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

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).

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.

Spinal arachnoid webs in adults: Clinical and imaging features in a multicenter study

BACKGROUND AND PURPOSE

Spinal arachnoid webs (SAWs) are rare and can present with myelopathic symptoms. This study aims to add 85 more cases of SAWs to the literature so we can continue to analyze clinical and imaging trends of SAWs to better understand this entity and its natural history.

METHODS

An institutional review board-approved retrospective review of SAW cases between 2016 and 2022 within a metropolitan, multihospital network was performed, searching for MR and CT reports that included "arachnoid web." Of 108 identified reports, 85 patients had imaging and/or pathologically proven arachnoid webs. Demographic and clinical data were collected. Images were analyzed for SAW level, point of maximum kyphosis, presence of cord expansion, and signal intensity. The electronic medical record (EMR) was reviewed for age, sex, symptom presentation and duration, management, and outcomes.

RESULTS

Of 85 cases, the most common presenting chief complaint was back pain and weakness. All (100%) SAWs were in the dorsal thoracic subarachnoid space, with 87% (74/85) located from thoracic (T) 2 to T6. Spinal cord expansion and signal abnormality were present in 54.1% and 23.5%, respectively. Twenty-six underwent surgical resection with 20 showing improvement of at least one symptom.

CONCLUSION

We present 85 additional cases of SAWs to the existing literature. Our cases all occurred in the dorsal thoracic subarachnoid space, predominantly from T2 to T6. Patients present with symptoms like other causes of cord compression, and spinal MR studies should be evaluated routinely for the findings of SAWs. Further research could focus on understanding SAW prevalence, risk factors, and pathophysiology.

Scalpel sign: Dorsal thoracic arachnoid web, thoracic arachnoid cyst and ventral cord herniation

The “Scalpel sign” is a radiological sign which can be identified on magnetic resonance imaging and indicates dorsal compression of the spinal cord [1]. Prior descriptions of a “Scalpel sign” have been reported in the literature and the awareness and identification of this pathognomonic sign may aid in the rapid diagnosis and treatment of patients with dorsal arachnoid web, dorsal arachnoid cyst or ventral cord herniation. We describe 3 cases which highlight these rare conditions for which this sign is pathognomonic and summarize the pertinent literature related to these disorders [1,2].

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.

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 Webs: Presentation, Natural History, and Outcomes in 38 Patients

BACKGROUND

Spinal arachnoid webs are rarely described bands of thickened arachnoid tissue in the dorsal thoracic spine. Much is unknown regarding their origins, risk factors, natural history, and outcomes.

OBJECTIVE

To present the single largest case series, detailing presenting symptoms and outcomes amongst operative and nonoperative patients, to better understand the role of intervention.

METHODS

This retrospective chart review identified 38 patients with arachnoid webs. Patient demographics, radiologic signs, symptoms, and surgical history data were extracted from the electronic medical record. Symptoms were divided by location and character. 28 patients were successfully contacted for follow up outcome surveys.

RESULTS

26 patients (68%) underwent surgical intervention, 12 (32%) were managed non-operatively. 15 (39%) patients had undergone a previous unsuccessful surgery at a different site for their symptoms prior to arachnoid web diagnosis. Commonly presenting symptoms included myelopathy (68%), focal thoracic back pain (68%), lower extremity weakness (45%), numbness and sensory changes (58%), and lower extremity radicular pain (42%), upper extremity weakness (24%), and radicular pain (37%). Focal thoracic pain was associated with thoracic level (P < .02). Myelopathic symptoms were less common in postoperative patients. Postoperative patients described significantly more upper extremity (P < .01) and thoracic (P < .01) numbness and paresthesias. Surveyed nonoperative patients universally described their symptoms as either stable or worsening.

CONCLUSION

Spinal arachnoid webs present with thoracic myelopathy and back pain but can also present with upper extremity symptoms. Surgical intervention stabilizes or improves symptoms and is well received. Nonoperative patients do not spontaneously improve.

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.

Syringopleural shunt placement in a pug with a cervical spinal diverticulum and associated syringomyelia

We report persistence of associated syringomyelia and formation of newly caudal spinal arachnoid diverticulum, following marsupialization surgery. We describe syringopleural shunt placement as a novel approach to treat both conditions in a Pug dog.

Persistent Syringomyelia After Posterior Fossa Decompression for Chiari Malformation

BACKGROUND

Chiari malformation (CM) is often comorbid with syringomyelia. The treatment of CM via posterior fossa decompression (PFD) may not improve syringomyelia in up to 40% of patients, based on historical cohorts. Management of these patients is problematic, as both reoperation and syrinx shunting have high failure rates in the long term.

METHODS

We retrospectively reviewed our cases in which patients with CM type 1 or 1.5 and syringomyelia underwent PFD without postoperative improvement in syringomyelia. Symptomatology and radiographic measurements were collected at presentation and on the first and latest available postoperative scans and analyzed. We present 2 cases to illustrate the challenges in the management of these patients.

RESULTS

Our cohort consisted of 48 consecutive patients with CM and syringomyelia who underwent PFD. Of these, 41 patients had postoperative improvement in or resolution of syringomyelia. We subsequently studied the cohort of 7 patients who underwent PFD with (n = 5) or without (n = 2) durotomy and demonstrated worsening of syringomyelia following surgery. This cohort had mean (±SEM) preoperative syrinx area of 23.9 ± 10.0 mm². Postoperatively, the mean syrinx area increased to 40.5 ± 9.6 mm² and 57.3 ± 12.5 mm² on the first and latest postoperative scans available (P = 0.02), for an increase of 106.9% ± 94.4% and 186.0% ± 107.4% (P = 0.04). Presenting symptoms included occipital headache, paresthesias, visual deterioration, and paraspinal pain. On last follow-up (mean 13.9 ± 4.9 months), the majority of symptoms were resolved in this cohort, despite persistence of syringomyelia.

CONCLUSIONS

In this small cohort of unique patients, syrinx resolution was not achieved via decompression surgery. Despite "radiographic failure," good symptom control was achieved, with most patients remaining or becoming asymptomatic postoperatively, thus supporting our rationale for what has largely been a conservative approach in this population.

MINIMALLY INVASIVE TREATMENT OF IDIOPATHIC SYRINGOMYELIA USING MYRINGOTOMY T-TUBES: A CASE REPORT AND TECHNICAL NOTE

Syringomyelia is characterized by a fluid-filled cavity within the spinal cord. Expansion of the syrinx often results in the clinical course of progressive neurologic deficit. Surgery for syringomyelia generally aims to treat the underlying cause, if it is known. However, little is known about idiopathic syringomyelia, which requires specific management. In our paper, an alternative, minimally invasive treatment option for large symptomatic idiopathic cervicothoracic syrinx is described and discussed. We present a case of a 44-year-old male without a history of spinal cord trauma, infection, or other pathologic processes, who presented for thoracic pain. Due to progressive pain and left leg paresis, magnetic resonance imaging (MRI) was performed and revealed extensive septated syringomyelia from T5 to T7 and hydromyelia cranially. We applied minimally invasive technique for shunting the idiopathic syrinx into the subarachnoid space using two Richards modified myringotomy T-tubes. Postoperative MRI revealed significant decrease in the syrinx size and clinical six-month follow-up showed improvement of clinical symptoms. This minimally invasive treatment of syringomyelia was found to be an effective method for idiopathic septated syrinx, without evident underlying cause. However, long-term follow-up and more patients are necessary for definitive evaluation of this technique.

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.

Clinical Application of Diagnostic Imaging of Chiari-Like Malformation and Syringomyelia

Chiari-like malformation (CM) and syringomyelia (SM) is a frequent diagnosis in predisposed brachycephalic toy breeds since increased availability of MRI. However, the relevance of that MRI diagnosis has been questioned as CM, defined as identification of a cerebellar herniation, is ubiquitous in some breeds and SM can be asymptomatic. This article reviews the current knowledge of neuroanatomical changes in symptomatic CM and SM and diagnostic imaging modalities used for the clinical diagnosis of CM-pain or myelopathy related to SM. Although often compared to Chiari type I malformation in humans, canine CM-pain and SM is more comparable to complex craniosynostosis syndromes (i.e., premature fusion of multiple skull sutures) characterized by a short skull (cranial) base, rostrotentorial crowding with rostral forebrain flattening, small, and ventrally orientated olfactory bulbs, displacement of the neural tissue to give increased height of the cranium and further reduction of the functional caudotentorial space with hindbrain herniation. MRI may further reveal changes suggesting raised intracranial pressure such as loss of sulci definition in conjunction with ventriculomegaly. In addition to these brachycephalic changes, dogs with SM are more likely to have craniocervical junction abnormalities including rostral displacement of the axis and atlas with increased odontoid angulation causing craniospinal junction deformation and medulla oblongata elevation. Symptomatic SM is diagnosed on the basis of signs of myelopathy and presence of a large syrinx that is consistent with the neuro-localization. The imaging protocol should establish the longitudinal and transverse extent of the spinal cord involvement by the syrinx. Phantom scratching and cervicotorticollis are associated with large mid-cervical syringes that extend to the superficial dorsal horn. If the cause of CSF channel disruption and syringomyelia is not revealed by anatomical MRI then other imaging modalities may be appropriate with radiography or CT for any associated vertebral abnormalities.

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.

Thoracic spinal cord impingement by an arachnoid web at the level of a hemivertebra: case report

Congenital scoliosis due to a hemivertebra requires surgical stabilization prior to skeletal maturity if rapidly progressive curve growth occurs. Here the authors present the unique case of a man who, at the age of 12 years, had undergone Harrington rod placement for stabilization of progressive congenital scoliosis due to a T-11 hemivertebra and then, at the age of 53 years, presented with acutely progressive myelopathy due to spinal cord compression from an arachnoid web at T-11 despite a solid fusion mass at the prior surgical site. The patient underwent a posterior midline approach for resection of the T-11 pedicle at the level of the hemivertebra, intradural spinal cord detethering with resection of the arachnoid web at T-11, and T2-L2 instrumented fusion with deformity correction, leading to subsequent resolution of his acute myelopathic symptoms. In conclusion, arachnoid web formation superimposed on preexisting tension on the thoracic spinal cord from congenital scoliosis due to a T-11 hemivertebra caused acute myelopathy in an adult with a previously solid fusion mass from childhood. The resolution of acute myelopathy and halting of further progression occurred with pedicle resection, arachnoid web fenestration, and spinal deformity correction.

Clinical and Radiologic Outcomes After Fenestration and Partial Wall Excision of Idiopathic Intradural Spinal Arachnoid Cysts Presenting with Myelopathy

BACKGROUND

Intradural spinal arachnoid cysts (ISACs) with associated neurologic deficits are encountered infrequently. Various management strategies have been proposed with minimal data on comparative outcomes.

OBJECTIVE

We describe the clinical and radiologic presentation as well as the outcomes of 14 surgically managed patients who presented with an ISAC and associated myelopathy.

METHODS

We retrospectively reviewed the clinical course of consecutive patients presenting with neurologic deficits associated with idiopathic ISACs at our institution. The diagnoses were based on preoperative magnetic resonance imaging studies followed by intraoperative and histopathological confirmation.

RESULTS

A total of 14 consecutive patients with ISACs (1 cervicothoracic, 12 thoracic, and 1 thoracolumbar) and associated myelopathy were identified. Syringomyelia was noted in 8 patients. All ISACs were treated with cyst fenestration and partial wall resection through a posterior approach. Preoperative neurologic symptoms were noted to be stable or improved in all patients starting at 6-week postoperative follow-up. The median (interquartile range) preoperative mJOA score was 13 (12.0-14.8), whereas the postoperative median score at a mean follow-up of 22 months (range 6-50 months) was 16 (14.0-17.0), which represents a median improvement (ΔmJOA) of 2.0 (1.3-3.0) (P < 0.001). Comparison of ΔmJOA scores between cases without and with associated syrinxes did not reveal a significant difference (P = 0.23). Postoperative magnetic resonance imaging scans revealed spinal cord re-expansion at the level of the ISAC in all cases and either complete or partial syrinx resolution in 7 of 8 cases.

CONCLUSIONS

Early treatment with fenestration and partial wall resection allows for cord decompression, syrinx resolution, and gradual resolution of myelopathic symptoms in most cases.