Spinal arachnoid web: a systematic review of a rare entity, with two illustrative case reports

Spinal arachnoid web (AW) is a very rare entity, with a limited number of cases documented in the literature. Our manuscript represented a comprehensive general review, encompassing various aspects of the subject matter without focusing on any single element. The objective of this systematic review was to describe and analyze reported cases of surgically proven spinal arachnoid webs (AWs) to elucidate their imaging and clinical features, pathophysiology, and optimal management strategies, and to determine the total number of documented cases in the literature. Patterns and commonalities across reported cases were identified to provide a clearer framework for diagnosing and treating this elusive condition. A search of Web of Science, PubMed, and Scopus, respecting PRISMA guidelines, was conducted to include reported cases of surgically proven spinal AW. Our surgically proven case was included as well. The search yielded 196 cases of surgically confirmed spinal AWs in the literature. Adding our case, the total is 197. They are seen commonly in middle-aged patients, slightly more prevalent in males, and often without an evident cause. Sensation disturbances were the most frequently found clinical signs, followed by gait difficulties, weakness, and pain. Symptoms were predominantly located in the lower limbs and trunk. On imaging, an indentation to the rear aspect of the spinal cord was most frequently found at the mid-thorax followed by the upper thorax, often associated with a syrinx or a hyperintense T2 cord signal, usually extending rostrally. Excision was the most efficient treatment. The assessment found that AW cases are rare in the literature, indicating the disease's scarcity. It manifests insidiously, with the shortest latency reported being 2 weeks. Upper limb symptoms occur in a quarter of cases regardless of the AW's thoracic location, likely due to rostral syrinx and cerebrospinal fluid flow disturbances. Most pathology results revealed fibrous connective tissue, similar to findings in arachnoid cysts, suggesting that AW may result from a ruptured arachnoid cyst or its precursor. Using 3D SPACE STIR and CISS MRI sequences is recommended to visualize the arachnoid band directly.