October 1 2023 (6th edition)

MEG Centerfor Clinical Research in Minamata Disease

The MEG Center is investigating objective assessment methods for
Minamata disease using magnetoencephalography and MRI.
It also conducts the latest therapeutic research on the symptoms of
Minamata disease, which are difficult to treat.

Guide to the MEG Center
The MEG Center was established at Minamata City General Hospital& Medical Center in 2009 to investigate an objective evaluation method
for methylmercury poisoning. MEG stands for magnetoencephalography,
which is a noninvasive technique for examining brain activity.
The MEG Center conducts up-to-date examinations for patients with
Minamata disease and elderly people in Minamata disease-affectedareas and provides health counseling, including lifestyle counseling,based on the results of these examinations. In addition, the “StudyGroup on Improvement of Minamata Disease Treatment” was establishedat the National Institute for Minamata Disease to conduct researchon latest treatment methods to improve the symptoms of Minamata
Disease.

The MEG Center was established at
Minamata City General Hospital & Medical Center.
Minamata City General Hospital & Medical Center
Guide map of the hospital (1F)

リハビリ館
通用口

リハビリ館駐車場

トイレ

小児科

吹き抜け
（中庭）

循環器
内科

外科
トイレ

薬剤科

総合案内・会計窓口

本館
（東館）

再来受付機

自動入金機

階段通用口

糖尿病
内分泌センター（代謝内科）

整形外科

エスカレーター

体外
衝撃波
破砕
治療室

脳神経センター

呼吸器内科

MEG CenterEV

トイレ
EVEV
ATM

立体駐車場

EV

通用口

西館

地域医療支援センター

正面玄関

EV

1

時間外入口

外来
化学療法
センター

救急センター・総合
診療科

待合

EV
EV

時間外受付

Collaboration withthe local community
To improve the quality of life of patients with Minamata disease,
the National Institute for Minamata Disease has been working withthe local community, including Minamata City General Hospital &Medical Center, Minamata Ashikita Medical Association, and Minamata
City Meisuien. In addition, in cooperation with the Minamata Ashikita
Medical Association, a "Regional Medical Committee" consisting ofcommunity physicians has been established to regularly exchange
information and discuss treatment.
National Institute for
Minamata Disease
・Study Group on theImprovement of theTreatment of Minamata
diseaseMinamata City Meisuien

MEGCenter

Minamata Ashikita
MedicalAssociation

Local Medical
Facilities
Regional MedicalCommittee※Provided by Minamata City Social Welfare Foundation

Minamata City General Hospital & Medical Center
・Neurology Center
・Department ofRadiology
・Clinical Laboratory
・Community MedicalSupport Center
・Department ofRehabilitation※Provided by Minamata City General Hospital & Medical Center2

Tests and treatments offeredat the MEG Center
Objective Methods for Evaluating Minamata Disease
The symptoms of Minamata disease include sensory disturbances, concentric
constriction of the visual fields, and ataxia. We are now able to objectively evaluate
to some extent the abnormalities in the primary somatosensory cortex using MEG,
and atrophy of the cerebellum and thalamus using magnetic resonance imaging(MRI). Using these indices, we aimed to establish an optimal method for theobjective assessment of Minamata disease.

MEG

MEG is a device that records brain activity bymeasuring small magnetic fields generated by
the brain in real time. An objective assessmentof sensory dysfunction was performed bymeasuring the somatosensory evoked magneticfields (SEFs) produced by stimulating the median
nerve at the wrist. Sensory dysfunction is seen
in many patients with Minamata disease, but
it can be caused by a variety of other factors.
Therefore, whether it is due to methylmercury
needs to be fully investigated, including otherneurological findings.

● What an MEG test can tell us
While the N20m is always present in normal individuals, it is diminished or absent in patients with
Minamata disease, and the waveform is not constant; therefore, this measurement provides an objective
assessment of sensory disturbance.
Comparison of N20m amplitudePatients with
Minamata disease

Healthy individuals

10060

60

2020N20m amplitude(fT/cm)

10000-2-2-4

Patients with
Minamata disease

Healthy individuals-403

Comparison of N20m reproducibility

10 20 30 40Time(ms)01020 30401020Time(ms)30102030Brain MRI scan

MRI can measure brain morphology and thedegree of brain atrophy by evaluating thedensity and volume of each brain region. Inaddition, the MEG Center uses the latest MRI
technology to conduct examinations, whichenables performing corrections even when thepatient is moving. This is expected to reducethe burden of examination for patients with
Minamata disease whose bodies are subject tomovement.

● What a brain MRI scan can tell us
The cerebellum and thalamus weresigniﬁcantly atrophied in patientswith Minamata disease. In addition,
the latest MRI technology can beused to evaluate nerve fibers inthe brain, which shows that nerve
fibers are reduced in the cerebellum
and thalamus of patients withMinamata disease.

ThalamusCerebellum

Location of thalamus andcerebellum Thalamus Cerebellum

Neeve fibers in a healthy individual imaged by MRI

Based on these results, the cerebellum and thalamus were determined to be useful in MRI to discriminate
between patients with Minamata disease and healthy individuals .

By combining MEG and brain MRI, the sensitivity (probability of correctly identifying
a person with the disease as having the disease) was approximately 80% and thespecificity (probability of correctly identifying a person without the disease as nothaving the disease) was approximately 90%.

● Information regarding inspections
We are seeking people willing to participate
in our research on objective assessment
methods for Minamata disease. We alsooffer health counseling to those withconcerns regarding brain function byperforming the latest tests.
Explanation of examination（approximately 15 min）

Inspection Approximately 2 htime*Recommended to take a restroom break or other breaks.
Subjects

Those born before 1970 in Minamata Cityor its suburbs

Test
Results

Detailed explanations and lifestyle guidancefor dementia prevention will be provided
later at the MEG Center.

MEG（approximately 80 min）

Brain MRI（approximately 30 min）

*Precautions ・To eliminate the effects of magnetism, all metal objects are required to be removed.
・Since there are instances where you may not be able to take the test, we will confirm your medical history when you apply.

4

Magnetic stimulation therapy

This treatment does not require surgery but stimulates the brain almost painlessly by applying
magnetism generated by magnetic coils to the brain, thereby relieving symptoms. Magneticstimulation of the motor cortex, an area of the brain involved in controlling movement on the side
opposite to the site of pain, is thought to reduce neuropathic pain.

● Navigation Systems
In magnetic stimulation therapy, it is important
to apply magnetism precisely to the treatmentarea. The MEG Center uses a “navigation system”
to precisely apply magnetic stimulation tothe motor cortex.

Navigation system5Magnetic stimulator

● Effects of magnetic stimulation therapy◯ Neuropathic pain is expected to reduce.
◯ Magnetic stimulation therapy before rehabilitation canincrease rehabilitation effectiveness.
* There have been many reports on the effectiveness of magnetic stimulation therapy for neuropathic pain; however, it iscurrently not approved by health insurance. This research is approved by the authorized clinical research review committee(Kyushu University Certified Institutional Review Board for Clinical Trials) as stipulated by the “Clinical Trials Act.”● Test ﬂow
We are looking for patients with neuropathicpain, including patients with Minamata
disease, who are willing to participate in our
research on magnetic stimulation therapy.

Treatment Approximately 40 minutes per session ofduration magnetic stimulation therapy
Eligible
persons

Patients aged 50 years or older suffering froma neuropathic pain for 6 months or longer* No gender restrictions.
* Non-Minamata disease patients can participate as well.

Referral/appointment
from primarycare physician

Assessment

Initialconsultation

Examination

Explanationof results

Treatment

Evaluation

whether magnetic stimulation therapy is applicable will be checked first by
examining ❶level of the pain, ❷pain threshold, ❸questionnaire about thepain, ❹MEG testing (approximately 80 minutes), ❺blood test and ❻cervical spine MRI testing(approximately 30 minutes). Depending on the result, the patient may not be able to participate in thetherapy. Therapeutic benefits will be assessed objectively through an in-depth examination of the sensory
function with the use of MEG testing.

● Consent Form
For this magnetic stimulation
treatment, the patient must
submit a consent form fortreatment research prior totreatment.

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Please contact us for inquiries
about examination and treatment.
Comprehensive Medicine Section,
Department of Clinical Medicine

TEL +81-966-63-3111

4058-18 Hama, Minamata City, Kumamoto, 867-0008
TEL +81-966-63-3111

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