Recent clinical evidence has significantly advanced our understanding of iatrogenic cerebral amyloid angiopathy (iCAA), an acquired form of cerebral small vessel disease. This distinct condition arises after historical exposure to contaminated neurosurgical materials, such as cadaveric dura mater grafts or surgical instruments, during childhood or early adult interventions. Although sporadic cerebral amyloid angiopathy predominantly affects elderly populations, iCAA manifests decades earlier. Clinicians frequently encounter these patients in their late forties or early fifties. The disease is characterized by the prion-like seeding and transmissible propagation of amyloid-beta peptides throughout cortical and leptomeningeal vessels. Because the latency period often spans three to four decades, many affected individuals do not readily recall their remote surgical histories. Consequently, establishing an accurate diagnosis demands exceptional clinical vigilance and specialized neuroimaging expertise. Neurologists, neurosurgeons, and radiologists must collaborate closely to identify early hemorrhagic signatures. Recognizing these unique radiological distributions is crucial for preventing severe secondary complications, optimizing secondary stroke prevention, and avoiding contraindicated antithrombotic therapies that could exacerbate intracranial hemorrhage.

Diagnostic Hallmarks of Iatrogenic Cerebral Amyloid Angiopathy

Diagnosing iatrogenic cerebral amyloid angiopathy requires meticulous integration of longitudinal clinical history and advanced neuroimaging findings. The modified Queen Square criteria provide a standardized framework for stratifying patients into probable and possible categories based on surgical history, young onset age, and characteristic vascular pathology. In contrast to sporadic disease, iCAA presents with a striking spatial predilection. Patients who previously underwent supratentorial brain surgery routinely demonstrate an ipsilateral-dominant distribution of vascular lesions. Haemorrhagic markers frequently emerge in the precise anatomical territory where the surgical inoculation or dural grafting originally took place. Furthermore, these hemorrhagic markers gradually spread outward from the initial surgical focus over subsequent decades. This spatial lateralization serves as a pivotal radiological clue for neuroradiologists. Clinicians should deliberately investigate any past neurosurgical intervention when evaluating young or middle-aged adults presenting with spontaneous lobar bleeding or unexplained cortical superficial siderosis. Prompt exclusion of genetic angiopathies and systemic vasculitides ensures diagnostic precision.

Neuroimaging Spectrum: Microbleeds and Deep Hemorrhagic Markers

Centralized radiological evaluations reveal that iCAA demonstrates both familiar and unexpected magnetic resonance imaging features. Most notably, high-resolution susceptibility-weighted sequences reveal substantial lobar microbleed burdens that expand significantly over time. However, deep cerebral microbleeds are also surprisingly prevalent in this population. Although deep microbleeds traditionally indicate hypertensive arteriopathy, longitudinal data demonstrate that deep microbleeds appear in nearly half of iCAA patients during follow-up. This unexpected finding highlights extensive vascular involvement beyond classical cortical and leptomeningeal borders. Additionally, enlarged perivascular spaces in the centrum semiovale occur in almost all patients as the disease progresses, signaling severe glymphatic clearance failure and perivascular amyloid congestion. Cortical superficial siderosis and acute subarachnoid hemorrhage are also frequently documented. Therefore, comprehensive MRI protocols incorporating gradient-echo, susceptibility-weighted imaging, and high-field T2 sequences are essential for mapping the full extent of microvascular disruption in these vulnerable individuals.

Transient Neuroinflammation and Amyloid Dynamics

An intriguing aspect of iCAA is the frequent occurrence of transient neuroinflammatory episodes. Approximately one-quarter of affected patients develop localized inflammatory changes during their disease course. These transient alterations manifest on magnetic resonance imaging as focal cortical or subcortical vasogenic edema, asymmetric white matter hyperintensities, and subtle sulcal FLAIR hyperintensities. Pathophysiologically, these episodes resemble spontaneous amyloid-related imaging abnormalities (ARIA) and cerebral amyloid angiopathy-related inflammation (CAA-ri). They reflect an active perivascular autoimmune or inflammatory reaction triggered by rapid vascular amyloid accumulation. Clinically, patients experiencing these neuroinflammatory flares may present with subacute cognitive decline, new-onset seizures, persistent headaches, or transient focal neurological episodes. Furthermore, differentiating neuroinflammation from acute cerebral ischemia or recurrent tumor growth is critical. Misdiagnosis can lead to inappropriate interventions, whereas proper recognition enables targeted immunomodulatory management and close radiological monitoring to mitigate permanent cortical injury.

Long-Term Hemorrhagic Trajectory and Clinical Outcomes

Longitudinal cohort monitoring underscores a remarkably aggressive natural history in patients living with iCAA. Over extended follow-up periods, patients experience a very high incidence of symptomatic intracerebral hemorrhage, reaching approximately 16.7 events per 100 patient-years. This substantial recurrence rate markedly exceeds that observed in typical sporadic CAA cohorts. Moreover, serial neuroimaging routinely uncovers numerous silent or asymptomatic intracerebral hemorrhages, predominantly presenting as small intragyral hematomas. These subclinical events demonstrate continuous microvascular remodeling and recurrent vessel wall rupture. Over time, the cumulative burden of symptomatic and silent hemorrhagic lesions causes progressive neurological disability and cognitive impairment. Consequently, clinicians must maintain rigorous blood pressure control to reduce vascular shear stress. Furthermore, practitioners should strictly avoid unnecessary anticoagulant and antiplatelet therapies, as these agents can dramatically amplify catastrophic intracranial bleeding risks in patients with advanced amyloid-laden cerebral vasculature.

Clinical Implications for Practice and Patient Management

Effectively managing iCAA necessitates a comprehensive, proactive multidisciplinary strategy across neurology and neurosurgery. Clinicians should systematically document childhood surgeries, trauma interventions, and cadaveric tissue exposures in all unexplained younger stroke cases. When neuroimaging reveals lobar microbleeds with marked spatial lateralization, providers must promptly initiate high-resolution surveillance imaging. Additionally, patient counseling regarding lifestyle modifications, aggressive hypertension management, and strict avoidance of unindicated antithrombotics is paramount. Multidisciplinary teams should also establish standardized protocols for identifying and treating acute inflammatory flares with cautious corticosteroid regimens when clinically warranted. Ultimately, increased awareness of this distinct vascular entity will facilitate earlier detection, reduce misdiagnosis, and improve long-term prognostic counseling for affected patients and their families.

Frequently Asked Questions

How does iatrogenic cerebral amyloid angiopathy differ from sporadic CAA?

Iatrogenic cerebral amyloid angiopathy manifests decades earlier than sporadic CAA, typically affecting adults under fifty-five years. It stems from historical neurosurgical exposure to amyloid-contaminated materials. Additionally, iCAA frequently exhibits distinct spatial lateralization corresponding to previous surgical sites, higher hemorrhagic recurrence rates, and more frequent deep cerebral microbleeds.

What are the classic neuroimaging features seen in iCAA?

Key neuroimaging features include progressive lobar and deep cerebral microbleeds, asymmetric cortical superficial siderosis, dilated centrum semiovale perivascular spaces, and frequent intragyral hemorrhages. Furthermore, over twenty-five percent of patients exhibit transient inflammatory changes, such as focal vasogenic edema and sulcal hyperintensities resembling amyloid-related imaging abnormalities.

What is the recommended management strategy for patients diagnosed with iCAA?

Management focuses on rigorous blood pressure control, avoidance of anticoagulants and antiplatelet agents, and regular serial MRI surveillance with susceptibility-weighted sequences. Additionally, acute neuroinflammatory presentations require multidisciplinary evaluation and potential immunosuppressive treatment with corticosteroids, alongside specialized neurological rehabilitation and tailored secondary stroke prevention strategies.

Disclaimer: This content is for informational and educational purposes only and should not be considered medical advice or a substitute for clinical judgment. Medical knowledge constantly evolves; clinicians must cross-reference findings with current literature, official prescribing information, and institutional protocols. Treatment decisions should always be individualized based on specific clinical circumstances, patient history, and applicable diagnostic evaluations. The authors and publishers assume no liability for errors, omissions, or clinical outcomes resulting from the use of this information. Refer to the latest local and national guidelines for clinical practice.

References

1. Fandler-Höfler S et al. Clinical-radiological presentation and natural history of iatrogenic cerebral amyloid angiopathy. J Neurol Neurosurg Psychiatry. 2025 Aug 14. doi: 10.1136/jnnp-2024-335164. PMID: 39939135.
2. Banerjee G, Adams ME, Jaunmuktane Z, et al. Early onset cerebral amyloid angiopathy following childhood exposure to cadaveric dura. Ann Neurol. 2019;85(2):284-290.
3. Jaunmuktane Z, Mead S, Ellis M, et al. Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy. Nature. 2015;525(7568):247-250.
4. Charidimou A, Boulouis G, Frosch MP, et al. The Boston criteria version 2.0 for cerebral amyloid angiopathy: a multicentre, retrospective, MRI-neuropathology diagnostic accuracy study. Lancet Neurol. 2022;21(8):714-725.