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.