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

Resection of an incidentally discovered spinal arachnoid web: illustrative case

BACKGROUND

Spinal arachnoid webs (SAWs) are rare pathologies of the spinal meninges often associated with syringomyelia and the radiographic "scalpel sign." Patients can experience pain, numbness, gait disturbances, or no symptoms at all. They are typically diagnosed via magnetic resonance imaging and treated with laminectomy and excision.

OBSERVATIONS

A 61-year-old male presented after a mechanical fall and had an incidentally discovered SAW on imaging. He was initially asymptomatic and was therefore conservatively managed. Several years later, however, the patient experienced new-onset back pain, paresthesia, and balance problems, with interval imaging demonstrating worsening of the edema surrounding his SAW. The patient subsequently underwent resection of the SAW, which led to significant resolution of his symptoms.

LESSONS

An SAW can be asymptomatic or can manifest with a wide variety of symptoms. When this condition is incidentally discovered in asymptomatic patients, neurosurgeons should guide these patients to follow-up urgently if they develop any neurological symptoms. At that time, further imaging can be performed to determine if surgical treatment is indicated. Although SAW is rare, clinicians should be aware of the signs and symptoms, because prompt surgical intervention can significantly improve neurological symptoms.

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.

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.

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.