Electrodiagnostic and Advanced Neuroimaging Characterization for Successful Treatment of Spinal Extradural Arachnoid Cyst

Pathogenesis, management strategies, and outcome of non-communicating extradural spinal arachnoid cyst (NEAC): a systematic review

OBJECTIVE

Non-communicating extradural spinal arachnoid cysts (NEACs) are extremely rare aetiology of symptomatic spinal cord compression. The aim of this study was to address their pathogenesis, optimum management strategy and outcome through systematic review of existing published studies.

MATERIALS AND METHOD

We have found 13 eligible publications by searching through PubMed, ScienceDirect, and Google Scholar databases, published from inception to December 2020. We have analysed the data of 21 patients extracted from those 13 publications by IBM SPSS version 23.

RESULTS

According to our analysis congenital predisposition, trauma, and previous surgery history are the aetiology of NEAC. Clinical presentation of cyst depends upon the location and extent of compression or involvement of the neurovascular structures. Paraparesis with variable degree of sensory disturbance was seen among patients. Based on neuroimaging findings, NEACs are most commonly found at dorsal and dorsolumbar region. Magnetic resonance imaging (MRI) is the diagnostic modalities of choice and CT myelography can demonstrate the communication with the subarachnoid space. Recurrence rate of cyst after surgery is very low as only one out of twenty patients showed recurrence. If dural defect is not accurately addressed, the recurrence rate increased significantly.

CONCLUSIONS

Our study has highlighted aetiology, treatment strategies, and neurological outcome of NEAC. These findings may help neurosurgeons to manage this rare surgical entity for favourable outcome.

How to locate the dural defect in a spinal extradural meningeal cyst: a literature review

Spinal extradural meningeal cysts (SEMCs) are rare lesions of the spinal canal. Although closure of the dural defect can achieve satisfactory therapeutic effects, locating the fistula is difficult. This review summarizes the methods for locating the fistula of SEMCs and the distribution and features of fistula sites.

This was a non-systematic literature review of studies on SEMCs. We searched PubMed for English-language articles to summarize the methods of locating the defect. The search words were “epidural arachnoid cyst,” “dural cyst,” “epidural cyst,” and “epidural meningeal cyst.” For the defect location component of the study, case reports, studies with a sample size less than four, controversial ventral dural dissection(s), and undocumented fistula location reports were excluded.

Our review showed that radiography and computed tomography (CT) may show changes in the bony structure of the spine, with the largest segment of change indicating the fistula site. Occasionally, magnetic resonance imaging (MRI) can show a cerebrospinal fluid (CSF) flow void at the fistula site. The middle segment of the cyst on sagittal MRI, the largest cyst area, and cyst laterality in the axial view indicate the fistula location. Myelography can show the fistula location in the area of the enhanced cyst and subarachnoid stenosis. Digital subtraction or delayed CT can be used to observe the location of the initial cyst filling. Cine MRI and time-spatial labeling inversion pulse techniques can be used to observe CSF flow. Steady-state image construction interference sequence MRI has a high spatial resolution. Neuroendoscopy, MRI myelography, and ultrasound fistula detection can be performed intraoperatively. Moreover, the fistula was located most often in the T12–L1 segment.

Identifying the fistula location is difficult and requires a combination of multiple examinations and experience for comprehensive judgment.

Transforaminal endoscopic excision of bi-segmental non-communicating spinal extradural arachnoid cysts: A case report and literature review

BACKGROUND

Spinal extradural arachnoid cysts (SEACs) are a rare cause of spinal cord compression. Typically, these cysts communicate with the intradural subarachnoid space through a small defect in the dural sac. For symptomatic SEACs, the standard treatment is to remove the cyst in total with a (hemi)laminectomy or laminoplasty. We present a rare case of bi-segmental non-communicating SEACs and describe our experience of using an endoscopic minimal access technique to remove bi-segmental non-communicating SEACs.

CASE SUMMARY

A 79-year-old female presented with pain related to bi-segmental SEACs at the T11-L1 segments. She underwent sequential transforaminal percutaneous endoscopic thoracic cystectomy of the SEACs. Following her first procedure, spinal magnetic resonance imaging demonstrated complete excision of the cyst at the T12-L1 segment. However, the cyst at the T11-T12 segment was still present. Thus, a second procedure was performed to remove this lesion. The patient’s right-sided lumbar and abdominal pain improved significantly postoperatively. Her Japanese Orthopaedic Association score increased from 11 to 25, her visual analogue scale score was reduced from 8 to 1. The physical and mental component summary of the 36-item short-form health survey (SF-36) were 15.5 and 34.375 preoperatively, and had increased to 79.75 and 77.275 at the last follow-up visit, respectively.

CONCLUSION

Bi-segmental non-communicating SEACs are extremely rare. Endoscopic surgery is a safe, effective, and reliable method for treating these cysts. In the event of bi-segmental SEACs, it is important to identify whether both cysts are communicating before surgery, and if not, to remove both cysts separately during the index surgery to avoid re-operation.

True Dural Spinal Epidural Cysts: Report of 5 Cases

BACKGROUND

Spinal arachnoid cysts are a rare cause of compressive myelopathy. Spinal extradural arachnoid cysts (SEACs) are even rarer.

METHODS

We retrospectively reviewed the SEACs operated on in our hospital between 2015 and 2019, according to their clinical and radiologic findings, treatments performed, and outcomes.

RESULTS

We identified 5 cases (2 males and 3 females), ranging in age from 21 months to 78 years. Except for the pediatric case, all patients presented with pain and 3 had some grade of neurologic impairment. Preoperative magnetic resonance imaging showed multiloculated cyst in 4 cases, and the communication with the dura was properly identified in only 1 case. The patients were operated through a laminectomy or laminoplasty and total removal of the cyst, and the communication with the dura was identified and repaired in all cases. In all cases, the defect was near the exit of a nerve root, and rootlets were seen through it, producing a ball-like valve mechanism. Histology of the cyst wall showed true dura in every case. One patient needed a reoperation for evacuation of a fluid collection (related to the dural sealant). Following Odom's criteria, 3 patients had an excellent outcome and 2 had a fair outcome.

CONCLUSIONS

Total excision of a symptomatic SEAC through either laminectomy or laminoplasty is a safe and effective treatment option. Although isolated repair of the dural communication without cyst removal may seem appealing, we have found it very difficult to identify the point of communication preoperatively.