Case ReportPreservation of Motor Function After Resection of Lower-Grade Glioma at the Precentral Gyrus and Prediction by Presurgical Functional Magnetic Resonance Imaging and Magnetoencephalography
Introduction
Increasing evidence is accumulating that the extent of resection for World Health Organization grade II and III gliomas is a significant prognostic factor for patients,1, 2, 3, 4 and awake craniotomy is frequently used to push the limit of the extent of resection, while avoiding postoperative neurologic declines.3, 4, 5 Nonetheless, surgeons and patients alike become hesitant to undertake aggressive removal of the tumor if the tumor is located in anatomically eloquent areas. The outcome of aggressive resection cannot be predicted during awake surgery, and methods that can provide a comprehensive understanding of the risks of aggressive tumor removal are needed to choose the optimal treatment strategy. As neuroplasticity remains in patients with low-grade glioma (LGG), primary neural functions are known to sometimes shift from conventional “eloquent cortices.” Previous reports have shown that lesions that were unremovable at initial surgery are sometimes removable later as a result of neuroplasticity.3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 These facts emphasize the importance of taking neuroplasticity into account when managing patients with LGG. In the present case, we detected a shift in primary motor function from the precentral gyrus to the postcentral gyrus on magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) in a patient with a lower-grade glioma and were able to achieve aggressive removal of the pathologic precentral gyrus without causing obvious motor function deficit.
Section snippets
Presentation to Reoperation
An intra-axial mass lesion was discovered at the right precentral gyrus in a 32-year-old Japanese woman during diagnostic work-up for a left-sided convulsive seizure attack. Despite the lesion completely residing at the precentral gyrus, the patient did not present with any neurologic deficits, including motor weakness. The lesion was nonenhancing on gadolinium-enhanced magnetic resonance imaging (MRI) and hyperintense on T2-weighted MRI. A biopsy specimen of the lesion was obtained under a
Discussion
Management of LGG is challenging in the field of surgical neuro-oncology. As these tumors tend to slowly evolve and often manifest with few neurologic symptoms at disease diagnosis, preoperative assessment should be performed from both oncologic and neurofunctional perspectives. Functional plasticity of the brain can be expected in some patients with LGGs,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 in which case primary neural functions, such as motor and sensory functions and language, are processes
Conclusions
From a clinical perspective, this case illustrates the importance of preoperative multimodal neurophysiologic functional assessment. As the expected neurologic deficit associated with tumor removal was hemiparesis or weakness of the left hand, the patient showed substantial courage in agreeing to surgical removal of the lesion via awake craniotomy. However, the objective information presented by preoperative MEG and fMRI indicating that neuroplasticity had occurred in the patient had a great
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2020, NeuroscienceCitation Excerpt :Neural plasticity can occur as a compensatory brain function after certain types of brain damage, such as stroke, trauma, brain tumors, and even after neurosurgery. Neural plasticity can occur from primary to higher cerebral functions (Pillai, 2010; Izutsu et al., 2017). The degree of neural plasticity differs depending on brain function and age (Feldman et al., 1992; Vargha-Khadem et al., 1997; Baciu et al., 2003).
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.