Moyamoya Disease




(1)
Neurosurgery Teaching Hospital, Baghdad, Iraq

 



This book contains some difficult questions marked with “ * “ sign.





  1. 1.


    Moyamoya Disease (MMD)

    Definition, the FALSE answer is:


    1. A.


      A rare chronic cerebrovascular disease characterized by stenosis-occlusion of the bilateral ICAs at their terminal portion and subsequent development of peculiar moyamoya vasculature at the base of the brain.

       

    2. B.


      The term moyamoya means “something hazy, like a puff of smoke.”

       

    3. C.


      The term moyamoya describes the characteristic angiographic appearance of abnormally dilated collateral vessels in MMD.

       

    4. D.


      An increasingly recognized cause of stroke.

       

    5. E.


      MMD is the most common pediatric cerebrovascular disease worldwide.

       

     





  • The answer is E.



    • MMD including 6 % of all strokes in children.


    • In Japan, it is the most common pediatric cerebrovascular disease.


    • Rare chronic cerebrovascular disease characterized by stenosis-occlusion of the bilateral ICAs at their terminal portion (carotid fork) and the subsequent development of peculiar moyamoya vasculature at the base of the brain.


    • The term moyamoya comes from a Japanese expression for something “hazy just like a puff of cigarette smoke drifting in the air” was first described by Suzuki and Takaku in 1969.




  1. 2.


    MMD

    Definition, the FALSE answer is:


    1. A.


      To have moyamoya disease, patients usually have bilateral stenosis.

       

    2. B.


      Patients with only unilateral findings have moyamoya syndrome.

       

    3. C.


      Individuals with a well-recognized associated condition are categorized as having moyamoya syndrome.

       

    4. D.


      Idiopathic cases with no known risk factors have moyamoya syndrome.

       

    5. E.


      The term moyamoya, when used alone without the modifier of disease or syndrome, refers to the distinctive findings on arteriography, independent of etiology.

       

     





  • The answer is D.



    • Individuals with a well-recognized associated condition are categorized as having moyamoya syndrome, whereas idiopathic cases with no known risk factors have moyamoya disease.


    • Classification of moyamoya



      • Moyamoya disease:



        • Bilateral, idiopathic steno-occlusive supraclinoid carotid disease


        • Bimodal age of diagnosis: 5 and 40 years old


        • Predominantly Asian heritage


        • Twice as common in females as in males


      • Moyamoya syndrome:


      • Associated disease state


      • Unilateral carotid disease (even if idiopathic)


      • Variable epidemiology


      • Atypical moyamoya:



        • Moyamoya vessels in non-carotid distribution


        • Associated aneurysm or pseudoaneurysms


        • Associated arteriovenous malformation




  1. 3.


    MMD

    Definition, the FALSE answer is:


    1. A.


      A bimodal age distribution of moyamoya, one group in the pediatric age range and a second group of adults in the 30- to 40-year-old range.

       

    2. B.


      Moyamoya affects young children in particular, with 50 % of patients identified by 10 years of age.

       

    3. C.


      Males are affected nearly twice as often as females.

       

    4. D.


      Asian Americans are more than four times as likely to have moyamoya.

       

    5. E.


      African Americans are twice as likely to have moyamoya.

       

     





  • The answer is C.



    • Females are affected nearly twice as often as males.


    • Its incidence is higher in Asian countries than in Europe or North America.


    • Asian Americans are more than four times as likely, African Americans are twice as likely, and Hispanic Americans are half as likely to have moyamoya.




  1. 4.


    MMD

    Pathology, the FALSE answer is:


    1. A.


      In all cases, the process extends to involve the posterior circulation.

       

    2. B.


      The proximal portion of the PCA is also involved in around half of affected patients.

       

    3. C.


      Pathologic analysis has demonstrated that affected vessels generally do not exhibit arteriosclerotic or inflammatory changes.

       

    4. D.


      Pathologic analysis has demonstrated that vessel occlusion results from a combination of both hyperplasia of smooth muscle cells and luminal thrombosis.

       

    5. E.


      Occlusion of the anterior circulation occurs simultaneously as characteristic arterial collateral vessels develop at the base of the brain in response to the resultant ischemia.

       

     





  • The answer is A.



    • Rarely, in advanced cases, the process can extend to involve the posterior circulation, including the basilar artery and PCA.




  1. 5.


    MMD

    Pathology, the FALSE answer is:


    1. A.


      The moyamoya collaterals are dilated perforating arteries believed to be a combination of preexisting and newly developed vessels.

       

    2. B.


      The familial incidence of affected first-degree relatives is 7–12 %.

       

    3. C.


      Basal moyamoya have abnormally dilated collaterals via the dural arteries.

       

    4. D.


      Ethmoidal moyamoya have abnormally dilated collaterals via the ethmoidal arteries.

       

    5. E.


      Vault moyamoya have abnormally dilated collaterals via the dural arteries.

       

     





  • The answer is C.



    • MMD is also characterized by an extensive peculiar development of collateral pathways: (1) basal moyamoya in the basal ganglia and thalamus, namely, abnormally dilated collaterals via the lenticulostriate arteries, the anterior choroidal artery, the posterior choroidal artery, and the posterior communicating artery, (2) ethmoidal moyamoya via the anterior and posterior ethmoidal arteries originating from the ophthalmic artery, and (3) vault moyamoya via the dural arteries, also called transdural anastomosis.




  1. 6.


    MMD

    Pathology, the FALSE answer is:


    1. A.


      The moyamoya vessels are thin walled, with a paucity of smooth muscle cells and incomplete internal elastic lamina.

       

    2. B.


      The moyamoya vessels never have aneurysmal dilatations.

       

    3. C.


      It is from the moyamoya (abnormal) vessels that the risk of ICH, IVH, and SAH arises.

       

    4. D.


      The ECA collateral networks providing extracranial (EC)-to-intracranial (IC) anastomoses also develop.

       

    5. E.


      The EC-to-IC anastomoses particularly from middle meningeal, ethmoidal, and occipital arteries.

       

     





  • The answer is B.



    • The moyamoya vessels may harbor aneurysmal dilatations.


    • The moyamoya vessels show increased expression of growth factors.




  1. 7.


    MMD, association, the FALSE answer is:


    1. A.


      Moyamoya is strongly associated with radiotherapy for gliomas.

       

    2. B.


      Moyamoya is strongly associated with radiotherapy for pituitary tumors.

       

    3. C.


      Moyamoya is associated with Down syndrome.

       

    4. D.


      Moyamoya is strongly associated with neurofibromatosis type II.

       

    5. E.


      Moyamoya is associated with sickle cell anemia.

       

     





  • The answer is D.



    • Strong associations exist between moyamoya and radiotherapy of the head or neck (especially for optic gliomas, craniopharyngiomas, and pituitary tumors), Down syndrome, neurofibromatosis type I (with or without hypothalamic-optic pathway tumors), and sickle cell anemia.




  1. 8.


    MMD*

    Genetics, the FALSE answer is:


    1. A.


      Moyamoya may be associated with mutation in loci on chromosomes 3.

       

    2. B.


      Moyamoya may be associated with mutation in loci on chromosomes 6.

       

    3. C.


      Moyamoya may be associated with mutation in loci on chromosomes 8.

       

    4. D.


      Moyamoya may be associated with specific HLA haplotypes.

       

    5. E.


      Moyamoya is strongly associated with haplotype at chromosome 2.

       

     





  • The answer is E.



    • Associations between moyamoya and loci on chromosomes 3, 6, 8, and 17 (MYMY1, MYMY2, MYMY3), as well as specific HLA haplotypes, have been described.


    • A single haplotype of the RNF213 locus at chromosome 17q is strongly associated with moyamoya disease. Mutation analysis of RNF213 identified a founder mutation present in 95 % of Japanese familial moyamoya disease, 73 % of nonfamilial moyamoya disease, and only 1.4 % of controls.




  1. 9.


    MMD

    Presentation, the FALSE answer is:


    1. A.


      Cerebral ischemic events are more common in children.

       

    2. B.


      Cerebral hemorrhages are more common in Asian adults.

       

    3. C.


      Cerebral ischemic events are more common in white adults.

       

    4. D.


      Cerebral hemorrhages are more common in males.

       

    5. E.


      Cerebral ischemia is the next most common manifestation in adults.

       

     





  • The answer is D.



    • Intracranial bleeding is the typical finding in Asian adults, especially females (up to 66 %).


    • The clinical findings are mainly cerebral ischemia in children and cerebral hemorrhage in Asian adults, but presumably also mainly ischemia in white adults.


    • TIAs is the most common finding (70 % to 80 %) in children.


    • The clinical features of moyamoya result from either direct cerebral ischemia (e.g., stroke, TIA) or the deleterious effects of responses to this ischemia (e.g., hemorrhage from fragile collateral vessels, headache as a result of dural irritation from collaterals).




  1. 10.


    MMD

    Presentation, the FALSE answer is:


    1. A.


      The symptoms of cerebral ischemia in moyamoya are generally related to the territory supplied by the ICAs.

       

    2. B.


      The watershed areas at the border zones between arterial territories are particularly susceptible.

       

    3. C.


      Hemiparesis, dysarthria, aphasia, and cognitive impairment are common.

       

    4. D.


      TIAs are common in children who are not precipitated by hyperventilation.

       

    5. E.


      Seizures occur frequently.

       

     





  • The answer is D.



    • TIAs may be precipitated by events particularly common in children, such as hyperventilation with crying or exertion.


    • The symptoms of cerebral ischemia in moyamoya are generally related to the territory supplied by the ICAs, including the frontal and temporal lobes.


    • The cerebral vessels, already maximally dilated in the setting of chronic ischemia, constrict in response to the decrease in PCO2 and can thus lead to a TIA or stroke.


    • Dehydration, a problem in children after colds or fevers, may also give rise to ischemic symptoms.




  1. 11.


    MMD

    Presentation, the FALSE answer is:


    1. A.


      Typically, hemorrhage is a hallmark of adult moyamoya, although children can also have this finding initially.

       

    2. B.


      Hemorrhage can be IVH, ICH, or rarely SAH.

       

    3. C.


      Children with moyamoya will often complain of headache.

       

    4. D.

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Jun 24, 2017 | Posted by in NEUROSURGERY | Comments Off on Moyamoya Disease

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