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Moya-Moya, disease or syndrome
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[MIM 252 350, 607 151, 608 796, 614 042]
Cerebral arteriopathy of unknown origin characterized by the progressive occlusion of the intracranial carotid vessels and/or proximal branches of the anterior and middle cerebral arteries. A collateral circulation develops from the leptomeningeal vessels and other extra- and intracranial carotid branches: their appearance to the angiogram looks like a puff of smoke, hence the name to the disease (moyamoya in Japanese).
Histology: progressive obliteration of the arterial lumen by hyperplasia of intima. The wall of the collateral vessels is fragile and can be the source of microaneurysms.
One distinguishes:
- the Moya-Moya 'disease', which is isolated and idiopathic
- the MoyaMoya 'syndrome', where the arteriopathy is associated with other clinical problems as: trisomy 21, neurofibromatosis type 1, Alagille syndrome, sickle cell disease, Marfan's syndrome, Fanconi anemia.
There are acquired Moyamoya syndromes following brain irradiation or bacterial meningitis.
There is a form of Moya-Moya disease, the transmission of which is X-linked and where the cerebrovascular anomaly is associated with a short stature and hypergonadotropic hypogonadism [MIM 300 845]
Angiographic staging according to Suzuki:
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Grade I |
carotid artery stenosis without collateral circulation |
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Grade II |
presence of collateral vessels at the level of the basal ganglia |
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Grade III |
very important collateral vessels |
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Grade IV |
stenosis or occlusion at the level of the circle of Willis and
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Grade V |
network of extracranial collaterals |
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Grade VI |
total occlusion of the carotid artery |
Clinical signs:
- repeated ischemic (transient ischemic hemiplegias or successive hemiparesias) and/or hemorrhagic attacks: it is the cause of about 6 % of strokes of the child. Ischemic attacks are typically caused by hyperpnea or emotions: hypocapnia causes vasoconstriction of the collateral vessels already dilated to compensate chronic ischemia.
- chronic cerebral circulatory insufficiency: headache, epilepsy
- renal artery stenosis is sometimes associated.
Treatment :
Medical: antiplatelet agents (aspirin), sometimes anticalcics
Surgical: surgical anastomoses between intra - and extracranial circulations.
These anastomoses are:
- either direct (superficial temporal artery => to middle cerebral artery) the effect of which is immediate
- or indirect, the results of which are progressive: 1) anastomosis of the temporalis muscle on the pia-mater or the underlying dura-mater, 2) multiple bur holes to put the vascularization of the scalp and the meninges into contact ...
Anesthetic implications:
the priority is to maintain a normal cerebral blood flow and perfusion pressure, and to avoid any cause of cerebral ischemia:
- aiming at normocapnia: because hypocapnia = vasoconstriction of healthy vessels and decrease in flow in both the collateral and diseased vessels. Hypercapnia = dilation of healthy vessels and subsequent « steal » to non-ischemic areas.
- avoidance of large BP variations (intubation, overdose...): maintain the mean arterial pressure in a range of ± 15 % of normal values
- in case of cranial surgery, propofol-based TIVA seems preferable to sevoflurane
- prevent hypovolemia: administer 20 ml/kg of crystalloids at induction and provide IV fluids for maintenance with 1.5 times the 4-2-1 rule
- prevent pain and crying (induction, alarm clock, care). No contraindication to regional anesthesia (aspirin. )
- avoidance of hypo- and hyperthermia.
Keeping in mind the limits of the technique, measuring NIRS at baseline (before induction) and its changes under anesthesia could help determine the limits of cerebral autoregulation and thus determine the ideal mean systemic arterial pressure for each patient. The risk of cerebral complications after anesthesia for a non-neurosurgical procedure is estimated to about 1 %.
References :
Updated: March 2021