Surgical management of a pulmonary neuroendocrine tumor causing epidural spinal cord compression and transdural intramedullary invasion: illustrative case

Abstract

BACKGROUND

Intramedullary spinal cord metastasis from local transdural invasion is an exceedingly rare event. Therefore, specific guidance on the timing, type, and extent of surgical intervention is lacking.

OBSERVATIONS

A 60-year-old male with a known pulmonary neuroendocrine tumor presented with 2 days of progressive lower extremity paraplegia rendering him nonambulatory. MRI demonstrated transpleural and paravertebral invasion by the mass with extension through the left T1–2 and T2–3 neural foramina causing significant epidural compression. There was also transdural invasion at T2 extending intramedullary to the C4 spinal level, with associated cord edema. He underwent posterior cervicothoracic laminectomy and fusion with transpedicular epidural tumor debulking. The intramedullary component was not removed. He received adjuvant radiation therapy and chemotherapy and at the 6-month follow-up demonstrated significant return of motor function in his lower extremities, ambulating with a walker.

LESSONS

This case illustrates that rapid surgical decompression can still provide benefit even for aggressive tumors causing transdural and intramedullary invasion. The decision on whether to remove the intramedullary component should be made on a case-by-case basis and guided by the patient’s neurological examination in combination with imaging findings.

https://thejns.org/doi/10.3171/CASE25200

Intramedullary spinal cord metastases (ISCMs) are a very rare occurrence, accounting for 1%–3% of all intramedullary spinal tumors, with the thoracic and cervical spine equally affected.¹ Patients commonly present with neurological symptoms including weakness, myelopathy, and sensory disturbances according to level of spinal cord involvement.^2,3 Like cerebral metastasis, the most common source of ISCM is lung and breast carcinoma.⁴ There are very few case reports of ISCM arising from pulmonary neuroendocrine carcinoma, and in each of these cases, the tumor arose via hematogenous spread.^5–8 As far as we are aware, there are currently no reports of direct transdural intramedullary spinal cord invasion by this tumor pathology.

Given that intramedullary metastasis is such a rare occurrence, surgical management continues to be guided by case reports and small case series.^1,9,10 In a recent series by Gazzeri et al., subtotal resection was associated with better functional outcomes when compared to those who received gross-total resection.⁴ Unfortunately, regardless of surgical strategy, overall survival remains dismal. Thus, surgical selection and surgical strategy remain controversial.^4,10

The epidural spinal cord compression (ESCC) scale and neurological, oncological, mechanical, and systemic (NOMS) framework are currently the most widely used tools to guide treatment modality in epidural spinal metastatic disease.^11,12 While these tools provide excellent guidance for managing ESCC, they lack specific guidelines regarding spinal metastasis with intramedullary extension. Thus, to help guide surgical decision-making in this rare event, we present a case of a male patient with a known pulmonary neuroendocrine tumor who presented with rapidly progressive bilateral lower extremity weakness and MRI demonstrating direct intradural intramedullary invasion by the lesion. This case illustration presents the surgical approach taken and subsequent postoperative course.

Illustrative Case

A 60-year-old male with known neuroendocrine pulmonary carcinoma presented with a 2-day history of urinary retention and progressive bilateral lower extremity weakness rendering him unable to ambulate. At the time of presentation, he had completed one round of etoposide and cisplatin plus radiation therapy. On neurological assessment, he had 1/5 motor strength in hip flexion, knee extension, dorsiflexion, and plantar flexion in the left lower extremity and 2/5 strength in the same muscle groups tested in the right lower extremity. He had 2/5 hand grip strength in the left upper extremity and full strength of the left bicep, triceps, and deltoid. He had full strength in all major muscle groups of the right upper extremity. He also had a T2 sensory level, and urinary retention was confirmed by a bladder scan. A radiograph of the chest revealed a left apical lung mass (Fig. 1). A CT scan of the cervicothoracic spine revealed intraspinal gas at the T1–2 spinal level and an osteolytic lesion extending from the left lung apex, through the pleural cavity, and into the paravertebral and epidural space. There was osseus destruction of the upper ribs and of the left T2 pedicle (Fig. 2A– C). MRI demonstrated invasion of the epidural space and a mass lesion causing significant cord compression ventrally at T1–2 (Fig. 3A–D). There was also transdural invasion at T2 with intramedullary extension of the lesion to the C4 spinal level with surrounding edema.

FIG. 1.

Patient’s presenting chest anteroposterior radiograph demonstrating the left apical lung mass (arrow).

FIG. 2.

Initial CT scans of the osteolytic lesion. A: Midsagittal CT scan at presentation demonstrating intraspinal gas locules at T1–2 (arrow). B: Parasagittal CT scan at presentation demonstrating air extending through the left T2 pedicle and into the vertebral body, indicating an osteolytic lesion (arrow). C: Axial CT scan at T2 demonstrating the left apical cavitary lung mass extending through the rib head, transverse process, and pedicle and into the vertebral body.

FIG. 3.

T1-weighted postcontrast MR images obtained prior to surgical intervention. A: Midsagittal postcontrast T1-weighted MR image demonstrating a ventral epidural compressive mass centered at T1–2 (arrow). There is contrast enhancement extending intramedullary to the inferior C4 spinal level. B: Axial MR image at T2 demonstrating the osteolytic lesion with epidural encasement and cord compression. C: Axial MR image at T1 demonstrating the contrasting-enhancing lesion extending through the dura and intramedullary. D: Axial MR image at C7 demonstrating the intramedullary contrast-enhancing lesion.

The patient was started on intravenous steroids and admitted to the neurocritical care unit for close monitoring. Given his progressive neurological decline and radiographic findings, the decision was made to proceed with posterior cervicothoracic laminectomy, tumor debulking, and fusion from C2 to T3. Intraoperatively, the mass was noted to have eroded through the pleura, through the paravertebral space, and into the epidural space. There was obvious communication of the thoracic cavity with the surgical field. The T2 body and T1–2 disc space was grossly invaded by tumor. First, a laminectomy was performed from C4 to T2. Then, all screws were placed, followed by a right-side temporary rod. A transpedicular decompression was then performed down the left T2 pedicle. The ventral mass could then be progressively debulked and subsequently separated using a combination of down-biting curette and pituitary rongeurs until a Woodson elevator could be passed ventral to the dura mater from the T1 to the T3 pedicle, which confirmed a successful ventral decompression. The dura was not opened and intradural resection of the tumor was not performed for fear of causing a CSF leak. Additionally, a small rind of tumor was left attached at the site of dural invasion to act as a CSF “plug.” Resection of the intramedullary disease was not performed due to the extent of intramedullary invasion and risk of causing an upper extremity deficit. Once successful circumferential decompression was achieved, the permanent rods were then secured, decortication was performed, and allograft was placed. On careful inspection, there was no CSF leak noted, and wound closure proceeded in a multilayered fashion.

Postoperative CT imaging demonstrated good hardware alignment with laminectomies from C2 to T2 (Fig. 4A– C). MRI showed adequate decompression with expected persistent intramedullary disease with cord edema (Fig. 5A– C). On postoperative assessment, the patient had experienced minor improvement in lower extremity strength; however, he was still unable to ambulate. He experienced minor improvement in his strength during his admission and was discharged to an inpatient rehabilitation facility. Unfortunately, he returned 1 month following surgery with a wound infection requiring washout and closure. After a brief stay, he was then discharged back to the inpatient rehabilitation facility. Two months following his index surgery he was started on pembrolizumab and had stabilization of radiographic tumor progression. At the 6-month follow-up, he was ambulating with assistance of a walker and complained of a left foot drop.

FIG. 4.

Postoperative CT scans. A: Midsagittal postoperative CT scan demonstrating the C2–T2 laminectomy. B: Parasagittal CT scan demonstrating resection of the left T2 pedicle, partial body, and posterior elements; instrumentation was placed from C2 to T3. C: Axial CT scan at T2 following resection of the pedicle, rib head, and partial body; a pedicle screw was placed on the right side at T2.

FIG. 5.

Postoperative MR images. A: Sagittal T2-weighted MR image following the C2–T2 laminectomy and debulking of the T1–2 ventral mass. The expansive intramedullary lesion extends to C4, while there is cord edema extending as high as the rostral medulla. B:Axial T1-weighted contrast-enhanced MR image at the T2 level demonstrating epidural debulking and ventral decompression. C: Axial T1-weighted contrast-enhanced MR image demonstrating the intramedullary contrast-enhancing mass expanding the cord outside of the laminectomy defect.

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

The most current evidence guiding management of spinal metastatic disease is the ESCC scale and the NOMS framework.^11,12 The ESCC scale uses T2-weighted MRI to determine the degree of ESCC by metastatic disease and the necessity for resection. This framework assigns a grade based on the degree of epidural tumor involvement and can be used to guide the surgeon on whether to perform separation surgery and/or radiation therapy. Grades 0, 1a, and 1b are typically considered for radiation therapy alone, while grades 2 and 3 (high-grade ESCC) require surgical decompression prior to radiation therapy.¹¹ The NOMS framework is an additional tool that assesses neurological status, tumor radiosensitivity and response to systemic therapy, spinal stability, and overall disease burden to determine the utility of surgical stabilization, decompression, radiotherapy, and systemic therapy in the setting of spinal metastatic disease.¹² Although these frameworks are excellent tools to help guide the surgeon in managing the majority of spinal metastatic disease, neither approach offers criteria inclusive of ISCM assessment or surgical decision-making.

Given that ISCM is such a rare occurrence, surgical decision-making continues to be guided by case reports and small series. Payer et al. retrospectively reviewed 22 surgically treated cases of ISCM from 1992 to 2014 and found an overall improvement in McCormick scale grade from the last follow-up in patients who underwent gross-total or near-gross-total resection.² Likewise, Gazzeri et al. retrospectively reviewed 30 patients with surgically treated ISCM and demonstrated functional improvement in 18 patients. However, they went on to show that gross-total resection was associated with worse functional outcomes when compared with subtotal resection.⁴

The majority of patients from the aforementioned series presented with focal neurological deficits caused by an isolated intramedullary metastasis from hematogenous spread. However, our patient presented with rapidly progressive lower extremity weakness with MRI demonstrating ESCC in addition to intradural intramedullary invasion from T2 to C4. Thus, a nuanced approach was required in the surgical decision-making. We decided to perform laminectomies from T2 to C2 to treat the extensive spinal cord expansion and edema that extended as high as the rostral medulla. We also performed a circumferential decompression of the ventral compressive lesion at T1–2 in accordance with current guidelines on ESCC.¹¹ We decided not to resect the intramedullary component for two reasons. First, given his primarily lower extremity weakness, we felt that his neurological deficit was largely being caused by the compressive mass lesion at T1–2. Second, given his good upper extremity strength, we wanted to avoid causing additional deficits by performing an intramedullary dissection from T2 to C4 without providing any survival benefit.^2,4

Observations

To our knowledge, this is the first report of a pulmonary neuroendocrine tumor causing severe ESCC and transdural intramedullary invasion. This patient presented with rapidly progressive lower extremity weakness and MRI showing severe ESCC at T1–2 in addition to transdural invasion with intramedullary extension of disease to C4 with associated edema extending as high as the rostral medulla. He underwent emergent laminectomy from T2 to C2 and circumferential decompression, while the intramedullary component was not resected. At the 6-month follow-up he had experienced significant improvement in his lower extremity strength and was able to ambulate with a walker. At his follow-up appointment, the patient expressed his content with the excellent multidisciplinary care that he had received. He was happy with his current level of ambulatory function and eager to continue getting stronger with physical therapy.

Lessons

Given the rarity of concomitant ESCC and direct transdural intramedullary invasion, this case illustration is intended to assist with surgical decision-making where current decision frameworks of spinal metastatic disease are limited. The management strategy in this case shows that rapid surgical decompression can still provide functional benefit in the setting of an aggressive tumor causing transdural and intramedullary invasion. The decision on whether to remove the intramedullary component should be made on a case-by-case basis and guided by the patient’s neurological examination in accordance with imaging level of disease. These findings are limited as they are isolated to a single case in a rare pathology. Larger series are needed to better understand the indications for surgical and nonsurgical management. In conclusion, this case demonstrates that aggressive management of an advanced disease presentation is warranted; however, the surgical strategy should always be guided by the neurological assessment and radiographic disease presentation.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Shoap, Tender. Acquisition of data: Tender. Analysis and interpretation of data: Tender. Drafting the article: Shoap, Gregory, Leoni. Critically revising the article: Shoap, Leoni, Tender. Reviewed submitted version of manuscript: Shoap, Leoni, Tender. Approved the final version of the manuscript on behalf of all authors: Shoap. Study supervision: Tender.

Correspondence

Wesley Shoap: Louisiana State University Health Sciences Center, New Orleans, LA. wshoap@lsuhsc.edu.