Understanding Central Nervous System Risks in Hereditary Transthyretin Amyloidosis

Clinicians historically viewed hereditary transthyretin amyloidosis as an exclusive disorder of peripheral nerves and cardiac muscle tissue. However, therapeutic advances have substantially extended patient survival across global cohorts. Consequently, clinicians now observe late-stage complications within the central nervous system with greater regularity. A recent cross-sectional investigation evaluated 151 patients carrying the pathogenic V30M variant at the Unidade Corino de Andrade in Porto. The cohort comprised predominantly male patients (56.3%) with a median age of 48 years. Notably, early-onset disease was present in 94.7% of the cohort, and the median overall disease duration reached 15 years. The investigators sought to systematically characterize central neurological manifestations and evaluate potential biochemical associations. Their findings confirmed that central involvement represents a frequent and clinically meaningful manifestation in longstanding disease. Therefore, multidisciplinary teams must broaden their traditional monitoring protocols beyond autonomic and peripheral nerve function. Neurologists should remain vigilant for cerebral signs in patients living longer with modern therapy. Regular screening for subtle cognitive changes and focal symptoms ensures timely diagnostic clarification and improves supportive interventions.

Clinical Characterization of Transient Focal Neurological Episodes

The primary clinical outcome evaluated in the study was a verified history of transient focal neurological episodes. Widely described as amyloid spells, these stereotyped events affected 29.1% of the evaluated patient cohort. Furthermore, patients reporting past episodes exhibited significantly longer disease durations than individuals who never experienced such events. In addition to focal spells, recurring headaches affected 23.8% of the participants. Seizures developed in 6.6% of patients, whereas overt ischemic or hemorrhagic strokes occurred in 1.3%. Because these brief episodes mimic transient ischemic attacks or migraine auras, clinicians frequently misclassify them during urgent evaluations. These spells typically produce spreading sensory paresthesias, motor weakness, or speech arrest that resolve within minutes. Importantly, treating physicians must distinguish these amyloid-related spells from atherosclerotic thromboembolism to avoid initiating inappropriate thrombolysis. Inappropriate antiplatelet therapy or thrombolytic administration exposes fragile amyloidotic vessels to disastrous intracranial hemorrhage. Consequently, precise clinical history taking and detailed cranial nerve examination remain fundamental for accurate diagnostic triage. Multidisciplinary teams must educate patients to report even minor transient events immediately, enabling timely differential diagnosis.

Evaluating Biomarkers and Plasma Neurofilament Light Chain Trajectories

To assess potential axonal injury markers, investigators quantified plasma neurofilament light chain concentrations cross-sectionally and longitudinally across a twelve-month surveillance protocol. Longitudinally, circulating biomarker levels demonstrated a statistically significant overall time effect across the evaluation periods. However, this fluctuation was driven primarily by a transient reduction occurring between the six-month and twelve-month assessments. Crucially, baseline biomarker levels showed no significant differences when compared directly against either subsequent follow-up assessment. Moreover, biomarker trajectories did not differ between patients with a history of focal episodes and those without events. Plasma neurofilament light chain reflects generalized neuroaxonal damage effectively in progressive peripheral neuropathy. Nevertheless, these longitudinal findings indicate that systemic blood measurements fail to capture localized leptomeningeal amyloid deposition adequately. Consequently, clinicians cannot rely on normal peripheral biomarker concentrations to exclude active central nervous system disease. Serial neuroimaging examinations and targeted clinical reviews remain indispensable for monitoring intracranial involvement. Further research must identify fluid biomarkers specific to central amyloid accumulation, including cerebrospinal fluid panels.

Pathophysiology of Leptomeningeal and Cerebrovascular Deposition

The biological origin of central nervous system involvement in this population relates directly to local transthyretin synthesis within the choroid plexus. While modern gene-silencing therapeutics and tetramer stabilizers successfully suppress hepatic transthyretin production, they demonstrate poor penetrance across the blood-brain barrier. Consequently, choroid plexus epithelial cells continue to produce and secrete amyloidogenic variant protein directly into the cerebrospinal fluid. Over successive decades, insoluble amyloid fibrils progressively deposit along leptomeningeal membranes and within the walls of penetrating cortical arterioles. This structural accumulation promotes severe cerebral amyloid angiopathy, progressive vessel brittleness, and loss of normal vascular autoregulation. Furthermore, leptomeningeal amyloid triggers cortical spreading depolarization, which directly produces the transient spreading deficits characteristic of amyloid spells. As contemporary disease-modifying therapies prolong overall survival, this autonomous intracranial disease process continues unchecked. Therefore, the stark divergence between controlled peripheral neuropathy and progressing intracranial amyloidosis represents an emerging management dilemma. Clinicians must recognize that systemic disease control does not imply central nervous system protection across prolonged survival horizons.

Practical Implications for Long-Term Surveillance in Clinical Practice

These clinical findings carry direct practical implications for neurology and internal medicine practitioners managing hereditary transthyretin amyloidosis cohorts. First, clinicians must incorporate structured central nervous system reviews into routine follow-up protocols, particularly for individuals living with the condition for more than a decade. Specialists should specifically ask patients about transient numbness, fleeting visual disturbances, persistent headaches, and unexplained cognitive fluctuations. Second, high-resolution brain magnetic resonance imaging utilizing blood-sensitive sequences represents an essential diagnostic evaluation. Specifically, susceptibility-weighted imaging can identify cortical superficial siderosis, microbleeds, and chronic convexal subarachnoid blood collections characteristic of cerebral amyloid angiopathy. Third, managing physicians must exercise extreme caution when prescribing antiplatelet or anticoagulant medications in this vulnerable population. Antithrombotic therapies drastically elevate catastrophic intracerebral hemorrhage risks in patients harboring extensive leptomeningeal angiopathy. Finally, future therapeutic development must prioritize central-penetrant transthyretin silencers and stabilizers to halt intracranial amyloid deposition definitively, safeguarding neurological function over decades.

Frequently Asked Questions

What are the primary central nervous system symptoms observed in ATTRv amyloidosis?

The primary central nervous system symptoms include transient focal neurological episodes, recurring headaches, epileptic seizures, and ischemic or hemorrhagic strokes. Transient focal episodes represent the most common manifestation, occurring in nearly thirty percent of patients. These episodes feature spreading sensory or motor deficits that mimic transient ischemic attacks or migraine auras.

Why does central nervous system involvement emerge late in disease progression?

Central nervous system involvement emerges late because the choroid plexus synthesizes transthyretin independently within the brain. While modern disease-modifying therapies effectively halt hepatic protein synthesis, they cannot cross the blood-brain barrier. Consequently, intracranial amyloid fibrils gradually accumulate along leptomeninges and cerebral vessels over fifteen or more years before provoking overt clinical symptoms.

Can plasma neurofilament light chain reliably track central nervous system disease activity?

No, plasma neurofilament light chain levels do not reliably track central nervous system disease activity in these patients. Although the biomarker reflects peripheral nerve damage, its longitudinal trajectory does not correlate with transient focal neurological episodes. Therefore, clinicians should rely on dedicated neuroimaging and rigorous clinical surveillance rather than blood biomarker measurements.

Disclaimer: This content is for informational and educational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider with any questions you may have regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

1. Sousa L et al. Central nervous system manifestations in hereditary transthyretin amyloidosis: a cross-sectional study with 151 patients. J Neurol. 2026 Sep 20. doi: 10.1007/s00415-026-14146-9. PMID: 42763823.


2. Sousa L, et al. CNS Involvement in Hereditary Transthyretin Amyloidosis. Neurology. 2021;97(24):1111-1119. doi:10.1212/WNL.0000000000012965.


3. Charidimou A, et al. Transient focal neurological episodes, cerebral amyloid angiopathy, and intracerebral hemorrhage risk: a meta-analysis. Ann Neurol. 2017;82(3):355-366. doi:10.1002/ana.25038.