Does reduction in internal anal sphincter tone after a lateral internal sphincterotomy compromise sexual fullness in a manner that cannot be restored with pelvic floor physical therapy?

Post-Lateral Internal Sphincterotomy Sexual Dysfunction: Prognosis with Pelvic Floor Physical Therapy

Sexual dysfunction after lateral internal sphincterotomy is primarily neuropathic and myofascial rather than mechanical, and typically improves significantly over 6-12 months with specialized pelvic floor physical therapy that includes internal myofascial release—this is not a permanent structural compromise that cannot be retrained. 1, 2

Understanding the Mechanism of Post-LIS Sexual Dysfunction

The sexual dysfunction following LIS stems from altered sensations and dysesthesia rather than structural sphincter damage. 1 This is a critical distinction because:

• Patients with sexual dysfunction after LIS typically maintain intact continence and preserved sphincter integrity, indicating the problem is not mechanical failure. 1, 2
• The underlying pathophysiology involves pelvic floor muscle tension and protective guarding patterns that developed during the painful fissure period and persist after surgery. 1, 2
• This represents a neuropathic pain syndrome rather than permanent anatomical compromise. 1

Evidence from Sphincter Physiology Studies

Manometric studies demonstrate that while LIS does reduce resting anal pressure (from ~138 mmHg pre-operatively to ~110 mmHg at 12 months), the sphincter gradually recovers tone over the first year and patients remain symptom-free without incontinence. 3 The post-operative pressures remain higher than healthy controls (110 vs 73 mmHg), confirming that adequate sphincter function is preserved. 3

Treatment Protocol for Post-LIS Sexual Dysfunction

Initiate specialized pelvic floor physical therapy 2-3 times weekly with the following components: 1, 2

• Internal and external myofascial release targeting pelvic floor muscle tension 1, 2
• Gradual desensitization exercises guided by a physical therapist 1
• Muscle coordination retraining to reduce protective guarding patterns 1
• Warm sitz baths to promote muscle relaxation 1

Adjunctive Neuropathic Pain Management

• Apply topical lidocaine 5% ointment to affected areas for neuropathic pain control. 1, 2

Why Internal Therapy Is Essential

Internal pelvic floor therapy is mandatory because internal anal sphincter dysfunction and impaired rectal sensory feedback cannot be adequately treated with external techniques alone. 2 Biofeedback therapy specifically targets rectal sensation, tolerance of distention, and coordination of the internal sphincter, which necessitates internal assessment and treatment. 2

Expected Timeline and Prognosis

The dysesthesia and altered sensations typically improve significantly over 6-12 months with appropriate pelvic floor therapy and neuropathic pain management. 2 This timeline reflects the gradual resolution of the neuropathic component and retraining of protective muscle patterns.

Critical Pitfalls to Avoid

Never Pursue Additional Surgery

Do not pursue additional surgical interventions for post-LIS sexual dysfunction, as this would likely worsen the neuropathic component rather than improve it. 1, 2 The problem is not structural failure requiring surgical revision—it is a functional and neuropathic issue requiring rehabilitation.

Avoid Manual Anal Dilatation

Manual anal dilatation is absolutely contraindicated and carries a 30% temporary and 10% permanent incontinence rate. 1, 2

Alternative for Future Patients

For patients not yet treated, botulinum toxin injection represents a safer alternative to LIS, achieving 75-95% cure rates with no risk of permanent incontinence or sexual dysfunction. 1, 4 The mechanism involves temporary paresis of the anal sphincter, reducing resting tone and allowing fissure healing through reversible sphincter relaxation without permanent damage. 1

Botulinum toxin should be considered after 8 weeks of failed topical therapy, with calcium channel blockers as first-line treatment and nitroglycerin as second-line treatment. 1

Key Distinction: Neuropathic vs. Mechanical

The evidence consistently demonstrates that post-LIS sexual dysfunction is typically neuropathic/myofascial rather than mechanical sphincter failure. 1 This requires physical therapy and neuropathic pain management rather than surgical revision. 1 Patients maintain intact continence, confirming that the sphincter mechanism remains functionally adequate despite altered sensations. 1, 2