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VOLUME 1, YEAR 2025

  Letter to the Editor     2025  
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Botulinum Toxin Injection Versus Lateral Internal Sphincterotomy for the Treatment of Chronic Anal Fissure: Equally Effective?

By Semra Demirli Atici

Affiliations

  1. Department of General Surgery, Acibadem Kent Hospital, Izmir, Turkiye
doi: 10.29271/jcpsppg.2025.01.151

Sir,

We read with interest the article by Shoaib et al., which compares botulinum toxin (BT) injection and lateral internal sphincterotomy (LIS) for treating chronic anal fissure.1 While the study provides valuable contributions, we have substantive concerns regarding the conclusion that both interventions are equally safe, especially concerning faecal incontinence (FI) risk.

The study did not adequately address critical gender-specific pathophysiological variables, notably obstetric history, which significantly affects the risk of FI after sphincter-disrupting procedures such as LIS. Although the authors reported similar FI rates for LIS (9.52%) and BT (4.76%; p = 0.430), this comparison failed to account for a significant baseline gender distribution imbalance: women constituted 35.71% of the BT cohort but only 16.67% of the LIS cohort (p = 0.047). More importantly, the study lacked assessment or control for obstetric history, a well-established determinant of anal sphincter integrity and dysfunction.

A meta-analysis by Jin et al. has demonstrated that post-LIS FI rates are significantly elevated in women compared to men, with an odds ratio of 2.3.2 Women with a history of vaginal delivery, particularly with episiotomy, operative vaginal delivery (forceps or vacuum), or occult obstetric anal sphincter injuries (OASIS), are at markedly increased risk of incontinence following any intervention compromising sphincter function.3,4 The small number of women in the LIS group (n = 7) raises the possibility that undiagnosed obstetric sphincter damage might have biased the FI outcomes downward, underestimating LIS-associated incontinence in a general female population. Furthermore, women with known risk factors for incontinence may have self-selected for the BT group due to concerns about the potential for sphincter damage, possibly introducing a selection bias into the results. The transient effect of BT likely confers a lower intrinsic risk of exacerbating pre-existing sphincter weakness compared to the irreversible sphincterotomy performed in the LIS group. Additionally, the limited female sample size in the LIS group undermines the statistical power to detect meaningful gender-based differences in FI rates and constrains  the  external  validity  of  the  conclusion.

In conclusion, despite the informative data on short-term recovery presented by Shoaib et al.,1 the assertion of equivalent procedural safety—particularly regarding FI—is undermined by the omission of gender-specific pathophysiological factors and obstetric history. Future research should include obstetric history stratification, preprocedural sphincter assessment using a scoring system or imaging modalities such as endoanal ultrasound, and gender-specific statistical adjustments to provide clinically meaningful guidance for personalised treatment selection for chronic anal fissure.

COMPETING  INTEREST:
The  author  declared  no  conflict  of  interest.

AUTHOR’S  CONTRIBUTION:
SDA: Designed, drafted, and approved the final version of the manuscript to be published.

REFERENCES

  1. Shoaib SS, Hussain SM, Mallih MA, Salar B, Nusrat D, Arshad MJ. Comparison of botulinum toxin injection and lateral internal sphincterotomy for the treatment of chronic anal fissure. JCPSP Postgrad 2025; 1(1):33-7. doi: 10.29271/  jcpsp.2025.07.33.
  2. Jin JZ, Bhat S, Park B, Hardy MO, Unasa H, Mauiliu-Wallis M, et al. A systematic review and network meta-analysis comparing treatments for anal fissure. Surgery 2022; 172 (1):41-52. doi: 10.1016/j.surg.2021.11.030.
  3. Jia Y, Liu Q, Zeng L, Wang Y. Risk factors accounting for anal incontinence during the first year after vaginal delivery-A case control study in China. Front Med (Lausanne) 2023; 10:1073073. doi: 10.3389/fmed.2023.1073073.
  4. Arslan NC, Ozdenkaya Y. Duration of the symptoms ınfluence the outcome after botulinum toxin injection in anal fissure. Turk J Colorectal Dis 2019; 29(1):33-8. doi: 10. 4274/tjcd.galenos.2018.94547.

Authors Reply Section

By Syed Shaheryar Shoaib

Affiliations

  1. Dr. Syed Shaheryar Shoaib, Department of General Surgery, Combined Military Hospital, Rawalpindi, Pakistan



AUTHOR’S   REPLY

We are grateful to the correspondent for their interest in our article and insightful comments on our prospective study comparing botulinum toxin (BT) injection and lateral internal sphincterotomy (LIS) for chronic anal fissure. We appreciate their focus on the interpretation of faecal incontinence (FI) outcomes and the potential influence of gender-specific and obstetric  factors  on postoperative  continence.

We acknowledge that obstetric history and pelvic floor integrity are important determinants of anal sphincter function. While our study prospectively documented baseline characteristics, obstetric details were not included as predefined variables because all participants were clinically assessed for sphincter tone and continence status prior to intervention, and those with pre-existing incontinence were excluded from the study.1 Nonetheless, we recognise that incorporating obstetric history and pelvic floor evaluation modalities (e.g., endoanal ultrasonography or manometry) will further refine risk stratification and enhance interpretation of FI outcomes, particularly among female   patients.

Although the proportion of women differed between the treatment groups, subgroup analysis did not reveal a higher rate of FI among female participants undergoing LIS. The small number of women in the LIS group, however, limits the ability to perform gender-specific inferential analysis, as the correspondent has rightly highlighted. Future multicenter studies with larger female representation and stratified analyses by obstetric history are warranted to validate these findings since FI has been  reported  to  be  more  common  in  women.2,3

Treatment allocation was based on clinical indication and patient preference following standardised counselling about each option’s benefits and risks. This pragmatic approach reflects real-world clinical decision-making. The conclusion that both interventions demonstrated comparable efficacy and safety was based on prospectively observed outcomes within the follow-up period, and we agree that long-term studies incorporating gender-based risk adjustment will add further clarity.

We sincerely thank the correspondent for their constructive feedback, which will help guide future research toward more individualised and evidence-based management of chronic anal fissure.
 

REFERENCES

  1. Shoaib SS, Hussain SM, Mallih MA, Salar B, Nusrat D, Arshad MJ. Comparison of Botulinum Toxin Injection and Lateral Internal Sphincterotomy for the Treatment of Chronic Anal Fissure. JCPSP Postgrad 2025; 1(1):33-7. doi: 10.29271/ jcpsp.2025.07.33
  2. Jin JZ, Bhat S, Park B, Hardy MO, Unasa H, Mauiliu-Wallis M, et al. A systematic review and network meta-analysis comparing treatments for anal fissure. Surgery 2022; 172 (1): 41-52. doi: 10.1016/j.surg.2021.11.030.
  3. Jia Y, Liu Q, Zeng L, Wang Y. Risk factors accounting for anal incontinence during the first year after vaginal delivery-A case control study in China. Front Med (Lausanne) 2023; 10:1073073. doi: 10.3389/fmed.2023.1073073.