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Dive into the research topics where Jan D. M. Metzemaekers is active.

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Featured researches published by Jan D. M. Metzemaekers.


Neurosurgery | 2010

International subarachnoid aneurysm trial 2009: endovascular coiling of ruptured intracranial aneurysms has no significant advantage over neurosurgical clipping.

Nicolaas A. Bakker; Jan D. M. Metzemaekers; Rob J. M. Groen; Jan Jakob A. Mooij; J. Marc C. van Dijk

In the May 2009 issue of The Lancet Neurology, the 5-year follow-up results of the International Subarachnoid Aneurysm Trial (ISAT) were published. The authors concluded that, although the significant difference between coiling and neurosurgical clipping of ruptured intracranial aneurysms in terms of death and severe disability after 1 year has vanished (primary endpoint), coiling should still be favored over neurosurgical clipping because mortality rates significantly favored coiling. In this commentary, it is this particular conclusion that is challenged by combining data from previous ISAT publications with the current 5-year follow-up results. This modified intent-to-treat analysis clearly demonstrates that the significant advantage in terms of mortality in favor of the endovascularly treated patients is no longer present, with a hazard ratio of 0.80 in favor of endovascular treatment (95% confidence interval: 0.60-1.05; P = .10). Therefore, for everyday clinical practice and decision making, coiling and clipping are to be considered equivalent in the long term.


Stroke | 2015

Predictive Factors for Rebleeding After Aneurysmal Subarachnoid Hemorrhage: Rebleeding Aneurysmal Subarachnoid Hemorrhage Study

Carlina E. van Donkelaar; Nicolaas A. Bakker; Nic J. G. M. Veeger; Maarten Uyttenboogaart; Jan D. M. Metzemaekers; Gert-Jan Luijckx; Rob J. M. Groen; J. Marc C. van Dijk

Background and Purpose— Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating type of stroke associated with high morbidity and mortality. One of the most feared complications is an early rebleeding before aneurysm repair. Predictors for such an often fatal rebleeding are largely unknown. We therefore aimed to determine predictors for an early rebleeding after aSAH in relation with time after ictus. Methods— This observational prospective cohort study included all consecutive patients admitted with aSAH between January 1998 and December 2014 (n=1337) at our University Neurovascular Center. Clinical predictors for rebleeding ⩽24 hours were identified using multivariable Cox regression analyses. Kaplan–Meier analyses were applied to evaluate the time of rebleeding ⩽72 hours after aSAH. Results— A modified Fisher grade of 3 to 4 was a predictor for an in-hospital rebleeding ⩽24 hours after ictus (adjusted hazard ratio, 4.4; 95% confidence interval, 2.1–10.6; P<0.001). The numbers needed to treat to prevent 1 rebleeding ⩽24 hours was calculated 15 (95% confidence interval, 10–25). Also, the initiation of external cerebrospinal fluid-drainage (adjusted hazard ratio, 1.9; 95% confidence interval, 1.4–2.5; P<0.001) was independently associated with a rebleeding ⩽24 hours. Cumulative in-hospital rebleeding rates were 5.8% ⩽24 hours, and 1.2% in the time frame 24–72 hours after ictus. Conclusions— In our opinion, timing of treatment of aSAH patients, especially those with an modified Fisher grade of 3 or 4 in a good clinical condition, should be reconsidered. These aSAH patients might be regarded a medical emergency, requiring aneurysm repair as soon as possible. In this respect, our findings should provoke the debate on timing of aneurysm repair, especially in patients considered to be at high risk for rebleeding.


Acta Radiologica | 2010

Feasibility of magnetic resonance angiography (MRA) follow-up as the primary imaging modality after coiling of intracranial aneurysms.

Nicolaas A. Bakker; Henriette E. Westerlaan; Jan D. M. Metzemaekers; J. Marc C. van Dijk; Omid S. Eshghi; Jan Jakob A. Mooij; Rob J. M. Groen

Background: Digital subtraction angiography (DSA) is still regarded as the gold standard for detecting residual flow in treated aneurysms. Recent reports have also shown excellent results from magnetic resonance angiography (MRA) imaging. This is an important observation, since DSA is associated with a risk of medical complications, is time consuming, and is more expensive. Purpose: To determine whether MRA could replace conventional DSA and serve as the primary postinterventional imaging modality in patients with coiled intracranial aneurysms. Material and Methods: We studied a prospectively enrolled cohort of 190 patients treated endovascularly for a first-ruptured and/or unruptured intracranial aneurysm between January 2004 and December 2008. The imaging protocol included a 1.5T time-of-flight (TOF) MRA and a DSA at 3 months (on the same day) and, depending on comparability, a 1.5T TOF-MRA or DSA 1 year after treatment. All images were evaluated by a multidisciplinary panel. Results: In 141/190 patients, both an MRA and DSA were performed after 3-month follow-up. In 2/141 patients (1.4%), (small) neck remnants gave false-negative MRA results. In one patient (0.7%), this led to additional neurosurgical clipping of the aneurysm. In 25/141 patients, future follow-up (>3 months) consisted of DSA because of various reasons. In 24/25 of these patients, primary MRA images alone would invariably have led to additional DSA imaging. Conclusion: The present study shows that 1.5T TOF-MRA is a feasible primary follow-up modality after coiling of intracranial aneurysms. Given our data, we now suggest that, in every patient with a coiled intracranial aneurysm, the first follow-up, 3 months after coiling, should be an MRA study. Only when this MRA is inconclusive (e.g., because of coil artifacts), or in the case of suspicion of recanalization, should DSA be performed additionally.


Acta Neurochirurgica | 2005

Timing of aneurysm surgery in subarachnoid haemorrhage--an observational study in The Netherlands.

Dennis J. Nieuwkamp; K. de Gans; A Algra; K. W. Albrecht; S. Boomstra; P. J. A. M. Brouwers; Rob J. M. Groen; Jan D. M. Metzemaekers; P. C. G. Nijssen; Yvo B.W.E.M. Roos; C. A. F. Tulleken; W. P. Vandertop; J. van Gijn; P.E. Vos; G. J. E. Rinkel

SummaryBackground. There is still lack of evidence on the optimal timing of surgery in patients with aneurysmal subarachnoid haemorrhage. Only one randomised clinical trial has been done, which showed no difference between early and late surgery. Other studies were observational in nature and most had methodological drawbacks that preclude clinically meaningful conclusions. We performed a retrospective observational study on the timing of aneurysm surgery in The Netherlands over a two-year period.Method. In eight hospitals we identified 1500 patients with an aneurysmal subarachnoid haemorrhage. They were subjected to predefined inclusion criteria. We included all patients who were admitted and were conscious at any one time between admission and the end of the third day after the haemorrhage. We categorised the clinical condition on admission according the World Federation of Neurological Surgeons (WFNS) grading scale. Early aneurysm surgery was defined as operation performed within three days after onset of subarachnoid haemorrhage; intermediate surgery as performed on days four to seven, and late surgery as performed after day seven. Outcome was classified as the proportion of patients with poor outcome (death or dependent) two to four months after onset of subarachnoid haemorrhage. We calculated crude odds ratios with late surgery as reference. We distinguished between management results (reconstructed intention to treat analysis) and surgical results (on treatment analysis). The results were adjusted for the major prognosticators for outcome after subarachnoid haemorrhage.Findings. We included 411 patients. There were 276 patients in the early surgery group, 36 in the intermediate surgery group and 99 in the late surgery group. On admission 78% were in good neurological condition (WFNS I–III).Management results. Overall, 93 patients (34%) operated on early had a poor outcome, 13 (36%) of those with intermediate surgery and 37 (37%) in the late surgery group had a poor outcome. For patients in good clinical condition on admission and planned for early surgery the adjusted odds ratio (OR) was 1.3 (95% CI 0.5 to 3.0). The adjusted OR for patients admitted in poor neurologicalcondition (WFNS IV–V) and planned for early surgery was 0.1 (95% CI 0.0 to 0.6).Surgical results. For patients in good clinical condition on admission who underwent early operation the adjusted OR was 1.1 (95% CI 0.4 to 3.2); it was 0.2 (95% CI 0.0 to 0.9) for patients admitted in poor clinical condition.Conclusions. In this observational study we found no significant difference in outcome between early and late operation for patients in good clinical condition on admission. For patients in poor clinical condition on admission outcome was significantly better after early surgery. The optimal timing of surgery is not yet settled. Ideally, evidence on this issue should come from a randomised clinical trial. However, such a trial or even a prospective study are unlikely to be ever performed because of the rapid development of endovascular coiling.


Neurosurgery | 2015

Recurrence Rates After Surgical or Endovascular Treatment of Spinal Dural Arteriovenous Fistulas : A Meta-analysis

Nicolaas A. Bakker; Maarten Uyttenboogaart; Gert Jan Luijckx; Omid S. Eshghi; Aryan Mazuri; Jan D. M. Metzemaekers; Rob J. M. Groen; J. Marc C. van Dijk

BACKGROUND There is an increasing tendency to treat spinal dural arteriovenous fistulas (SDAVFs) endovascularly despite the lack of clear evidence favoring embolization over surgery. OBJECTIVE To compare the initial failure and recurrence rates of primary treatment of SDAVFs by surgery and endovascular techniques. METHODS A meta-analysis using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) standard was performed. All the English literature from 2004 onward was evaluated. From each article that compared the 2 treatment modalities, the odds ratio (OR) was calculated. Combined ORs were calculated with Review Manager 5.3 of The Cochrane Collaboration. RESULTS A total of 35 studies harboring 1112 patients were assessed. Initial definitive fistula occlusion was observed in 588 of 609 surgical patients (96.6%; 95% confidence interval [CI], 94.8-97.8) vs 363 of 503 endovascularly treated patients (72.2%; 95% CI, 68.1-75.9; P < .001). The combined OR from 18 studies that assessed both treatment modalities (730 patients) was 6.15 (95% CI, 3.45-11.0) in favor of surgical treatment. Late recurrence (13 studies, 480 patients) revealed an OR of 3.15 (95% CI, 1.66-5.96; P < .001) in favor of surgery. In a subgroup, recurrence was reported in 10 of 22 patients (45%) treated with Onyx vs 8 of 35 (23%) treated with n-butyle-2-cyanoacrylate (OR, 2.51; 95% CI, 0.75-8.37; P = .13). CONCLUSION Although hampered by inclusion of poor quality studies, this meta-analysis shows a definite advantage of primary surgical treatment of SDAVF over endovascular treatment in initial failure rate and late recurrences. The often-used argument that endovascular techniques have improved and therefore outweigh surgery is not supported by this meta-analysis.


Neurosurgical Review | 2015

The current status of 5-ALA fluorescence-guided resection of intracranial meningiomas-a critical review

Arash Motekallemi; Hanne-Rinck Jeltema; Jan D. M. Metzemaekers; Gooitzen M. van Dam; Lucy M. A. Crane; Rob J. M. Groen

Meningiomas are the second most common primary tumors affecting the central nervous system. Surgical treatment can be curative in case of complete resection. 5-aminolevulinic acid (5-ALA) has been established as an intraoperative tool in malignant glioma surgery. A number of studies have tried to outline the merits of 5-ALA for the resection of intracranial meningiomas. In the present paper, we review the existing literature about the application of 5-ALA as an intraoperative tool for the resection of intracranial meningiomas. PubMed was used as the database for search tasks. We included articles published in English without limitations regarding publication date. Tumor fluorescence can occur in benign meningiomas (WHO grade I) as well as in WHO grade II and WHO grade III meningiomas. Most of the reviewed studies report fluorescence of the main tumor mass with high sensitivity and specificity. However, different parts of the same tumor can present with a different fluorescent pattern (heterogenic fluorescence). Quantitative probe fluorescence can be superior, especially in meningiomas with difficult anatomical accessibility. However, only one study was able to consistently correlate resected tissue with histopathological results and nonspecific fluorescence of healthy brain tissue remains a confounder. The use of 5-ALA as a tool to guide resection of intracranial meningiomas remains experimental, especially in cases with tumor recurrence. The principle of intraoperative fluorescence as a real-time method to achieve complete resection is appealing, but the usefulness of 5-ALA is questionable. 5-ALA in intracranial meningioma surgery should only be used in a protocolled prospective and long-term study.


Acta Neurochirurgica | 1987

Cerebrospinal Fluid Shunting for Hydrocephalus: A retrospective analysis

Jan D. M. Metzemaekers; J. W. F. Beks; J. S. van Popta

SummaryA series of 383 extracranial CSF shunts performed between Jan. 1980 and Jan. 1985 for hydrocephalus in children and adults is reviewed. Ventriculoatrial (VA) and ventriculoperitoneal (VP) shunts were compared with a special attention to infections. The difference between VA and VP shunts concerning indication of revision, operative mortality and infection related morbidity and mortality was not significant.


Journal of Neurology, Neurosurgery, and Psychiatry | 2014

Appreciation of CT-negative, lumbar puncture-positive subarachnoid haemorrhage: risk factors for presence of aneurysms and diagnostic yield of imaging

Nicolaas A. Bakker; Rob J. M. Groen; Mahrouz Foumani; Maarten Uyttenboogaart; Omid S. Eshghi; Jan D. M. Metzemaekers; Gert Jan Luijckx; J. Marc C. van Dijk

Objective Patients without a subarachnoid haemorrhage (SAH) on brain CT scan (CT-negative), but a lumbar puncture (LP)-proven SAH, are a challenging patient category. The optimal diagnostic approach is still a matter of debate. Also, there is little knowledge on the probability of finding an underlying vascular lesion. Design In this observational study, a consecutive cohort of 94 patients with CT-negative, LP-positive SAH was prospectively collected between 1998 and 2013. The yield of diagnostic modalities as well as patient outcome was studied. In addition, risk factors for the presence of a vascular lesion were analysed. Results In 40 patients (43%), an intracranial vascular abnormality was detected: 37 aneurysms and three arterial dissections. Female gender was significantly associated with detection of a vascular lesion. Time between ictus and diagnosis of SAH was not associated with the presence of vascular pathology. Overall, 99% of patients had a modified Rankin Score of 0–2 after a median follow-up of 72 months. The yield of additional digital subtraction angiography in patients with a negative CT angiography was zero. Conclusions In this study, the chance of finding a vascular lesion in a patient with CT-negative, LP-positive SAH was 43%, underlining the need for an adequate diagnostic workup. In general, the patient outcome was favourable. Female gender was found to be predictive for detecting a vascular lesion. In contrast with previous reports, the interval between ictus and LP was not associated with the presence of an aneurysm.


Journal of Neurosurgery | 2017

Prediction of outcome after subarachnoid hemorrhage: Timing of clinical assessment

Carlina E. van Donkelaar; Nicolaas A. Bakker; Nic J. G. M. Veeger; Maarten Uyttenboogaart; Jan D. M. Metzemaekers; Omid S. Eshghi; Aryan Mazuri; Mahrouz Foumani; Gert-Jan Luijckx; Rob J. M. Groen; J. Marc C. van Dijk

OBJECTIVE Currently, early prediction of outcome after spontaneous subarachnoid hemorrhage (SAH) lacks accuracy despite multiple studies addressing this issue. The clinical condition of the patient on admission as assessed using the World Federation of Neurosurgical Societies (WFNS) grading scale is currently considered the gold standard. However, the timing of the clinical assessment is subject to debate, as is the contribution of additional predictors. The aim of this study was to identify either the conventional WFNS grade on admission or the WFNS grade after neurological resuscitation (rWFNS) as the most accurate predictor of outcome after SAH. METHODS This prospective observational cohort study included 1620 consecutive patients with SAH admitted between January 1998 and December 2014 at our university neurovascular center. The primary outcome measure was a poor modified Rankin Scale score at the 2-month follow-up. Clinical predictors were identified using multivariate logistic regression analyses. Area under the receiver operating characteristic curve (AUC) analysis was used to test discriminative performance of the final model. An AUC of > 0.8 was regarded as indicative of a model with good prognostic value. RESULTS Poor outcome (modified Rankin Scale Score 4-6) was observed in 25% of the patients. The rWFNS grade was a significantly stronger predictor of outcome than the admission WFNS grade. The rWFNS grade was significantly associated with poor outcome (p < 0.001) as well as increasing age (p < 0.001), higher modified Fisher grade (p < 0.001), larger aneurysm size (p < 0.001), and the presence of an intracerebral hematoma (OR 1.8, 95% CI 1.2-2.8; p = 0.002). The final model had an AUC of 0.87 (95% CI 0.85-0.89), which indicates excellent prognostic value regarding the discrimination between poor and good outcome after SAH. CONCLUSIONS In clinical practice and future research, neurological assessment and grading of patients should be performed using the rWFNS to obtain the best representation of their clinical condition.


Journal of Neurosurgery | 2014

Repeat microvascular decompression for recurrent idiopathic trigeminal neuralgia

Nicolaas A. Bakker; J. Marc C. van Dijk; Steven Immenga; Michiel Wagemakers; Jan D. M. Metzemaekers

OBJECTIVE Microvascular decompression (MVD) is considered the method of choice to treat idiopathic trigeminal neuralgia (TN) refractory to medical treatment. However, repeat MVD for recurrent TN is not well established. In this paper, the authors describe a large case series in which patients underwent repeat MVD for recurrent TN, focusing on outcome, risk factors, and complication rates. METHODS Between 1990 and 2012, a total of 33 consecutive patients underwent repeat MVD for recurrent TN at the University Medical Center Groningen. The authors performed a retrospective chart review and telephone interviews. Risk factors were analyzed by binary logistic regression analysis. RESULTS After 12 months of follow-up, 22 (67%) operations were successful, of which 19 patients were completely free of pain without medication. With multivariate analysis significant risk factors for success were older age (OR 1.11, p < 0.01) and direct absence of pain after repeat MVD (OR 25.2, p < 0.01). Previous neurodestructive procedures did not influence success rates. Facial numbness occurred in 9 patients (27%), while other morbidity was minimal. There was no mortality. CONCLUSIONS This study demonstrates that repeat MVD is a feasible therapeutic option with good chances of success, even in patients who have undergone neurodestructive procedures. Complication rates, particularly facial numbness, can be avoided if only a limited neurolysis is performed.

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Rob J. M. Groen

University Medical Center Groningen

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J. Marc C. van Dijk

University Medical Center Groningen

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Nicolaas A. Bakker

University Medical Center Groningen

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Maarten Uyttenboogaart

University Medical Center Groningen

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Omid S. Eshghi

University Medical Center Groningen

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Gert-Jan Luijckx

University Medical Center Groningen

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Mahrouz Foumani

University Medical Center Groningen

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Aryan Mazuri

University of Groningen

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Gert Jan Luijckx

University Medical Center Groningen

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Peter Jan van Laar

University Medical Center Groningen

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