Background: Navigated transcranial magnetic stimulation (nTMS) is a nonsurgical mapping technique used in mapping of motor and language eloquent areas within and/or surrounding brain tumors. Previous reports support this as a safe technique with minor side effects associated with minor headaches and discomfort around the stimulation area. Currently there are no published reports concerning the accuracy and safety of this procedure in patients with a titanium cranioplasty in situ.
Case presentation: A 59-year-old lady was diagnosed with a recurrent glioma in the context of increasing seizure frequency, left-sided numbness, and weakness. She was diagnosed with a World Health Organization grade 2 oligodendroglioma 10 years before her presentation, which was initially treated with radiotherapy and then surgical resection of this lesion 5 years later. The procedure was complicated with a wound infection, treated with a craniectomy and wound washout, followed by a titanium cranioplasty. Before proceeding with surgery for recurrence, nTMS was performed for motor mapping. No complications were identified. She underwent a craniotomy for tumor resection with aminolevulinic acid HCl (Gliolan), and the tumor was completely removed. Intraoperatively, the direct cortical stimulation correlated with the preoperative nTMS. The pathologic diagnosis on recurrence was an anaplastic oligodendroglioma grade III, and the patient is currently undergoing adjuvant chemotherapy.
Conclusion: This report confirms that nTMS is a safe and accurate procedure in patients who have a titanium cranioplasty in situ.
Keywords: Cranioplasty; Mapping; Safety; Transmagnetic stimulation.
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