Non-Ischemic Cerebral Enhancing (NICE) lesions after flow diversion for intracranial aneurysms: a systematic review with case-level synthesis.
Pablo Albiña-Palmarola, Noel P Schechtman, Andrés Gallardo et al.
✦ AI-curated · Sources linked
In 30 seconds
This PROSPERO-registered systematic review synthesized reports of delayed non-ischemic cerebral enhancing (NICE) lesions after flow-diverter treatment of intracranial aneurysms; heterogeneity precluded meta-analysis. Twenty-two studies were included, identifying 40 unique patients. The only FD-specific incidence estimate was 12 cases among 1201 treated aneurysms (1.0%), but the true incidence remains uncertain. Lesions typically appeared after a median of 73 days. The evidence supports a possible foreign-body inflammatory mechanism involving device coatings or other materials, without identifying a single culprit. Corticosteroid-associated improvement was common, although courses could fluctuate or recur.
Key findings
- The only FD-specific denominator yielded 12 NICE cases among 1201 FD-treated aneurysms (1.0%); the true incidence remains uncertain.
- Lesions appeared after a median of 73 days and were commonly multifocal, predominantly ipsilateral, and associated with MRI edema.
- Biopsy found hydrophilic polymer or other foreign material in four of six patients; device-coating detachment was directly observed in one additional case.
- Radiologic improvement or resolution occurred in 12/25 cases, while recurrent or fluctuating activity occurred in 11/25.
Why it matters
Delayed enhancing lesions after flow diversion may present with headache, focal deficits, or seizures and can have a relapsing course. Recognizing the reported imaging and timing patterns may help clinicians consider this complication in the appropriate context. The review also highlights uncertainty about incidence and mechanism, so the findings should inform diagnostic awareness rather than imply a settled causal explanation.
What to keep in mind
Evidence came from heterogeneous reports, and only one multicenter survey provided an FD-specific denominator. Case-level data were incomplete, and heterogeneity precluded meta-analysis.