Abstract:
Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating multisystem disorder characterized by profound fatigue, post-exertional malaise (PEM), immune dysregulation, and mitochondrial dysfunction. While radiation exposure has been linked to fatigue syndromes with overlapping pathophysiology, no previous reports have described the effects of therapeutic radiation, including proton beam radiotherapy (PBRT), in patients with ME/CFS.
Case presentation: We report the case of a 46-year-old woman with a pre-existing, clinically confirmed diagnosis of ME/CFS (Bell score 60, ECOG 1), who underwent postoperative PBRT (50.4 Gy in 28 fractions) for a recurrent left sphenoid wing meningioma (CNS WHO grade 1). The tumor had been surgically resected but showed residual disease with early postoperative progression and close proximity to the left optic nerve, prompting the indication for adjuvant radiotherapy. The patient initially tolerated treatment well, with only mild acute worsening of pre-existing fatigue and transient corticosteroid-responsive symptoms. However, within weeks of completing radiotherapy, she developed progressive and severe worsening of fatigue, myalgia, vertigo, and hypersensitivity to sensory stimuli as well as cognitive decline. Over several months, she became completely bedridden (Bell score 0, ECOG 4) with persistent ME/CFS aggravation unresponsive to supportive measures persisting until the last known contact 20 months after radiation. Follow-up imaging showed stable postoperative findings without tumor progression or new structural brain lesions.
Discussion: This case illustrates a profound and irreversible deterioration of ME/CFS following PBRT, suggesting that radiation-induced mitochondrial dysfunction, oxidative stress, and chronic inflammatory activation may critically worsen pre-existing metabolic fragility. Despite the theoretical advantages of proton radiotherapy in reducing normal tissue exposure, its protective effects may be insufficient in patients with baseline mitochondrial malfunction.
Conclusion: This is, to our knowledge, the first reported case of severe and sustained ME/CFS exacerbation after radiotherapy. The case emphasizes the urgent need for risk stratification, tailored consent processes, and research in the field of radiotherapy tolerance in ME/CFS patients, as conventional expectations regarding side effects may not predict outcomes in this vulnerable population.
Source: Fischer C, Seidlitz A, Krause M. Significant aggravation of pre-existing myalgic encephalomyelitis/chronic fatigue syndrome following proton beam therapy for sphenoid wing meningioma: case report. Strahlenther Onkol. 2026 Jun 11. doi: 10.1007/s00066-026-02553-w. Epub ahead of print. PMID: 42277311. https://link.springer.com/article/10.1007/s00066-026-02553-w (Full text)