Iatrogenic intradural spinal arachnoid cyst as a complication of lumbar spine surgery

A Rare Diagnosis of Paraesthesia in the Pediatric Age Group: Unmasking the Male Factor

Spinal extradural arachnoid cysts are an uncommon condition and their exact causative triggers are still unclear. They appear to be extradural arachnoid outpouchings that connect to the intraspinal subarachnoid region via a little dura defect. These cysts are most commonly seen in the thoracic spine, followed by the lumbosacral junction. Compression of the spinal cord or nerve roots leads to the development of the symptoms. The most morbid symptom associated with these compressing extradural cysts is paresthesia. Numerous theories have been proposed about their origins, and the related conditions include spinal trauma, spina bifida, and the lymphedema-distichiasis syndrome. Their position in the spine influences the symptoms manifested. The diagnosis is made via MRI. Surgery is only performed on individuals with neurological impairment, and treatment is based on the clinical presentation. The preferred course of therapy is total surgical excision. We present a case that involves the successful surgical removal of an extradural spinal arachnoid cyst in a 10-year-old girl. Given the rarity of this pathology, its wide array of presenting symptoms, and the successful therapeutic protocol that was followed in this particular case, we believe this article shall prove beneficial to the medical fraternity.

Symptomatic secondary spinal arachnoid cysts: a systematic review

BACKGROUND

Secondary spinal arachnoid cysts have rarely been reported but present significant challenges for management. These cysts could be anteriorly located with long rostral-caudal extensions and many are related to arachnoiditis, leading to difficult-to-treat disorders. Thus far, due to the scarcity of reports, the features of the disease and the optimal therapeutic strategies remain unclear.

PURPOSE

To investigate clinical features and the optimal treatment modalities of secondary spinal arachnoid cysts compared to primary spinal arachnoid cysts STUDY DESIGN: Systematic review PATIENT SAMPLE: Systematic review identified 103 secondary cases from 80 studies and reports; OUTCOME MEASURES: Condition of symptom relief and duration of treatment response were analyzed.

METHOD

An electronic literature search of the PubMed database was conducted for studies on secondary spinal arachnoid cysts between 1990 to 2022. Non-English publications, non-human studies, reports of a primary cyst, studies not including case details, and studies of non-symptomatic cases were excluded.

RESULTS

This systematic review included 103 secondary cases. The most commonly reported etiologies were iatrogenic factors, trauma, and subarachnoid hemorrhage, accounting for 88 intradural extramedullary, 11 extradural, 1 intradural/extradural, 1 interdural, and 1 intramedullary spinal arachnoid cyst after a median duration of 30, 12, and 9 months, respectively. Extradural cysts were more prone to occur at dorsal locations and affect thoracic segments (mean cyst length: 3.4 segments). Intradural cysts showed a relatively higher ventral/dorsal ratio (1:1.09, 1.75:1, and 3.50:1 for cysts occurring from iatrogenic factors, trauma, and subarachnoid hemorrhage, respectively) and thoracic distribution, with a mean cyst length of 4.3 segments (5.1 for ventral and 3.5 for dorsal cysts). For intradural cysts, recurrence risk was lower after surgical resection than after fenestration/marsupialization (12-month recurrence risk: 21.43% vs. 50.72%, log-rank test: P = 0.0248, Gehan-Breslow-Wilcoxon test: P = 0.0126). In cases treated with shunting, one recurrence (1/8 cases) was noted after external shunting and two recurrences (2/5 cases) after internal shunting at a median follow-up of 12 months.

CONCLUSION

Secondary spinal arachnoid cysts, particularly intradural cysts, are rarer and more challenging to treat than primary spinal cysts. Although fenestration/marsupialization is the commonly adopted treatment, the recurrence rate is high. For unresectable cysts, shunting procedures, particularly shunting into a body cavity (e.g., pleural or peritoneal cavity) away from the subarachnoid space, could be a therapeutic alternative besides fenestration/marupialization, yet its efficacy requires confirmation by more data.

Spinal Intradural Arachnoid Cysts in Adults: An Institutional Experience and Literature Review

BACKGROUND

Adult spinal intradural arachnoid cysts are rare pathologic entities with an unclear etiopathogenesis. These lesions can be dichotomized into primary (idiopathic) or secondary (related to inflammation, intradural surgery, or trauma) etiologies. Limited series have depicted optimal management strategies and clinical outcomes.

OBJECTIVE

To illustrate our experience with spinal intradural arachnoid cysts and to present a literature review of surgically treated cysts to elucidate the clinical and anatomic differences between etiologies.

METHODS

Institutional review revealed 29 patients. Various data were extracted from the medical record. Initial and follow-up symptomatologies of the surgical cohort were compared. The literature review included case series describing cysts managed surgically.

RESULTS

From patients treated surgically at our institution (22), there was a significant reduction in thoracic back pain postoperatively ( P = .034). A literature review yielded 271 additional cases. Overall, primary and secondary lesions accounted for 254 and 39 cases, respectively. Cysts of secondary origin were more likely localized ventral to the spinal cord ( P = .013). The rate of symptomatic improvement after surgical intervention for primary cysts was more than double than that of secondary cysts ( P < .001). Compared with primary etiologies, the rates of radiographic progression ( P = .032) and repeat surgery ( P = .041) were each more than double for secondary cysts.

CONCLUSION

Surgical intervention for spinal intradural arachnoid cysts improves thoracic back pain. The literature supports surgical intervention for symptomatic primary spinal intradural arachnoid cysts with improved clinical outcomes. Surgery should be cautiously considered for secondary cysts given worse outcomes.

Post-operative tension spinal subdural extra-arachnoid hygroma of the lumbar spine: case series, literature review, and recommendations for clinical management

OBJECTIVE

Case series presentation and literature review of patient group suffering from symptomatic tension subdural extra-arachnoid hygroma following decompressive surgery for degenerative lumbar stenosis or disc disease. The purpose was to better understand this rare post-operative complication with a pathognomic radiological sign to help recommend optimal strategies for clinical management.

METHODS

Retrospective case series comprising seven cases from one tertiary Neurosurgical centre spanning a 10-year period from 2011 to 2021. Patients included were those known to have undergone a spinal procedure and subsequently to have developed a symptomatic spinal subdural extra-arachnoid hygroma (SSEH). A literature review was conducted using PubMed, MEDLINE and EMBASE (keywords 'subdural hygroma', 'lumbar CSF hygroma', 'extra arachnoid hygroma', 'extra-arachnoid CSF collection', 'CSF tension hygroma', 'lumbar extra arachnoid hygroma', 'lumbar spinal hygroma', 'post-operating spinal hygroma', 'post-operative spinal CSF collection') and through reading references cited in relevant articles. Articles involving post-operative SSEH following lumbar spinal surgery were included.

RESULTS

Rare complication with only five other cases in the literature. Dural breach described intra-operatively in only 5 of 12 total cases from our series and the literature. 5 patients in our series were managed surgically with 2 being managed conservatively. All patients in our series improved symptomatically and radiologically following surgical or conservative management.

CONCLUSIONS

This is a rare post-lumbar surgery complication that can cause rapidly deteriorating lower limb and sphincteric function. Surgical management with wide durotomy and arachnoid marsupialisation can lead to reversal of neurological deterioration and excellent clinical results. A delayed presentation with pseudomeningocele formation may be managed conservatively if neurology is stable or improving. It is a condition that it is important for the clinician to recognise in order to instigate appropriate management in a time-dependent fashion.

Surgical management and outcomes in spinal intradural arachnoid cysts: the experience from two tertiary neurosurgical centres

PURPOSE

Evaluation of the presentation and outcomes of different surgical treatment approaches for spinal intradural arachnoid cysts (SIAC).

METHODS

Cases were identified from electronic records of two major neurosurgical centres in London over the last 10 years (October 2009-October 2019) that have been surgically treated in both institutions. Clinical findings, surgical technique, and recurrence by procedure were statistically analysed. Statistical analysis was performed with STATA 13.1 Software.

RESULTS

A total of 42 patients with SIAC were identified for this study with a mean age at the time of surgery of 53.6 years and a male:female ratio of 8:13. There were 31 patients with primary SIACs and 11 with secondary SIACs. The most common presenting symptom was paraesthesia (n = 27). The most common location of the cyst was in the thoracic region (n = 33). Syrinx was present in 26.2% of SIACs (n = 11). Resection was associated with significantly better postoperative pain compared to other surgical techniques (p = 0.01), significantly poorer postoperative urinary function (p = 0.029), and lower rates of sensory recovery in patients who presented preoperatively with sensory deficit (p = 0.041). No significant difference was seen in symptomatic outcomes between patients with primary and secondary SIACs.

CONCLUSION

Resection and drainage are both effective methods of managing SIACs. In this observational study, resection was associated with significantly reduced pain postoperatively when compared with drainage, however also with significantly less improvement in postoperative urinary function. Therefore, resection should be the gold standard management option for SIACs, with drainage as an option where resection is unsafe, and drainage should also be considered in patients presenting with urinary dysfunction.

Review/Perspective On the Diagnosis and Surgical Management of Spinal Arachnoid Cysts

Background:

Spinal arachnoid cysts (SAC) are typically congenital, spontaneous, traumatic (i.e., including iatrogenic/surgical), or inflammatory in origin. In descending order, they occur in the thoracic, lumbar, and cervical spine, and originate from focal entrapment of the arachnoid membrane. Arachnoid cysts represent 1–2% of all cystic spinal masses/tumors. The majority are extradural arachnoid cysts (EDAC) while 10% of all arachnoid cysts are intradural (IDAC) including subarachnoid, or extra-arachnoidal/subdural. Only rarely are they intramedullary in location. The clinical symptoms/signs of IDAC/EDAC include; intracranial hypotension (i.e., due to continued cerebrospinal fluid drainage), radiculopathy, and/or myelopathy.

Methods:

Magnetic Resonance Images (MR) and Myelo-Computed Tomography (Myelo-CT) studies classically document the predominant dorsal location of IDAC/EDAC. They also show their extent and severity contributing to root, cord, and/or cauda equina compression. In the cervical/thoracic spine, MR/Myelo-CT studies classically show the “double cord” or “windsock” signs, while the “fake arachnoiditis sign” may be seen in the lumbar spine. The latter sign signals the presence of a circumferential extra-arachnoidal-subdural cyst that centrally “traps” the cauda equina. Note, that this resembles and is often misinterpreted as adhesive archnoiditis.

Results:

Patients with significant SAC-related neurological deficits typically warrant early surgery. That surgery includes; partial/total resection/fenestration of cyst walls, and occlusion of communicating fistulas with or without accompanying shunts.

Conclusion:

It is critical to recognize the clinical (i.e., intracranial hypotension, radiculopathy, and/or myelopathy) and radiographic MR/Myelo-CT signs (i.e., “double cord,” “windsock signs”, or “fake arachnoiditis sign”) of IDAC, EDAC, or intramedullary spinal arachnoid cysts to appropriately offer treatment. For those with significant neurological deficits, early surgery (i.e. optimally 0-< 24 hours after the onset of symptoms/signs consisting of laminectomies, partial/total cyst resection/fenestration, and ligation/occlusion of the subarachnoid-cyst fistula with or without shunt placement), is essential to avoid significant permanent neurological sequelae.

Post-op lumbar subdural hygroma: a case report

Lumbar spinal decompression surgery is commonly performed to relieve radicular symptoms to good effect. The formation of post-operative spinal subdural hygroma, or spinal subdural extra-arachnoid hygromas (SSEH) following incidental intra-operative durotomies, have been described in previous literatures. We report a case of a 63 years old lady who had initially underwent an uneventful posterior lumbar decompression for lower limb radiculopathy, without intraoperative durotomy, with development of concurrent SSEH and spinal subarachnoid hygroma (SSSH) during the early post-operative period with cauda equina compression. Urgent surgical intervention was performed with limited durotomy to decompress the cyst through wide fenestration of the arachnoid layers and decompress the cauda equina nerve roots, with immediate recovery of her symptoms. To our knowledge, this is the first case reporting a concurrent post-operative SSEH and SSSH, without intra-operative durotomy. Both of which causing cauda equina nerve root compression which required surgical intervention. When a patient develops early post-operative recurrence of lower limb or cauda equina neurological symptoms after spinal decompression surgery, the rare entities of SSEH and/or SSSH should be considered as one of the differentials even without intraoperative durotomy as in our case. If diagnosis is suspected, surgical exploration should be performed to decompress the hygroma, as the signs and symptoms are readily reversible with prompt and early surgical treatment.

Extradural arachnoid cyst with bony erosion: a rare case report

The authors present the case of an otherwise healthy 38-year-old female with an atypical extradural arachnoid cyst with multi-level involvement in the lumbar spine leading to left quadriceps weakness and dysesthesia. Upon presentation, a lumbar spine MRI with contrast and plain radiographs revealed extensive L4 bony erosion. An MR angiogram and cervical spine MRI with contrast were then obtained in order to rule out any aortic root or cervical spine pathology. With no other apparent clinically relevant pathology revealed by these additional tests, an L3-5 posterior decompression and fusion procedure was performed. Her preoperative symptoms were successfully resolved following the procedure, with no resultant surgical complications. The cyst is atypical not only due to its size and location, but also due of the significant bony erosion of the left L4 pedicle and vertebral body. To the authors' knowledge, this is the first reported case of an extradural arachnoid cyst in the lumbar spine with bony erosion of the pedicle and vertebral body. In cases such as this, a CT myelogram may be useful in planning the operative approach through visualization of the exact communication between cyst and dura. This approach may also aid in diagnosing and identifying atypical cyst presentations such as the one presented here.

Intradural symptomatic arachnoid cyst formation following non-instrumented lumbar decompression

PURPOSE

Intradural arachnoid cyst is a rare complication of lumbar puncture, post-trauma or post-intraoperative durotomies. We aim to estimate the incidence of early intradural arachnoid cyst radiologically in non-instrumented posterior lumbar decompression among symptomatic patients, and establish clinical correlation.

MATERIALS AND METHODS

Patients who underwent lumbar decompression without instrumentation at a tertiary spinal service between December 2014 and January 2018 were identified. When MRI scans were performed post-operatively within 14 days, imaging, medical and operative records were reviewed by two consultant neuroradiologists.

RESULTS

488 operations were included. 46 operations were followed by an early MRI scan. 59% were requested to investigate new or ongoing pain. Ten demonstrated an intradural arachnoid cyst - seven had no documented durotomy. Eight were primary operations, three were emergency operations. Statistically, we have not identified durotomy, primary-vs-revision surgery, and elective-vs-emergency surgery as risk factors. Two patients required revision operations, of these, one had a repeat post-operative scan, where the cyst resolved following further decompression at the index level, without intradural exploration.

CONCLUSIONS

Intradural arachnoid cyst may complicate posterior lumbar decompression. To our knowledge, this is the first study to assess its incidence as an early post-operative radiological finding, which is likely to be commoner than we recognise. It may be a cause of persisting post-operative pain.

Iatrogenic Lumbar Arachnoid Cyst Fenestration for Tethered Cord: 2-Dimensional Operative Video

Iatrogenic lumbar arachnoid cysts are a rare occurrence after intradural surgery.^1,2 To our knowledge, there is only 1 other previous case reported in the literature contributing to a symptomatic tethered cord.³ We present a surgical video (Video 1) demonstrating the history, preoperative workup, and operative technique for exploration and fenestration of a symptomatic iatrogenic lumbar arachnoid cyst with a tethered cord. The patient is a 57-year-old female with a history of a closed neural tube defect with a lipoma that was resected over 20 years before her evaluation. She was lost to follow-up and did not retain any previous medical documentation. She complained of a 2-month history of progressive bilateral lower extremity weakness, leg pain, and worsening of chronic urinary incontinence. Imaging demonstrated a cystic lesion compressing her conus and cauda equina at the L3-4 level. The risks, benefits, and alternatives were discussed, and the patient elected to proceed with surgery. Intraoperative findings demonstrated a complex multiloculated arachnoid cyst with tethering of the conus. The cysts were dissected from the conus and fenestrated, allowing spontaneous flow of cerebrospinal fluid and conus pulsations. Biopsy of the cyst wall confirmed the diagnosis of arachnoid cyst without neoplastic tissue. Due to the presence of multiple loculations, primary pial closure could not be performed. Thus, a circumferential detethering of the conus was performed to ensure complete decompression of the neural elements. Postoperatively, the patient demonstrated improvement in her bilateral lower extremity pain and weakness. Magnetic resonance imaging was scheduled during routine follow-up at 3 months.

Extradural Arachnoid Cyst Excision

Arachnoid cysts are an uncommon postoperative complication and can result in back pain, radiculopathy, and/or cauda equina syndrome. For symptomatic postoperative arachnoid cysts, surgical management is the accepted treatment. While excision of arachnoid cysts is the preferred surgical method, cysts with adhesions to nerve roots and/or dura can be treated with cyst fenestration to reduce morbidity of excision. Surgeons should be prepared for dural defects after cyst excision, which can require dural grafting and lumbar drains for cerebrospinal fluid diversion.

Diagnostic Dilemma in Discriminating Between Spinal Neurenteric Cysts and Simple Arachnoid Cysts Based on Embryogenesis and Surgical Correlation

BACKGROUND

Neurenteric cyst (NEC) is a rare intradural spinal tumor, but a correct preoperative diagnosis remains challenging. A misdiagnosis of arachnoid cyst (AC) often leads to conflicting surgical management and significantly higher recurrence.

CASE DESCRIPTION

We report the case of a 26-year-old woman who presented with progressive spastic quadriparesis with myelopathy below the C4 level, which was caused by a ventral intradural extramedullary cystic tumor at the C3-4 level. Magnetic resonance images showed the cystic content as identical to cerebrospinal fluid, which prompted the tentative diagnosis of spinal AC. Surgical fenestration was scheduled. However, intraoperative findings of a thick-walled cyst and severe adhesion to the neural structure without a history of trauma and inflammation were more compatible with the pathogenesis of an NEC. Because of the high recurrence rate after an incomplete resection of an NEC, we did a complete resection of the cyst with adhesive rootlets instead. Pathology analysis and immunohistochemical staining confirmed the diagnosis of an endodermal-derived NEC.

CONCLUSIONS

NECs must be differentiated from ACs because they are different diseases and require different surgical management. In cases with clear cystic content, however, the diagnosis is likely to be AC, but a thick cystic wall and structural adhesions should suggest the differential diagnosis of NEC. Gross total removal of NECs should be attempted to reduce NEC recurrence.

Analysis of detailed clinical characteristics of spinal subdural hematoma following lumbar decompression surgery

BACKGROUND

Only a few reports have described symptomatic patients with postoperative spinal subdural hematoma (SSH) for which further surgery may have been required. No report has focused on the detailed clinical characteristics of postoperative SSH, including asymptomatic cases, in a case series. The reasons for this may be that SSH is an implicitly recognized rare entity, and there is no established consensus regarding the significance of performing postoperative magnetic resonance imaging (MRI) for all cases and the time at which to perform it. In this case-controlled retrospective analysis, we attempted to identify a detailed clinical presentation of SSH after open lumbar decompression surgery using MRI taken uniformly at 14 days before hospital discharge.

METHODS

We retrospectively studied 196 patients who underwent routine MRI following open lumbar spinous process-splitting decompression surgery between 2012 and 2016. We assessed the frequency, clinical presentation, and radiological findings of SSH that developed postoperatively. Furthermore, we used a multivariate analysis to identify factors that were postulated to increase the risk of SSH postoperatively.

RESULTS

None of the patients developed serious neurologic deficits, such as paresis or bladder and bowel dysfunction that required emergency evacuation. However, our results showed that postoperative SSHs, including asymptomatic SSHs, developed considerably frequently (43/182 patients, 23.6%). Furthermore, of the 43 patients with SSH, three presented with new postoperative neurologic findings that were strongly suspected to be associated with SSH. Multivariate analysis identified that preoperative hypertension (adjusted odds ratio [aOR]: 2.501, P = 0.018), anticoagulant therapy (aOR: 2.716, P = 0.021), and multilevel procedures (aOR: 2.327, P = 0.034) were significant risk factors of postoperative SSH.

CONCLUSIONS

Spine surgeons should be aware that postoperative SSH is not rare and is a potential cause of recurrent pain or neurologic deterioration perioperatively.

Postoperative Spinal Subdural Lesions Following Lumbar Spine Surgery: Prevalence and Risk Factors

Study Design

Retrospective case–control study

Purpose

To clarify the prevalence and risk factors for spinal subdural lesions (SSDLs) following lumbar spine surgery.

Overview of Literature

Because SSDLs, including arachnoid cyst and subdural hematoma, that develop following spinal surgery are seldom symptomatic and require reoperation, there are few reports on these pathologies. No study has addressed the prevalence and risk factors for SSDLs following lumbar spine surgery.

Methods

We conducted a retrospective analysis of the magnetic resonance (MR) images and medical records of 410 patients who underwent lumbar decompression surgery with or without instrumented fusion for degenerative disorders. SSDLs were classified into three grades: grade 0, no obvious lesion; grade 1, cystic lesion; and grade 2, lesions other than a cyst. Grading was based on the examination of preoperative and postoperative MR images. The prevalence of SSDLs per grade was calculated and risk factors were evaluated using multivariate logistic regression analysis.

Results

Postoperative SSDLs were identified in 123 patients (30.0%), with 50 (12.2%) and 73 (17.8%) patients being classified with grade 1 and 2 SSDLs, respectively. Among these, one patient was symptomatic, requiring hematoma evacuation because of the development of incomplete paraplegia. Bilateral partial laminectomy was a significantly independent risk factor for SSDLs (odds ratio, 1.52; 95% confidence interval, 1.20–1.92; p<0.001). In contrast, a unilateral partial laminectomy was a protective factor (odds ratio, 0.11; 95% confidence interval, 0.03–0.46; p=0.002).

Conclusions

The prevalence rate of grade 1 SSDLs was 30%, with no associated clinical symptoms observed in all but one patient. Bilateral partial laminectomy increases the risk for SSDLs, whereas unilateral partial laminectomy is a protective factor.

Iatrogenic Spinal Subdural Extra-Arachnoid Hygroma Following Uncomplicated Lumbar Decompression

Intradural spinal arachnoid cysts (ISACs) have been reported in the current literature as either an idiopathic disease or exceedingly rare sequelae after lumbar puncture, spinal trauma, or meningitis. Other studies have more appropriately termed the iatrogenic pathology as a spinal subdural extra-arachnoid hygroma (SSEH), as there is not often a clear cyst wall as in a true arachnoid cyst. However, to the best of our knowledge, none of the previous studies described an SSEH following uncomplicated posterior lumbar surgery, as they have previously involved clear durotomies during the initial operation. Here, we report the case of a 53-year-old woman who presented to the emergency department with a persistent severe orthostatic headache and worsening leg pain, six days following an uneventful L5-S1 discectomy and left L4-5 laminoforaminotomy, without intraoperative durotomy. Lumbar magnetic resonance imaging (MRI) scan revealed a pseudomeningocele and an SSEH extending from the S1 up to the lower thoracic spine, compressing and displacing the cauda equina. Although the hygroma extended up to the lower thoracic spine, surgical exploration was performed only at the index surgical site with bilateral L5 laminectomy, wide durotomy, and wide fenestration of the arachnoid layer. Postoperatively, her headaches dissipated and her pain improved with complete radiographic resolution of the collection. Iatrogenic SSEH is an exceedingly rare complication of posterior lumbar decompression and can occur in the absence of a durotomy during the index surgery. Although these hygromas may span multiple levels, the initial surgical site or the site of known durotomy should be explored first. They can potentially be treated with only a limited durotomy and arachnoid fenestration at a single level rather than at a multilevel arachnoid fenestration.

A New Classification for Pathologies of Spinal Meninges—Part 2: Primary and Secondary Intradural Arachnoid Cysts

BACKGROUND: Spinal intradural arachnoid cysts are rare causes of radiculopathy or myelopathy. Treatment options include resection, fenestration, or cyst drainage.

OBJECTIVE: To classify intradural spinal arachnoid cysts and present results of their treatment.

METHODS: Among 1519 patients with spinal space occupying lesions, 130 patients demonstrated intradural arachnoid cysts. Neuroradiological and surgical features were reviewed and clinical data analyzed.

RESULTS: Twenty-one patients presented arachnoid cysts as a result of an inflammatory leptomeningeal reaction related to meningitis, subarachnoid hemorrhage, intrathecal injections, intradural surgery, or trauma, ie, secondary cysts. For the remaining 109 patients, no such history could be elucidated, ie, primary cysts. Forty-six percent of primary and 86% of secondary cysts were associated with syringomyelia. Patients presented after an average history of 53 ± 88 months. There were 122 thoracic and 7 lumbar cysts plus 1 cervical cyst. Fifty-nine patients with primary and 15 patients with secondary cysts underwent laminotomies with complete or partial cyst resection and duraplasty. Mean follow-up was 57 ± 52 months. In the first postoperative year, profound improvements for primary cysts were noted, in contrast to marginal changes for secondary cysts. Progression-free survival for 10 years following surgery was determined as 83% for primary compared to 15% for secondary cysts. Despite differences in clinical presentation, progression-free survival was almost identical for patients with or without syringomyelia.

CONCLUSIONS: Complete or partial resection leads to favorable short- and long-term results for primary arachnoid cysts. For secondary cysts, surgery can only provide clinical stabilization for a limited time due to the often extensive arachnoiditis.

Iatrogenic intradural lumbosacral cyst following epiduroscopy

We report a rare complication of iatrogenic spinal intradural following minimally invasive extradural endoscopic procedues in the lumbo-sacral spines. To our knowledge, intradural cyst following epiduroscopy has not been reported in the literature. A 65-year-old woman with back pain related with previous lumbar disc surgery underwent endoscopic epidural neuroplasty and nerve block, but her back pain much aggravated after this procedure. Postoperative magnetic resonance imaging revealed a large intradural cyst from S1-2 to L2-3 displacing the nerve roots anteriorly. On T1 and T2-weighted image, the signal within the cyst had the same intensity as cerebrospinal fluid. The patient underwent partial laminectomy of L5 and intradural exploration, and fenestration of the cystic wall was accomplished. During operation, the communication between the cyst and subarachnoid space was not identified, and the content of the cyst was the same as that of cerebrospinal fluid. Postoperatively, the pain attenuated immediately. Incidental durotomy which occurred during advancing the endoscope through epidural space may be the cause of formation of the intradural cyst. Intrdural cyst should be considered, if a patient complains of new symptoms such as aggravation of back pain after epiduroscopy. Surgical treatment, simple fenestration of the cyst may lead to improved outcome. All the procedures using epiduroscopy should be performed with caution.

Spinal arachnoid cysts in the pediatric population: report of 31 cases and a review of the literature

OBJECT

The goal of this study was to review all cases of pediatric spinal arachnoid cysts (SACs) surgically treated at the authors' institution between 1992 and 2008 and to compare these cases to the published literature for the general population.

METHODS

The charts of all pediatric patients with SACs were reviewed for demographics, medical history, presenting symptoms, imaging findings, operative procedure(s), complications, and outcomes. Following a complete literature review, the pediatric data were compared with data from the general population and unique findings associated with pediatric patients were identified.

RESULTS

Thirty-one pediatric patients (median age 6.9 years) underwent operative intervention for SACs between 1992 and 2008 (median duration of follow-up 4.2 years). There were 17 female patients (55%) and 14 male patients (45%). Twenty-one patients (68%) presented with symptoms of radiculopathy or myelopathy. The most common presenting symptoms were pain (42%), lower-extremity weakness (39%), gait instability (32%), spasticity (19%), sensory loss (10%), and bladder dysfunction (7%). In 3 patients (10%) SACs were incidental findings. Intradural SACs were more common (18 patients, 58%) than extradural SACs (11 patients, 36%). One patient (3%) had extradural and intradural components. One patient (3%) had a purely intramedullary cyst, and 1 patient (3%) had both an intradural and intramedullary component. Of the 18 intradural SACs, 9 (50%) were located ventral to the spinal cord and 9 (50%) were dorsally situated. One dorsal intradural SAC had an intramedullary component. All extradural SACs were located dorsal to the spinal cord. Intradural SACs were primarily concentrated in the cervical and thoracic regions (67%), whereas extradural cysts were more evenly distributed between the thoracic, lumbar, and sacral regions. Of the 18 patients with intradural SACs, 13 (72%) had significant previous CNS abnormalities, compared with 3 (27%) of 11 patients with extradural SACs. There were 2 operative complications. One patient had a CSF leak treated with a lumbar drain, and the second patient had a pseudomeningocele. No patients had neurological deterioration as a result of surgical intervention. Twenty-one patients (68%) had complete remission of symptoms, 6 (19%) had improvement, 3 (10%) were stable, and 1 (3%) has worsening of symptoms with recurrence that ultimately required cystoperitoneal shunting, despite multiple failed attempts at fenestration.

CONCLUSIONS

Spinal arachnoid cysts are rare lesions in the pediatric population. Affected patients present with back pain, weakness, and/or gait instability. In children, SACs predominantly develop in the thoracic region and are more likely to occur intradurally, compared with SACs in the general population. Overall outcomes following surgical fenestration or excision of SACs are excellent, with complete remission or improvement of symptoms achieved in 87% of cases.