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Int J Surg Case Rep
Int J Surg Case Rep
International Journal of Surgery Case Reports
2210-2612
Elsevier

S2210-2612(24)01046-0
10.1016/j.ijscr.2024.110265
110265
Case Report
Diagnosis and surgical treatment strategies for spinal extradural arachnoid cyst: Case report and treatment insights
Gu Longyuan a
Mei Shuhong a
Fan Yuechao b
Zhang Hui b
Ji Peizhi jpz2201@163.com
b⁎
a Department of Neurosurgery, Ji'an Central People's Hospital, Ji'an, Jiangxi, China
b Department of Neurosurgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
⁎ Corresponding author. jpz2201@163.com
10 9 2024
10 2024
10 9 2024
123 1102655 8 2024
3 9 2024
6 9 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction

Spinal extradural arachnoid cyst (SEAC) is a rare condition that can cause significant neurological symptoms. Accurate diagnosis and effective surgical treatment are crucial for patient recovery. This study aims to elucidate the diagnostic process and surgical treatment strategies for SEAC through a case report.

Case presentation

A 33-year-old female patient with no significant medical history presented with intermittent lower back pain for over three months, which gradually worsened, but without accompanying limb numbness or weakness. Neurological examination revealed no abnormalities. Magnetic resonance imaging (MRI) and myelography confirmed a spinal extradural arachnoid cyst at the thoracic level. The patient underwent minimally invasive surgical resection of the cyst and dural repair, resulting in significant relief of pain postoperatively.

Discussion

This case highlights the importance of precise diagnostic localization and meticulous surgical technique in treating SEAC. The patient showed significant improvement in symptoms post-surgery, with no recurrence observed during follow-up.

Conclusion

The successful treatment of SEAC in this case demonstrates the effectiveness of minimally invasive surgical resection and dural repair. This case provides valuable insights and recommendations for managing similar cases in clinical practice.

Highlights

• Detailed diagnostic process of spinal extradural arachnoid cyst (SEAC) using MRI and myelography

• Effective minimally invasive surgical resection and dural repair strategies

• Case report demonstrating significant symptom improvement and good postoperative recovery

• Emphasis on precise diagnostic localization and meticulous suturing techniques

• Practical recommendations for managing similar SEAC cases

Keywords

Spinal extradural arachnoid cyst (SEAC)
Minimally invasive surgery
Dural repair
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pmc1 Introduction

Spinal extradural arachnoid cyst, also known as Dural dissection cysts, is relatively rare intradural spinal lesions, accounting for 1 % to 3 % of primary intradural spinal masses [1,2]. These cysts, also referred to as extradural meningeal cysts (EMCs), are formed by the herniation of arachnoid or cerebrospinal fluid (CSF) through weak points in the dura mater, creating cystic or diverticular structures [3]. Due to a one-way valve effect, the cysts gradually enlarge, often containing CSF, and leakage points are usually found within the inner dura mater [4,5]. Although the etiology of Dural dissection cysts is not fully elucidated, most cases are congenital non-traumatic extradural arachnoid cysts, while a minority are acquired, with potential factors including trauma, inflammation, hemorrhage, and iatrogenic causes. Clinical manifestations typically include thoracolumbar pain, limb numbness, weakness, radiating pain, and muscle atrophy, with some patients experiencing bladder and bowel dysfunction. The most common symptoms and signs are pain and progressive spastic or flaccid paralysis, usually asymmetrical [6]. Clinical presentations vary depending on the cyst's location, often resulting from nerve root or spinal cord compression [7].

This case report aims to delve into the diagnostic process and surgical treatment strategies for a specific case of spinal extradural arachnoid cyst, providing clinicians with deeper insights and guidance for the management of this condition. All our work was reported in accordance with the SCARE criteria and guidelines [8].

2 Presentation of the case

We present a 33-year-old lady with a 3-month history of back pain which was intermittent and gradually worsened over the subsequent months. Her pain worsened during daytime activities, coughing, and straining, but improved with rest at night, and there was no radiation of the pain to other areas. There was no associated limb weakness or numbness. One month after the onset of symptoms, she presented at a facility where an MRI revealed a lesion in her spine. She has no history of sphincter dysfunction and no history of trauma.

Neurosurgical physical examination findings were as follows: The patient demonstrated no abnormalities in cognition, orientation, or comprehension. She weighed 60 kg with a BMI of 22.86. Ocular movements were intact and symmetric, as were the forehead wrinkles and nasolabial folds. The neck was supple, without resistance. Muscle bulk was normal, and muscle strength in all four limbs was graded as V, with normal muscle tone. Abdominal reflexes, as well as bilateral patellar and Achilles tendon reflexes, were within normal limits. Sensory examination revealed symmetrical responses to both deep and superficial stimuli across all four limbs, and bilateral Babinski signs were negative.

Magnetic resonance imaging (MRI) of her thoracolumbar spine is as depicted in Fig. 1. The MRI revealed an extradural lesion extending from T12 to L2, isointense on T1 sequence and hyperintense on T2. On post-contrast T1 image, the lesion demonstrated no enhancement. A radiologic diagnosis of an extradural arachnoid cyst was made. Following multidisciplinary case review, the decision was made to proceed with surgery. She was planned for a hemilaminectomy and microsurgical resection of the spinal extradural cyst.Fig. 1 Preoperative MRI images (Sagittal [A] and axial [B]) reveal a posteriorly located irregular mass spanning T12 to L2 displacing/plastering the thecal sac anterolaterally and to the left.

Fig. 1

The surgery was performed with the patient in the prone position under general anesthesia. The L1 spinous process was localized using a C-arm, and a longitudinal midline incision approximately 10 cm in length was marked with the L1 spinous process as the midpoint. After routine skin disinfection and draping, a midline incision was made, and the dissection was carried out layer by layer down to the spinous process. The right paraspinal muscles were subperiosteally dissected from the spinous process and one side of the lamina using an electrocautery device, taking care to avoid damaging the supraspinous and interspinous ligaments. A 5 mm drill was used to remove the right hemilamina of L1, extending laterally to the facet joint and medially to the base of the spinous process (Fig. 2A). Special care was taken to avoid damaging the facet joint in order to maintain spinal stability. Intraoperatively, the dura mater was found to be bulging and thinned due to compression. A longitudinal incision was made in the dura, and clear, colorless fluid was observed to flow out. The fistula was identified at the upper border of the L1 vertebral level, measuring approximately 6 mm in length, with herniation of the nerve roots and arachnoid through the fistula (Fig. 2B). The herniated nerve roots were repositioned under the visceral dura (Fig. 3A), the arachnoid at the fistula site was excised, and the fistula was meticulously sutured using 6–0 PROLENE without the use of artificial dural grafts (Fig. 3B). The cyst cavity was packed with gelatin sponge (Fig. 3C), and no treatment was applied to the parietal dura. A drainage tube was placed in the cyst cavity and was removed within 48 h postoperatively. The muscle, fascia, and skin were closed in layers. No specimen was obtained intraoperatively, and no pathological examination was performed. The wound sutures were removed 10 days postoperatively.Fig. 2 A: Intraoperative image showing the removal of the right-side hemilamina of L1–2, preserving the facet joint and pars interarticularis laterally, with the dural layer of the cyst exposed. B: The dural layer of the cyst is incised, revealing the visceral layer of the dura and the fistula, with herniation of the nerve root and arachnoid membrane.

Fig. 2

Fig. 3 A:Nerve roots repositioned into subarachnoid space. B:Intraoperative photo after repairs of the arachnoid defect. C: Gelatin sponge laid over the arachnoid repair and dura prepared for primary closure.

Fig. 3

Postoperatively, the patient did well neurologically, with the disappearance of her back pain. She was discharged 5 days after surgery and continued follow-up in our clinic. Her postoperative MRI scans revealed gross total excision of the lesion and relief of thecal sac compression (Fig. 4). She has since returned to her activities of daily living.Fig. 4 A: Post-operative T2 sagittal MRI shows gross total excision of the cyst and relieved pressure on the thecal sac. B: Axial cuts show the trajectory of the surgical access and the hemilaminectomy.

Fig. 4

3 Discussion

The clinical manifestations of spinal extradural arachnoid cyst are diverse, making them easily confused with other spinal lesions and increasing the difficulty of diagnosis [9]. This patient mainly presented with persistent back pain and lower limb numbness. Despite multiple routine imaging examinations, a definitive diagnosis was not made until an MRI revealed the spinal extradural arachnoid cyst. Literature reports [[10], [11], [12]] indicate that MRI is the preferred imaging modality for diagnosing such cysts, although its specificity and sensitivity still need further validation. In this case, the patient's MRI results showed a cyst extending from the lower border of the T12 vertebral body to the upper border of the L2 vertebral body. The cyst was hypointense on T1, with high signal intensity on T2 weighted images. The appearance of the cyst contents mimiced that of CSF on all sequences. On contrasted T1 images, there was slight enhancement of the cyst wall.

The treatment of spinal extradural arachnoid cyst presents certain difficulties and challenges, especially in patients with large multisegmental cysts. These patients often have severe clinical neurological symptoms, vertebral damage, and thin dura mater around the defect, which makes suturing difficult. There could be adhesions between the dura mater, nerve roots, and spinal cord [13]. In cases of long-segment cysts, extensive laminectomy or laminoplasty may be required, which negatively impacts spinal stability and may lead to muscle injury, postoperative kyphosis, and scoliosis [14]. In this case, the patient experienced no neurological dysfunction or related postoperative complications after surgery, and the low back pain disappeared, allowing the patient to manage daily activities independently, demonstrating good clinical outcomes.

We introduced a surgical treatment for spinal extradural arachnoid cyst via a hemilaminectomy approach, involving cyst excision and leak suturing. We believe that the hemilaminectomy approach for microsurgical excision of spinal extradural arachnoid cyst is minimally invasive, simple, and reliable, allowing for early postoperative mobilization and functional recovery. However, it is essential to select appropriate cases.

In treating this patient, we strictly adhered to several key steps and principles to ensure the success of the surgery. Preoperatively, we used imaging to accurately localize the fistula, aiming to minimize disruption to the posterior column of the spine. Typically, myelography is required to locate the cyst's fistula; however, myelography is an invasive procedure that is relatively complex and carries certain risks. In the absence of myelography, the entry point can be determined by identifying the widest section of the cyst on preoperative MRI. A hemilaminectomy is then performed on the side of the cyst, followed by an incision of the outer dura mater of the cyst to locate the fistula (Fig. 1).

After the surgery began, a midline incision was made centered over the lesion, with the option to extend the incision superiorly and inferiorly as needed. The skin and subcutaneous tissues were incised in layers, followed by the fascia, to expose the spinous process. The supraspinous and interspinous ligaments, as well as the muscle attachments on the contralateral side, were preserved. The paraspinal muscles on the side of the window were separated subperiosteally to expose the hemilamina and facet joint on the affected side. A high-speed drill was used to remove the necessary bone, or a Kerrison rongeur was employed to remove the lamina. The extent of the laminectomy was from the facet joint laterally to the base of the spinous process medially, with a width of 1 to 1.5 cm (Fig. 2A). During the hemilaminectomy, it was crucial to perform the procedure delicately. When using the Kerrison rongeur to remove the lamina, care was taken not to damage the facet joint laterally and to extend medially to the base of the spinous process. Throughout the hemilaminectomy, careful handling was emphasized to avoid injuring the spinal cord, especially when dealing with a large extradural arachnoid cyst with high dural tension, where the use of a drill to carefully open the lamina may be necessary.

The key to the surgical treatment of an extradural arachnoid cyst lay in locating and sealing the cyst's fistula. The fistula was typically found above the axial plane of the cyst's largest dimension. After aspirating the cyst fluid, the flow direction of the cerebrospinal fluid (CSF) was observed, and the fistula was located by following the direction of CSF flow (Fig. 2B). Once the fistula was identified, if there was herniation of the nerve roots, they were repositioned under the dura using cottonoids (Fig. 3A). The arachnoid at the fistula site was excised, and the fistula was meticulously sutured with 6–0 or 7–0 sutures to ensure both closure of the fistula and prevention of leakage from suture sites (Fig. 3B). Care was taken during suturing to avoid damaging the spinal cord and nerves beneath the dura. After suturing, biological glue was applied to the suture site to ensure complete closure of the fistula and to prevent cyst recurrence. The remaining cyst cavity was appropriately packed with biological glue and gelatin sponge. The recurrence of the cyst was not related to whether the cyst wall was completely resected; similarly, the restoration of spinal cord function was not significantly affected by whether the cyst wall was completely removed. Therefore, the outer cyst wall was generally not resected or sutured (Fig. 3C), and no tissue was sent for pathological examination.

For some patients, the loss of spinal stability was still inevitable. Therefore, in the following situations, internal fixation was performed to maintain spinal structural stability: when imaging suggested spinal deformity or instability; in cases of a large extradural arachnoid cyst with multiple fistulas requiring exposure of three or more vertebral segments; when the cyst was located at the thoracolumbar junction; or when there was significant compression and thinning of multiple vertebral pedicles with kyphotic deformity, potentially leading to spinal instability. For patients with significantly compressed and thinned pedicles, pedicle screw implantation was challenging; in such cases, direct vertebral body fixation or placing screws in adjacent normal vertebral segments was considered.

In this case, the patient's symptoms and imaging findings were typical of an extradural arachnoid cyst, but the persistent back pain posed a challenge for initial diagnosis. The uniqueness of this case lies in the extensive range of the cyst, which was not clearly diagnosed through routine imaging examinations and was ultimately identified and confirmed by MRI. During the diagnostic process, we adhered strictly to principles of precise localization and detailed assessment, using MRI to clarify the extent and characteristics of the lesion, which provided critical guidance for surgical decision-making.

Compared to other similar reports, our management strategy in this case particularly focused on minimizing disruption to spinal stability and reducing postoperative complications. Although the literature [[15], [16], [17]] has reported successful cases using different surgical methods, including the use of internal fixation devices [18] (such as pedicle screw/rod fixation with posterolateral fusion using autologous bone chips from T11 to L2), the hemilaminectomy approach employed in this case was simpler to perform, less invasive, and led to faster postoperative recovery without significant complications. Unlike some reported cases [19] where postoperative spinal instability or neurological dysfunction occurred despite the use of internal fixation, our patient experienced a smooth recovery and was able to quickly resume daily activities, reflecting the effectiveness and safety of our surgical method.

By comparing our management experience with other literature, we have further recognized that in the surgical treatment of extradural arachnoid cysts, precise preoperative assessment and meticulous intraoperative technique are key factors in avoiding complications and improving treatment outcomes. Although the overall results are satisfactory, further exploration and research are needed to optimize treatment strategies in future clinical practice and improve patient prognosis. Future developments should include the application of new imaging technologies and the exploration of minimally invasive surgical techniques. Additionally, multicenter studies and long-term follow-up are essential for comprehensively evaluating the efficacy of different treatment strategies.

4 Conclusion

This case report emphasizes that precise localization and meticulous suturing of the leak are crucial for treating spinal extradural arachnoid cyst. Through this case, we demonstrated an effective treatment regimen, providing practical experience and recommendations for managing similar cases.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

Ethical approval for this study (Ethical Committee N° XYFY2024-KL173-01) was provided by the Ethics Committee of The Affiliated Hospital of Xuzhou Medical University on 29 Apr 2024.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

All authors have read and approved the final version of the manuscript.

Guarantor

Peizhi Ji.

Research registration number

This paper is case report. The authors don't need to register this work.

Declaration of competing interest

The authors state that they have no conflicts of interest for this report.
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