Cerebral radionecrosis: is surgery necessary?

Laser interstitial thermal therapy for treatment of cerebral radiation necrosis

Radiation necrosis is a well described complication after radiosurgical treatment of intracranial pathologies - best recognized after the treatment of patients with arteriovenous malformations and brain metastases but possibly also affecting patients treated with radiosurgery for meningioma. The pathophysiology of radiation necrosis is still not well understood but is most likely a secondary local tissue inflammatory response to brain tissue injured by radiation. Radiation necrosis in brain metastases patients may present radiographically and behave clinically like recurrent tumor. Differentiation between radiation necrosis and recurrent tumor has been difficult based on radiographic changes alone. Biopsy or craniotomy therefore remains the gold standard method of diagnosis. For symptomatic patients, corticosteroids are first-line therapy, but patients may fail medical management due to intolerance of chronic steroids or persistence of symptoms. In these cases, open surgical resection has been shown to be successful in management of surgically amenable lesions but may be suboptimal in patients with deep-seated lesions or extensive prior cranial surgical history, both carrying high risk for peri-operative morbidity. Laser interstitial thermal therapy has emerged as a viable, alternative surgical option. In addition to allowing access to tissue for diagnosis, thermal treatment of the lesion can also be delivered precisely and accurately under real-time imaging guidance. This review highlights the pertinent studies that have shaped the impetus for use of laser interstitial thermal therapy in the treatment of radiation necrosis, reviewing indications, outcomes, and nuances toward successful application of this technology in patients with suspected radiation necrosis.

Laser interstitial thermotherapy (LITT) for the treatment of tumors of the brain and spine: a brief review

INTRODUCTION

Laser Interstitial Thermotherapy (LITT; also known as Stereotactic Laser Ablation or SLA), is a minimally invasive treatment modality that has recently gained prominence in the treatment of malignant primary and metastatic brain tumors and radiation necrosis and studies for treatment of spinal metastasis has recently been reported.

METHODS

Here we provide a brief literature review of the various contemporary uses for LITT and their reported outcomes.

RESULTS

Historically, the primary indication for LITT has been for the treatment of recurrent glioblastoma (GBM). However, indications have continued to expand and now include gliomas of different grades, brain metastasis (BM), radiation necrosis (RN), other types of brain tumors as well as spine metastasis. LITT is emerging as a safe, reliable, minimally invasive clinical approach, particularly for deep seated, focal malignant brain tumors and radiation necrosis. The role of LITT for treatment of other types of tumors of the brain and for spine tumors appears to be evolving at a small number of centers. While the technology appears to be safe and increasingly utilized, there have been few prospective clinical trials and most published studies combine different pathologies in the same report.

CONCLUSION

Well-designed prospective trials will be required to firmly establish the role of LITT in the treatment of lesions of the brain and spine.

Temporal Lobe Necrosis Following Radiotherapy in Nasopharyngeal Carcinoma: New Insight Into the Management

Cerebral radiation necrosis (CRN) is one of the most prominent sequelae following radiation therapy for nasopharyngeal carcinoma (NPC), which might have devastating effects on patients' quality of life (QOL). Advances in histopathology and neuro-radiology have shed light on the management of CRN more comprehensively, yet effective therapeutic interventions are still lacking. CRN was once regarded as progressive and irreversible, however, in the past 20 years, with the application of intensity-modulated radiation therapy (IMRT), both the incidence and severity of CRN have declined. In addition, newly developed medical agents including bevacizumab-a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), nerve growth factor (NGF), monosialotetrahexosylganglioside (GM1), etc., have shown great potency in successfully reversing radiation-induced CRN. As temporal lobes are most frequently compromised in NPC patients, this review will summarize the state-of-the-art progress regarding the incidence, pathophysiology, prevention, treatment, and prognosis of temporal lobe necrosis (TLN) after IMRT in NPC.

[Management of cerebral radionecrosis: experience in the Department of Neurology at the Mohammed V Military Teaching Hospital]

La radionécrose cérébrale est une complication rare mais redoutable de la radiothérapie externe pour les cancers ORL en particulier du nasopharynx et pour les tumeurs cérébrales. Peu de travaux se sont intéressés à cette complication aussi bien dans la population maghrébine qu'africaine. L'objectif de notre étude est donc de décrire les aspects démographiques, cliniques, paracliniques, thérapeutiques et évolutifs de la radionécrose cérébrale au sein du Service de Neurologie de l'Hôpital Militaire d'Instruction Mohammed V de Rabat (HMIMV) sur une durée de 18 ans (2000-2017). Il s'agissait de 04 femmes et 13 hommes âgés en moyenne de 50 ans. Le délai moyen entre la fin de la radiothérapie et le début des signes neurologiques était de 28 mois. La réalisation systématique d'une IRM cérébrale parfois complété d'une spectro-IRM avait permis de faire le diagnostic chez 100% des cas. Sur le plan étiologique, cette complication survenait après radiothérapie pour cancer du cavum et du larynx chez tous les cas. 15 patients ont été traités par l'association: corticothérapie en bolus, antiagrégants plaquettaires, associée à l'oxygénation hyperbare (OHB) avec une bonne évolution, et 2 patients, chez qui l'oxygénothérapie était contre-indiquée pour problème pulmonaire, et ORL, ont reçu l'association corticothérapie en bolus et antiagrégants plaquettaires avec une évolution stationnaire. À la lumière de ces résultats, nous insistons sur l'intérêt du diagnostic précoce en raison de la gravité potentielle de certains tableaux surtout neuropsychiatriques ainsi que sur le traitement par association bolus de corticoïdes + OHB car il est le meilleure garant d'une évolution favorable de ces atteintes, sans omettre le rôle crucial des mesures de prévention.

Cerebral Radiation Necrosis: Incidence, Pathogenesis, Diagnostic Challenges, and Future Opportunities

PURPOSE OF REVIEW

Cerebral radiation necrosis (CRN) is a major dose-limiting adverse event of radiotherapy. The incidence rate of RN varies with the radiotherapy modality, total dose, dose fractionation, and the nature of the lesion being targeted. In addition to these known and controllable features, there is a stochastic component to the occurrence of CRN-the genetic profile of the host or the lesion and their role in the development of CRN.

RECENT FINDINGS

Recent studies provide some insight into the genetic mechanisms underlying radiation-induced brain injury. In addition to these incompletely understood host factors, the diagnostic criteria for CRN using structural and functional imaging are also not clear, though multiple structural and functional imaging modalities exist, a combination of which may prove to be the ideal diagnostic imaging approach. As the utilization of novel molecular therapies and immunotherapy increases, the incidence of CNR is expected to increase and its diagnosis will become more challenging. Tissue biopsies can be insensitive and suffer from sampling biases and procedural risks. Liquid biopsies represent a promising, accurate, and non-invasive diagnostic strategy, though this modality is currently in its infancy. A better understanding of the pathogenesis of CRN will expand and optimize the diagnosis and management of CRN by better utilizing existing treatment options including bevacizumab, pentoxifylline, hyperbaric oxygen therapy, and laser interstitial thermal therapy.

Surgical Management of Adverse Radiation Effects After Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformations: A Population-Based Cohort Study

OBJECTIVE

The goal of this study is to report our experience in the surgical treatment of cerebral arteriovenous malformations (cAVMs) related permanent symptomatic adverse radiation effects (PSAREs), to clarify an appropriate surgical management and to identify the risk factors related to their development.

METHODS

We evaluated 549 patients treated with Gamma Knife radiosurgery (GKRS) for cAVMs with a follow-up of at least 8 years. Univariate and multivariate analyses were used to test different risk factors related to the development of PSARE. We retrospectively reviewed the records of these patients to analyze the clinical outcome.

RESULTS

Fourteen patients (2.5%) developed PSARE and were submitted to surgery. Higher average treated volume represents a significant risk factors for the development of PSARE (P < 0.05); on the other hand, older age and higher average dose reduce the risk of PSARE (P < 0.05). A favorable clinical outcome was achieved in 13 patients (93%) after surgery; in 1 patient, the unfavorable outcome was due to hemorrhage that occurred months after GKRS. Serial MRI scans following either surgical removal of the nodule or Ommaya reservoir positioning showed progressive reduction of brain edema in all cases.

CONCLUSIONS

The management of PSARE is controversial, especially for cAVMs treated with SRS. Surgical removal is rarely needed, but-if unavoidable-it can be a valuable option in experienced hands. A careful preoperative planning is always necessary to detect pathologic blood flow through the PSARE.

A prospective, multicentre, single-arm clinical trial of bevacizumab for patients with surgically untreatable, symptomatic brain radiation necrosis†

Background

Brain radiation necrosis (BRN) can be a complication of radiotherapy for primary and secondary brain tumors, as well as head and neck tumors. Since vascular endothelial growth factor (VEGF) is also a vascular permeability factor in the brain, bevacizumab, a humanized antibody that inhibits VEGF, would be expected to reduce perilesional edema that often accompanies BRN.

Methods

Patients with surgically untreatable, symptomatic BRN refractory to conventional medical treatments (eg, corticosteroid, anticoagulants, or hyperbaric oxygen therapy) were enrolled. We judged that a major cause of perilesional edema with a lesion-to-normal brain ratio ≤1.8 on ¹¹C-methionine or ≤2.5 on ¹⁸F-boronophenylalanine PET was BRN, not tumor recurrence, and 6 cycles of biweekly bevacizumab (5 mg/kg) were administered. The primary endpoint was a ≥30% reduction from the patients' registration for perilesional edema continuing for ≥1 month.

Results

Of the 41 patients enrolled, 38 were fully eligible for the response assessment. The primary endpoint was achieved in 30 of the 38 (78.9%) patients at 3.0 months (median) after enrollment. Sixteen patients (42.1%) experienced improvement of their Karnofsy Performance Score. Corticosteroid use could be reduced in 29 patients (76.3%). Adverse events at grade ≥3 occurred in 10 patients (24.4%).

Conclusions

Bevacizumab treatment offers certain clinical benefits for patients with surgically untreatable, symptomatic BRN. The determination of BRN using amino-acid PET, not biopsy, is adequate and less invasive for determining eligibility to receive bevacizumab.

Delayed cerebral radiation necrosis after neutron beam radiation of a parotid adenocarcinoma: a case report and review of the literature

Cerebral radiation necrosis (CRN) is a well described possible complication of radiation for treatment of intracranial pathology. However, CRN as sequelae of radiation to extracranial sites is rare. Neutron beam radiation is a highly potent form of radiotherapy that may be used to treat malignant tumors of the salivary glands. This report describes a patient who underwent neutron beam radiation for a parotid adenocarcinoma and who developed biopsy-confirmed temporal lobe radiation necrosis thirty months later. This represents the longest time interval described to date, from initial neutron radiation for extracranial pathology to development of CRN. Two other detailed case studies exist in the literature and are described in this report. These reports as well as our patient's case are reviewed, and additional recommendations are made to minimize the development of CRN after extracranial neutron beam radiation. Physicians should include the possible diagnosis of CRN in any patient with new neurologic signs or symptoms and a history of head and neck radiation that included planned fields extending to the base of the skull. Counseling of patients prior to neutron beam radiation should include potential neurologic complications associated with CRN and risks of treatment for CRN including neurosurgical intervention.

Cerebral radiation necrosis: a review of the pathobiology, diagnosis and management considerations

Radiation therapy forms one of the building blocks of the multi-disciplinary management of patients with brain tumors. Improved survival following radiation therapy may come with a cost, including the potential complication of radiation necrosis. Radiation necrosis impacts the quality of life in cancer survivors, and it is essential to detect and effectively treat this entity as early as possible. Significant progress in neuro-radiology and molecular pathology facilitate more straightforward diagnosis and characterization of cerebral radiation necrosis. Several therapeutic interventions, both medical and surgical, may halt the progression of radiation necrosis and diminish or abrogate its clinical manifestations, but there are still no definitive guidelines to follow explicitly that guide treatment of radiation necrosis. We discuss the pathobiology, clinical features, diagnosis, available treatment modalities, and outcomes in the management of patients with intracranial radiation necrosis that follows radiation used to treat brain tumors.

Radionécrose cérébrale chez les patients irradiés pour cancer du nasopharynx: à propos de neuf cas

PURPOSE

To study the clinical, radiological, therapeutic and progressive aspects of brain radionecrosis after treatment for nasopharyngeal carcinoma.

PATIENTS AND METHODS

Nine patients (seven men and two women) of mean age 47.7 years old (extremes: 18-57 years old) were treated for UCNT (undifferentiated carcinoma of the nasopharynx) between 1989 and 2003 and developed cerebral radionecrosis. All patients were treated with radical radiotherapy. The mean total dose was 73.5 Gy (70-75 Gy). Dose per fraction was 2 to 2.5 Gy, one fraction daily. One patient received adjuvant brachytherapy to the dose of 8 Gy and four patients also received chemotherapy.

RESULTS

Brain radionecrosis was authenticated by brain imaging (CT scan+/-MRI): the imaging was ordered in seven cases to elucidate non-specific neurological signs and two cases were discovered fortuitously. The time to the appearance of neurological signs was 40.3 months (10 to 108 months). The localization was temporal in six cases, parieto-occipital (one case) and bulbomedullar (two cases). After a mean follow-up period of 30.6 months (12-84 months), clinical outcomes were favorable in all cases receiving medical treatment (corticoids), with a stabilization of the radiological lesions in eight cases and complete radiological regression in one patient.

CONCLUSION

Brain radionecrosis is a late complication rarely occurring in patients irradiated for UCNT. Imaging techniques (CT scan but more so MRI) play a major role in the diagnosis. Corticotherapy resulted in a durable objective response in all patients and, in most cases, resulted in radiological stabilization.

Cerebral necrosis after 25Gy radiotherapy in childhood followed 28 years later by 54Gy radiotherapy

The development of brain necrosis is life-long risk of repeat radiation therapy, even after a long time interval and a moderate radiation dose. We report on a 34-year-old patient who had prophylactic cranial irradiation with 25Gy and adjuvant chemotherapy in childhood for leukaemia and in adulthood, 28 years later, therapeutic radiotherapy with 54Gy for an atypical (WHO grade II) meningioma. About 2 years later he developed a contrast-enhancing lesion on MRI-scan that was indicative of a tumor according to a thallium-201 ((201)Tl) SPECT scan. Histopathology of the operated contrast-enhancing lesion showed extensive radionecrosis. Radiation necrosis is a small but serious risk after repeat radiation therapy, even after a very long-term interval, the delivery of small fractions and an average cumulative total dose. Patients undergoing repeat radiotherapy therefore need to be followed life-long for potential late radiation toxicity.

Cerebral radiation necrosis: incidence, outcomes, and risk factors with emphasis on radiation parameters and chemotherapy

PURPOSE

To investigate radiation necrosis in patients treated for glioma in terms of incidence, outcomes, predictive and prognostic factors.

METHODS AND MATERIALS

Records were reviewed for 426 patients followed up until death or for at least 3 years. Logistic regression analysis was performed to identify predictive and prognostic factors. Multivariate survival analysis was conducted using Cox proportional hazards regression. Separate analyses were performed for the subset of 352 patients who received a biologically effective dose (BED) > or =85.5 Gy2 (> or =45 Gy/25 fractions) who were at highest risk for radionecrosis.

RESULTS

Twenty-one patients developed radionecrosis (4.9%). Actuarial incidence plateaued at 13.3% after 3 years. In the high-risk subset, radiation parameters confirmed as risk factors included total dose (p < 0.001), BED (p < 0.005), neuret (p < 0.001), fraction size (p = 0.028), and the product of total dose and fraction size (p = 0.001). No patient receiving a BED <96 Gy2 developed radionecrosis. Subsequent chemotherapy significantly increased the risk of cerebral necrosis (p = 0.001) even when adjusted for BED (odds ratio [OR], 5.8; 95% confidence interval [CI], 1.6-20.3) or length of follow-up (OR, 5.4; 95% CI, 1.5-19.3). Concurrent use of valproate appeared to delay the onset of necrosis (p = 0.013). The development of radionecrosis did not affect survival (p = 0.09).

CONCLUSIONS

Cerebral necrosis is unlikely at doses below 50 Gy in 25 fractions. The risk increases significantly with increasing radiation dose, fraction size, and the subsequent administration of chemotherapy.

Cerebral radionecrosis in patients with nasopharyngeal carcinoma

This study involved seven patients with cerebral radionecrosis following radiation therapy for nasopharyngeal carcinoma (NPC). Their charts were reviewed and the relationship of extracranial malignancies to cerebral radionecrosis was investigated. The radiation dose ranged from 70 to 135 Gy, and the latency was from 6 to 39 months. Two of seven patients died of NPC-related complications during follow-up. The crude incidence of cerebral radionecrosis in patients with NPC was 0.93% in our series. Improvement of symptoms could be achieved by corticosteroid therapy, with or without surgery. In a review of the literature, there were 306 cases of cerebral radionecrosis in extracranial malignancies. The nasopharynx is the most common primary site in cerebral radionecrosis of extracranial malignancies, followed by the scalp and sinonasal tract. The 3-year overall survival rate in our series was 68.57%, as provided by the Kaplan-Meier product limited method. Cerebral radionecrosis in NPC patients should be differentiated from tumor recurrence, in order to apply the appropriate treatment.

Radiation-induced brain disorders in patients with pituitary tumours

Radiation-induced brain disorders (RIBD) are uncommon and they are grave sequelae of conventional radiotherapy. In the present report, we describe the clinical spectrum of RIBD in 11 patients who received post-surgery conventional megavoltage irradiation for residual pituitary tumours. Of these 11 patients (nine men, two women), seven had been treated for non-functioning pituitary tumours and four for somatotropinomas. At the time of irradiation the age of these patients ranged from 30 to 59 years (mean, 39.4 +/- 8.3; median, 36) with a follow-up period of 6-96 months (mean, 18.3 +/- 26.4; median, 11). The dose of radiation ranged from 45 to 90 Gy (mean, 51.3 +/- 13.4; median, 45), which was given in 15-30 fractions (mean, 18.6 +/- 5.0; median, 15) with 2.8 +/- 0.3 Gy (median, 3) per fraction. The biological effective dose calculated for late complications in these patients ranged from 78.7 to 180 Gy (mean, 99.1 +/- 27.5; median, 90). The lag time between tumour irradiation and the onset of symptoms ranged from 6 to 168 months (mean, 46.3 +/- 57.0; median, 57). The clinical spectrum of RIBD included new-onset visual abnormalities in five, cerebral radionecrosis in the form of altered sensorium in four, generalized seizures in four, cognitive dysfunction in five, dementia in three and motor deficits in two patients. Magnetic resonance imaging (MRI)/CT of the brain was suggestive of radionecrosis in eight, cerebral oedema in three, cerebral atrophy in two and second neoplasia in one patient. Associated hormone deficiencies at presentation were hypogonadism in eight, hypoadrenalism in six, hypothyroidism in four and diabetes insipidus in one patient. Autopsy in two patients showed primitive neuroectodermal tumour (PNET) and brainstem radionecrosis in one, and a cystic lesion in the left frontal lobe following radionecrosis in the other. We conclude that RIBD have distinctive but varying clinical and radiological presentations. Diabetes insipidus and PNET as a second neoplastic disorder in adults following pituitary irradiation have not been reported previously.

Klüver-Bucy syndrome in a patient with nasopharyngeal carcinoma: a late complication of radiation brain injury

We report a patient with dementia and Klüver-Bucy syndrome who presented 17 years after radiotherapy for nasopharyngeal carcinoma. Computerized tomography of the brain revealed bilateral temporal lobe atrophy. The possibility of delayed effects of radiation brain injury in causing the human Klüver-Bucy syndrome is discussed.

Intractable partial epilepsy following low-dose scalp irradiation in infancy

We report the development of intractable epilepsy in 3 patients treated with irradiation to "strawberry" scalp nevi in infancy. Low-dose radiation was used (12 and 13 Gy in 2 of the patients). The clinical evolution suggested a recognizable and distinctive postradiation syndrome. There was concordance between the site of radiation as shown by localized alopecia, the clinical features of the partial seizures, and electrographic abnormalities. The clinical picture was unlike delayed cerebral radiation necrosis of adulthood, which is not thought to occur at doses below 50 Gy, in 2-Gy fractions. Neurological deficits were not progressive and in 2 patients there was no evidence of parenchymal injury on cranial magnetic resonance imaging scanning. These differences suggest pathogenetic differences to cerebral radiation injury of adulthood, probably relating to the interaction between nervous system development, individual susceptibility, and the low doses of radiation employed.

Common emergencies in cancer medicine: infectious and treatment-related syndromes, Part II

This article completes a summary of the common medical emergencies that can occur as a result of infectious processes (Part I) and antitumor treatment secondary to chemotherapy, biological response modifiers, or radiotherapy (Part II). The use of high-dose cytotoxic agents, coupled with the common instillation of indwelling central venous access devices, have altered the spectrum of infectious etiologies that are appreciated in clinical practice. In addition, a myriad of cytotoxic agents and radiotherapeutic treatment schemes are used widely in clinical oncologic practice. While most of their related side effects are not considered life-threatening emergencies, they can be fatal if not recognized early and treated promptly. Moreover, some of these infectious and treatment-related sequelae can be prevented. This article highlights some of these clinical observations.

Radionecrosis secondary to interstitial brachytherapy: correlation of magnetic resonance imaging and histopathology

Radiation-induced tissue damage in the central nervous system is a well-known complication of interstitial brachytherapy for brain tumors, yet imaging correlates have historically been based upon computed tomographic scans. We now present magnetic resonance imaging (MRI) to correlate radiation changes after interstitial brachytherapy with the histopathology. The central nervous system of a 38-year-old man with a left frontal cerebral glioma diagnosed by stereotactic biopsy was treated with interstitial brachytherapy (iridium-192, 47 Gy), followed by limited-field irradiation (45 Gy). With progressive deterioration, a second biopsy demonstrated radiation changes. Despite aggressive medical management, the patient died 9 months after completion of radiation therapy. Postmortem evaluation compared MRI scans of the intact, fixed brain with the histopathology. Axial sections (10 mm) obtained by MRI scan and autopsy brain slices were cut in the identical plane. Neuroimaging and histopathological findings of the lesion correlated within 2 to 3 mm resolution. In the peripheral white matter, MRI scan did not indicate the extent of radiation effect histologically. We suggest that MRI has limited utility in assessing the extent of impact of radiation on surrounding brain.

Effects of radiation therapy on neuropsychological functioning in patients with nasopharyngeal carcinoma

Sixteen patients who had a nasopharyngeal carcinoma (NPC) who were treated with radiation therapy were followed up after a median duration of 5.5 years and given a battery of neuropsychological tests. Results were compared with a comparable group of newly diagnosed NPC patients awaiting radiation therapy. The irradiated group was significantly poorer in overall IQ, non-verbal memory recall, and reported a substantially greater number of memory related complaints. These results contrast with the complacent general assumption that radiation therapy has a negligible effect on adult functioning.

Temporal lobe and hypothalamic-pituitary dysfunctions after radiotherapy for nasopharyngeal carcinoma: a distinct clinical syndrome

Eleven patients with combined neurological and endocrine complications after external radiotherapy for nasopharyngeal carcinoma are described. Neurologically, memory disturbance, complex partial seizures and hypodense areas in one or both temporal lobes on CT were typical features. Endocrinologically, hypopituitarism was the prominent manifestation. This constellation of clinical features in a patient with previous radiotherapy to the nasopharynx characterises radiation injury to the inferomedial aspects of the temporal lobes and the hypothalamic-pituitary axis. While the parenchymal brain lesions may mimic metastases or glioma on CT, the associated endocrine disturbance would betray the correct diagnosis. The importance of recognising the hypopituitarism which may be clinically asymptomatic and which is amenable to therapy is emphasised, as is the need for a proper fractionation of the radiation dose to minimise the incidence of these disabling complications.