Iatrogenic cerebral amyloid angiopathy: Two case reports to explore clinical heterogeneity and pathological patterns.

Introduction: These case reports illustrate Iatrogenic Cerebral Amyloid Angiopathy (iCAA) due to neurosurgical procedures. Recent studies propose prion transmission during neurosurgery as a potential mechanism for β-amyloid seed implantation, linking neurosurgical history to the development of iCAA. The majority of reported cases in the literature have an unfavorable prognosis, with recurrence of intracerebral hemorrahge (ICH) and subsequent death during the first months of follow-up. There is no effective treatment for preventing the progression of the disease.

Results: a 41-year-old man with a previous history of left frontotemporal traumatic brain injury and subsequent neurosurgical intervention in childhood was admitted with an ICH leading to the diagnosis of iCAA. The patient's history of exposure, combined with imaging studies and neuropsychological assessments, supported the suspicion of iCAA. Confirmatory PET-CT scans revealed β-amyloid deposits in the cortical regions, aligning with the proposed criteria for iCAA. At the 2-year follow-up, the patient presents an NIHSS of 0 and a Modified Rankin Scale (mRS) of 1. The second case involved a 50-year-old man with a history of surgical treatment for Arnold-Chiari malformation, who developed transient neurological deficits and presented multiple ICH. The patient's history of neurosurgical intervention and the radiological and clinical features supported the diagnosis of probable iAAC. Despite a negative PET-CT result, CSF analysis provided evidence of ß-amyloid accumulation in the CNS. At the 6-year follow-up, the patient presented an NIHSS of 1(hemihypoesthesia) and mRS of 3.

Conclusion: iCAA is an emerging pathology probably driven by prion transmission of β-amyloid seed after neurosurgical interventions. It is important to suspect this condition in young patients with ICH and a history of neurosurgical procedure. Recognizing iCAA's clinical and radiological features is crucial for early identification. The diagnosis process is based on demonstrating the accumulation of β-amyloid protein in the central nervous system using PET-CT or cerebrospinal fluid (CSF) studies and also conducting genetics studies. As an evolving pathology without a clear pathophysiology and a potential divergent evolution between phenotypes, establishing standardized diagnostic criteria and a multicenter registry is imperative for a comprehensive understanding of iCAA.