Introduction: Intradural, nerve root metastasis is extremely rare, with only a few cases ever reported, and most commonly in the lumbar region. We report the first case of metastasis to and invasion of a ventral cervical nerve root in a patient previously diagnosed with low-grade follicular thyroid carcinoma, who presented with right upper extremity radiculopathy and weakness after being in remission for 10 years.
Methods: Cervical spine MRI revealed a ventral, intradural mass at C4-5 that appeared to be a nerve sheath tumor compressing and displacing the spinal cord. The patient underwent a posterolateral cervical approach for resection of tumor, followed by C3-5 posterior instrumented fusion. Intraoperatively, the tumor had clearly invaded the ventral C5 nerve root but was completely resected without changes in neuromonitoring.
Results: Post-operative MRI demonstrated gross total resection and histopathology revealed metastatic thyroid carcinoma (follicular vs. anaplastic type), with high Ki-67 labeling indices. Positive immunohistochemical staining with NFP and S-100 confirmed invasion of nerve fibers. A whole-body radioactive iodine scintigraphy revealed multi-organ metastases, advancing her diagnosis to Stage 4. Right deltoid strength improved from 2/5 to 4/5 but the patient died within 8 months, despite salvage radioactive iodine treatment.
Conclusions: Intradural metastasis with invasion of a nerve root is extremely unusual, especially in a patient with low grade thyroid carcinoma thought to be in remission. This is the first report of follicular thyroid cancer with malignant transformation that metastasized to and invaded a ventral cervical nerve root. Any history of thyroid carcinoma, regardless of staging, grading, or remission status, should raise the suspicion of metastasis, as it can mimic other spine and nerve sheath tumors and represent malignant transformation. Gross total resection can be safely achieved with intra-operative neuromonitoring and result in improved function; however, treatment is likely only palliative.
Patient Care: 1) It will help raise suspicion of metastasis and/or malignant transformation of a primary malignancy, regardless of grading, staging, or remission status, in a patient with intradural, nerve root/sheath masses.
2) It will demonstrate that gross total resection can be achieved safely via a posterolateral cervical approach with neuromonitoring, and can result in improved function with low morbidity.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Recognize that any history of malignancy, regardless of staging, grading, or remission status, should raise the suspicion of metastasis and may represent malignant transformation.
2) Recognize that although rare, metastases can mimic other spine or nerve sheath tumors.
3) Recognize that a posterolateral cervical approach followed by instrumentation, can be utilized safely to achieve a gross total resection with the aid of neuromonitoring.
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