Rare Bleeding Inside Vestibular Schwannomas After Radiosurgery Reviewed in 47 Cases

Vestibular schwannomas are benign tumors of the vestibulocochlear nerve, and stereotactic radiosurgery (SRS) is a widely used, generally well-tolerated way to control them without open surgery. A new systematic review now pulls together the published record of one of its rarest complications: bleeding inside the tumor after radiosurgery. The review, registered with PROSPERO (CRD42024511320) and conducted under PRISMA 2020 guidelines, identified 11 studies encompassing 47 patients who developed intratumoral hemorrhage (ITH) after SRS or Gamma Knife surgery.

The search covered PubMed, Google Scholar, the Cochrane Library, Embase, Web of Science and Scopus through January 2024, and started from 719 articles. After removing 173 duplicates and screening 546 records, the authors assessed 15 papers for eligibility and excluded five that lacked evidence of radiosurgery. Only cases in which hemorrhage occurred after SRS were included; tumors that bled before or independently of radiosurgery were eliminated, as were reviews, articles without full text, and reports lacking detailed clinical information. Reference lists were also hand-searched for additional qualifying cases.

The patients ranged from 25 to 79 years old, with an average age of 52 years and a clustering of cases in the sixth decade and among people aged 60 and above. Fifty-four percent of the patients were female, while 4.3% could not be clearly identified as male or female. Because every included study was a case report or small case series, these demographic patterns are descriptive summaries of a heterogeneous literature rather than population-level estimates.

A subset of patients carried identifiable bleeding risk factors. Six individuals showed elevated susceptibility to bleeding: two had uncontrolled hypertension, three were taking antiplatelet medications, and two were on anticoagulation. One case combined bleeding and clotting abnormalities with hypertension and trauma-induced coagulopathy, and one patient had hypertension while two others were prescribed the anticoagulants rivaroxaban and apixaban for atrial fibrillation. The authors argue that these patterns underscore the value of evaluating each patient’s risk profile, since pre-existing conditions and medications may contribute substantially to post-radiosurgical bleeding events.

The radiosurgical techniques and doses varied across reports. Marginal doses for SRS typically ranged around 12 Gy (12.0 to 12.3 Gy), with maximum doses between 21.8 and 24.0 Gy and isodose lines of 50 to 55%. Within the Gamma Knife subgroup, median marginal doses ranged around 11 Gy (10 to 12.5 Gy) with isodose lines of 46 to 50%. One unusual case combined subtotal microsurgical resection with Gamma Knife treatment at 13 Gy to the 46% isodose surface, alongside a hemicraniectomy for a large residual tumor.

The timing of bleeding varied widely. The interval between radiosurgery and first symptoms was documented for 34 of the 47 patients. Five patients developed symptoms at 2, 3, 6, 106 and 130 months after treatment; one experienced tumor enlargement and hemorrhage 27 months after Gamma Knife surgery; another showed mass enlargement and irregular enhancement on T2-weighted imaging three and a half years after Gamma Knife radiosurgery; and one patient reported severe vertigo, worsening ataxia and mild facial deviation just ten days after treatment. Among 26 participants, the mean interval between SRS and hemorrhage symptoms was 10 months.

Symptoms were heterogeneous. Trigeminal neuropathy was the most frequently reported presentation, affecting roughly 23.91% of patients, while dysequilibrium, facial weakness and facial sensory loss in the V2 and V3 distributions together accounted for about 21.74%. Cerebellar ataxia appeared in about 17.39% of cases, and headache and hearing decline or loss each in about 13.04%. Rarer manifestations included facial pain, right facial dysesthesia, cranial nerve V through X palsy, hemifacial spasm and severe facial motor paresis. The authors attribute this pattern to the tumor’s location at the cerebellopontine angle, where expanding hemorrhage can compress the brainstem and nearby cranial nerves.

Management ranged from observation to urgent surgery. Radiological monitoring, a wait-and-scan approach with serial imaging, was the most common single intervention at about 17.39% of cases, and a further cautious observational strategy accounted for 8.70%. Radical resection combined with salvage microsurgery was used in 8.70% of patients. Less common procedures, each at 2.17%, included a retrosigmoid approach with steroids and osmotherapy, oral steroids with surgical decompression, retrosigmoid suboccipital craniotomy, retromastoid craniectomy with subtotal tumor resection, initial observation with late resection, and translabyrinthine approaches. Choice of treatment, the review notes, depends on how acutely the patient presents, hemorrhage size, evidence of expansion, and compression of surrounding neurovascular structures.

Outcomes must be read with considerable caution. On descriptive analysis, approximately half of the 47 patients had outcomes the original authors classified as favorable, with 2.17% remaining stable, 4.35% showing no recurrence and 2.17% reporting improved symptoms. Disease progression and mortality were each reported in 4.35% of patients, corresponding to 2 deaths among 47. The review’s own limitations section is explicit: all included studies were case reports or small series with high risk of bias, no meta-analysis was possible due to heterogeneity, outcome definitions were not standardized, and there was no comparator group of untreated patients, so no causal conclusion about SRS-attributable hemorrhage risk can be drawn. Under the GRADE framework, the certainty of evidence for all outcomes is rated as very low.

Context from prior work helps frame the findings. Niknafs and colleagues estimated spontaneous hemorrhage in 0.4 to 1% of vestibular schwannomas, while Carlson and colleagues reported clinically significant post-radiosurgical hemorrhage in 1.6% of patients, identifying tumor size and cystic change as risk factors. The multi-institutional study by Bin-Alamer and colleagues, which contributed 25 of the 47 patients in this review, corroborated those factors and added anticoagulant use, with dysequilibrium as the most common presenting symptom. Larger tumors over 3.0 cm, cystic change, hypointense T2-weighted areas, hemosiderin deposition and anticoagulation have all been associated with bleeding. The review concludes that personalized management, vigilant monitoring for new or worsening symptoms after radiosurgery, and multidisciplinary collaboration between neurosurgeons and radiation oncologists remain essential, and that future studies should directly compare irradiated and non-irradiated patients to clarify any additional risk radiosurgery may confer.

Subject of Research: Intratumoral hemorrhage after stereotactic radiosurgery for vestibular schwannomas

Article Title: Intratumoral hemorrhage in vestibular schwannomas post-radiosurgery: a systematic review

Article References: Fareed, A., Qureshi, K., Farhat, S., Chaurasia, B., Moradeyo, A., Ghanem, L., Vaid, R., Akhtar, S. M. M., Awaida, I., Kerhani, A. A., & Yangi, K. (2026). Intratumoral hemorrhage in vestibular schwannomas post-radiosurgery: a systematic review. Chinese Neurosurgical Journal, 12(1), Article 18. https://doi.org/10.1186/s41016-026-00439-5

Image Credits: AI Generated

DOI: 10.1186/s41016-026-00439-5

Keywords: vestibular schwannoma, intratumoral hemorrhage, stereotactic radiosurgery, Gamma Knife, systematic review, hypertension, anticoagulants, trigeminal neuropathy, case reports, PROSPERO, Intratumoral, hemorrhage