Moyamoya disease is associated with cerebrovascular accident in young patients. This disease is more common in Japan and East Asia compared to Europe and America with a clear ethnic difference. In reported cases, the onset age has two peaks: at around 5 years old and at 30–40 years old.1 2
Almost all paediatric cases develop cerebral ischaemia, whereas in adult cases about half have cerebral ischaemia and half develop cerebral haemorrhage. Moyamoya disease is caused by collateral circulation routes (moyamoya vessels) that develop to compensate for cerebral ischaemia with worsening of stricture of the circle of Willis starting from the carotid artery on both sides. The moyamoya vessels may expand into the main brain bloodstream and cause deterioration of brain circulatory reserve. As the brain blood flow deteriorates due to hyperpnoea, ischaemia can develop and bleeding is generated by the failure of moyamoya vessels. The side effects of pentazocine include decreases in the cardiac index3
and blood pressure.4
For this patient, because the episode that affected the brain circulation was only intramuscular injection of pentazocine and his consciousness level deteriorated twice in 30 min after administration of pentazocine twice, we concluded that pentazocine was the probable cause of the ischaemic attack. However, few articles have discussed the influence of pentazocine on blood circulation and we were unable to draw our conclusion with confidence.
Ischaemia of the cerebral hemisphere in moyamoya disease leads to symptoms of transient paralysis, perception disorders such as transient numbness, epileptic stroke and disturbance of consciousness. It is often accompanied by hyperventilation in children in whom moyamoya disease may occur during a musical instrument performance, exercise, heat, crying and excitement. For adults, bleeding caused by haemodynamic stress or rupture of a minute aneurysm may produce moyamoya vessels (). Our case developed as a sudden disturbance of consciousness. The brain blood flow from the bilateral frontal lobe to the parietal lobe can deteriorate due to a pathological change in the first part of the circle of Willis. These lobes control consciousness and this may explain the disturbance of consciousness in our case. Cerebral ischaemia occurs with reduced brain blood flow and brain oxygen consumption, but blood flow to the cerebellum, medulla oblongata and base nucleus are comparatively unaffected,5
which results in maintenance of vital life signs such as breathing and circulation.
The cause of moyamoya disease is unclear. Family onset has been reported in about 15% of cases6
and asymptomatic moyamoya disease in blood relatives has been shown by MRA.7
In our case, the patient had three blood relatives with cerebral haemorrhage. This indicates that taking a clear family history is important when moyamoya disease is suspected. Cerebral blood vessel imaging is essential for diagnosis based on contraction or obstruction at the end of the carotid artery and in the anterior cerebral artery and proximal MCA in MRA. Bilateral abnormal blood vessels may also be observed in the cerebellum basal nucleus in MRA.8 9
Our case showed typical characteristics of moyamoya disease because obstruction was observed on both sides of the proximal part of the MCA in MRA.
Untreated cases of adult moyamoya disease have high rates of recurrence of cerebral blood vessel events. Convalescence is poor and re-establishment of blood flow is recommended10 11
for improvement of transient cerebral ischaemic attack, reduction of the risk of cerebral infarction, improvement of activities of daily living postoperatively and long-term brain function.12
In Japan, a case with onset of cerebral infarction such as that caused by moyamoya disease is treated as an atheroma blood clot-related cerebral infarction, but evidence to support this approach is lacking. Cerebrovascular accident related to moyamoya results in major deterioration of function during convalescence10 11
and surgery should always be considered. However, this cannot be performed in most patients due to failure of early detection with resultant serious after effects.13 14
The patient in our case had repeated transient cerebral ischaemic attacks and late diagnosis led to development of broad cerebral infarction and serious after effects. From our experience with this case, we suggest that cerebrovascular accident should be suspected in a young patient with disturbance of consciousness in whom breathing and circulation are stable, particularly if there is an episode in which a drug treatment affects the brain circulation before onset of disturbance of consciousness. In such a case, moyamoya disease should be suspected based on medical or family history. In our case, moyamoya disease was diagnosed using emergency MRA. For ischaemia-type moyamoya disease, early re-establishment of blood circulation is important to reduce serious after effects.
Reports on surgery for re-establishment of blood flow indicate stable outcomes and good convalescence. Many cases arrive at the emergency room with a slight ischaemic attack before a complete cerebrovascular accident occurs and it is important to make an appropriate diagnosis based on MRI and MRA at the stage of the slight ischaemic attack before performance of re-establishment surgery. Currently, there is no effective evidence-based treatment for cerebrovascular accident. We want to emphasise that ‘the best method is to discover moyamoya disease at the stage of a slight ischemic attack and perform re-establishment surgery to prevent a cerebrovascular accident.’
- Non-arteriosclerosis-related diseases such as moyamoya disease should be considered in young Asian patients with cerebral infarction after an episode that affects the brain circulation.
- Pentazocine, which decreases the cardiac index and blood pressure, may be a risk factor for onset of cerebral infarction in a patient with moyamoya disease.
- In a young patient with disturbance of consciousness in whom moyamoya disease is suspected by physical examination or based on medical or family history, MRI and MRA should be performed at an early stage to facilitate early diagnosis and treatment.