Correspondence

Outcome after Language Mapping for Glioma Resection

N Engl J Med 2008; 358:1750-1751April 17, 2008

Article

To the Editor:

To preserve language function during glioma resection in or near language areas, Sanai and colleagues, including Berger (Jan. 3 issue),1 advocate negative mapping through intraoperative cortical stimulation (negative cortical stimulation) instead of traditional positive cortical stimulation. Positive cortical stimulation identifies cortical sites associated with and sites not associated with motor, somatosensory, or language function, whereas negative cortical stimulation typically identifies only sites not associated with such function.

However, language requires not only cortical language sites but also subcortical (white-matter) language tracts to connect them. So preserving language function depends on preserving not only cortical language sites but also subcortical language tracts in the resected region.2-5

Intraoperative subcortical stimulation can reliably identify functional subcortical language tracts, thereby helping to maximize resection and minimize morbidity.3-5 But Keles and colleagues,6 also including Berger, as well as others3,4 prescribe positive cortical mapping before intraoperative subcortical stimulation. That way, subcortical language tracts can be followed downward from cortical language sites (mapped previously).3,6 Indeed, Keles, Berger, and colleagues6 advise “extreme caution” should anyone attempt intraoperative subcortical stimulation after negative cortical stimulation.

Do Sanai and colleagues now recommend negative cortical stimulation before intraoperative subcortical stimulation? If so, on what evidence is this recommendation based? If not, would the authors, including Berger, explain their conclusion that negative cortical stimulation should be used for resecting gliomas in or near language areas — areas where Berger5 and others4 advocate routine use of intraoperative subcortical stimulation?

Lawrence Mayer, M.D.
16 Hudson Rd., Lexington, MA 02421
lmayer@axigenmail.com

6 References

1. 1

   Sanai N, Mirzadeh Z, Berger MS. Functional outcome after language mapping for glioma resection. N Engl J Med 2008;358:18-27
   Full Text | Web of Science | Medline

2. 2

   Henry RG, Berman JI, Nagarajan SS, Mukherjee P, Berger MS. Subcortical pathways serving cortical language sites: initial experience with diffusion tensor imaging fiber tracking combined with intraoperative language mapping. Neuroimage 2004;21:616-622
   CrossRef | Web of Science | Medline

3. 3

   Duffau H, Capelle L, Sichez N, et al. Intraoperative mapping of the subcortical language pathways using direct stimulations: an anatomo-functional study. Brain 2002;125:199-214
   CrossRef | Web of Science | Medline

4. 4

   Bello L, Gallucci M, Fava M, et al. Intraoperative subcortical language tract mapping guides surgical removal of gliomas involving speech areas. Neurosurgery 2007;60:67-82
   CrossRef | Web of Science | Medline

5. 5

   Berger MS. Comment on: Intraoperative subcortical language tract mapping guides surgical removal of gliomas involving speech areas. Neurosurgery 2007;60:82-82
   Web of Science

6. 6

   Keles GE, Lundin DA, Lamborn KR, Chang EF, Ojemann G, Berger MS. Intraoperative subcortical stimulation mapping for hemispherical perirolandic gliomas located within or adjacent to the descending motor pathways: evaluation of morbidity and assessment of functional outcome in 294 patients. J Neurosurg 2004;100:369-375
   CrossRef | Web of Science | Medline

Author/Editor Response

Traditionally, we have not routinely used the technique of subcortical language mapping during the course of glioma resection guided by language mapping while the patient was awake. This approach has been advocated by Bello and colleagues,1 and as a commentator on their report, one of us (Dr. Berger) stated that it would be important to use these subcortical-stimulation-mapping techniques in the course of language mapping. This is particularly true if the surgeon attempts to resect tumor under positive or negative cortical sites when the tumor resection is within deep white-matter fasciculi, such as the superior longitudinal fasciculus connecting posterior to anterior language sites. However, for routine resections underneath the cortex, but not traversing these deep fasciculi, subcortical stimulation mapping would not be routinely advocated if the overlying cortical site is negative for language. The assumption to date is that subcortical language pathways descend perpendicularly to their cortical site of origin; thus, if a site is negative, it can be undercut with impunity, which is not the case for a positive site. The use of subcortical stimulation mapping is controversial, although recently there has been more evidence of its utility, especially in working deep within subcortical fasciculi that connect language regions.

Nader Sanai, M.D.
Mitchel S. Berger, M.D.
University of California at San Francisco, San Francisco, CA 94143-0112
sanain@neurosurg.ucsf.edu

1 References

1. 1

   Bello L, Gallucci M, Fava M, et al. Intraoperative subcortical language tract mapping guides surgical removal of gliomas involving speech areas. Neurosurgery 2007;60:67-82
   CrossRef | Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   M. Caulo, R. Esposito, D. Mantini, C. Briganti, C. Sestieri, P. A. Mattei, C. Colosimo, G. L. Romani, A. Tartaro. (2011) Comparison of Hypothesis- and a Novel Hybrid Data/Hypothesis-Driven Method of Functional MR Imaging Analysis in Patients with Brain Gliomas. American Journal of Neuroradiology 32:6, 1056-1064
   CrossRef