Diagnosis of moyamoya disease
Moyamoya disease is basically diagnosed by
both clinical symptoms and angiographic findings.
When the child develop transient ischemic
attack of hemiparesis, it is usually straightforward
to diagnosis moyamoya disease. However, when
the patient develop convulsion or involuntary
movements, its diagnosis is not easy. It
is sometimes experienced that the child with
moyamoya disease is diagnosed as 'psychological
problem' or 'autism'. Thus it happens that
long time is required to reach the diagnosis
of moyamoya disease.
Neuroimaging
X-ray computed tomography (CT): CT is useful to differentiate brain ischemia
from brain hemorrhage in the acute stage.
However, CT is not definitely diagnostic
for moyamoya disease. As a non-invasive imaging,
the following magnetic resonance imaging
comes the first line.
Moyamoya disease is, instead, diagnosed
by
catheter angiography and magnetic resonance
imaging (MRI).
Catheter angiography: The procedure to visualize the cerebral
vessels (arteries and veins) by iodine contrast
material which is injected through the small
tube (catheter) introduced into the cervical
arteries. This method is essentially required
for the diagnosis of moyamoya disease. However,
catheter angiography has an inherent risk
of cerebral infarction, drug allergy, etc,
although the incidence is very low. It should
be cautious to perform catheter angiography
because many moyamoya patients are in the
pediatric age who are at higher risk for
ischaemia than adults.
Magnetic resonance imaging (MRI) and magnetic
resonance angiography (MRA): To avoid the inherent risk of catheter angiography,
MRI and MRA are useful and safe, although
diagnostic efficacy of MRI and MRA
is inferior
to that of catheter angiography. Indication
of both methods should be balanced
in consideration
of their merits and risks. Amongst
moyamoya
patients, children are good candidates
for
MRI and MRA.
There is the diagnostic criteria of moyamoya
disease (the spontaneous occlusion of the
circle of Willis) proposed by the research
committee sponsored by the Japanese Ministry
of Health, Labor and Welfare.
|
The diagnostic criteria are summarized as
follows:
1. Steno-occlusive changes at the terminal
portions of the intracranial internal
carotid
arteries and development of "moyamoya
vessels" at the base of the brain.
2. The above-mentioned findings are observed
bilaterally.
When the lesion is bilateral, the diagnosis
of moyamoya disease is definite
, but otherwise it is probable.
Exclusion criteria include arteriosclerosis,
auto-immune diseases, brain tumor, head injury,
post-irradiation, von Recklinghausen's disease,
Down's syndrome, etc.
These criteria are proposed by Japanese research
committee of moyamoya disease. Many moyamoya
patients reported in the world is not based
on these criteria. When the angioarchitecture
is similar to that in moyamoya disease, it
is called moyamoya syndrome or moyamoya phenomena.
About unilateral moyamoya disease and quasi-moyamoya
disease
Cerebral blood flow and moyamoya disease
Staging of moyamoya disease (angiographic
staging)
Moyamoya disease and gene
Stenosis/Occlusion of the Middle Cerebral
Artery and Moyamoya
|