Nicolas Massager

Université Libre de Bruxelles, Bruxelles, Brussels Capital, Belgium

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Publications (106)218.22 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24-110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment.
    Surgical Neurology International 10/2015; 6(1):153. DOI:10.4103/2152-7806.166173 · 1.18 Impact Factor
  • S. Sohawon · P. Van Houtte · F. De Smedt · N. Massager · D. Devriendt ·

    Radiotherapy and Oncology 12/2014; 111:S13. DOI:10.1016/S0167-8140(15)31198-1 · 4.36 Impact Factor
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    ABSTRACT: To evaluate the precision of hypofractionated radiosurgery using the Gamma Knife Extend relocatable system in patients with benign neoplasms located close to the optic pathways.Methods and materialsA series of 59 irradiation procedures with the Extend system were performed on 12 patients. We treated 11 meningiomas and 1 craniopharyngioma. All patients except 1 were treated with 5 daily fractions of a 5-Gy margin dose; 1 patient was treated with 4 fractions of 6 Gy. The deviations on the X, Y, and Z axes were calculated as the mean value of all measures performed on each plate of the reposition check tool. An estimation of the patient's head motion during treatment was calculated as the difference between the radial deviations measured before and after each irradiation procedure.ResultsThe maximum deviation of all measures was 0.9 mm for the 59 procedures. The mean deviations in the X, Y, and Z axes were 0.23 mm (standard deviation [SD], 0.17; maximum, 0.85), 0.31 mm (SD, 0.21; maximum, 0.90), and 0.27 mm (SD, 0.20; maximum, 0.80), respectively. The mean radial intrafraction difference was 0.16 mm (SD 0.14) and the maximum intrafraction deviation was of 0.7 mm. The mean follow-up duration was 19.3 months (range, 6-32 months). The visual status remained stable for 11 patients and improved in 1 patient; the tumor volume remained stable for 4 patients and decreased for 8 patients. From a clinical point of view, no new symptoms were recorded and no vision deterioration occurred.Conclusions The Extend system provides good repositioning accuracy and adequate immobilization of the patient's head for multisession treatment. The clinical and radiological outcomes of a series of 12 patients who underwent 59 irradiation fractions were excellent.
    Practical Radiation Oncology 10/2014; 5(3). DOI:10.1016/j.prro.2014.08.021
  • O De Witte · S Lonneville · D Balériaux · F Devuyst · N Massager ·
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    ABSTRACT: Diagnosis of non-functioning pituitary adenoma is generally posted when there is a compression of the ophthalmic nerve or when a hypopituitarism occurred. Surgery will be the first treatment but complete removal can be achieved in less than 50% of the patients. In the great majority of the patients, there is a recurrence and a new treatment is proposed. The question is when we must treat a residue after surgery. We performed a retrospective study reviewing a series of 111 patients with a non-functioning pituitary adenoma. All patients had a pre- and post-operative MRI (1.5 T). A statistical analysis was done to determine the influence of the resection, the age of the patient on the recurrence. A complete removal was achieved for 45 patients and 11 of these present a recurrence. 39 patients out of 66 patients who had a partial removal presented also a recurrence. The mean age of the population is 53 years. The statistical analysis demonstrates that patients with a complete removal had less recurrence. Patient with an age below 60 years had more frequently a recurrence compared with older than 60 years old. In conclusion, treatment for non-functioning pituitary adenoma is a transsphenoidal approach surgery. A complete surgery must be the aim of the neurosurgeon. And when a residue is present, a secondary treatment must be given for patient with an age below 60 years old like radiosurgery or radiation therapy.
    Revue medicale de Bruxelles 11/2013; 32(6):509-12. DOI:10.1016/j.wneu.2013.07.055

  • World Neurosurgery 11/2013; 80(5):672. DOI:10.1016/j.wneu.2013.07.068 · 2.88 Impact Factor
  • Nicolas Massager · Françoise De Smedt · Daniel Devriendt ·
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    ABSTRACT: The objective of the study was to assess the long-term radiological outcome of benign intracranial tumors (BIT) after Gamma Knife radiosurgery. We report the radiological outcome of 280 patients who underwent radiosurgical irradiation for BIT in a single center. Our series included 120 meningiomas, 139 vestibular schwannomas, 12 other schwannomas and 9 pituitary adenomas. Serial imaging studies were performed after irradiation for at least 5 years for all patients. The median tumor volume was 1.9 cc, and the median margin dose was 12 Gy. After a median follow-up of 6.8 years, the tumor control rate was 92.1 %: tumor decreased in 176 cases (62.9 %), remained unchanged in 82 lesions (29.3 %) and increased in 22 cases (7.9 %). The actuarial tumor control rate was 93.2 % at 5 years, 92.3 % at 7.5 years and 91.0 % at 10 years. No atypical or malignant transformation of irradiated tumors occured during the follow-up period. Gamma Knife radiosurgery provides a high rate of tumor control for BIT even in the medium to long-term.
    05/2013; 113(4). DOI:10.1007/s13760-013-0211-9
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    ABSTRACT: BACKGROUND: Pharmacoresistant epilepsy can be treated by either resection of the epileptic focus or functional isolation of the epileptic focus through complete disconnection of the pathways of propagation of the epileptic activity. OBJECTIVE: To evaluate long-term seizure outcome and complications of temporal lobe disconnection (TLD) without resection for mesial temporal lobe epilepsy (MTLE). METHODS: Data of 45 patients operated on for intractable MTLE using a functional disconnection procedure have been studied. Indication of TLD surgery was retained after a standard preoperative evaluation of refractory epilepsy and using the same criteria as for standard temporal resection. RESULTS: Mean follow-up duration was 3.7 years. At the last follow-up, 30 patients (67%) were completely seizure-free (Engel-Ia/International League Against Epilepsy class 1) and 39 patients (87%) remained significantly improved (Engel-I or -II) by surgery. Actuarial outcome displays a 77.7% probability of being seizure-free and an 85.4% probability of being significantly improved at 5 years. No patient died after surgery and no subdural haematoma or hygroma occurred. Permanent morbidity included hemiparesis, hemianopia and oculomotor paresis found in three, five and one patient, respectively, after TLD. CONCLUSIONS: TLD is acceptable alternative surgical technique for patients with intractable MTLE. The results of TLD are in the range of morbidity and long-term seizure outcome rates after standard surgical resection. We observed a slightly higher rate of complications after TLD in comparison with usual rates of morbidity of resection procedures. TLD may be used as an alternative to resection and could reduce operating time and the risks of subdural collections.
    Journal of neurology, neurosurgery, and psychiatry 04/2013; 84(12). DOI:10.1136/jnnp-2012-304083 · 6.81 Impact Factor
  • N Massager · C Delbrouck · J Masudi · F De Smedt · D Devriendt ·
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    ABSTRACT: We analyzed the effects of stereotactic radiosurgery on tumour control and cranial nerve function in patients with vestibular schwannomas (VS) secondary to neurofibromatosis type 2 (NF2). Irradiation was performed with a Gamma Knife, model C equipped with a high-precision, robotized positioning system (APS). This study included 18 patients with 25 VSs secondary to NF2 that were treated from 2001 to 2010 with radiosurgery at our Gamma Knife Center. The radiosurgical procedure included high-resolution conformational dose-planning with multiple, small-diameter isocenters, a single-fraction, low-dose irradiation prescription, and highly accurate gamma rays delivery to the target with the APS. The median follow-up time was 4.4 y. For 16 tumours in 12 patients with available follow-up data, we observed an actuarial tumour control of 87.5% at 2 y and 80.2% at 5 y, based on the Kaplan-Meier method. No patient developed facial weakness. Serviceable hearing was preserved in 78% of cases. Patients treated for bilateral and unilateral tumours had similar outcomes. Radiosurgery could control tumour growth and preserve hearing function and facial weakness in patients with VS secondary to NF2. The enhanced techniques of radiosurgical irradiation provided with the Gamma Knife model C have improved the results of this treatment alternative to microsurgery.
    B-ENT 03/2013; 9(1):29-36. · 0.08 Impact Factor
  • N Massager ·
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    ABSTRACT: Gamma Knife radiosurgery can be used as an alternative or complementary therapy to neurosurgery or radiotherapy for the treatment of some brain disorders or tumors of small volume. The most frequent indications are brain metastases, vestibular schwannomas, meningiomas, trigeminal neuralgia, arteriovenous malformations, some gliomas, and pituitary adenomas. Created in 1999, the Gamma Knife Center of the ULB remains currently the unique center in Belgium where a Gamma Knife radiosurgery treatment can be performed.
    Revue medicale de Bruxelles 09/2012; 33(4):367-70.
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    ABSTRACT: This prospective, bicentre, blinded, intention to treat study assessed the clinical added value of magnetic source imaging (MSI) in the presurgical evaluation of patients with refractory focal epilepsy (RFE). 70 consecutive patients with RFE (42 men; mean age 31.5 years, range 3-63) from two Belgian centres were prospectively included. All patients underwent conventional non-invasive presurgical evaluation (CNIPE) and a whole head magnetoencephalography recording (Elekta Neuromag). Equivalent current dipoles corresponding to interictal epileptiform discharges (IED) were fitted in the patients' spherical head model and coregistered on their MRI to produce MSI results. Results of CNIPE were first discussed blinded to the MSI results in respective multidisciplinary epilepsy surgery meetings to determine the presumed localisation of the epileptogenic zone and to set surgical or additional presurgical plans. MSI results were then discussed multidisciplinarily. MSI influence on the initial management plan was assessed. Based on CNIPE, 21 patients had presumed extratemporal epilepsy, 38 had presumed temporal epilepsy and 11 had undetermined localisation epilepsy. MSI showed IED in 52 patients (74.5%) and changed the initial management in 15 patients (21%). MSI related changes were significantly more frequent in patients with presumed extratemporal or undetermined localisation epilepsy compared with patients with presumed temporal epilepsy (p≤0.001). These changes had a clear impact on clinical management in 13% of all patients. MSI is a clinically relevant, non-invasive neuroimaging technique for the presurgical evaluation of patients with refractory focal epilepsy and, particularly, in patients with presumed extratemporal and undetermined localisation epilepsy.
    Journal of neurology, neurosurgery, and psychiatry 04/2012; 83(4):417-23. DOI:10.1136/jnnp-2011-301166 · 6.81 Impact Factor

  • Neurochirurgie 09/2011; 57(s 4–6):275. DOI:10.1016/j.neuchi.2011.09.080 · 0.41 Impact Factor
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    ABSTRACT: We investigated variations in the distribution of radiation dose inside (dose inhomogeneity) and outside (dose falloff) the target volume during Gamma Knife (GK) irradiation of vestibular schwannoma (VS). We analyzed the relationship between some parameters of dose distribution and the clinical and radiological outcome of patients. Data from dose plans of 203 patients treated for a vestibular schwannoma by GK C using same prescription dose (12 Gy at the 50% isodose) were collected. Four different dosimetric indexes were defined and calculated retrospectively in all plannings on the basis of dose-volume histograms: Paddick conformity index (PI), gradient index (GI), homogeneity index (HI), and unit isocenter (UI). The different measures related to distribution of the radiation dose were compared with hearing and tumor outcome of 203 patients with clinical and radiological follow-up of minimum 2 years. Mean, median, SD, and ranges of the four indexes of dose distribution analyzed were calculated; large variations were found between dose plans. We found a high correlation between the target volume and PI, GI, and UI. No significant association was found between the indexes of dose distribution calculated in this study and tumor control, tumor volume shrinkage, hearing worsening, loss of functional hearing, or complete hearing loss at last follow-up. Parameters of distribution of the radiation dose during GK radiosurgery for VS can be highly variable between dose plans. The tumor and hearing outcome of patients treated is not significantly related to these global indexes of dose distribution inside and around target volume. In GK radiosurgery for VS, the outcome seems more to be influenced by local radiation dose delivered to specific structures or volumes than by global dose gradients.
    International journal of radiation oncology, biology, physics 05/2011; 81(4):e511-8. DOI:10.1016/j.ijrobp.2011.03.047 · 4.26 Impact Factor
  • C Delbrouck · S Hassid · G Choufani · O De Witte · D Devriendt · N Massager ·
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    ABSTRACT: Leksel Gamma Knife (LGK) radiosurgery is a safe and efficient therapeutic approach for vestibular schwannoma (VS) with low side effects. The goal of radiosurgery is not necessarily to cause significant tumour necrosis or to obtain a complete radiographic response, but to halt the tumour's growth permanently through its biological elimination. The 2 major aims of radiosurgery for VS are long-term tumour control and functional hearing preservation. The purpose of this study is to report our experience with LGK radiosurgery in the management of VS and to evaluate the hearing preservation rate after a minimum one-year follow-up. Between January 2000 and January 2011, 415 patients with unilateral VS underwent LGK radiosurgery at the University Erasmus Hospital of Brussels. There were 349 patients with previously untreated VS (86 grade I, 96 grade II, 141 grade III, 9 grade IVa, 17 unknown grades, according to Koos) and 66 patients with post-operative residual tumour. All patients in our series underwent evaluation with high resolution neurodiagnostic imaging including computed tomography and magnetic resonance imaging, and clinical evaluation as well as audiological tests that included tonal and speech audiometries. The Gardner Robertson (GR) classification is used to report the results of this study. We identified 276 patients treated for VS with LGK, tested and retested with speech and tonal audiometries by the same team, and followed for a minimum of one year. Before LGK, 144 patients had serviceable (85 GR class I and 59 GR class II) hearing; 95 (65.97%) of these patients had preservation of serviceable hearing (Pure tone average < or = 50 db and Speech discrimination > or = 50%) at minimum one-year audiological follow-up. It was observed that 44 of the 85 GR class I patients (51.76%) maintained their level of audition and 66 of these (74.64%) preserved serviceable hearing. In the 34 patients with preradiosurgery non-serviceable hearing (GR class III-IV) 25 of these patients (73.52%) maintained their hearing. The tumour was stable or declining in size in 90.44% of cases. LGK radiosurgery provides excellent tumour control in vestibular schwannomas and has low toxicity even after long-term follow-up.
    B-ENT 01/2011; 7 Suppl 17:77-84. · 0.08 Impact Factor
  • N. Massager · J. Brotchi · O. De Witte ·

    Neurochirurgie 12/2010; 56(6):557-558. DOI:10.1016/j.neuchi.2010.10.106 · 0.41 Impact Factor
  • S. Lonneville · O. De Witte · N. Massager ·

    Neurochirurgie 12/2010; 56(6):549-550. DOI:10.1016/j.neuchi.2010.10.080 · 0.41 Impact Factor
  • S. Schuind · D. Devriendt · O. De Witte · N. Massager ·

    Neurochirurgie 12/2010; 56(6):534-535. DOI:10.1016/j.neuchi.2010.10.033 · 0.41 Impact Factor
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    ABSTRACT: In this paper, the authors' goal was to evaluate the impact of PET information on brain tumor surgery in children. Between 1995 and 2007, 442 children were referred to the authors' institution for a newly diagnosed brain lesion. Of these, 85 were studied with FDG-PET and/or L-(methyl-(11)C)-methionine -PET in cases in which MR images were unable to assist in selecting accurate biopsy targets (35 patients) or to delineate tumors for maximal resection (50 patients). In surgical cases, PET and MR images were combined in image fusion planning for stereotactic biopsies or navigation-based resections. The preoperative planning images were compared postoperatively with MR imaging and PET findings and histological data for evaluating the clinical impact on the diagnostic yield and tumor resection. The PET data influenced surgical decisions or procedures in all cases. The use of PET helped to better differentiate indolent from active components in complex lesions (in 12 patients); improved target selection and diagnostic yield of stereotactic biopsies without increasing the sampling; provided additional prognostic information; reduced the amount of tissue needed for biopsy sampling in brainstem lesions (in 20 cases); better delineated lesions that were poorly delineated on MR imaging and that infiltrated functional cortex (in 50 cases); significantly increased the amount of tumor tissue removed in cases in which total resection influenced survival (in 20 cases); guided resection in hypermetabolic areas (in 15 cases); improved early postoperative detection of residual tumor (in 20 cases); avoided unnecessary reoperation (in 5 cases); and supported the decision to undertake early second-look resection (in 8 cases). The authors found that PET has a significant impact on the surgical decisions and procedures for managing pediatric brain tumors. Further studies may demonstrate whether PET improves outcomes in children.
    Journal of Neurosurgery Pediatrics 05/2010; 5(5):486-99. DOI:10.3171/2010.1.PEDS09481 · 1.48 Impact Factor
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    ABSTRACT: In this paper, the authors' goal was to evaluate the impact of PET data on the clinical management of incidental brain lesions in children. Between 1995 and 2007, 442 children with a newly diagnosed brain lesion were referred to the authors' department. Of these, 55 presented with an incidental brain lesion and were selected for study because MR imaging sequences revealed limitations in assessing the tumor, its evolving nature, and/or the malignant potential of the lesion diagnosed. Thirteen children were studied using FDG-PET and 42 with L-(methyl-(11)C)-methionine (MET)-PET; 3 children underwent both FDG-PET and MET-PET but only the MET-PET results were used in the analysis. The PET and MR images were combined in image fusion navigation planning. Drawing on their experience with PET in adults, the authors proposed the following treatment plans: 1) surgery in children with imaging evidence of increased PET tracer uptake, which is highly specific of tumor and/or malignant tumor tissue; or 2) conservative treatment in children in whom there was little or no tracer uptake on PET. The authors compared the PET data with the MR imaging-based diagnosis and either 1) the results of histological examination in surgically treated cases, or 2) the long-term outcome in untreated cases. They studied PET and MR imaging sensitivity and specificity in detecting tumor and malignant tissues, and evaluated whether PET data altered their clinical management. Seventeen children had increased PET tracer uptake and underwent surgery. Tumor diagnosis was confirmed in all cases (that is, there were no false-positive findings). Cases in which there was little or no PET tracer uptake supported conservative treatment in 38 children. However, because PET was under evaluation, 16 of 38 lesions that were judged accessible for resection were surgically treated. Histological examination results demonstrated neither malignant nor evolving tumor tissue but yielded 9 indolent tumors (6 dysembryoplastic neuroectodermal tumors, 2 low-grade astrocytomas, and 1 low-grade astrocytoma and dysplasia) and 7 nontumoral lesions (3 cases of vasculitis, 3 of gliosis, and 1 of sarcoidosis). In 22 of the untreated 38 children, stable disease was noted during follow-up (range 18-136 months). Although an absence of PET tracer uptake might not exclude tumor tissue, PET did not reveal any false-negative findings in malignant or evolving tumor tissue detection in cases in which MR imaging showed false-positive and -negative cases in > 35 and 25% of the cases, respectively. These data confirmed the high sensitivity and specificity of PET to detect tumor as well as malignant tissue. Regarding the treatment of the incidental brain lesions, the PET findings enabled the authors to make more appropriate decisions regarding treatment than those made on MR imaging findings alone. Therefore, the risk of surgically treating a nontumoral lesion was reduced as well as that for conservatively managing a malignant tumor. Nowadays, it is estimated that these data justify conservative management in incidental lesions with low or absent PET tracer uptake.
    Journal of Neurosurgery Pediatrics 05/2010; 5(5):479-85. DOI:10.3171/2010.1.PEDS08336 · 1.48 Impact Factor

  • Neurochirurgie 10/2009; 55(4):497-497. DOI:10.1016/j.neuchi.2009.08.019 · 0.41 Impact Factor
  • N. Massager · D. Devriendt · F. Supiot · D. Z. De Beyl · O. De Witte ·

    Neurochirurgie 10/2009; 55(4):503-504. DOI:10.1016/j.neuchi.2009.08.041 · 0.41 Impact Factor

Publication Stats

2k Citations
218.22 Total Impact Points


  • 1998-2014
    • Université Libre de Bruxelles
      • • Gamma Knife Centre
      • • Laboratory of Functional Mapping of the Brain (LCFC)
      Bruxelles, Brussels Capital, Belgium
  • 2013
    • Gamma Knife of Spokane
      Spokane, Washington, United States
  • 2004-2011
    • University Hospital Brussels
      • Department of Neurosurgery
      Bruxelles, Brussels Capital, Belgium
  • 2000-2009
    • Vrije Universiteit Brussel
      • Department of Neurosurgery
      Bruxelles, Brussels Capital, Belgium
  • 2008
    • University Hospital of Lausanne
      • Service de neurochirurgie
      Lausanne, VD, Switzerland