A 44-year-old man without hypertension, diabetes mellitus or congenital disease was referred from an outside hospital as a result of a 1-year history of limb weakness and defecation difficulties. He initially complained of progressive right limb weakness of unknown origin and became progressively quadriplegic with difficulty defecating after a fall. He was diagnosed with a metastatic spinal tumor after magnetic resonance imaging (MRI) was performed at a Grade ⅢA hospital. He was told that the survival time was about 6-12 months, and the specialist recommended that further visits to the radiotherapy department be available. However, the patient abandoned further treatment. After one year bedridden at home, his symptoms persisted with no new discomforts. The patient had not received any treatment before referral.
Upon neurological examination, the results revealed that muscle power had been reduced in all limbs: right upper limb middle finger muscle strength was 2/5, both lower limb hip flexion and knee flexion muscle strength was 3/5, and remaining limb muscle strength was 0/5. His biceps reflexes, triceps reflexs and knee-jerk reflexes were exaggerated bilaterally. The patient exhibited serious hypoesthesia to light touch sensations and thermal nociception on his chest, abdomen and both lower extremities. Myelopathy was assessed with the modified Japanese Orthopedic Association (mJOA) scale; the patient scored 4 of 15 points preoperatively.
MRI (Figure 1) of the cervical spine revealed that an extradural tumor, localized at the C3 to C5 levels, compressed the spinal cord to the left side and invaded the C4 vertebral body and attachment. The tumor penetrated the C4 vertebral body at the anterior edge. In addition, T2-weighted images (T2WI) revealed the lesion was hyperintense compared with the spinal cord. After the administration of intravenous gadolinium, the tumor demonstrated significant enhancement. Computed tomography (CT, Figure 2) subsequently delineated the VBC of the C4 and soft tissue density in the cancellous substance of C4. Finally, a comparison of CT (Figure 2C) and MRI (Figure 1C and 1D) images was performed at the external hospital in 2017. There was no significant progress in the range of the lesion.
A two-stage operation by posterior and anterolateral approaches was planned due to the large extradural component and eroded nature of the entire C4 with VBC. After obtaining written informed consent, the patient underwent microsurgically-assisted extradural exploration and intraoperative tumor biopsy through a posterior approach. The pathological results of intraoperative tumor biopsy indicated a “neurogenic tumor”. Therefore, the tumor was removed except for the portions remaining in C4 and lateral mass plating was added for stability. During the second surgery, the patient underwent C4 vertebrectomy and intervertebral bone graft fusion with instrumentation for stability. The histological diagnosis of tumor tissue from both operations was consistent with schwannoma (Figure 3).
The postoperative course was uneventful, and the patient’s limb weakness gradually resolved. One year after surgery, the patient could walk and write on their own, strength was regained to 4/5 in the upper extremities and 5/5 in the lower extremities, and the mJOA of the patient was 15 of 15 points at that time. A review of cervical MRI (Figure 4A and 4B) one year after surgery showed no recurrence of the tumor, CT (Figure 4C) showed good fusion of the vertebral bodies, and X-ray films (Figure 4D) showed stable fixation materials without loosening or displacement. At present, the bowel function of the patient are improved, however the patient remains with the need to defecate in bed.