Management of 5mm Unruptured Intracranial Aneurysm at Proximal Circle of Willis with Symptomatic Presentation
This patient requires urgent neurosurgical evaluation and strong consideration for treatment given the symptomatic presentation with mass effect symptoms (double vision, facial tingling, neck tightness) despite the aneurysm being only 5mm in size. 1
Critical Clinical Context
This case deviates from typical asymptomatic small aneurysm management because the patient is symptomatic. The constellation of headaches, diplopia, facial paresthesias, and neck tightness over 4 months suggests the aneurysm is causing mass effect or may represent sentinel symptoms of impending rupture 1.
Immediate Diagnostic Steps
Obtain formal catheter angiography immediately to definitively characterize this aneurysm, as standard CT has limitations for small aneurysms and cannot adequately define presence, morphology, or daughter sac formation 1. Catheter angiography remains the gold standard with <0.5% permanent neurological morbidity in experienced centers 1.
- Look specifically for: daughter sac formation, irregular morphology, aneurysm growth compared to any prior imaging, and precise anatomical relationships to perforating vessels 1
- CT angiography or MRA can be considered if catheter angiography is not immediately available, though MRA has only 69-93% sensitivity for aneurysms 3-5mm 1
Treatment Recommendation
Symptomatic aneurysms warrant strong consideration for treatment regardless of size 1. The presence of cranial nerve symptoms (diplopia, facial tingling) indicates mass effect, which is an indication for intervention even in aneurysms <10mm 1.
Factors Strongly Favoring Treatment in This Case:
- Symptomatic presentation with mass effect symptoms 1
- Patient age of 47 years with long life expectancy 1
- Proximal Circle of Willis location (posterior circulation/basilar tip aneurysms carry relatively high rupture risk) 1
- Progressive symptoms over 4 months suggesting possible aneurysm growth 1
Treatment Modality Selection:
Both endovascular coiling and microsurgical clipping are options, with choice depending on specific aneurysm anatomy, neck characteristics, and institutional expertise 1, 2. Endovascular approaches have become increasingly utilized since 2002 1.
Risk-Benefit Analysis
Natural History Risk:
While asymptomatic aneurysms <10mm without prior SAH have rupture rates of only 0.05%/year 1, symptomatic aneurysms change this calculus entirely 1. The symptoms themselves indicate the aneurysm is already causing neurological compromise.
Treatment Risk:
Modern neurosurgical centers report:
- Catheter angiography: <0.5% permanent neurological morbidity 1
- Surgical/endovascular treatment: risks vary by approach but are generally acceptable for symptomatic lesions in experienced centers 1
Critical Pitfalls to Avoid
Do not apply conservative management guidelines for asymptomatic small aneurysms to this symptomatic patient 1. The standard teaching that aneurysms <10mm can be observed applies primarily to truly asymptomatic, incidentally discovered lesions without prior SAH 1.
Do not dismiss symptoms as unrelated - the temporal relationship of worsening headaches, new diplopia, and facial paresthesias over 4 months in a patient with a known aneurysm at the Circle of Willis strongly suggests aneurysm-related pathology 1.
Do not delay evaluation - these symptoms could represent sentinel warnings of impending rupture or progressive aneurysm enlargement 1.
Follow-up if Conservative Management Chosen
If after neurosurgical consultation a decision is made for observation (unlikely given symptoms), the patient requires:
- Periodic imaging surveillance with CT angiography or MRA to detect growth 1
- Any change in aneurysm size or configuration mandates reconsideration for treatment 1
- Immediate re-evaluation if symptoms worsen 1
However, given the symptomatic nature with mass effect, observation alone is not the recommended approach 1.