---
title: 自己免疫性運動異常症の症候学
tags: 
author: [下畑享良](https://docswell.com/user/8003883581)
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description: MDS 2026（ソウル）の教育コースで使用したスライドです．
published: October 06, 26
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---
# Page. 1

![Page Image](https://bcdn.docswell.com/page/VJPKDPGNE8.jpg)

Phenomenology of Autoimmune Movement Disorders
Recognizing Treatable Disorders Through Movement Phenomenology
Takayoshi Shimohata, MD, PhD, FAAN
Department of Neurology
Gifu University Graduate School of Medicine, Japan
COI; I have nothing to disclose.


# Page. 2

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Why Does Phenomenology Still Matter?
• Autoimmune movement disorders are treatable.
• However, antibody results take time. Patients cannot wait.
• Phenomenology can guide early diagnosis and treatment.


# Page. 3

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Three Questions at the Bedside
Whenever I encounter an unusual movement,
I try to avoid making an immediate diagnosis.
Instead, I ask myself three simple questions.


# Page. 4

![Page Image](https://bcdn.docswell.com/page/4EQYPVQQJP.jpg)

When Should We Suspect
an Autoimmune Movement Disorder?
Acute or subacute onset
Rapid progression
Mixed movement phenomenology
Seizures
Encephalopathy
Dysautonomia
The more red flags present, the stronger the suspicion.


# Page. 5

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What Do You See?
Lancet. 2014;383(9933):2018
• It is extremely brief (usually <3 s),
stereotyped, frequent, and unilateral.
• Dystonic posturing of the face and arm
Phenomenology: faciobrachial
dystonic seizures (FBDS)
Diagnosis: LGI1 antibodyassociated encephalitis


# Page. 6

![Page Image](https://bcdn.docswell.com/page/LE1Y685N7G.jpg)

FBDS is not always restricted to one side.
Mov Disord Clin Pract. 2020; 7: 228–9.
Patient
1. Unilateral
2. Bilateral
The attacks may alternate
between sides. In addition,
this patient had mildly
impaired awareness.


# Page. 7

![Page Image](https://bcdn.docswell.com/page/GEWGWZWMJ2.jpg)

FBDS may also involve the leg:
Facio-brachio-crural dystonic seizures.
The attack occurred when he tried to stand up.
This can cause sudden falls, so fall prevention is important.
Neurol Clin Pract. 2024;14(3):e200301.
Lancet. 2026;407(10542):1968-83


# Page. 8

![Page Image](https://bcdn.docswell.com/page/47ZL515MJ3.jpg)

What Do You See?
Lancet. 2026;407:1968-83
There are continuous, variable
orofacial and limb dyskinesias.
Phenomenology:
Orofacial and limb dyskinesias
Diagnosis:
Anti-NMDAR encephalitis


# Page. 9

![Page Image](https://bcdn.docswell.com/page/YJ6W9L95JV.jpg)

What Do You See?
Mov Disord. 2013;28:543-7.
repetitive and stereotyped
movement of the left upper limb.
Phenomenology: Stereotypy
Diagnosis:
Anti-NMDAR encephalitis


# Page. 10

![Page Image](https://bcdn.docswell.com/page/GJ5MN1NGJ4.jpg)

Stereotypies can aid in the diagnosis of
anti-NMDAR encephalitis.
Mov Disord. 2014;29:1539-42.
• Vigorous stereotyped
movements involve the
upper limbs, trunk, and
lower limbs.
• Complex mixed hyperkinetic
movements are common in
anti-NMDAR encephalitis.


# Page. 11

![Page Image](https://bcdn.docswell.com/page/LE3W212PE5.jpg)

What Do You See?
Mov Disord. 2014;29:1539-42.
• The right arm remains in
a sustained posture.
Phenomenology: Tonic
perseveration
It is another characteristic
movement in anti-NMDAR
encephalitis.


# Page. 12

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What Do You See?
Case Rep Neurol 2022;14:494–500
• This patient has a rhythmic
“yes–yes” head movement.
Phenomenology: Head titubation
and cerebellar ataxia
Diagnosis: mGluR1 antibodyassociated cerebellitis


# Page. 13

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The patient improved markedly
after immunotherapy (IVIg).
Case Rep Neurol 2022;14:494–500
This illustrates the importance
of early recognition and treatment.


# Page. 14

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Head titubation
in mGluR1 antibody-associated cerebellitis
Neurology. 2018;90(16):746-747
Following apathy and
catatonia, the patient
developed head
titubation that
persisted for more
than one month.
Severe ataxia
emerged several
weeks later.


# Page. 15

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Head titubation may occur
with other antibodies.
•
27-year-old woman
•
Headache, gait disturbance, and limb tremor
•
Seizures and mild cognitive impairment
•
This patient had GluK2 antibody-associated
encephalitis with cerebellar ataxia and limbic
encephalitis.
Ann Neurol. 2023;93:635-636


# Page. 16

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Cerebellar Microglial Activation on 18F-DPA-714 PET/MRI
in GluK2 Antibody-Associated Encephalitis
Ann Neurol. 2023;93:635-636
• Imagings showed
limbic abnormalities
and cerebellar
microglial activation.
• These findings were
consistent with the
clinical manifestations.


# Page. 17

![Page Image](https://bcdn.docswell.com/page/K74WYMY3E1.jpg)

What Do You See?
Mov Disord Clin Pract. 2021;8:1260-2
• There are rhythmic, continuous abdominal movements.
• The movement resembled belly dancing, raising the
possibility of diaphragmatic involvement.
Phenomenology: Abdominal segmental myoclonus
Diagnosis: CASPR2 antibody-associated encephalomyelitis


# Page. 18

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Differential Diagnosis of Abdominal Segmental Myoclonus
• Trauma, including surgery
• Drug (e.g., salbutamol, levodopa, and galantamine)
• Neurodegenerative diseases (e.g., PSP)
• Functional neurological disorders
• Autoimmune encephalitis
Consider CASPR2 antibody testing, particularly in patients with coexisting
other autoimmune diseases or thymoma.


# Page. 19

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What Do You See?
Neurology. 2021;97(14):e1367-e1381.
• Slow, rhythmic tongue movements
at a frequency of 1–4 Hz
• These movements were
continuous at rest and persistent
during wakefulness
Phenomenology:
Lingual myorhythmia
Diagnosis: IgLON5 disease


# Page. 20

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Synchronous Lingual and Abdominal Myorhythmia
associated with IgLON5 Disease has been reported.
Mov Disord Clin Pract. 2026
https://doi.org/10.1002/mdc3.70594
The movements occurred
at a frequency of 1-4 Hz
and became more
prominent in the supine
position.


# Page. 21

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Myorhythmia may also occur in
CASPR2 antibody-associated encephalitis
Mov Disord Clin Pract. 2025;12:2004-6.
This patient had rhythmic
movements of the soft
palate and tongue,
together with cerebellar
ataxia.


# Page. 22

![Page Image](https://bcdn.docswell.com/page/G75MN1NL74.jpg)

Differential Diagnosis of Myorhythmia
Mov Disord Clin Pract. 2025;12:2004-6.
• Autoimmune encephalitis
• Anti-NMDAR encephalitis
• IgLON5 disease
• CASPR2 antibody-associated encephalitis
• Tr/DNER antibody-associated encephalitis
• Whipple disease
• Stroke involving the Guillain–Mollaret triangle
• Celiac disease
• Drug-induced myorhythmia
Therefore, think autoimmune,
but keep these alternatives
in mind.


# Page. 23

![Page Image](https://bcdn.docswell.com/page/9J295153ER.jpg)

Mov Disord Clin Pract.
2022;10(1):135-7.
What Do You See?
• The patient exhibited repetitive head drops and
trunk flexion.
• Associated features included insomnia, visual
hallucinations, memory impairment, and recurrent
falls.
Phenomenology:
Complex axial involuntary movements
Diagnosis: IgLON5 disease


# Page. 24

![Page Image](https://bcdn.docswell.com/page/DEY4KZK8JM.jpg)

FDG-PET of the patient showed
bilateral caudate hypometabolism.
Mov Disord Clin Pract.
2022;10(1):135-7.
This finding suggests caudate-predominant basal ganglia
dysfunction may have contributed to these unusual
involuntary movements.
18F‐FDG‐PET


# Page. 25

![Page Image](https://bcdn.docswell.com/page/VJNYR3R978.jpg)

What Do You See?
Neurology. 2024;102:e208110.
This was an 82-year-old man with a two-year history
of limb stiffness and unsteady gait. He also developed
widespread fasciculations and muscle cramps.
Phenomenology: Widespread fasciculations, muscle
cramps, and limb rigidity (neuromuscular
hyperexcitability)
Diagnosis: IgLON5 disease


# Page. 26

![Page Image](https://bcdn.docswell.com/page/YE9PM9M3J3.jpg)

IgLON5 disease can involve
both central and peripheral nervous systems.
Therefore, unexpected combinations, such as rigidity and fasciculations, may occur.
【Clinical Phenotypes of IgLON5 disease】
1. Sleep disorder phenotype
2. Bulbar syndrome phenotype
3. Movement disorder phenotype (PSP-like, CBS, cerebellar syndrome, and MSA-like syndromes)
4. Dementia phenotype with chorea
5. Peripheral nerve hyperexcitability phenotype


# Page. 27

![Page Image](https://bcdn.docswell.com/page/GE8DL9LLED.jpg)

What Do You See?
Phenomenology: Postural tremor, abdominal wall myoclonus
These patients also had cerebellar ataxia and urinary dysfunction.
Diagnosis: autoimmune GFAP astrocytopathy
Provided by Dr. Yosuke Takeuchi, Kumamoto University and Akio Kimura, Gifu University


# Page. 28

![Page Image](https://bcdn.docswell.com/page/LELMLWLQ7R.jpg)

Autoimmune GFAP astrocytopathy is associated
with a wide variety of movement disorders.
Clin Exp Neuroimmunol, 2025；16: 174-187.
Brain Sci. 2022;12:462.
(1)The major movement disorders are ataxia, tremor, and myoclonus
They usually appear relatively early, with approximately half of patients
developing within 28 days. Most are mild to moderate in severity.
Tremor and myoclonus predominantly affect the upper limbs.
(2) Less common but diagnostically important involuntary movements
• Dyskinesia
• Opsoclonus
• Rigidity
• Myokymia
• Choreoathetosis


# Page. 29

![Page Image](https://bcdn.docswell.com/page/4JMYM91KJW.jpg)

What Do You See?
Phenomenology: Ocular flutter
It consists of rapid horizontal saccadic oscillations.
Diagnosis:
autoimmune GFAP astrocytopathy
SPECT revealed increased blood flow in the
cerebellar vermis, including the fastigial nucleus,
suggesting hyperactivity in this region may
underlie ocular flutter.
Clin Neurol Neurosurg. 2022;219:107307.


# Page. 30

![Page Image](https://bcdn.docswell.com/page/PJR9VGL679.jpg)

What Do You See?
Neurology. 2019;92:e2298.
A 49-year-old man presented with marked weight loss, headache, and memory impairment.
These are multidirectional
saccades without an
intersaccadic interval.
Phenomenology:
Opsoclonus
Diagnosis:
DPPX antibodyassociated encephalitis


# Page. 31

![Page Image](https://bcdn.docswell.com/page/PEXQZXWDJX.jpg)

What Do You See?
Neurology. 2022;99(8):356.
The patient developed progressive stiffness,
predominantly affecting the left leg.
Delayed relaxation of the quadriceps was
observed after eliciting the patellar reflex.
Surface EMG showed continuous motor
activity in the left iliopsoas muscle.
Phenomenology； fluctuating left leg
stiffness with a hung-up reflex
Diagnosis: GAD65 antibody-associated
stiff-limb syndrome


# Page. 32

![Page Image](https://bcdn.docswell.com/page/3EK98WVDED.jpg)

Anti-GAD65 antibodies can cause treatable cerebellar ataxia,
which is not necessarily bilateral.
Mov Disord Clin Pract. 2026 Jul 23
:10.1002/mdc3.70741.


# Page. 33

![Page Image](https://bcdn.docswell.com/page/L73W21MP75.jpg)

Summary 1. Different movement patterns may suggest
specific neural antibodies as shown in this Table.
LGI1
Facial dyskinesia, Orofacial dyskinesia, Chorea,
Athetosis
FBDS, FBCDS
CASPR2
Myoclonus, Tremor, Ataxia
IgLON5
Myorhythmia, Chorea, Parkinsonism
GFAP
Tremor, Myoclonus, Ataxia
mGluR1
Ataxia, Head titubation
DPPX
Myoclonus, Tremor, Hyperekplexia
GAD65
Stiff-person spectrum disorder, Ataxia
NMDA receptor
The key message is:
Recognize movement patterns. Diagnose early ! Treat early !


# Page. 34

![Page Image](https://bcdn.docswell.com/page/87DKZX63JG.jpg)

Summary 2. Consider antibody testing in the following cases:
• Subacute onset of involuntary movements progressing over days to weeks
• Combination of multiple movement phenomenologies
• Associated cognitive impairment, psychiatric symptoms, or seizures
Take-home message
• The more red flags that coexist, the stronger the indication for neural antibody testing.
Thank you for your attention.