Abstract

Background: Intramedullary spinal cord abscesses (ISCA) can result in high morbidity and mortality if not treated in a timely manner. The incidence and outcomes of postsurgical ISCA are unknown. We present a case of a 52-year-old male patient with neurofibromatosis type 1 who developed an intramedullary spinal cord abscess after a previous resection of a cervical intradural, extramedullary neurofibroma.

Case Description: A 52-year-old male with a history of neurofibromatosis type 1 had previously undergone multiple resections of cervical intradural, extramedullary neurofibromas with internal stabilization. Sixteen months after his initial surgery, he developed acute-onset interscapular pain with bilateral lower extremity pain and left hemi-body weakness. Magnetic resonance imaging (MRI) of the cervical spine demonstrated an enlarging contrast-enhancing intramedullary lesion. Surgical exploration and evacuation of the lesion were completed. Intramedullary cultures confirmed a Serratia marcescens abscess. After abscess evacuation and intravenous antibiotics, the patient’s symptoms resolved.

Conclusion: Given the potential for permanent neurologic damage and loss of independence with intramedullary spinal cord abscess, we advocate that clinicians maintain a high index of suspicion in the postsurgical patient. Diagnostic imaging through contrasted MRI or computed tomography myelogram should be obtained, and prompt intervention, including evacuation and/or antibiotics, should be implemented for the best chance of a favorable outcome.

Keywords: Intramedullary spinal cord abscess, Spinal cord abscess, Postoperative complication

INTRODUCTION

First reported in 1830, intramedullary spinal cord abscesses (ISCA) are rare entities previously associated with high morbidity and mortality.[ 8 ] Before advances in antibiotics, diagnostic imaging modalities, and early surgical interventions, ISCA carried a mortality rate of nearly 90% that dramatically improved to approximately 4%.[ 2 , 11 ] On the same lines, antibiotics have reduced the most common means of dissemination through hematogenous spread from 50% to about 8%.[ 4 ] In 1949, Foley. Proposed multiple mechanisms for its rare occurrence, including the smaller volume of the spinal cord compared to the brain, the small lumen diameter and acute angles of the spinal arteries, and the protective barrier of the dura.[ 6 ]

The usual acute clinical presentation of ISCA often includes fever, pain, and neurologic deficit; however, in a chronic setting, fever and pain may be absent.[ 10 ] Given the severe consequences of a delayed intervention, a high index of suspicion, early diagnosis, and intervention are prerequisites for optimal outcomes. We report a case of a patient at our institution who developed an ISCA in a delayed fashion after neurosurgical intervention.

CASE REPORT

A 52-year-old male with a history of neurofibromatosis type 1 presented to our institution in 2020 for a second opinion regarding a cervical intramedullary lesion causing severe pain and myelopathy. He initially developed cervical myelopathy with ambulatory dysfunction and loss of fine motor hand dexterity. Magnetic resonance imaging (MRI) of the cervical spine demonstrated a cervical intradural, extramedullary lesion at the level of C2. In March 2017, he underwent an intradural resection of the extramedullary lesion and instrumented fusion with pathology consistent with neurofibroma. Postoperative MRI of the cervical spine demonstrated decompression of the spinal cord without evidence of intramedullary lesion [ Figure 1a ]. He received adjuvant radiation therapy for the residual cervical tumor.

Figure 1:

(a) Postoperative sagittal magnetic resonance imaging (MRI) of the cervical spine with contrast showing lack of enhancement in the spinal cord. (b) Follow-up sagittal MRI of the cervical spine with contrast showing enhancement in the spinal cord. (c) Sagittal MRI of the cervical spine with contrast showing enhancement in the spinal cord. (d) Postoperative sagittal MRI of the cervical spine with contrast showing resolution of the intramedullary abscess. Arrows indicate intramedullary enhancement of the spinal cord.

In December 2020, he developed rapidly progressive myelopathy with the inability to walk and frequent falls. MRI of the cervical spine demonstrated the progression of known neurofibromas with spinal cord compression and edema bilaterally from C3 to C6 [ Figure 1b ]. Fluorodeoxyglucose (FDG)-positron emission tomography scan demonstrated a small focal uptake of FDG within the spinal cord at the level of C5–C6. In February 2021, he underwent resection of the C5–C6 intradural, extramedullary tumor with internal stabilization. Pathology confirmed neurofibroma. His symptoms improved following surgery.

In November 2021, he developed left-sided neck and upper extremity pain, which was associated with bilateral shoulder abduction and left elbow flexion weakness. MRI of the cervical spine demonstrated increased size of the intradural nerve sheath tumor in the dorsal aspect of the canal at C6–C7 with persistent intramedullary enhancement at C6 [ Figure 1c ]. Differential diagnosis included spinal cord demyelination, ependymoma, meningioma, and infection. Computed tomography (CT) myelogram demonstrated lucency at his left C3 and C6 screws with anterior spondylolisthesis of C3 on C4. He was recommended to have a staged anterior and posterior instrumented fusion. He underwent C3–C7 anterior cervical discectomy and fusion in May 2022. Initially, after surgery, he improved but developed acute, severe intra-scapular pain with radiation into the bilateral lower extremities and left hemi-body weakness after six weeks. MRI of the cervical spine demonstrated an increase in size of an enhancing intramedullary lesion at the level of C6–C7 with worsening edema.

In July 2022, the patient underwent an exploration of the intramedullary lesion at C6–C7. On the sharp opening of the dura, the spinal cord surface showed scarring but no other abnormality. Using intraoperative ultrasound, a midline myelotomy was made directly over the location of the suspected intramedullary lesion. The creamy exudate was appreciated on dissection. Intramedullary cultures were positive for Serratia marcescens. MRI of the cervical spine postoperatively demonstrated evacuation of the intramedullary lesion [ Figure 1d ]. Postoperatively, the patient recovered full strength in his extremities. He was discharged to home with a plan for life-long suppressive antibiotics. The patient provided written consent for personal images to be included in this report.

DISCUSSION

As proposed by Foley (1949), the spinal cord’s unique anatomy renders it relatively resistant to infection. The blood-spinal cord barrier is the equivalent of the blood-brain barrier and protects against intradural infections. As such, ISCAs are considered quite rare, with only 141 reported cases since the first documentation by Hart in 1830.[ 8 , 10 , 21 ] In pediatric patients, congenital structural abnormalities such as dermal sinus tracts and epidermoid tumors are associated with an increased risk of intradural infections. In contrast, structural lesions in adults such as dermoid cysts, meningomyelocele, spinal cord tumors, and vascular malformations (Dural arteriovenous malformations or fistulas) are also associated. Systemic comorbidities associated with increased incidence of ISCA include immunosuppression, diabetes, intravenous drug use, alcoholism, infective endocarditis, genitourinary infections, pulmonary disease, and trauma.[ 1 , 3 , 5 , 12 , 13 , 16 - 19 ]

When first described, ISCA was associated with hematogenous spread from an extraspinal source in 50% of cases, which has since been reduced to about 8% with the invention of antibiotics.[ 4 ] Through a review of the literature, seven papers described eight patients who developed ISCA, presumably through direct inoculation following neurosurgical intervention. Postoperative central nervous system infection, such as meningitis, is more frequent and dependent on multiple factors. One such factor contributing to the decreased incidence is the use of prophylactic preoperative antibiotics targeted at the patient’s skin flora. Cefazolin is commonly used in neurosurgical procedures, whereas vancomycin is preferred if the patient is colonized with multi-resistant Staphylococcus aureus (MRSA) or if MRSA is prevalent in the institution. We cannot determine the prophylactic antibiotics used in these eight cases. Of interest, only 25% of the cases involved skin flora, while 75% of the organisms were gram-negative. Another important contributing factor is the role of adequate water-tight closure of the dura and overlying tissue to prevent local spread. Patients who are on immune suppressants or prolonged steroids following neurosurgical procedures can be predisposed to pyogenic infections. Further, steroids can cause immunosuppression, which can delay or dampen the response to infection (i.e., fever, leukocytosis, etc.). We cannot account for the prolonged average interval (6.4 years) from surgery to the presentation of ISCA described in the literature. We speculate that this may be related to an abscess being essentially walled off from the immune system in the spinal cord and only becoming symptomatic when it reaches a size large enough to cause mass effect and neurologic compromise. A review of cases documented in the literature is described in Table 1 .[ 7 , 9 , 14 , 20 ]

Table 1:

Cases of intramedullary spinal cord abscess after neurosurgical intervention.

In our case, the patient developed acute pain and neurologic deficits 16 months after the initial resection of his cervical intramedullary neurofibroma with imaging concerning an enlarging lesion with worsening edema. On surgical exploration through laminectomy and midline myelotomy, purulent drainage was appreciated, and cultures were positive for S. marcescens. In general, early diagnosis and urgent intervention followed by long-term antibiotic therapy have improved neurologic prognosis.[ 4 , 15 ] Of the reported postsurgical cases, all patients had MRI or CT myelogram findings consistent with an intramedullary pathology concerning abscess. In only three cases, cerebrospinal fluid was obtained before treatment. All but one case required surgical evacuation of the abscess followed by long-term intravenous antibiotics, while one patient had a resolution of a presumed ISCA with antibiotic therapy alone. Outcome data were reported in all eight cases, including two patients with complete recovery similar to our patient. Three patients were ambulatory within five months of surgery, two patients were nonambulatory, and one patient succumbed to his systemic infection.

CONCLUSION

ISCA is a rare entity, and even more so in the postoperative patient. Initial presentation of ISCA can often be vague but rapidly progresses to neurologic deficit, requiring a thorough history and physical. Given the potential for permanent neurologic damage and loss of independence with intramedullary spinal cord abscess, as clinicians, we need to have a high index of suspicion in the postsurgical patients. We recommend diagnostic imaging, either through MRI with contrast or CT myelogram. However, the previous study is the best choice today, is obtained expediently, and urgent intervention, including evacuation and/or antibiotics, should not be delayed for the best chance of a favorable outcome.

Authors contributions

NDT and ALV: Conceptualized the study. AA, JG, and GL: Conducted the literature review. ALV: Collected the patient data and wrote the manuscript with. NDT: Assisting and supervising. ALV and NDT: Accept full responsibility for the work, had access to the data, and controlled the decision to publish. All authors reviewed the final manuscript. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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