Stereotactic Radiotherapy for Cervical Spinal Intramedullary Metastasis and Multiple Brain Metastases: A Case Report

Abstract

A case of cervical (C) spinal intramedullary metastasis and multiple small brain metastases from papillary thyroid carcinoma was presented. Spinal metastasis caused posterior neck and left shoulder pain, dysesthesia in both legs, and motor weakness in both legs and left arm, though the brain metastases were asymptomatic. Both the spinal and brain metastases were successfully treated by frameless stereotactic radiotherapy (SRT)/stereotactic radiosurgery (SRS). The patient's symptoms were almost entirely relieved within two months. A 76-year-old woman was diagnosed as having a thyroid tumor and lung metastasis by roentgenography and computed tomography. Biopsy of the thyroid tumor extending into the mediastinum revealed papillary thyroid carcinoma. She underwent surgical resection of thyroid with dissection of the mediastinum lymph node area. Internal oral radioisotope therapy was not effective for the multiple small lung metastases. She did well for 15 months, but later developed posterior neck and left shoulder pain and dysesthesia in the right leg and then dysesthesia and motor weakness in both legs. Then she experienced weakness in the left upper extremity. Magnetic resonance imaging (MRI) disclosed a small cervical spinal intramedullary mass lesion at the level of C6 and C7 on the left side as well as nine small brain lesions. The cervical spinal intramedullary metastatic tumor was treated by volumetric modulated arc radiotherapy (VMAT) SRT and the nine small brain metastatic tumors were treated by dynamic conformal arc (DCA) SRS uneventfully. A total dose of 39 Gy (100% dose) was delivered in 13 fractions for the spinal lesion (prescription, D95=95% dose; maximum dose=46.3 Gy). Single fraction SRS of 22 Gy (prescription, D95=100% dose) was performed for each of the nine small brain tumors. The spinal tumor was decreased in size on follow-up MRI two months after SRT. Three of the nine brain lesions had disappeared and six were decreased in size on follow-up MRI two months after SRS. Motor weakness in the left extremities and right leg was fully improved, and she could walk again without a cane within two months after SRT. She had only slight dysesthesia in the right leg, possibly due to lumbar spondylosis at the end of the six-month follow-up after SRT. The spinal tumor continued to decrease in size on follow-up MRI five months after SRT. Eight of the nine brain lesions had disappeared and one was decreased in size on follow-up MRI five months after SRS.

Keywords: Stereotactic Radiosurgery; brain metastasis; dynamic conformal arc therapy; intramedullary spinal cord metastases; papillary thyroid carcinoma; simultaneous integrated boost; spine metastasis; stereotactic radiotherapy; true beam s tx; volumetric modulated arc therapy (vmat).

Figure 1. Pre-SRT and post-SRT MRIs of cervical spinal lesion

Left : sagittal and axial view of gadolinium (Gd) enhanced magnetic resonance images (MRI) before stereotactic radiotherapy (SRT). Right: sagittal and axial view two months after SRT. A spinal intramedullary lesion (arrows) at the level of cervical (C) 6th and 7th vertebra shrank within two months after volumetric arc modulated therapy (VMAT) SRT.

Figure 2. Pre-SRS MRI of brain lesions (Dose planning on iPlan)

Axial MRI with Gd enhancement on iPlan (BrainLAB, Tokyo) radiation therapy planning system (RTPS) workstation. Nine small brain lesions (arrows) were treated by single session stereotactic radiosurgery (SRS). Each lesion was targeted with four arcs by dynamic conformal arc (DCA). 100% dose=22 Gy (single fraction SRS), D95=100%dose.

Figure 3. Pre-SRT CT of cervical lesion (Dose planning on Eclipse)

Sagittal (left upper), axial (right upper), and coronal (right lower) images of iodine enhancement computed tomography (CT) on Eclipse (Varian, Tokyo) RTPS workstation. Dose-volume histogram is also shown (left lower). The enhanced intramedullary lesion was targeted with excellent conformity by VMAT simultaneously with sparing of the surrounding normal spinal medulla (See also pre-SRT axial MRI of Figure 1 left). A simultaneous boost up to 46.3 Gy was performed inside the tumor. 100% dose=39 Gy in 13 fractions, D95=95% dose.