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  • An Extent of Resection Threshold for Low-Grade Glioma Seizure Control

    Final Number:

    David S. Xu MD; Al-Wala Awad; Robert F. Spetzler MD; Nader Sanai MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2013 Annual Meeting

    Introduction: Seizures are the most common presenting symptom of WHO grade II gliomas (LGGs) and impose significant coststo patients’ quality of life. Prior studies have demonstrated that gross total resection of LGGs is associated with higher rates of seizure control. However, many patients present with diffuse lesions unamenable to gross-total resection and it is unclear whether an extent of resection (EOR) threshold exists for long-term seizure control.

    Methods: We reviewed the Barrow Neurological Institute’s experience with low-grade gliomas from 2000-2012. Pre- and post-operative MR imagingwas used to volumetrically calculate tumor volumes and EOR. Univariate analysis of patient characteristics included the chi-squared test and the Mann-Whitney U test. Analysis of post-operative seizure control was performed by applying a Cox Proportional Hazards model to independent pre-operative variables.

    Results: One hundred and sixty cases were included for analysis; 109 patients presented with seizure activity (48 simple partial, 12 complex partial, 49 generalized). Temporal lobe involvement and oligodendroglial tumor subtype were associated with seizure presentation (p <.001 and p = 0.029 respectively). Among the cohort of patients presenting with seizures, the Engel class at 3 months immediately after surgery were as follows: Class I 86%, Class II 7%, Class III 3%, Class IV 3%. Among a scatter-plot of patients with seizures, all but one at Engel Class >1 had initial EOR less than 80%. Utilizing a multivariate Cox Proportional Hazards Model, we found an EOR under 80% to be associated with reduced length of post-operative seizure freedom (p = .003).

    Conclusions: While recent data suggests a survival benefit associated with subtotal resection of LGGs, the corresponding impact on seizure control – a critical determinant of quality of patient life – remains unclear. Here, we demonstrate that, for newly-diagnosed LGG patients presenting with seizures, an EOR>80% is associated with greater post-operative seizure freedom.

    Patient Care: This research attempts to define a threshold of surgical resection for low grade gliomas that will confer seizure control for patients. Such knowledge may be critically important when dealing with surgical planning for diffuse lesions that may not be amenable to gross-total resection, but where operative resection may still offer significant improvements in patient quality of life.

    Learning Objectives: 1) Describe the impacts of seizure on quality of life for low grade glioma patients. 2) Describe the factors associated with seizure presentation of low grade gliomas. 3) Discuss the extent of resection threshold for low grade gliomas in order to control seizures.

    References: 1. Chang EF, Potts MB, Keles GE, et al. Seizure characteristics and control following resection in 332 patients with low-grade gliomas. Journal of neurosurgery. 2008;108(2):227-235. 2. Englot DJ, Han SJ, Berger MS, Barbaro NM, Chang EF. Extent of surgical resection predicts seizure freedom in low-grade temporal lobe brain tumors. Neurosurgery. Apr 2012;70(4):921-928; discussion 928. 3. Jakola AS, Myrmel KS, Kloster R, et al. Comparison of a strategy favoring early surgical resection vs a strategy favoring watchful waiting in low-grade gliomas. JAMA : the journal of the American Medical Association. Nov 14 2012;308(18):1881-1888. 4. Luyken C, Blumcke I, Fimmers R, et al. The spectrum of long-term epilepsy-associated tumors: long-term seizure and tumor outcome and neurosurgical aspects. Epilepsia. Jun 2003;44(6):822-830. 5. Lote K, Stenwig AE, Skullerud K, Hirschberg H. Prevalence and prognostic significance of epilepsy in patients with gliomas. European journal of cancer (Oxford, England : 1990). Jan 1998;34(1):98-102.

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