Letter to the Editor. Vessel stenosis after Gamma Knife radiosurgery for benign lesions

View More View Less
  • 1 Postgraduate Institute of Medical Education and Research, Chandigarh, India
  • 2 National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
  • 3 Postgraduate Institute of Medical Education and Research, Chandigarh, India
Free access

If the inline PDF is not rendering correctly, you can download the PDF file here.

TO THE EDITOR: We have read with great interest the article by Graffeo et al.1 (Graffeo CS, Link MJ, Stafford SL, et al. Risk of internal carotid artery stenosis or occlusion after single-fraction radiosurgery for benign parasellar tumors [published online October 25, 2019]. J Neurosurg. doi:10.3171/2019.8.JNS191285). We would like to congratulate the authors for evaluating a complication that is otherwise limited to anecdotal case reports. However, we would also like to draw the authors’ attention to a similar topic discussed by us in our earlier publication on the role of Gamma Knife radiosurgery (GKRS) for confined benign cavernous sinus tumors.2

Their article outlines several messages. Vascular complications following GKRS are uncharted territory, and the literature is very sparse and scattered in its discussion. In the authors’ subgroup analysis of 283 patients with cavernous sinus meningioma (CSM) or growth hormone–secreting pituitary adenoma (GHPA), 8 (2.8%) patients showed evidence of internal carotid artery (ICA) occlusion/stenosis, of which only 2 (0.71%) cases were clinically symptomatic. No GHPA or category 1 CSM patient developed postradiosurgical ICA occlusion/stenosis. The median time to stenosis was 4.8 years (IQR 1.8–7.6 years). The 5- and 10-year actuarial risks of any new ICA stenosis/occlusion in category 2 and 3 CSM were 7.5% and 12.4%, respectively. Five- and 10-year risks of ischemic stroke in category 2 and 3 CSM patients were both 1.2%. The only variables predictive of stenosis/occlusion were the pre–stereotactic radiosurgery (SRS) carotid encasement grade and a younger patient age. Interestingly, there was no difference in outcome in terms of the dosimetry parameter.3

Post-SRS occlusive vasculopathy is a rare phenomenon. To date, the tolerance dose for a vessel has not been decided.2 Conventional wisdom dictates that high-flow vessels such as the carotid segment of the ICA are relatively more resistant to any radiation vasculopathy. GKRS can lead to both occlusive or proliferative vasculopathy. Our experience with post-GKRS vasculopathy is mostly driven by laboratory studies and patients with arteriovenous malformations (AVMs).4,5 In an unpublished analysis, we identified 19 patients who suffered from stenosis/obliteration of vessels most commonly in the zone of radiation and sometimes in the zone outside the radiation. Most of these patients were treated for AVM, CSM, or trigeminal neuralgia. Proliferative vasculopathy includes the development of additional vascular pathologies after radiation owing to the proliferation of existing vessels and neovascularization. The proliferative pathologies are cavernous malformation, angiomatous changes, capillary hemangioma, or development of moyamoya vasculature.

From the authors’ study, one cannot ascertain if dosimetry does not influence vessel occlusion. Because of the inherent dose inhomogeneity of GKRS, it remains a fair possibility that zones of high radiation, also known as “hot spots,” may have been on the vessel wall, causing a high dose distribution in that area. The authors themselves have mentioned this limitation in their article as the treatment plan could not be reproduced and coregistered to analyze the same. This concern has already been raised by Abeloos et al.6 in their experience with a CSM patient who slowly developed occlusion of the ipsilateral cavernous ICA over 40 months but remained clinically asymptomatic. Similarly, Maher and Pollock7 reported occlusion of the superior cerebellar artery (SCA) along with accompanying veins in a patient with trigeminal neuralgia treated with GKRS.8 The patient did not respond to GKRS and underwent microvascular decompression. Intraoperatively, both the SCA and the accompanying veins had vasculopathy presumably due to radiation. Whether the exposed length of vessel or hot spot on the vessel has any significant prognostic value and in what time frame remain matters for further research. Historically, GK pallidotomy for dystonia was a contraindication, while GK thalamotomy was established as a suitable alternate technique for essential tremors. One of the reasons for the high complications with pallidotomy has been the predictability of hyperresponders in the pallidum. The popular hypothesis is radiation-induced injury to the lenticulostriate arteries in that territory whose response cannot be predicted. Contrary to this, thalamotomy results in the expected lesion size in nearly 98% of patients.

Interestingly, symptomatic occlusion is very rare and mostly manageable with observation and conservative management with aspirin. In the authors’ literature review, only one patient needed emergent balloon angioplasty, and all patients but one improved significantly. The literature also stresses that most ICA stenosis/occlusion is asymptomatic thanks to sufficient flow from the contralateral side. Another possibility is the development of alternate channels (which may be a feature of compensatory proliferative vasculopathy) bypassing the occluded channel.

Over the last 3 decades, robust literature in support of GKRS for benign confined cavernous sinus tumor has documented its safety and efficacy over microsurgical resection.2 However, whether one needs to change the policy in deciding the best treatment modality for future patients in light of the current article remains a question. We believe that patients with category 2–3 ICA encasement should be informed of this risk but should also be assured that the 5- and 10-year actuarial risks of symptomatic stroke are very remote (1.2%).1 For these high-risk patients, follow-up imaging should routinely involve CT or MR angiography apart from routine follow-up radiology.

Whether we should titrate the risk as per the pathology remains elusive as, contrary to the authors’ experience, other reports have shown a higher risk of occlusion in cases of pituitary adenoma (29%) than in CSM (18%).1 It is interesting to note that no case has been reported for other cavernous sinus tumors such as cavernous sinus hemangiomas (CSHs), trigeminal schwannomas, or metastatic cavernous sinus tumors. We support the authors’ hypothesis of a likely cause of vascular encroachment and contraction post-GKRS in the case of CSM, which is a less likely phenomenon with lesions such as CSHs or schwannomas, which push rather than infiltrate the vessel.

Although the authors found a statistical inverse correlation between the chance of ICA occlusion/stenosis and increased patient age, this does not seem plausible as vessels have higher chances of occlusion due to atherosclerotic changes with advancing age. Given the authors’ small sample size, most likely this finding needs further evaluation and follow-up.

In the absence of conclusive evidence, vascular complications after radiosurgery for intracranial pathologies can be ignored as a freak accident. Until more robust literature becomes available, the article by Graffeo et al. may help with risk stratification in the small subgroup of CSM patients only.1

Disclosures

The authors report no conflict of interest.

References

  • 1

    Graffeo CS, Link MJ, Stafford SL, Risk of internal carotid artery stenosis or occlusion after single-fraction radiosurgery for benign parasellar tumors [published online October 25, 2019]. J Neurosurg. doi:10.3171/2019.8.JNS191285

    • Search Google Scholar
    • Export Citation
  • 2

    Mukherjee KK, Kumar N, Tripathi M, Dose fractionated gamma knife radiosurgery for large arteriovenous malformations on daily or alternate day schedule outside the linear quadratic model: proof of concept and early results. A substitute to volume fractionation. Neurol India. 2017;65(4):826835.

    • Search Google Scholar
    • Export Citation
  • 3

    Tripathi M, Batish A, Kumar N, Safety and efficacy of single-fraction gamma knife radiosurgery for benign confined cavernous sinus tumors: our experience and literature review [published online April 9, 2018]. Neurosurg Rev. doi:10.1007/s10143-018-0975-8

    • Search Google Scholar
    • Export Citation
  • 4

    Tripathi M, Rekhapalli R, Batish A, Safety and efficacy of primary multisession dose fractionated Gamma Knife radiosurgery for jugular paragangliomas. World Neurosurg. 2019;131:e136e148.

    • Search Google Scholar
    • Export Citation
  • 5

    Tripathi M. Dose-fractionated Gamma Knife radiosurgery for large-volume arteriovenous malformations [letter]. J Neurosurg. 2018;129(6):16601662.

    • Search Google Scholar
    • Export Citation
  • 6

    Abeloos L, Levivier M, Devriendt D, Massager N. Internal carotid occlusion following gamma knife radiosurgery for cavernous sinus meningioma. Stereotact Funct Neurosurg. 2007;85(6):303306.

    • Search Google Scholar
    • Export Citation
  • 7

    Maher C, Pollock B. Radiation induced vascular injury after stereotactic radiosurgery for trigeminal neuralgia: case report. Surg Neurol. 2000;54(2):189193.

    • Search Google Scholar
    • Export Citation
  • 8

    Tripathi M. Trigeminal neuralgia: an orphan with many fathers. Neurol India. 2019;67(2):414416.

View More View Less
  • Mayo Clinic, Rochester, MN

Response

We appreciate the interest of Tripathi and colleagues in our recent article. At a center that has performed SRS for 30 years, we believe that it is important not only to report on the long-term successes of this approach for a wide variety of diseases, but also to chronicle rare complications that may not have been encountered at centers with less experience.1–5 We agree that patients should be fully counseled regarding the risk of infrequent complications following SRS. However, these complications should not be used as justification for choosing alternative treatment approaches over SRS for appropriate patients.

References

  • 1

    Maher CO, Pollock BE. Radiation induced vascular injury after stereotactic radiosurgery for trigeminal neuralgia: case report. Surg Neurol. 2000;54(2):189193.

    • Search Google Scholar
    • Export Citation
  • 2

    Nagy G, McCutcheon BA, Giannini C, Radiation-induced cavernous malformations after single-fraction meningioma radiosurgery. Oper Neurosurg (Hagerstown). 2018;15(2):207212.

    • Search Google Scholar
    • Export Citation
  • 3

    Pollock BE, Brown RD Jr. Management of cysts arising after radiosurgery of intracranial arteriovenous malformations. Neurosurgery. 2001;49(2):259265.

    • Search Google Scholar
    • Export Citation
  • 4

    Pollock BE, Link MJ, Branda ME, Storlie CB. Incidence and management of late adverse radiation effects after arteriovenous malformation radiosurgery. Neurosurgery. 2017;81(6):928934.

    • Search Google Scholar
    • Export Citation
  • 5

    Pollock BE, Link MJ, Stafford SL, The risk of radiation-induced tumors or malignant transformation after single-fraction intracranial radiosurgery: results based on a 25-year experience. Int J Radiat Oncol Biol Phys. 2017;97(5):919923.

    • Search Google Scholar
    • Export Citation

If the inline PDF is not rendering correctly, you can download the PDF file here.

Contributor Notes

Correspondence Manjul Tripathi: drmanjultripathi@gmail.com.

INCLUDE WHEN CITING Published online January 3, 2020; DOI: 10.3171/2019.11.JNS192948.

Disclosures The authors report no conflict of interest.

  • 1

    Graffeo CS, Link MJ, Stafford SL, Risk of internal carotid artery stenosis or occlusion after single-fraction radiosurgery for benign parasellar tumors [published online October 25, 2019]. J Neurosurg. doi:10.3171/2019.8.JNS191285

    • Search Google Scholar
    • Export Citation
  • 2

    Mukherjee KK, Kumar N, Tripathi M, Dose fractionated gamma knife radiosurgery for large arteriovenous malformations on daily or alternate day schedule outside the linear quadratic model: proof of concept and early results. A substitute to volume fractionation. Neurol India. 2017;65(4):826835.

    • Search Google Scholar
    • Export Citation
  • 3

    Tripathi M, Batish A, Kumar N, Safety and efficacy of single-fraction gamma knife radiosurgery for benign confined cavernous sinus tumors: our experience and literature review [published online April 9, 2018]. Neurosurg Rev. doi:10.1007/s10143-018-0975-8

    • Search Google Scholar
    • Export Citation
  • 4

    Tripathi M, Rekhapalli R, Batish A, Safety and efficacy of primary multisession dose fractionated Gamma Knife radiosurgery for jugular paragangliomas. World Neurosurg. 2019;131:e136e148.

    • Search Google Scholar
    • Export Citation
  • 5

    Tripathi M. Dose-fractionated Gamma Knife radiosurgery for large-volume arteriovenous malformations [letter]. J Neurosurg. 2018;129(6):16601662.

    • Search Google Scholar
    • Export Citation
  • 6

    Abeloos L, Levivier M, Devriendt D, Massager N. Internal carotid occlusion following gamma knife radiosurgery for cavernous sinus meningioma. Stereotact Funct Neurosurg. 2007;85(6):303306.

    • Search Google Scholar
    • Export Citation
  • 7

    Maher C, Pollock B. Radiation induced vascular injury after stereotactic radiosurgery for trigeminal neuralgia: case report. Surg Neurol. 2000;54(2):189193.

    • Search Google Scholar
    • Export Citation
  • 8

    Tripathi M. Trigeminal neuralgia: an orphan with many fathers. Neurol India. 2019;67(2):414416.

  • 1

    Maher CO, Pollock BE. Radiation induced vascular injury after stereotactic radiosurgery for trigeminal neuralgia: case report. Surg Neurol. 2000;54(2):189193.

    • Search Google Scholar
    • Export Citation
  • 2

    Nagy G, McCutcheon BA, Giannini C, Radiation-induced cavernous malformations after single-fraction meningioma radiosurgery. Oper Neurosurg (Hagerstown). 2018;15(2):207212.

    • Search Google Scholar
    • Export Citation
  • 3

    Pollock BE, Brown RD Jr. Management of cysts arising after radiosurgery of intracranial arteriovenous malformations. Neurosurgery. 2001;49(2):259265.

    • Search Google Scholar
    • Export Citation
  • 4

    Pollock BE, Link MJ, Branda ME, Storlie CB. Incidence and management of late adverse radiation effects after arteriovenous malformation radiosurgery. Neurosurgery. 2017;81(6):928934.

    • Search Google Scholar
    • Export Citation
  • 5

    Pollock BE, Link MJ, Stafford SL, The risk of radiation-induced tumors or malignant transformation after single-fraction intracranial radiosurgery: results based on a 25-year experience. Int J Radiat Oncol Biol Phys. 2017;97(5):919923.

    • Search Google Scholar
    • Export Citation

Metrics

All Time Past Year Past 30 Days
Abstract Views 57 57 0
Full Text Views 39 39 10
PDF Downloads 39 39 10
EPUB Downloads 0 0 0