Dear Editor,

We read the recent article by Tran et al.,[ 10 ] which presented a case of a 31-year-old male with right lower limb weakness and persistent numbness. Investigation revealed the presence of a “scalpel sign” at the T7 level, attributed to a spinal arachnoid web (SAW). By the 10^th postoperative day, the patient demonstrated substantial improvement, with regained muscle strength of 5/5 and significantly reduced numbness. Idiopathic SAW is characterized by a thick arachnoid band spanning the subarachnoid space, extending from the pial surface of the spinal cord to the dura mater.[ 6 , 9 ] The condition is considered idiopathic if a thorough medical history review reveals no probable culprit.[ 2 - 4 ] The etiology of SAW remains speculative, giving rise to various hypotheses.[ 6 , 8 , 9 ] Since its initial description by Mallucci et al.,[ 6 ] the literature on SAW has predominantly consisted of individual case reports. Recent efforts have aimed to enhance our understanding through case series.[ 3 , 5 , 7 , 11 ] The most recent series, with the earliest publication dating back to 2019, has shed light on the postoperative prognosis of idiopathic SAW. These studies have highlighted favorable short- and intermediate-term outcomes, as well as a reduced propensity for postoperative recurrence.[ 3 , 5 , 7 , 11 ] Consequently, these intriguing findings suggest that idiopathic SAW may constitute a distinct arachnoidopathy, distinct from both traumatic and nontraumatic spinal arachnoiditis pathologies.[ 3 , 11 ]

In light of the case report by Tran et al.,[ 10 ] we wish to underscore two aspects of SAW that warrant further clarification and scholarly exploration.

First, a central theme in discussions about SAW pertains to the ongoing uncertainty regarding its rarity versus potential underreporting.[ 2 , 3 , 5 , 7 , 8 , 11 ] A thorough examination of the available multicenter case series could provide a more precise answer. Notably, Hirai et al. documented a cohort of five SAW cases; however, the specific timeframe of their medical registry survey remains undisclosed.[ 5 ] Similarly, Nisson et al. conducted a comprehensive systematic review of SAW, supplementing their findings with cases from the distinguished Weill Cornell Brain and Spine Center in New York, USA, revealing merely two cases.[ 7 ] Likewise, Voglis et al. published a multicenter case series involving SAW patients treated from 2014 to 2020 at Saint Michael’s University Hospital in Toronto, Canada, and Geneva and Zurich University Hospitals in Switzerland, yielding a cumulative total of 12 cases.[ 11 ] Adib et al. investigated all patients with syringomyelia between 2003 and 2023 at Tuebingen University Hospital, Germany, and found only 3 cases of SAW.[ 1 ] Notably, our institution, The Bicetre University Hospital, Kremlin-Bicetre, France, holds a pivotal role as a regional reference center for Chiari, spinal, and medullary malformations. Our independent series, encompassing patients operated on for idiopathic SAW between 2005 and 2020, yielded 12 cases.[ 3 ] Chellathurai et al., in a study conducted at Stanley Medical College Hospital in India over a 4-year period, examined 1350 spinal magnetic resonance images of patients with and without neurological complaints but without a history of spinal trauma or surgery. They identified only 6 cases of SAW.[ 4 ]

After carefully examining the number of cases stemming from the various international university health centers, it becomes evident that the idiopathic SAW is likely a rare phenomenon rather than an underreported one.

Second, the current body of literature about SAW predominantly consists of case reports elucidating immediate and/or short-term postoperative outcomes. Similarly, available case series often report the short- to intermediate-term clinical statuses postoperatively. The longest reported postoperative outcome analysis, a recent contribution by our research team, encompassed an observation period extending to 9.1 years.[ 3 ] The second longest follow-up spanned a duration of 6.5 years.[ 11 ] Therefore, to facilitate an informed prognostication concerning the enduring postoperative trajectory of SAW, a conspicuous deficiency of extended follow-up data is apparent within the existing literature. Consequently, an imperative emerges for including more expansive longitudinal investigations in the scholarly discourse. This inclusion would offer valuable insights into the prolonged postoperative evolution of SAW.

Declaration of patient consent

Patient’s consent is not required as there are no patients in this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The authors confirm that they have used artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript or image creations.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

References

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