ABSTRACT
BACKGROUND: To determine the reliability and usefulness of intraoperative monitoring of the abducens nerve during extended endonasal endoscopic skull base tumor resection. METHODS: We performed abducens nerve intraoperative monitoring in 8 patients with giant clival lesions recording with needle electrodes sutured directly into the lateral rectus muscles of the eye to evaluate spontaneous electromyographic activity and triggered responses following stimulation of the abducens nerves. RESULTS: A total of 16 abducens nerves were successfully recorded during endoscopic endonasal skull base surgeries. Neurotonic discharges were seen in two patients (12% [2/16] abducens nerves). Compound muscle action potentials of the abducens nerves were evoked with 0.1-4mA and maintained without changes during the neurosurgical procedures. No patient had new neurological deficits or ophthalmological complications post-surgery. CONCLUSIONS: Intraoperative monitoring of the abducens nerve during the extended endonasal endoscopic approach to skull base tumors appears to be a safe method with the potential to prevent neural injury through the evaluation of neurotonic discharges and triggered responses.
Subject(s)
Abducens Nerve/physiology , Endoscopy/methods , Monitoring, Intraoperative/methods , Skull Base Neoplasms/surgery , Adult , Aged , Aged, 80 and over , Electrodes , Electromyography/methods , Female , Humans , Male , Middle Aged , Muscle, Skeletal , Nose , Pilot Projects , Reproducibility of ResultsABSTRACT
Follicular thyroid cancer rarely manifests itself as a distant metastatic lesion. We report a case of a 61-year-old woman presented with a solid mass located in the left temporo-occipital region. The 3D computed tomography showed a large solid mass with high vascularity, skull erosion and supra-infratentorial epidural mass effect. After magnetic resonance imaging (MRI) a suspect diagnosis of meningioma was made. The patient underwent surgery where a soft mass with transverse sinus invasion was encountered, the tumor was successfully resected employing microsurgical techniques. Histological examination revealed a thyroid follicular neoplasm with positive staining for follicular carcinoma in immunohistochemical analysis. Postoperatively levels of thyroid hormones were normal. Treatment was planned for the thyroid gland, but the patient did not consent. The present case emphasizes that although they are uncommon, dural metastasis can be mistaken for meningiomas. The definitive diagnosis of a meningioma should be established only after the histopathological analysis. Thyroid follicular carcinoma should be included in the differential diagnosis in cases of extrinsic tumoral lesions.
