Resection of gliomas deemed inoperable by neurosurgeons based on preoperative imaging studies

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OBJECTIVE

Maximal safe resection is a primary objective in the management of gliomas. Despite this objective, surgeons and referring physicians may, on the basis of radiological studies alone, assume a glioma to be unresectable. Because imaging studies, including functional MRI, may not localize brain functions (such as language) with high fidelity, this simplistic approach may exclude some patients from what could be a safe resection. Intraoperative direct electrical stimulation (DES) allows for the accurate localization of functional areas, thereby enabling maximal resection of tumors, including those that may appear inoperable based solely on radiological studies. In this paper the authors describe the extent of resection (EOR) and functional outcomes following resections of tumors deemed inoperable by referring physicians and neurosurgeons.

METHODS

The authors retrospectively examined the cases of 58 adult patients who underwent glioma resection within 6 months of undergoing a brain biopsy of the same lesion at an outside hospital. All patients exhibited unifocal supratentorial disease and preoperative Karnofsky Performance Scale scores ≥ 70. The EOR and 6-month functional outcomes for this population were characterized.

RESULTS

Intraoperative DES mapping was performed on 96.6% (56 of 58) of patients. Nearly half of the patients (46.6%, 27 of 58) underwent an awake surgical procedure with DES. Overall, the mean EOR was 87.6% ± 13.6% (range 39.0%–100%). Gross-total resection (resection of more than 99% of the preoperative tumor volume) was achieved in 29.3% (17 of 58) of patients. Subtotal resection (95%–99% resection) and partial resection (PR; < 95% resection) were achieved in 12.1% (7 of 58) and 58.6% (34 of 58) of patients, respectively. Of the cases that involved PR, the mean EOR was 79.4% ± 12.2%. Six months after surgery, no patient was found to have a new postoperative neurological deficit. The majority of patients (89.7%, 52 of 58) were free of neurological deficits both pre- and postoperatively. The remainder of patients exhibited either residual but stable deficits (5.2%, 3 of 58) or complete correction of preoperative deficits (5.2%, 3 of 58).

CONCLUSIONS

The use of DES enabled maximal safe resections of gliomas deemed inoperable by referring neurosurgeons. With rare exceptions, tumor resectability cannot be determined solely by radiological studies.

ABBREVIATIONS ADP = afterdischarge potential; DES = direct electrical stimulation; DTI = diffusion tensor imaging; EOR = extent of resection; GTR = gross-total resection; KPS = Karnofsky Performance Scale; MAC = minimum alveolar concentration; MSI = magnetic source imaging; PR = partial resection; STR = subtotal resection; TMS = transcranial magnetic stimulation.

Article Information

Correspondence Derek G. Southwell, Department of Neurological Surgery, University of California, San Francisco, 513 Parnassus Ave., M787, San Francisco, CA 94143. email: dereksouthwell@gmail.com.

INCLUDE WHEN CITING Published online November 10, 2017; DOI: 10.3171/2017.5.JNS17166.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

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    Representative case involving a 31-year-old right-handed man who presented with complaints of seizures. The biopsy performed at an outside hospital indicated Grade II astrocytoma. Preoperative FLAIR MRI sequences (axial slice, A; coronal slice, B) depicted a nonenhancing lesion involving the left frontal lobe. Resection was performed using awake cortical and subcortical mapping of language function, as well as awake cortical sensorimotor mapping; cortical language mapping identified 1 positive site. A GTR (EOR 99%) was achieved, as demonstrated by the postoperative MRI (axial slice, C; coronal slice, D). The patient exhibited intact neurological function 6 months after surgery.

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    Representative case involving a 52-year-old right-handed man who presented with complaints of seizures and language disturbances (mild expressive aphasia). The biopsy performed at an outside hospital indicated glioblastoma. Preoperative T1-weighted Gd MRI sequences (axial slice, A; coronal slice, B) depicted an enhancing lesion involving the left parietal lobe. Resection of the lesion was performed using awake cortical and subcortical mapping of language function; no positive language sites were identified. A GTR (EOR 99%) was performed, as demonstrated by the postoperative MRI (axial slice, C; coronal slice, D). The patient exhibited improved and intact neurological function 6 months after surgery.

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    Representative case involving a 61-year-old right-handed man who presented with complaints of seizures and right foot weakness. The outside hospital biopsy indicated Grade II astrocytoma. Preoperative FLAIR MRI sequences (axial slice, A; sagittal slice, C) depicted a nonenhancing lesion involving the left frontal and parietal lobes. Resection was performed using cortical and subcortical mapping of motor function, both of which demonstrated positive sites in and around the lesion. A PR (EOR 75%) was achieved, as demonstrated by the postoperative MRI (axial slice, B; sagittal slice, D). The patient exhibited stable neurological function 6 months after surgery (i.e., persistent, but not worsened, right foot weakness).

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