Idiopathic syringomyelia and the importance of occult arachnoid webs, pouches and cysts

Arachnoid webs causing rostral syrinx due to ball-valve effect: an illustrative report of two cases

An arachnoid web is a pathological formation of the arachnoid membrane. It is a rare phenomenon but is known to lead to syrinx formation in the spinal cord along with pain and neurological deficits. On imaging, the 'scalpel sign' is pathognomonic for an arachnoid web. The etiology of syrinx formation from an arachnoid web is currently unknown. This report documents the only two cases of arachnoid webs with an extensive syrinx in which a likely pathophysiologic mechanism is identified. Both cases presented with motor deficits. The patients had no history of trauma or infection. After extensive workup in both patients and observation of the scalpel sign an arachnoid web was suspected. In both cases, the patients were treated surgically after an arachnoid web was suspected. Intra-operative ultrasound visualized in both cases demonstrates a fenestration in the web that allowed passage of cerebrospinal fluid in a rostral-caudal direction due to a ball-valve effect.

The occult spinal arachnoid web with inimitable imaging: a case report with 5 years of follow-up

OBJECTIVES

The spinal arachnoid web (SAW) is intradural extramedullary thickened bands of the arachnoid tissue, causing a focal indentation of the spinal cord. In our study, we sought to provide a comprehensive description of the nonoperative progression of this condition, drawing from a 5-year follow-up based on our institutional experience.

CASE PRESENTATION

A 67-year-old male patient, presenting with chest and back pain, was admitted to our hospital. During a constructive interference in steady state (CISS) sequence examination, a typical dorsal indentation of the spinal cord at thoracic vertebrae referred to as the "scalpel sign", was noted. Subsequently, a diagnosis of SAW was confirmed. The patient refused surgical intervention and underwent a series of three MR imaging sessions over 5 years.

CONCLUSION

SAW is a rarely reported pathology with varying clinical presentation and whose etiology remains unknown. Secondary syrinx formation may be a consequence of chronically altered cerebrospinal fluid dynamics. The CISS sequence can visualize the SAW despite its comparatively thin width. The web is commonly curable, and treatment should be personalized and take into consideration the severity of symptoms, as well as clinical and radiological findings.

Surgical management of syringomyelia associated with spinal arachnoid web: strategies and outcomes

Spinal arachnoid web (SAW) is a rare disease entity characterized as band-like arachnoid tissue that can cause spinal cord compression and syringomyelia. This study aimed to analyze the surgical management of the spinal arachnoid web in patients with syringomyelia, focusing on surgical strategies and outcomes. A total of 135 patients with syringomyelia underwent surgery at our department between November 2003 and December 2022. All patients underwent magnetic resonance imaging (MRI), with a special syringomyelia protocol (including TrueFISP and CINE), and electrophysiology. Among these patients, we searched for patients with SAW with syringomyelia following careful analysis of neuroradiological data and surgical reports. The criteria for SAW were as follows: displacement of the spinal cord, disturbed but preserved CSF flow, and intraoperative arachnoid web. Patients were evaluated for initial symptoms, surgical strategies, and complications by reviewing surgical reports, patient documents, neuroradiological data, and follow-up data. Of the 135 patients, 3 (2.22%) fulfilled the SAW criteria. The mean patient age was 51.67 ± 8.33 years. Two patients were male, and one was female. The affected levels were T2/3, T6, and T8. Excision of the arachnoid web was performed in all cases. No significant change in intraoperative monitoring was noted. Postoperatively, none of the patients presented new neurological symptoms. The MRI 3 months after surgery revealed that the syringomyelia improved in all cases, and caliber variation of the spinal cord could not be detected anymore. All clinical symptoms improved. In summary, SAW can be safely treated by surgery. Even though syringomyelia usually improves on MRI and symptoms also improve, residual symptoms might be observed. We advocate for clear criteria for the diagnosis of SAW and a standardized diagnostic (MRI including TrueFISP and CINE).

Long-term outcome of surgical treatment for idiopathic spinal arachnoid web: A case series

OBJECTIVE

Spinal arachnoid web (SAW) is a rare condition of the spine with limited long-term follow-up data in the literature. The longest reported follow-up period was an average 3.2 years. The objective of this study is to report our long-term results of patients who underwent surgical treatment for symptomatic idiopathic SAW.

METHODS

We conducted a retrospective review of cases of idiopathic SAW that were operated between 2005-2020. We collected preoperative and last follow-up (LFU) data on motor force, sensory loss, pain, upper motor neuron (UMN) sign, gait disorder, sphincter dysfunction, syringomyelia, hyperintensity on T2-MRI, appearance of newer symptoms and number of reoperations.

RESULTS

Our study included 9 patients with a mean follow-up period of 3.6years (range 2-9.1years). The surgical intervention involved a standard centered laminectomy, durotomy and arachnoid lysis. At presentation, motor weakness was present in 77.8% of patients, sensory loss in 66.7%, pain in 88.9%, sphincter dysfunction in 33.3%, UMN sign in 22%, gait disorder 55.6%, syringomyelia in 55.6% and MRI T2 hyperintensity in 55.6% of patients. At LFU, there was an improvement in all symptoms and signs to varying degrees. No new neurological symptoms appeared postoperatively, and there was no recurrence during the follow-up period.

CONCLUSION

Our results demonstrate that the reported immediate and short-term favorable outcomes following arachnoid lysis for symptomatic SAW persist over a long-term period and the risk of readhesion-correlated neurological deterioration following conventional surgical intervention is low.

Spinal arachnoid web-a distinct entity of focal arachnopathy with favorable long-term outcome after surgical resection: analysis of a multicenter patient population

BACKGROUND CONTEXT

Spinal arachnoid web (SAW) is a rare condition characterized by focal thickening of the arachnoid membrane causing displacement and compression of the spinal cord with progressive symptoms and neurological deficits. Recent reports and clinical experience suggest that SAW is a distinct entity with specific radiological findings and treatment strategies distinguishable from other arachnopathies and potential differential diagnoses.

PURPOSE

To better define the diagnostic and clinical features, treatment options and outcomes of surgically treated SAW.

STUDY DESIGN

Multicentric retrospective cohort study.

PATIENT SAMPLE

Twelve cases of SAW surgically treated at three different centers.

OUTCOME MEASURES

Self-reported and neurological outcome measurements (pain, sensory-motor deficits, vegetative dysfunctions) were assessed at follow-up timepoints.

METHODS

Retrospective review of prospectively collected data on all patients surgically treated for SAW from three participating neurosurgical centers between 2014 and 2020. Clinicopathological data, including neurological presentation, radiological and histological findings and outcome data were analyzed.

RESULTS

Twelve radiologically and surgically confirmed cases of SAW were analyzed. Mean patient age was 54.7 [±12.7], 67% were male. All SAWs were located in the posterior thoracic dural sac. On magnetic resonance imaging (MRI), the "scalpel sign" - a characteristic focal dorsal indentation of the spinal cord resembling a scalpel blade - was identified in all patients. A focal intramedullary syrinx was present in 83%. Preoperative clinical symptoms included signs of myelopathy, pain, weakness and sensory loss, most commonly affecting the trunk/upper back or lower extremities. Laminectomy or laminoplasty with intradural excision of the SAW was the surgical treatment of choice in all cases. Intraoperative ultrasound was valuable to visualize the cerebrospinal fluid (CSF) flow obstruction, confirm the SAW location before dura incision and to control adequacy of resection. After surgery, sensory loss and weakness in particular showed significant improvement.

CONCLUSIONS

The present study comprises the largest series of surgically treated SAW, underscoring the unique clinical, radiographic, histopathological, and surgical findings. We want to emphasize SAW being a distinct entity of spinal arachnopathy with a favorable long-term outcome if diagnosed correctly and treated surgically. Intraoperative ultrasound aids visualizing the SAW before dural incision, as well as verifying restored CSF flow after resection.

Spinal Arachnoid Web: A didactic report of two cases with clinical, radiological, surgical and pathological correlations

BACKGROUND

Arachnoid web (AW) is a rare but probably underestimated cause of spinal cord injury that is complex to diagnose due to subtle MRI findings and similarities to other better-known diseases such as arachnoid cyst (AC) or transdural spinal cord herniation (TSCH). Increased recognition of AW is mandatory since delay in diagnosis can lead to potentially serious neurological sequelae.

CASE PRESENTATIONS

We report two additional cases of AW for didactic purposes, with special emphasis on the distinctive MRI and intraoperative findings. Both patients presented with progressively worsening neurological symptoms, including proprioceptive ataxia, motor weakness, numbness and neuropathic pain. The diagnosis of AW was suspected on the basis of specific MRI criteria, especially the so-called "scalpel sign". Formal confirmation of the diagnosis was obtained in two patients that were managed surgically. Postoperative follow-up demonstrated significant functional recovery.

DISCUSSION

There is a need for better recognition of AW by the medical community. Careful analysis of MRI semiology is crucial for the distinction between AW, AC and TSCH. Prompt and accurate diagnosis is mandatory to conserve functional prognosis, since appropriate surgical treatment with AW resection is curative, halting or even resolving the neurological symptoms.

Neuroimaging findings and pathophysiology of dorsal spinal arachnoid webs: illustrative case

BACKGROUND

Spinal arachnoid webs are uncommon and difficult to diagnose, especially because causative intradural transverse bands of arachnoid tissue are radiographically occult. Left untreated, arachnoid webs may cause progressive, debilitating, and permanent neurological dysfunction. Conversely, more than 90% of patients may experience rapid neurological recovery after resection, even with a prolonged duration of presenting symptoms. Indirect imaging signs such as spinal cord indentation and compression with cerebrospinal fluid (CSF) flow alteration provide crucial diagnostic clues that are critical in guiding appropriate management of such patients.

OBSERVATIONS

The authors reported a patient with no significant medical history who presented with back pain, progressive lower extremity weakness, gait ataxia, and bowel and bladder incontinence. They discussed multimodality imaging for determining the presence of arachnoid webs, including magnetic resonance imaging, phase-contrast CSF flow study, computed tomography myelography, and intraoperative ultrasound. They also discussed the detailed anatomy of the spinal subarachnoid space and a plausible pathophysiological mechanism for dorsal arachnoid webs.

LESSONS

The authors report on a patient who underwent comprehensive imaging evaluation detailing the arachnoid web and whose subsequent anatomical localization and surgical treatment resulted in a full neurological recovery.

Arachnoid web of the spine: a systematic literature review

OBJECTIVE

An arachnoid web of the spine (AWS) is a rare and oftentimes challenging lesion to diagnose, given its subtle radiographic findings. However, when left untreated, this lesion can have devastating effects on a patient's neurological function. To date, only limited case reports and series have been published on this topic. In this study, the authors sought to better describe this lesion, performing a systematic literature review and including 2 cases from their institution's experience.

METHODS

A systematic literature search was performed in September 2018 that queried Ovid MEDLINE (1946-2018), PubMed (1946-2018), Wiley Cochrane Library: Central Register of Controlled Trials (1898-2018), and Thompson Reuters Web of Science: Citation Index (1900-2018), per PRISMA guidelines. Inclusion criteria specified all studies and case reports of patients with an AWS in which any relevant surgery types were considered and applied. Studies on arachnoid cysts and nonhuman populations, and those that did not report patient treatments or outcomes were excluded from the focus review.

RESULTS

A total of 19 records and 2 patients treated by the senior authors were included in the systematic review, providing a total of 43 patients with AWS. The mean age was 52 years (range 28-77 years), and the majority of patients were male (72%, 31/43). A syrinx was present in 67% (29/43) of the cases. All AWSs were located in the thoracic spine, and all but 2 (95%) were located dorsally (1 ventrally and 1 circumferentially). Weakness was the most frequently reported symptom (67%, 29/43), followed by numbness and/or sensory loss (65%, 28/43). Symptoms predominated in the lower extremities (81%, 35/43). It was found that nearly half (47%, 20/43) of patients had been experiencing symptoms for 1 year or longer before surgical intervention was performed, and 35% (15/43) of reports stated that symptoms were progressive in nature. The most commonly used surgical technique was a laminectomy with intradural excision of the arachnoid web (86%, 36/42). Following surgery, 91% (39/43) of patients had reported improvement in their neurological symptoms. The mean follow-up was 9.2 months (range 0-51 months).

CONCLUSIONS

AWS of the spine can be a debilitating disease of the spine with no more than an indentation of the spinal cord found on advanced imaging studies. The authors found this lesion to be reported in twice as many males than females, to be associated with a syrinx more than two-thirds of the time, and to only have been reported in the thoracic spine; over 90% of patients experienced improvement in their neurological function following surgery.

Microscope and Fiberscope-assisted Subarachnoid-Subarachnoid (S-S) Bypass: A Novel Surgical Technique to Reestablish Cerebrospinal Fluid Flow in Treating Dorsal Spinal Arachnoid Webs, Diagnosed by Cine-MRI

A "dorsal spinal arachnoid web" is the thickened arachnoid band on the surface of the spinal cord which disturbs the cerebrospinal fluid (CSF) flow, known as a rare cause of thoracic myelopathy. The ideal treatment is controversial because of the risk of readhesion after simple resection of the web. A subarachnoid-subarachnoid bypass is a method to reestablish CSF flow through a silicon tube between the cranial and caudal subarachnoid space. This method is reported to be useful for traumatic syringomyelia, adhesive arachnoiditis, etc. We applied this technique for arachnoid webs with the assistance of a microscope and fiberscope. After a dura incision, the thickened arachnoid web can be seen fluttering within the CSF flow inside the arachnoid space, which partitions the subarachnoid space into cranial and caudal parts. After opening the subarachnoid space and resection of the web under a microscope, the fiberscope is inserted toward the cranial and caudal directions to check for the presence of another arachnoid web. If another web is found, it is penetrated using a guiding wire. Then, a silicone tube is inserted into the cranial and caudal normal subarachnoid space. In this paper, we would like to introduce this technique.

Minimally Invasive Excision of Thoracic Arachnoid Web

OBJECTIVE

Arachnoid webs are rare intradural lesions that can cause direct spinal cord compression or alteration of the cerebrospinal fluid flow with syringomyelia. Surgery has been historically performed through wide-open laminectomies. The aim of this study is to prove the feasibility of minimally invasive techniques for the excision of arachnoid webs.

METHODS

A retrospective review of two cases of minimally invasive excision of thoracic arachnoid webs was performed. Surgery was undertaken through expandable tubular retractors.

RESULTS

Complete excision was achieved through the described approach, with minimal bony removal and soft tissue disruption. There were no intraoperative or perioperative complications. Both patients were mobilized early and discharged home within 24 hours after surgery. Postoperative imaging showed good re-expansion of the spinal cord, with no evidence of residual compression or tethering.

CONCLUSIONS

For symptomatic arachnoid webs, surgery remains the only definitive treatment. In expert hands, the excision of arachnoid webs can be achieved with tubular retractors and minimally invasive techniques.

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.

Update on the pathophysiology and management of syringomyelia unrelated to Chiari malformation

INTRODUCTION

Much has been published on syringomyelia related to Chiari malformation. In contrast, little is known about the condition when it is not associated with this malformation, but this presentation of syringomyelia constitutes a different entity and therefore requires specific management. We conducted a literature review to summarise the most accepted and widespread ideas about the pathophysiology, management and other aspects of syringomyelia unrelated to Chiari malformation.

DEVELOPMENT

We reviewed the most relevant literature on this condition, focusing on the pathophysiology, clinical presentation, diagnosis, and treatment.

CONCLUSIONS

Syringomyelia unrelated to Chiari malformation is a distinct entity that must be well understood to guarantee correct diagnosis, monitoring, and management. When the disease is suspected, a thorough study should be conducted to identify its aetiology. Treatment must aim to eliminate the cause of the disease; symptomatic treatment should remain a second-line option.

Syringomyelia secondary to "occult" dorsal arachnoid webs: Report of two cases with review of literature

In a certain group of patients with syringomyelia, even with the advent of sophisticated magnetic resonance imaging (MRI), no associated abnormality or cerebrospinal fluid (CSF) block is easily identified. This type of syringomyelia is often termed idiopathic. Current literature has less than 10 reports of arachnoid webs to be the causative factor. We present our experience in the management of two cases of syringomyelia secondary to arachnoid webs. Both our patients presented with progressive neurological deterioration with MRI scans demonstrating cervical/thoracic syrinx without Chiari malformation or low-lying cord. There was no history of previous meningitis or trauma. Both patients underwent myelography that demonstrated dorsal flow block implying CSF obstruction. Cord displacement/change in caliber was also noted and this was not evident on MRI scans. Both patients underwent thoracic laminectomy. After opening the dura, thickened/abnormal arachnoid tissue was found that was resected thus widely communicating the dorsal subarachnoid space. Postoperatively at 6 months, both patients had significant symptomatic improvement with follow-up MRI scans demonstrating significant resolution of the syrinx. In patients with presumed idiopathic syringomyelia, imaging studies should be closely inspected for the presence of a transverse arachnoid web. We believe that all patients with idiopathic symptomatic syringomyelia should have MRI CSF flow studies and/or computed tomography (CT) myelography to identify such arachnoid abnormalities that are often underdiagnosed. Subsequent surgery should be directed at the establishment of normal CSF flow by laminectomy and excision of the offending arachnoid tissue.

Clinical-radiological improvement following low-tech surgical treatment of an extensive cervical-medullary idiopathic syringomyelia in a low-resource African neurosurgical practice

Surgical intervention is not so commonly deployed for idiopathic syringomyelia, even the symptomatic ones; is only undertaken, in the current era, after thorough clinical evaluation and extensive high-resolution neuroimaging; and is more assuredly performed, high-tech, in health facilities in the developed world with cutting edge logistic supports. In the practice environment of a low-resource African developing country, a 41-year-old young man recently presented in severe clinical-neurological deficit, Nurick grade 5, with an extensive cervical-medullary idiopathic syringomyelia. In spite of severe preoperative and intraoperative resource limitations, he successfully underwent spinal surgical decompression, fenestration of syrinx, and expansile duraplasty. He improved clinically postoperatively and achieved mobility, Nurick grade 3, before hospital discharge. He sustained this improvement, Nurick grade 3 to 2, 20 months post-op. He is now independent, needing only a walking stick to aid ambulation, and an MRI at this time showed only minimal focal post-op changes but total disappearance of the syrinx.

Pathophysiology of primary spinal syringomyelia

OBJECT

The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression.

METHODS

To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing.

RESULTS

In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space.

CONCLUSIONS

These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245.

Idiopathic syringomyelia: retrospective case series, comprehensive review, and update on management

Object

A syrinx is a fluid-filled cavity within the spinal cord that can be an incidental finding or it can be accompanied by symptoms of pain and temperature insensitivity. Although it is most commonly associated with Chiari malformation Type I, the advancement of imaging techniques has resulted in more incidental idiopathic syringes that are not associated with Chiari, tumor, trauma, or postinfectious causes. The authors present a comprehensive review and management strategies for the idiopathic variant of syringomyelia.

Methods

The authors retrospectively identified 8 idiopathic cases of syringomyelia at their institution during the last 6 years. A PubMed/Medline literature review yielded an additional 38 articles.

Results

Two of the authors' patients underwent surgical treatment that included a combination of laminectomy, lysis of adhesions, duraplasty, and syrinx fenestration. The remaining 6 patients were treated conservatively and had neurologically stable outcomes. Review of the literature suggests that an etiology-driven approach is essential in the diagnosis and management of syringomyelia, although conservative management suffices for most cases. In particular, it is important to look at disturbances in CSF flow, as well as structural abnormalities including arachnoid webs, cysts, scars, and a diminutive posterior fossa.

Conclusions

The precise etiology for idiopathic syringomyelia (IS) is still unclear, although conceptual advances have been made toward the overall understanding of the pathophysiology of IS. Various theories include the cerebellar piston theory, intramedullary pulse pressure theory, and increased spinal subarachnoid pressure. For most patients with IS, conservative management works well. Continued progression of symptoms, however, could be approached using decompressive strategies such as laminectomy, lysis of adhesions, and craniocervical decompression, depending on the level of pathology. Management for patients with progressive neurological dysfunction and the lack of flow disturbance is unclear, although syringosubarachnoid shunting can be considered.

Amelioration of caudal thoracic syringohydromyelia following surgical management of an adjacent arachnoid cyst

A nine-year-old male, neutered, pug was presented for investigation of progressive ambulatory paraparesis and pelvic limb ataxia of three months' duration. Magnetic resonance imaging was suggestive of caudal thoracic syringohydromyelia with an adjacent intradural arachnoid cyst. The cyst was marsupialised following dorsal laminectomy. Neurological status had improved 10 weeks following surgery when repeat magnetic resonance imaging revealed reduced spinal cord compression both as a result of resolution of the cyst and reduction in size of the syringohydromyelia. At 17 months following surgery, the dog showed further improvements in neurological status, exhibiting mild pelvic limb ataxia and proprioceptive deficits. Improved cerebrospinal fluid flow following surgery may have played a role in the improvement in both conditions. The presence of syringohydromyelia in this context does not preclude a favourable clinical outcome following surgical management.

Endoscope-assisted surgery of spinal intradural adhesions in the presence of cerebrospinal fluid flow obstruction

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To investigate whether the adjunctive use of endoscopy of the subarachnoid space (arachnoscopy) can improve the success of microsurgery for spinal arachnoid adhesions.

SUMMARY OF BACKGROUND DATA

Intradural adhesions that obstruct pulsatile cerebrospinal fluid (CSF) flow are a typical spinal cause of syringomyelia. Phase-contrast magnetic resonance imaging (MRI) allows CSF flow obstructions to be reliably localized. The treatment of choice is the microsurgical removal of CSF flow obstructions caused by adhesions. Microsurgery, however, does not lend itself to assessments of further adhesions beyond the borders of the exposed area. In this study, we therefore investigated whether endoscopic assistance allows adhesions in the vicinity of the exposed area to be detected.

METHODS

From 2006 to 2009, a single neurosurgeon performed 27 consecutive microsurgical procedures with endoscopic assistance in 25 patients with spinal arachnoid adhesions. A MurphyScope endoscope was used for this purpose. CSF flow was studied before and after surgery in all patients using phase-contrast MRI in the region of the craniocervical junction, the cervical spine, the thoracic spine, and the lumbar spine.

RESULTS

In all 27 procedures, CSF flow obstructions were detected at the level identified by phase-contrast MRI. In 25 procedures, image quality was sufficient for an inspection of the adjacent subarachnoid space. In six cases, the surgeon detected further adhesions that obstructed CSF flow in the adjacent subarachnoid space not visualized with the microscope. In all cases, these adhesions were identified and removed during microsurgery.Postoperative MRI scans demonstrated free CSF flow in all patients and a decrease in syrinx size in six patients.

CONCLUSION

Arachnoscopy is a helpful adjunct to microsurgery and can be performed safely and easily. It allows the surgeon to detect further adhesions in the subarachnoid space, which would remain undetected by microscopy alone.

Arachnoscopy: a special application of spinal intradural endoscopy

Object

The microsurgical removal of obstructions to CSF flow is the treatment of choice in the surgical management of intradural arachnoid cysts. Cardiac-gated phase-contrast MR imaging is an effective tool for the primary diagnosis and localization of arachnoid cysts. Microsurgery, however, does not lend itself to assessments of further adhesions beyond the borders of the exposed area. The use of a thin endoscope allows surgeons to assess intraoperatively whether the exposure is wide enough.

Methods

Between 2006 and 2010, a single neurosurgeon performed 31 consecutive microsurgical procedures with endoscopic assistance in 28 patients with spinal arachnoid adhesions. A MurphyScope endoscope was used for this purpose. The CSF flow was studied before and after surgery in all patients by using phase-contrast MR imaging in the region of the craniocervical junction, the cervical spine, the thoracic spine, and the lumbar spine.

Results

In all 31 procedures, CSF flow obstructions were detected at the level identified by phase-contrast MR imaging. In 29 procedures, image quality was sufficient for an inspection of the adjacent subarachnoid space. In 6 cases, the surgeon detected further adhesions that obstructed CSF flow in the adjacent subarachnoid space that were not visualized with the microscope. In all cases, these adhesions were identified and removed during microsurgery.

Conclusions

Arachnoscopy is a helpful adjunct to microsurgery and can be performed safely and easily. It allows the surgeon to detect further adhesions in the subarachnoid space that would remain undetected by microscopy alone.

Syringomyelia associated with a spinal arachnoid cyst

While syringomyelia is not a rare spinal disorder, syringomyelia associated with a spinal arachnoid cyst is very unusual. Here, we report a 62-year-old man who suffered from gait disturbance and numbness of bilateral lower extremities. Spinal magnetic resonance imaging (MRI) showed the presence of a spinal arachnoid cyst between the 7th cervical and 3rd thoracic vertebral segment and syringomyelia extending between the 6th cervical and 1st thoracic vertebral segment. The cyst had compressed the spinal cord anteriorly. Syringomyelia usually results from lesions that partially obstruct cerebrospinal fluid flow. Therefore, we concluded that the spinal arachnoid cyst was causing the syringomyelia. After simple excision of the arachnoid cyst, the symptoms were relieved. A follow-up MRI demonstrated that the syringomyelia had significantly decreased in size after removal of the arachnoid cyst. This report presents an unusual case of gait disturbance caused by syringomyelia associated with a spinal arachnoid cyst.

CARDIAC-GATED PHASE-CONTRAST MAGNETIC RESONANCE IMAGING OF CEREBROSPINAL FLUID FLOW IN THE DIAGNOSIS OF IDIOPATHIC SYRINGOMYELIA

OBJECTIVE

Syringomyelia without an obvious cause, such as a Chiari malformation, a tumor, or a spinal injury, is rare and may be associated with an arachnoid web or cyst. In the literature, conventional myelography is the diagnostic method of choice. In this retrospective study, we evaluated the diagnostic value of magnetic resonance imaging (MRI) cerebrospinal fluid (CSF) flow studies as compared with conventional myelography in patients with syringomyelia.

METHODS

From early 2003 to late 2006, 320 patients with syringomyelia underwent cardiac-gated phase-contrast MRI of CSF flow in the brain and spine. We assessed the presence of CSF flow blockage as well as syrinx site, shape, and size. Additional myelography was performed in 8 patients. CSF flow blockage and progressive neurological symptoms or progression of syringomyelia were indications for surgery.

RESULTS

Syringomyelia without an obvious cause was found in 125 patients. CSF flow blockage was detected in 33 patients. Seven of these patients underwent cyst wall resection and decompression of the subarachnoid space via a unilateral approach without laminectomy. Myelography revealed CSF flow blockage in only 2 of 8 cases. In the other 6 patients, MRI detected a blockage and surgery revealed arachnoid cysts or webs. Postoperative CSF flow studies revealed free CSF flow in all 10 surgically treated patients. In 6 of these patients, syrinx size was reduced after surgery.

CONCLUSION

Myelography should not be the method of choice for the diagnosis of idiopathic syringomyelia. MRI CSF flow studies were found to be more reliable.

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

OBJECT

Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning.

METHODS

Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed.

RESULTS

The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images.

CONCLUSIONS

Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.

TRANSIENT SYRINGOMYELIA LEADING TO ACUTE NEUROLOGICAL DETERIORATION AFTER REPAIR OF A LIPOMYELOMENINGOCELE

OBJECTIVE

Transient paraplegia in the immediate postoperative period after lipomyelomeningocele repair is uncommon and is not discussed in the literature. We present the unique case of a patient who developed transient paraplegia 48 hours after lipomyelomeningocele repair attributable to the acute development of a thoracic syrinx.

CLINICAL PRESENTATIOn

At birth, the patient was noted to have a large skin-covered mass in the lumbosacral region. On neurological examination, both iliopsoas and quadriceps exhibited 3/5 motor function, and the plantar flexors and dorsiflexors exhibited 1/5 motor function. Urodynamic studies were normal. Magnetic resonance imaging demonstrated the presence of a lipomyelomeningocele associated with tethering of the spinal cord in the lumbosacral region.

INTERVENTION

At 5 months of age, the patient underwent repair of the lipomyelomeningocele. After surgery, the patient developed progressive paraplegia along with bowel and bladder dysfunction. Given the concern about a postoperative hematoma resulting in cauda equina syndrome, the patient returned to the operating room for a wound exploration. No compressive lesion such as a hematoma was found at surgery. A postoperative magnetic resonance imaging scan obtained afterward, however, demonstrated the presence of a large thoracic syrinx.

CONCLUSION

Syrinx formation can occur as early as 48 hours after lipomyelomeningocele repair, leading to progressive lower extremity weakness and bowel and bladder incontinence. In the immediate postoperative period, an acute syrinx can mimic cauda equina syndrome, and a magnetic resonance imaging scan is necessary to distinguish between these two entities. In this patient, the syrinx was transient and resolved without a shunting procedure.

Nontraumatic cervicothoracic syrinx as a cause of progressive neurologic dysfunction

BACKGROUND/OBJECTIVE

Syringomyelia is characterized by a fluid-filled cavity within the spinal cord. While its pathogenesis is currently debated, the relationship of syringomyelia with other conditions, such as Chiari I malformation and cord/column trauma, is well accepted. Despite these common associations, a nidus for syrinx formation has not been identified in a subset of patients. We report 2 patients with idiopathic cervicothoracic syringomyelia who presented with progressive neurologic dysfunction. Diagnostic and treatment algorithms used in the care of these patients are presented.

METHODS

Retrospective review, including preoperative and postoperative studies, intraoperative findings, and the patients' surgical outcomes.

RESULTS

Patients underwent laminectomy, lysis of adhesions, untethering of spinal cord, fenestration of syrinx, and duraplasty after preoperative studies demonstrated evidence of focal cerebrospinal fluid flow block at the level of the syrinx. One patient's neurologic condition improved after surgery, whereas the other's remained unchanged without further deterioration; both showed radiographic decrease in the syrinx on immediate postoperative magnetic resonance imaging.

CONCLUSIONS

These 2 cases illustrate patients who develop a cervicothoracic syrinx in the absence of any trauma, infection, previous manipulation of the neuraxis, or malformations known to be associated with a syringomyelia. Whereas there is no consensus on the optimal management of these patients, the patients reported here experienced arrest in deterioration or improvement of their neurologic examination, making the identification of this condition important as a potentially reversible cause of neurologic deficits. Long-term follow-up is required to determine the efficacy, durability, and lifestyle impact of the procedure.

Primary spinal syringomyelia. Invited submission from the joint section meeting on disorders of the spine and peripheral nerves, March 2005

In the present review the author describes the different types of syringomyelia that originate from abnormalities at the level of the spinal cord rather than at the craniovertebral junction. These include posttraumatic and postinflammatory syringomyelia, as well as syringomyelia associated with arachnoid cysts and spinal cord tumors. The diagnosis and the principles of managing these lesions are discussed, notably resection of the entity restricting cerebrospinal fluid flow. Placement of a shunt into the syrinx cavity is reserved for patients in whom other procedures have failed or who are not candidates for other procedures.

Arachnoid cyst resulting in tonsillar herniation and syringomyelia in a patient with achondroplasia

Achondroplasia has been associated with varying degrees of cervicomedullary and spinal compression, although usually in the pediatric population. Large arachnoid cysts have also been found to result in tonsillar herniation and syringomyelia. The authors present the case of a patient with achondroplasia who presented with symptoms of foramen magnum compression and syringomyelia, and who was subsequently found to have a large posterior fossa arachnoid cyst.

This 38-year-old woman with achondroplasia presented with an 8-month history of headache and numbness of the hands and fingers. Admission magnetic resonance (MR) imaging of the head and spine revealed a large arachnoid cyst in the posterior cranial fossa, a 6-mm tonsillar herniation consistent with an acquired Chiari malformation, and a large cervicothoracic syrinx. The patient was treated using suboccipital craniectomy, C-1 laminectomy, fenestration of the arachnoid cyst, and decompression of the acquired Chiari malformation with duraplasty.

Surgical decompression resulted in improvement of the presenting symptoms, adequate decompression of crowding at the foramen magnum, and resolution of the syrinx. Although there was only partial reduction in the retrocerebellar cisternal space on follow-up MR imaging, no residual symptoms were related to this.

Surgical treatment of a syringomyelia associated with an idiopathic arachnoid malformation disclosed by preoperative MRI

BACKGROUND

We describe the very rare condition of an idiopathic spinal arachnoid malformation associated with syringomyelia (SM) and depicted on preoperative magnetic resonance imaging (MRI) whose features were confirmed at surgery.

CASE DESCRIPTION

A 34-year-old female suffered from progressive gait impairment because of lower limb palsy and sensory disturbances. MRI demonstrated a bulging membrane at the T6 level that was transversely stretched between the dorsal aspect of the spinal cord and the posterior dura mater. At this level, the spinal cord appeared atrophic and pushed anteriorly against the dura with enlargement of the posterior subarachnoid spaces (SAS) and focal collapse of an associated panmedullar SM. Surgery consisted in releasing the arachnoid malformation and opening the inferior segment of the syringomyelic cavity. Pathological examination revealed a fibro-sclerotic tissue with cellular areas of meningo-endothelial cells. Postoperative neurological status progressively improved but slightly. Three-months and 1 year postoperatively, MRI showed the collapse of the whole SM and restoration of cerebrospinal fluid (CSF) flow at the treated T6 level.

CONCLUSION

Spinal arachnoid malformations associated with SM are very rare and have never been described up to now on MRI. Surgical removal of the causative malformation allows spinal cord decompression and prevents the recurrence of the SM by restoring normal CSF circulation.

L’arachnoïdite médullaire adhésive : une complication tardive de l’analgésie péridurale obstétricale

A 30-year-old woman, G3P3, was progressively affected by spastic paraparesis with loss of sensitivity and urinary incontinence due to medullar adhesive arachnoiditis occurring five months after an epidural analgesia for repeat cesarean section. Magnetic resonance imaging showed a voluminous subarachnoid cyst and a septated syringomyelic cavitation attributed to metabisulfite, the preservative of epinephrine and to multiple lidocaine injections through the catheter in the postoperative period. Despite two decompressive neurosurgical operations, the neurological state of the patient continues to worsen.

Post-traumatic syringomyelia: a review

More than a quarter of spinal cord injured patients develop syringes and many of these patients suffer progressive neurological deficits as a result of cyst enlargement. The mechanism of initial cyst formation and progressive enlargement are unknown, although arachnoiditis and persisting cord compression with disturbance of cerebrospinal fluid flow appear to be important aetiological factors. Current treatment options include correction of bony deformity, decompression of the spinal cord, division of adhesions, and shunting. Long-term improvement occurs in fewer than half of patients treated. Imaging evidence of a reduction in syrinx size following treatment does not guarantee symptomatic resolution or even prevention of further neurological loss. A better understanding of the causal mechanisms of syringomyelia is required to develop more effective therapy.

Spinal arachnoid cysts associated with syringomyelia: report of two cases and a review of the literature

We describe two cases of spinal arachnoid cyst associated with syringomyelia and report the clinical results after surgical treatment using excision of the cyst without a shunt operation for the syringomyelia. Case 1 is a 73-year-old woman who presented with a spastic gait and numbness of her bilateral lower extremities. Magnetic resonance imaging (MRI) showed the presence of a spinal arachnoid cyst extending from T3 to T8 and syringomyelia from T8 to T10. The cyst had compressed the spinal cord anteriorly. We excised the cyst without applying a shunt tube for the syringomyelia. Case 2 is a 68-year-old woman who presented with gait disturbance and numbness of her left lower extremity. MRI indicated that the spinal cord had been compressed anteriorly by a spinal arachnoid cyst extending from T10 to T11. Syringomyelia existed just caudal to the cyst at T11. In our surgical treatment, we excised only the cyst. In both cases, neurologic examination after the operation showed amelioration of the condition. Postoperative MRI indicated that the spinal cord had moved to the center, its original position, and the syringomyelia had decreased in size. Conclusively, spinal arachnoid cyst associated with syringomyelia can be treated by simple excision of the cyst without shunting the syrinx if the decompression effect resulting from removal of the cyst is sufficient.

Intraoperative measurement of spinal cord blood flow in syringomyelia

The role of spinal cord ischemia in the pathophysiology of syringomyelia remains undetermined. Previous reports in the literature suggest that shunting of syringes can improve spinal cord blood flow. In order to determine the effects of syrinx decompression on spinal cord blood flow in patients with syringomyelia, we prospectively measured regional spinal cord blood flow (RSCBF) intraoperatively pre and post shunting in patients with symptomatic syringomyelia using laser doppler flowmetry. Six patients with MRI documented syringomyelia were studied (three with Arnold Chiari I malformation and associated syrinx and three with post-traumatic syringomyelia). Surgery was performed on all patients with either a syringopleural or syringoperitoneal shunt. Laser doppler blood flow and somatosensory evoked potentials were monitored prior to myelotomy and after shunt insertion. Results indicate that there was a significant increase in RSCBF after decompression of the syrinx. This study supports the hypothesis that spinal cord ischemia is important in the pathophysiology of syringomyelia and confirms previous reports in the literature regarding RSCBF in syringomyelia.

Treatment of terminal syringomyelia in association with tethered cord syndrome: clinical outcomes with and without syrinx drainage

Object

Current use of magnetic resonance (MR) imaging has led to increased awareness of the frequency of terminal syringomyelia in patients with tethered cord syndrome. However, that the surgical treatment of terminal syringomyelia is necessary remains unclear.

In this study the authors attempted to assess the clinical impact, if any, brought after syrinx decompression on the clinical outcome of tethered cord syndrome.

Methods

They randomly assigned 30 cases of pediatric tethered cord into two treatment groups: those in whom an untethering procedure was performed (Group I) and those in whom this procedure was combined with syrinx decompression (Group II). The 1-year follow-up clinical results obtained in the two groups, in correlation with MR imaging findings, were compared to evaluate the benefit of added syrinx drainage.

Clinical follow-up evaluation revealed that surgical drainage of the syrinx, when combined with spinal cord untethering, resulted in better outcomes in terms of resolution of sensory deficits (p = 0.036) and bladder dysfunction (p = 0.05). The improvement in clinical outcome correlated with the radiologically documented resolution of the syrinx cavity; however, response rates of symptoms differed for each tethering subgroup.

Conclusions

Preliminary results of this study indicated that terminal syringomyelia should be considered as a comorbidity that contributes to the clinical outcome of patients with tethered cord syndrome. A better clinical outcome is achieved following successful decompression of the syrinx in addition to untethering the spinal cord. These findings emphasize the importance of recognizing, evaluating, and treating this pathological entity.