Can Internal Anal Sphincter Sensation Be Restored After Lateral Sphincterotomy?
Internal anal sphincter sensation typically does not return to pre-operative baseline after lateral internal sphincterotomy because the procedure causes permanent structural division of the sphincter muscle, though altered sensations and hypersensitivity can significantly improve over 6-12 months with appropriate pelvic floor physical therapy. 1
Understanding the Permanent vs. Reversible Changes
The key distinction is between structural sphincter damage (permanent) and functional sensory alterations (potentially reversible):
Lateral internal sphincterotomy permanently divides the internal anal sphincter muscle, which provides the majority of anal resting tone and baseline sensation 2. This structural change cannot be reversed.
However, the altered sensations and hypersensitivity that patients experience post-operatively are primarily due to neuropathic pain, dysesthesia, and protective pelvic floor muscle guarding rather than the sphincter division itself 1, 2. These functional components can improve substantially.
The protective guarding patterns develop during the painful fissure period and persist even after surgical healing 1, 3.
Treatment Algorithm for Post-Sphincterotomy Sensory Symptoms
When patients report altered sensations after lateral internal sphincterotomy but maintain continence:
First-line therapy:
- Initiate specialized pelvic floor physical therapy 2-3 times weekly focusing on internal and external myofascial release 1
- Include gradual desensitization exercises under physical therapist guidance 1
- Implement muscle coordination retraining to address persistent guarding patterns 1
- Prescribe warm sitz baths for muscle relaxation 1
Adjunctive pain management:
- Apply topical lidocaine 5% ointment to affected areas for neuropathic pain control 1
Expected timeline:
- Dysesthesia and altered sensations typically improve significantly over 6-12 months with this regimen 1
Critical Pitfalls to Avoid
- Never pursue additional surgical interventions for sensory complaints, as this will worsen the neuropathic component rather than improve it 1
- Absolutely avoid manual anal dilatation, which carries a 30% temporary and 10% permanent incontinence rate 1, 3
- Recognize that these sensory symptoms represent neuropathic/myofascial dysfunction requiring physical therapy, not mechanical sphincter failure requiring surgical revision 2
The Reality of Continence After Sphincterotomy
While you asked specifically about sensation restoration, it's critical to understand the continence implications:
- Some degree of fecal incontinence occurs in 45% of patients at some point after lateral internal sphincterotomy, with women affected more than men (53.4% vs 33.3%) 4
- However, by 5+ years post-operatively, only 6% report flatus incontinence, 8% have minor soiling, and 1% experience solid stool loss 4
- Importantly, only 3% of patients report that incontinence ever affected their quality of life 4
- More conservative sphincterotomy (to fissure apex rather than dentate line) significantly reduces postoperative incontinence (2.17% vs 10.86%) 5
Alternative Approach for Future Patients
For patients not yet treated, botulinum toxin injection represents a superior alternative, achieving 75-95% cure rates with no risk of permanent incontinence or sexual dysfunction 1, 2, 3. This avoids the permanent structural changes that prevent sensation restoration after sphincterotomy.