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Central nervous system embolisation of left atrial myxoma is well documented.1 The most common neurological sequel is acute cerebral ischaemia secondary to vessel occlusion by tumour.2 Delayed neurological complications are much less common and may result from tumour recurrence with embolisation, progressive vascular stenosis, aneurysm formation with subsequent rupture, or parenchymal metastasis.2 We report the occurrence of multiple myxomatous aneurysms in a patient six years after resection of a left atrial myxoma who was experiencing transient ischaemic attacks in the same distribution as the largest aneurysms. These lesions included bilateral fusiform aneurysms of the superior cerebellar and posterior cerebral arteries.
A 60 year old woman had a two week history of progressive occipital headache, intermittent visual changes, right facial pain, and imbalance. On examination, she had mild left upper and lower extremity weakness and mild cerebellar asymmetry. The patient reported a history of left atrial myxoma resection six years before presentation. Atherosclerotic risk factors included remote tobacco use and raised serum cholesterol. Pertinent drug treatment included fluvastatin and clopidogrel.
Magnetic resonance imaging (MRI) of the brain suggested aneurysms of the superior cerebellar arteries or posterior cerebral arteries. The MRI also revealed areas of previous infarction in multiple vascular distributions including the left superior cerebellar artery and both posterior cerebral arteries. Digital subtraction angiography showed large irregular fusiform aneurysms of the proximal superior cerebellar arteries (fig 1A⇓). Fusiform dilatation of the P1 segment of the right posterior cerebral artery and the P2 segment of the left posterior cerebral artery were also noted. Small peripheral fusiform aneurysms were identified in multiple vascular territories including the right anterior cerebral artery territory and both middle cerebral artery distributions (fig 1B⇓). The angiographic appearance of the aneurysms was not specific and the differential diagnosis included an infectious (bacterial or fungal) or neoplastic aetiology (myxoma, choriocarcinoma), connective tissue disorders (Ehlers–Danlos syndrome, Marfan’s syndrome), and neurocutaneous syndromes (for example, neurofibromatosis type 1). There were no branch vessel occlusions. There was no evidence of atherosclerotic disease in the head or neck and no radiographic evidence of myxoma recurrence in the heart.
A right pterional craniotomy was undertaken and showed grossly abnormal superior cerebellar arteries. The right superior cerebellar artery was more involved than the left and had a markedly thickened, whitish, partially calcified wall. No component of the aneurysm was suitable for clipping. The superior cerebellar arteries were reinforced with a cotton wrap before closure. The risk of obtaining a pathological specimen without significant bleeding complications was felt to be too high. Given the patient’s history of myxoma resection and lack of clinical or objective evidence for an alternate aetiology, the aneurysms were felt to be secondary to remote myxoma embolisation.
Cardiac myxomas account for more than 50% of primary cardiac neoplasms, with over 70% occurring in the left atrium.3 Up to 45% of left atrial myxomas embolise systemically, and as many as half involve the cerebral vasculature.1 Neurological symptoms attributable to cardiac myxoma can be categorised as acute or delayed. In the acute setting, tumour embolisation with branch vessel stenosis or occlusion resulting in cerebral ischaemia is the proposed mechanism. It is more common for neurological symptoms related to cardiac myxoma to precede the diagnosis.2 In a Mayo Clinic series of 40 patients with atrial myxoma, 10 (25%) experienced neurological symptoms at the time of diagnosis. Thirty five of these patients were followed for 12 to 235 months: one patient (3%) had a probable delayed neurological complication.
There are several case reports of delayed neurological symptoms related to cerebral myxomatous embolisation, ranging between one and eight years from initial diagnosis and reflecting a unique underlying neuropathology.4 Delayed imaging findings include fusiform and saccular aneurysms, vessel irregularity with stenosis, and intra-axial metastasis.4,5,6,7 Myxomatous aneurysms can rupture, but the risk of this has not been quantified.5 Intracranial myxomatous aneurysms occur with the highest frequency in the peripheral arterial branches of the anterior and middle cerebral artery distribution, although central fusiform aneurysms have been reported.3 Saccular aneurysms are a less common feature of myxomatous emboli. Thromboembolic events emanating from an aneurysm can result in transient ischaemic attacks, which are radiographically occult. Haemodynamically significant vessel stenosis can cause intermittent ischaemic symptoms. Parenchymal and intraventricular metastases, although uncommon, result in symptoms referable to the area of brain involved and the mass effect they create.
Two theories on the pathophysiology of myxomatous aneurysms have been widely accepted. The original theory suggested that postembolic vascular damage and subsequent scarring resulted in an alteration of flow dynamics that promoted aneurysm formation.3 In later studies, histopathological evidence showed active invasion of the vascular wall by viable tumour emboli.4,5,6 The ensuing inflammation and fibrosis weaken the elastic media, resulting in erosion of the arterial wall and subsequent aneurysm formation. This process can be slowly progressive and may help explain why patients with myxomatous aneurysms present several years after resection of the primary tumour.
The current case highlights the occurrence of neurological symptoms at a time remote from the initial diagnosis of cardiac myxoma. The development of delayed symptoms is unusual but is a well documented phenomenon and should be considered in patients with an appropriate history. Although we cannot prove the relation between the symptoms and the aneurysms, we felt it compelling that our patient’s transient ischaemic attacks were concordant with the areas of brain supplied by the largest aneurysms. Moreover, the right superior cerebellar artery aneurysm was in close proximity to the right trigeminal nerve and could have played a role in her right facial pain. The patient has been stable on maximal medical management.
This case also illustrates the diagnostic value of conventional angiography in detecting vascular neuropathology related to myxomatous embolisation. Although the larger, posterior circulation aneurysms were suspected on MRI, and might have been detected on magnetic resonance or computed tomographic angiography (MRA, CTA), it is less likely that alternate vascular imaging studies would have detected multiple small peripheral aneurysms that are more typical of this disease. Several of the peripheral aneurysms were detectable only by delayed washout of contrast relative to the arterial phase, a finding that cannot be appreciated on MRA or CTA. Because small peripheral aneurysms are more frequent, the most sensitive vascular imaging study should be used for their detection.
Competing interests: none declared
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