Spontaneous Regression of Vestibular Schwannomas: Clinical Significance of two Cases

Introduction: Vestibular schwannomas are the most common tumors of the cerebellopontine angle. Although benign, their clinical course is highly variable. While surgery or radiosurgery is typically considered for enlarging or symptomatic lesions, some tumors may remain stable or rarely regress spontaneously. Such heterogeneity complicates decision-making in daily practice. Case Presentation: Case 1: A 64-year-old man presented with progressive hearing loss and tinnitus. MRI demonstrated a large left vestibular schwannoma measuring 4.7 cm. Suboccipital craniotomy achieved near total resection, leaving tumor capsule adherent to the facial nerve. Six months later, imaging showed regrowth of the residual mass, and adjuvant radiosurgery was considered. Unexpectedly, MRI performed 2.5 years later revealed marked spontaneous shrinkage to 1.5 cm, with the patient remaining clinically stable without additional intervention. Case 2: A 46-year-old man with a 3.3 cm right vestibular schwannoma consisting of cystic and solid components declined surgery. He was lost to follow-up and re-presented seven years later with imaging that revealed cyst absorption and reduction of the solid portion. A follow-up MRI three years afterward confirmed further decrease in tumor size to 2.4 × 1.4 × 1.2 cm, correlating with symptomatic improvement of headache. Discussion: Both cases illustrate that regression can occur in residual as well as untreated tumors, even after initial evidence of regrowth. These findings raise important clinical questions: Is immediate adjuvant treatment always necessary after postoperative regrowth? Can conservative monitoring be justified in larger, heterogeneous tumors when patients decline intervention? Long-term observation allowed safe documentation of regression in both patients, highlighting the need for careful follow-up before deciding on invasive strategies. Conclusion: Spontaneous regression of vestibular schwannomas, though uncommon, is a clinically relevant phenomenon. Management plans should incorporate the possibility of regression, particularly in patients with minimal symptoms or high surgical risk. Long-term imaging surveillance is an essential component of individualized care. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany