Reversible cerebral vasoconstriction syndrome (RCVS) is a complex neurovascular disorder characterized by severe thunderclap headaches and reversible cerebral vasoconstriction. Its clinical presentation can mimic that of an aneurysmal subarachnoid hemorrhage (SAH), which is complicated by cerebral vasospasm in approximately one-third of patients. Notably, vasospasm occurs sporadically after surgical clipping of unruptured intracranial aneurysms (UIAs)[
1], and the development of subsequent delayed ischemic stroke is a scarcely documented complication[
2,
3]. In addition, RCVS directly attributable to UIAs has been rarely reported.
Case report
A 52-year-old woman was transferred to our hospital for further management of weakness of the left leg following thunderclap onset of headache. The headache peaked in intensity within 2 minutes and then gradually subsided. The limb weakness partially improved after 2 hours, leaving a residual weakness that persisted at rest. The patient had an unremarkable past medical history and denied any substance abuse or medication use. She had no risk factors for cerebrovascular disease and denied any history of headache. On admission physical examination, neurological deficits were presented as a left facial droop with some loss of the nasolabial fold and slightly left lower extremity weakness. The National Institutes of Health Stroke Scale score was 2, indicating minor neurological deficits. SAH was highly suspected but excluded based on a head computed tomography (CT) scan (Figure 1) and subsequent lumbar puncture.
Cerebral magnetic resonance imaging (MRI) evealed an internal watershed infarction in the right hemisphere, localized to the border zone between the superficial and deep branches of the middle cerebral artery (MCA) (Figure 2(a) and 2(b)). Corresponding magnetic resonance angiography (MRA) demonstrated severe segmental narrowing of the right M1 segment of MCA, consistent with the underlying hemodynamic abnormalities of the infarction. Somewhat unexpectedly, MRA also demonstrated two intracranial aneurysms located at the supraclinoid portion and terminal segment of the right internal carotid artery (ICA), respectively (Figure 2). Cerebral CT perfusion demonstrated increased cerebral blood volume (CBV), prolonged mean transit time (MTT) and time to peak (TTP) while constant cerebral blood flow (CBF) in the right MCA territory, suggesting a stenosis in the MCA (Figure 3).
Subsequent cerebral angiography (digital subtraction angiography, DSA) confirmed multiple aneurysms along the right ICA while normal lumen diameter of MCA, indicating the narrowing was reversible vasoconstriction (Figure 4). Therefore, the acute infarction was attributed to spontaneous cerebral vasospasm, rather than to mass effect from an enlarging aneurysm or an existing atherosclerotic plaque in the MCA.
Discussion
Recurrent thunderclap headaches, seizures, strokes, and non-aneurysmal subarachnoid hemorrhage can all reveal RCVS. RCVS was overlapped with primary thunderclap headache, posterior reversible encephalopathy syndrome, Takotsubo cardiomyopathy, transient global amnesia, and other conditions[
4]. The main imaging finding is segmental constriction of intracranial arteries, which can be associated with SAH and/or ischemic lesions[
5].
Rare cases of RCVS have been linked to UIAs, as in a notable report by Dodick et al.[
6] describing two patients with the triad of thunderclap headache, reversible cerebral vasoconstriction, and an unruptured aneurysm. Another case report documented a female patient who developed vasospasm in the context of an unruptured posterior communicating artery aneurysm, followed by complete resolution of the vasospasm[
7]. In previously reported cases, vasospasm typically presented with severe headache rather than cerebral infarction. In contrast, we report a distinctive case of ischemic stroke resulting from reversible vasospasm associated with multiple unruptured aneurysms along the ICA.
The pathophysiology underlying RCVS remains largely unknown. The occurrence of vasospasm in the absence of subarachnoid blood suggests that factors other than blood components can trigger this phenomenon. Given its distribution, the vasospasm likely originated from the predisposing factors intrinsic to the aneurysm. Pathoanatomical alterations of the aneurysm wall may elicit vasoconstriction in the neighbouring vessels adjacent to the parent artery. Such a change might be either spontaneous, such as abrupt enlargement of the aneurysm, or iatrogenic, as seen with surgical clipping or carotid artery revascularization[
8,
9], which is postulated to damage the adjacent endothelium and impair its ability to produce prostacyclin, a vasorelaxant substance[
7].
The thrombo-embolic events derived from the aneurismal cavity were another plausible explanation involved the provoking of vasoconstriction and cerebral infarction. The setting of vasospasm in return elevated shear stress, which might lead to platelet activation and microthrombus formation accompanied by impaired washout of emboli in hypoperfusion states[
8].
We have noticed that aneurysms of this patient are close to the circle of Willis. It is now established that the circle of Willis receives rich sensory perivascular innervation from the trigeminal ganglion and sensitizes the ‘‘trigeminovascular system’’ (TGVS), which could be responsible for the spasm of vessels without aneurysm rupture[
10].
This report reminds of us that UIAs can be direct triggers for RCVS. This case contributes to the body of evidence and implies that the incidence of UIA-induced vasospasm may be greater than currently appreciated.
The Author(s) 2026. This article is published by Higher Education Press at journal.hep.com.cn.
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