DISCLOSURE: ALL AUTHORS REPORT NO CONFLICTS OF
INTEREST RELEVANT TO THIS ARTICLE.

134

G. IMATAKA ET AL.

thy. We started steroid pulse treatment with 30 mg/kg methylprednisolone for 3 days. Six hours after thesteroid pulse treatment, he regained consciousnessrapidly and his verbal response was normalized thenext morning. On the fourth day after admission, hisbody temperature increased again to 40°C and theblood WBC, CRP, ferritin, procalcitonin, and IL-2R
levels were 14,000×109/μl, 21.13 mg/dl, 105 ng/ml,13.36 ng/ml and 1,029 U/ml, respectively. Moreover,the BUN, creatinine, and sodium levels were 23 mg/dL, 1.2 mg/dl, and 135 mmol/L, respectively. At thispoint we started to identify the source of the bacterial infection. Data obtained from the blood test andthe abdominal enhanced CT showed a low-density
areain 1the left kidney (Fig. 2A). Additional brain
Figure

F3-A1
F4-A2
C3-A1
C4-A2
P3-A1
P4-A2
O1-A1
O2-A2
F7-A1
F8-A2
T3-A1
T4-A2
Resp.
ECG

FOORP

Figure 2

MRI-DWI revealed normal intensity, and abdominal MRI-DWI exhibited wedge-shaped high signal
intensities in the left kidney (Fig. 2 B, C). These abnormal intensities were compatible with AFBN diagnosis. We started a 10-day antibiotic treatment with4 g/day of ceftriaxone. After antibiotic therapy hisgeneral condition gradually improved. Urine culture
test revealed no specific infection and magnetic resonance cholangiography results were normal. Renal
123
I-meta-iodobenzylguanidine single photon emission computerized tomography showed lower left
renal uptake compared to the right. After a few years
of follow-up, his left kidney function was maintained
and brain recognition was normal.
In previous studies on the central nervous sys-

F3-F7
F7-T3
T3-O1
F3-C3
C3-P3
P3-O1
F4-C4
C4-P4
P4-O2F4-F8F8-T4T4-O2Resp.
ECG

ABFig. 1 . A) Monopolar pattern of EEG shows high voltage and 2 Hz slow Figurewave 2activities predominantly in both frontalareas. B) Bipolar pattern of EEG detected abnormal high voltage slow wave activities.

A

B

CFig. 2. A) Enhanced CT image showing a low-density abnormal area in the left kidney (arrows). B,C) Abdominal MRIDWI reveals wedge-like shaped high signal intensities in the left kidney (arrows).

135

Journal of Biological Regulators & Homeostatic Agentstem symptoms associated with AFBN, researchers
have reported abnormalities in MRI results. Theseabnormalities included clinically mild encephalitis/encephalopathy with reversible splenial lesion(MERS) (2-4), reversible posterior leukoencephalopathy syndrome (RPLS) (4), and acute encephalopathy with biphasic seizures and late reduced diffusion(AESD) (5). Our patient underwent two MRI scansat different phases, and neither of them showed any
MERS abnormalities. Moreover, our case was diagnosed based on abnormal frontal dominant highvoltage slow EEG results. The main symptoms in ourpatient included consciousness disorder, along withvisual and behavioral abnormalities. Our patient
did not experience any convulsions. We assumed
that our case was a non-convulsive acute encephalopathy case, which was clinically similar to MERS.
This might be one of the most clinically mild typesof a novel encephalopathy among the various typesof acute childhood encephalopathy cases. Acute encephalopathy with normal MRI and abnormal highvoltage and slow activity EEG findings associatedwith AFBN may be categorized as a new clinical phenotype of acute encephalopathy with milder clinicalsymptoms compared to MERS. In cases with symptoms of central nervous system anomalies that aresuggestive of acute encephalopathy, clinicians should
perform both EEG and MRI if the case is diagnosed

as AFBN. It may be possible to diagnose AFBN associated with MERS as well as AFBN associated withnormal MRI findings and abnormal high voltage andslow EEG wave patterns, similar to our case of acuteencephalopathy.
REFERENCES
1.

2.

3.

FO

Rosenfield AT, Glickman MG, Taylor KJ, Crade M,Hodson J. Acute focal bacterial nephritis (acute lobarnephronia). Radiology 1979; 132:553-61.
Maruyama Y, Sato M, Inaba Y, Fukuyama T. Comparison of mild encephalopathy with reversible splenial
lesion with and without acute focal bacterial nephritis. Brain Dev 2020; 42:56-63.
Kometani H, Kawatani M, Ohta G, et al. Marked elevation of interleukin-6 in mild encephalopathy witha reversible splenial lesion (MERS) associated withacute focal bacterial nephritis caused by Enterococcus faecalis. Brain Dev 2014; 36(6):551-53.
Kasuga Y, Fuchigami T, Fukuda A, et al. Acute focal
bacterial nephritis associated with central nervous system manifestations: a report of 2 cases and review ofthe literature. Pediatr Emerg Care 2017; 33(6):418-21.
Yamaguchi H, Nagase H, Ito Y, et al. Acute focal bacterial nephritis characterized by acute encephalopathy with biphasic seizures and late reduced diffusion.
J Infect Chemother 2018; 24(11):932-35.

POR4.

5.