Moyamoya Disease Associated with Graves' Disease and Down Syndrome: A Case Report and Literature Review.

BACKGROUND: Moyamoya vessels are cerebral vasculopathies characterized by net-like collateral vessel formation at the cerebral basal area and stenosis of the terminal internal carotid artery, proximal middle cerebral artery, and anterior cerebral artery. A diagnosis of Moyamoya disease depends on the bilateral presence of Moyamoya vessels. Moyamoya disease associated with Graves' disease has rarely been reported to be a cause of ischemic events due to hyperthyroidism. However, there are extremely rare cases of Moyamoya disease with concurrent Graves' disease and Down syndrome. We aimed to report such a case, and to compare these cases' clinical features, pathogenesis, and treatment effects to those of the cases of concurrent Moyamoya disease and Graves' disease alone. METHODS: We performed an English literature search using the PubMed database and the keywords Moyamoya, quasi-Moyamoya, Graves' disease, thyrotoxicosis, Down syndrome, and trisomy 21. RESULTS: Only five cases of Moyamoya disease with Graves' disease and Down syndrome have been reported, including our own. Four patients were female (80%), and all underwent antithyroid therapy and experienced ischemic episodes, including transient ischemic attacks. At the time of their vascular accident, two patients were in a thyrotoxic state; only our patient was in a euthyroid state. The mean age was 15.6 years (standard deviation: 6.1), which was younger than the mean age of 31.4 years (standard deviation: 13) in patients with Moyamoya disease and Graves' disease alone. Down syndrome is commonly associated with abnormal vascular networks due to increased endostatin concentrations or immunological abnormalities such as those that occur in Graves' disease. Graves' disease accelerates the progression of Moyamoya disease and ischemic attacks due to atherosclerosis, enhances sympathetic nervous system activity and immunological changes. As compared to Moyamoya disease patients, patients with concurrent Graves' disease only and Moyamoya disease patients with concurrent Graves' disease and Down syndrome may experience accelerated disease progression or more frequent ischemic attacks. CONCLUSION: Early imaging follow-ups and strict control of thyroid function are necessary in such cases; if ischemic attacks have already occurred, revascularization surgery may be effective.

A Case of Cerebral Hyperperfusion Showing Unique Characteristics on Susceptibility-weighted MR Imaging after Carotid Endarterectomy.

Cerebral hyperperfusion syndrome (CHS) is a potentially devastating complication of carotid endarterectomy (CEA). Early detection and treatment of hyperperfusion are important before the condition develops into CHS. We herein present a case involving a 65-year-old female with severe right internal carotid artery (ICA) stenosis, who experienced hyperperfusion after right CEA. During the postoperative course, changes in the resting cerebral blood flow (rCBF) were evaluated using single-photon emission computed tomography (SPECT), and were found to correlate with the changes in the signal intensity of cortical arteries, cortical veins, and perilateral ventricular veins of the right middle cerebral artery (MCA) territory on susceptibility-weighted imaging (SWI). SWI showed a prominent hyperintensity of cortical arteries in the right MCA territory at postoperative day 1 (POD1), but the hyperintensity gradually decreased over time and became indistinct by POD48. As for cortical veins and perilateral ventricular veins, SWI showed an increased signal intensity of these veins during the peak of rCBF on POD1, but later, the signal intensity decreased as rCBF decreased on POD5. The signal intensity of cortical veins and perilateral ventricular veins finally returned to normal on POD9. Those SWI findings could be related to an impairment of cerebral autoregulation and the resulting hyperperfusion. SWI could be potentially useful as an additional tool in the evaluation of hyperperfusion.

[Unruptured Aneurysm Arising from the Proximal End of the Duplicate Origin of the Middle Cerebral Artery].

We report a rare case of an unruptured aneurysm arising from the junction between the internal carotid artery(ICA)and duplicate origin of the middle cerebral artery(MCA). A 49-year-old man who presented with vertigo was admitted to our hospital. Subsequent MR and CT angiograms revealed an incidental aneurysm arising from the proximal end of the duplicate origin of the left MCA. He underwent clipping via the distal transsylvian approach. The aneurysm projected to the posterior direction and several perforators from the two M1 segments were attached to the neck of the aneurysm, which made neck dissection very difficult. Approaching the space from the posterior/lateral direction to reach the M1 segment, the aneurysm neck was successfully dissected and clipped without sacrificing any perforators or stenosis of parent vessels. The postoperative course was uneventful, and the patient was discharged within 2 weeks. Duplicate origin of the MCA has been confused with a fenestration of the proximal M1 segment or terminal segment of the ICA. In this condition, two MCA branches arise separately from the terminal segment of the ICA and fuse early to form an arterial ring at the proximal M1 segment. An aneurysm originating from this anomaly has never been described. However, some aneurysms associated with this type of origin may have incorrectly been reported as those associated with proximal MCA or terminal ICA fenestrations. We summarize the cases that are similar to our case of duplicate origin of the MCA with an aneurysm, and discuss the precise diagnosis and significant intraoperative problems that were described in the literature.

[A Rare Case of Ruptured/Unruptured Miniature Aneurysms Originating from the Infundibular Dilatation of the Callosomarginal Artery, Branching from the Infracallosal(A2)Segment of the Azygos Anterior Cerebral Artery].

We report the first case of two de novo miniature aneurysms(ruptured/unruptured)emerging from the infundibular dilatation(ID)of the callosomarginal artery, which branches from the infracallosal(A2)segment of the azygos anterior cerebral artery(AACA), in a 36-year-old woman. The patient had previously been diagnosed with a miniature, unruptured aneurysm, occurring in the A2 segment of the AACA, detected by CT angiography(CTA)at another hospital two years ago, and had been followed up with MR angiography(MRA)every 6 months. Three months after the final check-up with MRA, which did not indicate a significant change in the aneurysm, the patient presented with subarachnoid hemorrhage. Subsequent CTA and digital subtraction angiograms revealed that the right callosomarginal artery, originating from the apex of the aneurysmal bulge, had a maximal diameter of 3mm, indicating an ID of the artery. Additionally, two miniature bleb-like aneurysms emerged from the ID, projecting in opposite directions:one projecting to the right-posterior/superior direction and the other to the left-anterior/inferior direction. Both aneurysms were successfully clipped via a right pterional approach with partial resection of the gyrus rectus, and the right-projecting aneurysm was confirmed to be ruptured during surgery. In the current report, we review previously reported cases of AACA with aneurysms, and discuss their clinical characteristics, and the possible mechanisms underlying the formation of the ID and de novo aneurysms in this extremely rare case.

[A Rare Case of Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm Associated with Contralateral Delayed Oculomotor Nerve Palsy].

A 55-year-old man presented with difficulty breathing, chest pain, and disturbance of consciousness, and was transferred to our hospital. Initial whole body CT revealed a diffuse subarachnoid hemorrhage(SAH)with severe pulmonary edema that was considered neurogenic in origin. He received controlled ventilation under sedation and conservative care for the SAH. One day after the onset of the SAH, his left pupil suddenly became dilated to 6mm, with no reaction to light. Head CT showed no new bleeding. Subsequent CT angiogram revealed a right internal carotid-posterior communicating artery aneurysm(IC-PC AN)with a posterior-lateral projection; however, no vessel abnormality was observed in the left anterior or posterior circulations. The aneurysm was successfully treated with coil embolization. We reviewed reported cases of isolated oculomotor nerve palsy(ONP), without direct compression by ruptured aneurysms, and found that only 11 cases exist, including our case. Interestingly, six of them were associated with anterior communicating artery aneurysms. A mass effect, chemical stimulation, and a jet stream of blood were proposed as the mechanisms of this rare type of ONP, in addition to the specific neurovascular relationships between the oculomotor nerve and the posterior cerebral/posterior communicating/superior cerebellar arteries, with abnormal nerve contact or compression. Though rare, ruptured IC-PC ANs could cause contralateral ONP; other types of ruptured aneurysms may also lead to indirect effects on nervous structures without direct compression. This type of rare presentation of ruptured aneurysms should be considered, especially in cases of multiple aneurysms, such as IC-PC ANs.