Clinical Outcomes of Surgical Treatment for Arachnoid Web: A Case Series

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.

Arachnoid webs with spinal cord compression: insights from three cases

Spinal arachnoid webs are intradural bands of abnormally formed arachnoid tissue, located within the subarachnoid space and causing compression of the dorsal aspect of the spinal cord. Arachnoid webs are uncommon and can be difficult to treat. We report 3 patients presenting with a spinal arachnoid web within a 6-month period. All of them exhibited signs of thoracic myelopathy and the MRI showed the pathognomonic 'scalpel sign'. Two of the patients underwent surgery for removal of their spinal arachnoid web, whereas the third patient case is currently being managed conservatively. We also present our 2D intraoperative video for arachnoid web removal and spinal cord decompression.

A case of neurosurgical treatment of thoracic dorsal arachnoid web

Background

Dorsal arachnoid webs constitute abnormal formations of arachnoid that tend to occur in the upper thoracic spine and can lead to spinal cord displacement. Patients typically present with back pain, sensory disturbances, and weakness. It may also obstruct the cerebrospinal fluid (CSF) flow, leading to syringomyelia. In magnetic resonance (MR) studies, the "scalpel sign" is a classical finding, and it may also be accompanied by syringomyelia attributed to CSF flow. Definitive surgical resection is the mainstay of treatment.

Case Description

A 31-year-old male presented with mild weakness in the right leg and diffuse lower extremity sensory changes. The MR showed the typical "scalpel sign" at the T7 level consistent with diagnosing a spinal arachnoid web. He underwent a T6-T8 laminotomy for lysis of the web and decompression of the thoracic cord. Postoperatively, his symptoms improved markedly.

Conclusion

Surgical resection is the treatment of choice when an arachnoid web is documented on an MR and correlates with the patient's clinical symptoms/signs.

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.

Dorsal arachnoid web: A rare cause of syringomyelia and myelopathy

Dorsal arachnoidal webs are condensations of arachnoidal tissue densely adherent to the pial surface of the posterior aspect of the dorsal spinal cord. Infrequently described in literature they disrupt the flow of CSF in the spinal subarachnoid space leading to syringomyelia and myelopathy. While there are several theories on their origin, the "scalpel sign" on magnetic resonance imaging is considered to be pathognomonic of this condition. An illustrative case of a 58 year old man with syringomyelia and dorsal cord indentation who presented with spastic paraparesis, gait instability, parasthesias and bilateral non radicular upper limb pain that resolved following excision of the web is described to highlight the importance of considering this diagnosis when cases of so called "idiopathic" syringomyelia are encountered.

Thoracic spinal arachnoid web and syringomyelia with rostral expansion to the first cervical spinal cord level: Case report

INTRODUCTION AND IMPORTANCE

A spinal arachnoid web is a rare pathology that has been associated with the development of syringomyelia. Syrinx expansion can occur, which can result in the development of new symptoms. In the current literature, the farthest rostral expansion of the associated syrinx has been to the C3 spinal level.

CASE PRESENTATION

We present a 49-year-old Hispanic male with a thoracic spinal arachnoid web and an associated syrinx spanning from C1 to T7 spinal level. The patient developed upper extremities radicular symptoms that worsened over time. He underwent surgical management with T6-8 laminectomy and excision of the web. Postoperative follow-up evaluations demonstrated progressive clinical improvement with eventual resolution of symptoms and syringomyelia.

CLINICAL DISCUSSION

Syringomyelia secondary to a thoracic spinal arachnoid web is a progressive disease that can expand rostrally to the C1 spinal level. The clinical presentation usually involves the lower extremities. However, if the upper thoracic or cervical spinal cord is involved, patients can also present symptoms in the upper extremities. Management usually involves surgical excision of the web in order to decompress the subarachnoid space and restore the normal cerebrospinal fluid (CSF) flow.

CONCLUSION

Our case suggests that syringomyelia secondary to a spinal arachnoid web may continuously expand with concomitant worsening of symptoms. However, surgical resection is curative with possible remission of symptoms and normalization of spinal anatomy.

Clinical Characteristics, Outcomes, and Pathology Analysis in Patients With Dorsal Arachnoid Web

BACKGROUND

Dorsal arachnoid webs (DAWs) are rare pathological abnormalities of the arachnoid layer of the spinal cord that can result in pain and myelopathy.

OBJECTIVE

To present clinical, imaging, and pathological characteristics of patients diagnosed with DAW, case illustrations, and a review of the literature.

METHODS

Seventeen cases of DAW between 2015 and 2019 at a tertiary medical center were retrospectively identified through a case log search. Patient characteristics, preoperative imaging, operative notes, and pathology reports were collected. Our main outcome assessed was postoperative resolution of symptoms. Odds ratios were used to determine associations between preoperative signs and symptoms with postoperative symptom resolution.

RESULTS

The mean age of the cohort was 50.5 years (IQR = 16) and presented primarily with back pain (64.7%). On imaging, all patients were found to have the "scalpel sign," and nearly half had a syrinx present (41.2%). All DAWs were located in the thoracic spine, with the most common location being the midthoracic (70.6%). The mean follow-up length for all patients was 4.3 months. There were no preoperative symptoms significantly associated with postoperative symptom resolution; however, a trend was noted with the presence of a preoperative syrinx. Pathology samples consistently demonstrated fibroconnective or collagenous tissue with no evidence of inflammation or neoplasm.

CONCLUSION

DAW is a rare pathology that can result in myelopathy or inappropriate interventions if misdiagnosed. Surgical intervention using laminectomy with intradural exploration should be considered in symptomatic patients with DAW because it is curative with a strong chance of preoperative symptom resolution with relatively low complication rates.

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.

Thoracic dorsal arachnoid web with rapid onset of symptoms: A report of two cases and brief review of the literature

Background:

Thoracic arachnoid webs are a rare entity and can be challenging to diagnose with sometimes subtle radiographic findings. Arachnoid webs can cause severe cord compression with associated syrinx and resulting myelopathy, weakness, sensory loss, and bowel/bladder dysfunction. There have been a little over 60 cases total reported in the literature with only one systematic review. The cases presented here have unique features including rapid onset of symptoms, symptomatic syrinx extending into the cervical spine, and intraoperative syrinx drainage, all of which are quite rare in the current published literature for arachnoid webs.

Case Description:

Here, we present two patients, a 73-year-old man and 58-year-old man presenting with different symptoms and timing of symptom progression but both with “scalpel sign” and associated syrinx present on their MRIs. Each patient underwent a laminectomy with resection of arachnoid web with complete resolution of symptoms in the first case and significant improvement in the second case. Postoperative imaging in both cases showed almost complete resolution of the syrinx.

Conclusion:

Early clinical evaluation and workup followed by early surgical treatment can lead to dramatic improvement in outcomes after surgery. For patients that are symptomatic from an associated syrinx, a midline myelotomy to facilitate drainage can be considered to be done concomitantly with the arachnoid web resection.

Surgical treatment of spinal arachnoid web: Report of two cases and literature review

BACKGROUND

Arachnoid webs (AWs) can cause cord compression and syringomyelia in the thoracic spine. Here, we describe two patients who underwent operative treatment for AW and reviewed the literature.

CASE DESCRIPTION

Two patients underwent surgical treatment for thoracic AW. Both presented with spastic gait and numbness in the lower extremities. On MR, these lesions exhibited the "scalpel" sign (i.e. due to the accumulation of cerebrospinal fluid on the dorsal aspect of the spinal cord). Operative intervention, consisting of fenestration and web resection, resulted in symptom resolution.

CONCLUSION

Thoracic AWs are rare lesions that should be considered among the differential diagnosis of spinal compressive syndromes. Surgical fenestration and resection of the AW correct the flow dynamics allowing for full symptoms resolution.

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.

Multi-modality imaging evaluation of the dorsal arachnoid web

PURPOSE

Dorsal arachnoid web (DAW) is a rare intradural abnormality which is associated with progressive myelopathy. Our objective was to review multi-modality imaging techniques demonstrating the scalpel sign appearance in evaluation of DAW.

METHODS

We retrospectively reviewed various imaging modalities of patients found to have DAW at our institution during January 2015 to February 2020. Five patients underwent surgical decompression with pathological correlation. The remaining patients were presumptively diagnosed based on the characteristic finding of scalpel sign. Clinical data were evaluated and correlated to imaging findings. All imaging modalities demonstrated the characteristic scalpel sign.

RESULTS

Sixteen patients (10 females, and six males) with multi-imaging modalities were evaluated. Their mean age was 52 year (range 23-74 years). Fifteen patients underwent conventional spine MRI. Further high-resolution MR imaging techniques, e.g. 3D T2 myelographic sequence, were utilized with two patients. MRI spine CSF flow study was performed to evaluate the flow dynamic across the arachnoid web in one patient. Eight patients were evaluated with CT myelogram. Syrinx formation was discovered in seven (44%) patients; five (71%) of them underwent surgical resection and decompression. Two patients underwent successful catheter-directed fenestration of the web with clinical improvement. We found a statically significant positive correlation between the degree of cord displacement and compression with syrinx formation (r = 0.55 and 0.65 with p-value of 0.03 and 0.009, respectively).

CONCLUSION

DAW has characteristic scalpel sign independent of imaging modality. Multi-modality imaging evaluation of DAW is helpful for evaluation and surgical planning.

Diagnosis and Surgical Treatment of Thoracic Dorsal Arachnoid Web: A Report of Two Cases

Introduction

An arachnoid web (AW) is a relatively rare disease and shows clinical symptoms and radiological findings similar to those of an arachnoid cyst (AC) or spinal cord herniation (SCH). Since the operative procedures for an AW are generally different from those intrathecal disorders, correct preoperative differential diagnosis is important. The purposes of this study were to report the usefulness of magnetic resonance imaging (MRI) and computed tomography (CT) myelography for diagnosing AW and to show the histological findings and clinical results. Case Description. Two patients, a 79-year-old man and a 43-year-old woman, are presented. The primary diagnoses were AC with ossification of the ligamentum flavum and epidural hematoma, respectively, in previous hospitals. They were finally diagnosed by the characteristic MRI and CT myelogram finding called the “scalpel sign.” Histological findings showed epithelial cells and fibrous tissue derived from arachnoid tissues and microcalcifications. After surgery, the scalpel sign has vanished, and aggravation of their symptoms was prevented.

Conclusion

An AW is refractory, but early detection by MRI and CT myelography and early treatment improve outcomes after surgery.