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| '''For patient information, click [[Moyamoya disease (patient information)|here]]''' | | '''For patient information, click [[Moyamoya disease (patient information)|here]]''' |
| {{Infobox_Disease | | {{Infobox_Disease |
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| | Image = Circle of Willis.jpg | | | Image = Circle of Willis.jpg |
| | Caption = Schematic representation of the circle of Willis, arteries of the brain and brain stem. | | | Caption = Schematic representation of the circle of Willis, arteries of the brain and brain stem. |
| | DiseasesDB = 8384
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| | ICD10 = {{ICD10|I|67|5|i|60}}
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| | ICD9 = {{ICD9|437.5}}
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| | ICDO =
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| | OMIM = 252350
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| | MedlinePlus =
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| | eMedicineSubj = neuro
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| | eMedicineTopic = 616
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| | MeshID = D009072
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| }} | | }} |
| {{Moyamoya disease}} | | {{Moyamoya disease}} |
| {{CMG}} | | {{CMG}} |
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| ==Overview== | | ==[[Moyamoya disease overview|Overview]]== |
| '''Moyamoya syndrome''' is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by the constriction, and also by blood clots ([[thrombosis]]).<ref name="Scott">[http://content.nejm.org/cgi/content/full/360/12/1226 Moyamoya Disease and Moyamoya Syndrome], R. Michael Scott and Edward R. Smith, New England Journal of Medicine, 360:1226-1237, March 19, 2009</ref>
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| The blood vessels develop [[collateral circulation]] around the blocked vessels to compensate for the blockage, but the collateral vessels are small, weak, and prone to [[hemorrhage]], [[aneurysm]] and thrombosis. On X-rays, these collateral vessels have the appearance of a "puff of smoke" ("もやもや (moyamoya)" in Japanese).<ref name="Scott"/>
| | ==[[Moyamoya disease historical perspective|Historical Perspective]]== |
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| The disease causes constrictions primarily in the [[internal carotid artery]], which travels from the neck up inside the skull just under the brain in the cavernous sinus. At the Circle of Willis, the internal carotid artery flows into the [[middle cerebral artery]], which continues into the brain, and the [[anterior cerebral artery]], which is part of the Circle of Willis. Moyamoya disease often extends to the middle and anterior cerebral arteries.<ref name="Scott"/>
| | ==[[Moyamoya disease classification|Classification]]== |
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| When the internal carotid artery becomes completely blocked, the fine collateral circulation that it supplies is obliterated. Patients often survive on the collateral circulation from the back (posterior) of the Circle of Willis, from the [[basilar artery]].<ref name="Scott"/>
| | ==[[Moyamoya disease pathophysiology|Pathophysiology]]== |
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| Drugs such as [[antiplatelet]] agents (''e.g.'', aspirin) are usually given to prevent clots, but surgery is usually recommended. Since moyamoya tends to affect only the internal carotid artery and nearby sections of the adjacent anterior and middle cerebral arteries, surgeons can direct other arteries, such as the [[external carotid artery]] or the [[superficial temporal artery]] to replace its circulation. The arteries are either sewn directly into the brain circulation, or placed on the surface of the brain to reestablish new circulation after a few weeks. Although there is a 4% risk of stroke soon (30 days) after surgery, there is a 96% probability of remaining stroke-free over the next 5 years.<ref name="Scott"/>
| | ==[[Moyamoya disease causes|Causes]]== |
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| The constrictions of the arteries in moyamoya disease are unlike the constrictions in [[atherosclerosis]]. In atherosclerosis, the inner layer ([[Lumen (anatomy)|lumen]]) of the arteries suffers an immune reaction, fills with inflammatory cells, and accumulates fatty cells and debris. In moyamoya, the inner layer of the carotid artery overgrows inward to constrict the artery, and the artery also fills with blood clots, which cause strokes.<ref name="Scott"/>
| | ==[[Moyamoya disease differential diagnosis|Differentiating Moyamoya Disease from other Diseases]]== |
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| It is a disease that tends to affect children and adults in the third to fourth decades of life. In children it tends to cause strokes or seizures. In adults it tends to cause strokes or bleeding. The clinical features are [[cerebral ischemia]] (strokes), recurrent [[transient ischemic attack]]s (TIAs), sensorimotor paralysis (numbness and paralysis of the extremities), convulsions and/or [[migraine]]-like [[headaches]]. After an ischemic stroke, a hemorrhagic reperfusion stroke may occur. A hemorrhagic stroke may also stem from rupture of the weak neovascular vessel walls.
| | ==[[Moyamoya disease epidemiology and demographics|Epidemiology and Demographics]]== |
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| ==Pathophysiology== | | ==[[Moyamoya disease risk factors|Risk Factors]]== |
| The condition is believed to be hereditary and linked to q25.3, on chromosome 17 [http://emedicine.medscape.com/article/1180952-overview#ClinicalCauses]. In Japan the overall incidence is higher (0.35 per 100,000).<ref name="pmid9409395">{{cite journal |author=Wakai K, Tamakoshi A, Ikezaki K, ''et al.'' |title=Epidemiological features of moyamoya disease in Japan: findings from a nationwide survey |journal=[[Clin Neurol Neurosurg]] |volume=99 Suppl 2 |issue= |pages=S1–5 |year=1997 |pmid=9409395 |doi=10.1016/S0303-8467(97)00031-0}}</ref> In North America, women in the third or fourth decade of life are most affected. These women frequently experience transient ischemic attacks (TIA), cerebral hemorrhage or no symptoms. They have a higher risk of recurrent stroke and may be experiencing a distinct underlying pathophysiology compared to patients from Japan. Data suggest a potential benefit with surgery if early diagnosis is made.<ref name="pmid16645133">{{cite journal |author=Hallemeier C, Rich K, Brubb R, Chicoine M, Moran C, Cross D, Zipfel G, Dacey R, Derdeyn |title=Epidemiological features of moyamoya disease in Japan: findings from a nationwide survey |journal=[[Stroke]] |volume=37 |issue= 6|pages=1490–1496 |year=2006 |pmid=16645133 |doi=10.1161/01.STR.0000221787.70503.ca}}</ref> The pathogenesis of moyamoya disease is unknown.
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| Once it begins, the process of blockage (vascular occlusion) tends to continue despite any known medical management. In some people this leads to repeated strokes and severe functional impairment or even death. In others, this blockage may not cause any symptoms.
| | ==[[Moyamoya disease screening|Screening]]== |
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| Moyamoya can be either congenital or acquired. Patients with [[Down syndrome]], [[neurofibromatosis]], or [[sickle cell disease]] can develop moyamoya malformations. It is more common in women than in men, although about a third of those affected are male .<ref name="pmid18048855">{{cite journal |author=Kuriyama S, Kusaka Y, Fujimura M, ''et al.'' |title=Prevalence and clinicoepidemiological features of moyamoya disease in Japan: findings from a nationwide epidemiological survey |journal=Stroke |volume=39 |issue=1 |pages=42–7 |year=2008 |pmid=18048855 |doi=10.1161/STROKEAHA.107.490714 |url=http://stroke.ahajournals.org/cgi/pmidlookup?view=long&pmid=18048855}}</ref> Brain radiation therapy in children with neurofibromatosis increases the risk of its development.
| | ==[[Moyamoya disease natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| ==Diagnosis== | | ==Diagnosis== |
| The diagnosis is initially suggested by [[Computed tomography|CT]], [[MRI]], or [[angiogram]]. In fact, the name derives from its angiographic image; the "puff of smoke," which is how moyamoya loosely translates from [[Japanese language|Japanese]], refers to the appearance of multiple compensatorily dilated striate vessels seen on angiography. Contrast-enhanced T1-weighted images are better than FLAIR images for depicting the [[Leptomeninges|leptomeningeal]] ivy sign in moyamoya disease. MRI and MRA should be performed for the diagnosis and follow-up of moyamoya disease. Diffusion-weighted imaging can also be used for following the clinical course of children with moyamoya disease, in whom new focal deficits are highly suspicious of new infarcts.
| | [[Moyamoya disease history and symptoms|History and Symptoms]] | [[Moyamoya disease physical examination|Physical Examination]] | [[Moyamoya disease laboratory findings|Laboratory Findings]] | [[Moyamoya disease CT|CT]] | [[Moyamoya disease MRI|MRI]] | [[Moyamoya disease other imaging findings|Other Imaging Findings]] | [[Moyamoya disease other diagnostic studies|Other Diagnostic Studies]] |
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| Often nuclear medicine studies such as [[SPECT]] (single photon emission computerized tomography) are used to demonstrate the decreased blood and oxygen supply to areas of the brain involved with moyamoya disease. Conventional angiography provided the conclusive diagnosis of moyamoya disease in most cases and should be performed before any surgical considerations.
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| ==Treatment== | | ==Treatment== |
| There are many operations that have been developed for the condition, but currently the most favored are the in-direct procedures EDAS, EMS, and multiple burr holes and the direct procedure STA-MCA. Direct [[superficial temporal artery]] (STA) to [[middle cerebral artery]] (MCA) bypass is considered the treatment of choice, although its efficacy, particularly for hemorrhagic disease, remains uncertain. Multiple [[burr hole]]s have been used in frontal and parietal lobes with good neovascularisation achieved.
| | [[Moyamoya disease medical therapy|Medical Therapy]] | [[Moyamoya disease surgery|Surgery]] | [[Moyamoya disease primary prevention|Primary Prevention]] | [[Moyamoya disease secondary prevention|Secondary Prevention]] | [[Moyamoya disease cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Moyamoya disease future or investigational therapies|Future or Investigational Therapies]] |
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| The '''EDAS''' ([[encephaloduroarteriosynangiosis]]) procedure is a [[synangiosis]] procedure that requires dissection of a scalp artery over a course of several inches and then making a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
| | ==Case Studies== |
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| In the '''EMS''' ([[encephalomyosynangiosis]]) procedure, the [[temporalis]] muscle, which is in the temple region of the forehead, is dissected and through an opening in the skull placed onto the surface of the brain.
| | [[Moyamoya disease case study one|Case #1]] |
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| In the '''multiple burr holes''' procedure, multiple small holes (burr holes) are placed in the skull to allow for growth of new vessels into the brain from the scalp.
| | {{Cerebrovascular diseases}} |
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| In the '''STA-MCA''' procedure, the scalp artery (superficial temporal artery or STA) is directly sutured to an artery on the surface of the brain (middle cerebral artery or MCA). This procedure is also commonly referred to as an EC-IC (External Carotid-Internal Carotid) bypass.
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| All of these operations have in common the concept of a blood and oxygen "starved" brain reaching out to grasp and develop new and more efficient means of bringing blood to the brain and bypassing the areas of blockage. The modified direct anastomosis and encephalo-myo-arterio-synagiosis play a role in this improvement by increasing cerebral blood flow (CBF) after the operation. A significant correlation is found between the postoperative effect and the stages of preoperative angiograms. It is crucial for surgery that the anesthesiologist have experience in managing children being treated for moyamoya as the type of anesthesia they require is very different from the standard anesthetic children get for almost any other type of [[neurosurgical]] procedure.
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| ==Prognosis==
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| The natural history of this disorder is not well known. Symptomatic Moyamoya disease have occurred in individuals with seemingly asymptomatic stability thought due to vascular insufficiency secondary to brain trauma which may result from axonal shearing and acceleration / deceleration injuries such as falls and/or high speed motor vehicular accidents. The long term outlook for patients with treated moyamoya seems to be good.{{Definition|date=November 2011}} While symptoms may seem to improve almost immediately after the in-direct EDAS, EMS, and multiple burr holes surgeries, it will take probably 6–12 months before new vessels (blood supply) can develop sufficiently.{{Cn|date=November 2011}} With the direct STA-MCA surgery, increased blood supply is immediate.{{Cn|date=November 2011}}
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| Once major strokes or bleeding take place, even with treatment, the patient may be left with permanent loss of function so it is very important to treat this condition promptly.
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| ==References==
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| {{reflist|2}}
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| ==External links==
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| *http://www.moyamoya.com
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| *http://www.childrenshospital.org/moyamoya
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| *http://moyamoyainfo.blogspot.com/
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| *http://moyamoya.stanford.edu
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| *http://www.mir.wustl.edu/research/internal.asp?NavID=707
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| *http://www.moyamoya.net
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| *http://www.kispi.uzh.ch/Kinderspital/Chirurgie/Chirurgie-1/Neurochirurgie/Moyamoya_en.html
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| *http://www.krupp-krankenhaus.de/fileadmin/Bilddatenbank/Bilddatenbank_Kliniken_Abteilungen/Neurologie/Patienteninfo-Neurologie-Moyamoya-2010-03-15.pdf
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| * [http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=2573 Orphanet's disease page on Moyamoya disease]
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| {{Cerebrovascular diseases}}
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| [[Category:Cerebrovascular diseases]] | | [[Category:Disease]] |
| [[Category:Stroke]] | | [[Category:Medicine]] |
| [[Category:Neurology]] | | [[Category:Neurology]] |
| [[Category:Emergency medicine]] | | [[Category:Emergency medicine]] |
