Nerve Regeneration After Lateral Sphincterotomy Does Not Restore Sexual Function
Nearby nerves cannot take over sexual function sensation after lateral internal sphincterotomy, and the sexual dysfunction that occurs is primarily neuropathic and myofascial rather than due to permanent nerve transection. 1, 2
Understanding the Mechanism of Post-LIS Sexual Dysfunction
The sexual dysfunction following lateral internal sphincterotomy is fundamentally different from what your question assumes:
- The problem is neuropathic dysesthesia and pelvic floor muscle tension, not severed nerves requiring regeneration 1, 2
- Patients typically maintain intact sphincter integrity and continence, with altered sensations rather than mechanical problems 1
- The dysfunction develops from protective muscle guarding patterns and myofascial pain that developed during the painful fissure period, which persist after surgery 1, 2
Why Nerve "Takeover" Is Not the Solution
The premise of nerve regeneration or nearby nerve compensation does not apply here because:
- Lateral internal sphincterotomy does not intentionally transect the pudendal or other sexual function nerves 3
- The procedure targets only the internal anal sphincter muscle, not the nerve pathways responsible for sexual sensation 3
- Sexual dysfunction after LIS results from collateral neuropathic pain and muscle tension, not from cutting sexual function nerves 1, 2
Research on actual nerve transection (such as sacral nerve sacrifice during tumor resection) shows that unilateral loss of sacral nerves does not impair sexual function, while bilateral S2-S5 loss severely compromises it 4. However, this is irrelevant to LIS, which does not involve these nerves.
The Actual Treatment Pathway
Specialized pelvic floor physical therapy is the primary treatment, not waiting for nerve regeneration: 1, 2
- Physical therapy 2-3 times weekly focusing on internal and external myofascial release 1, 2
- Topical lidocaine 5% ointment to affected areas for neuropathic pain management 1, 2
- Gradual desensitization exercises guided by the physical therapist 1, 2
- Muscle coordination retraining to reduce protective guarding patterns 1, 2
- Warm sitz baths to promote muscle relaxation 1, 2
Expected Recovery Timeline
- Dysesthesia and altered sensations typically improve significantly over 6-12 months with appropriate pelvic floor therapy and neuropathic pain management 1
- The absence of incontinence or structural damage is favorable and suggests better potential for improvement with conservative management 1
- Recovery is gradual and may take 12-24 months for maximal function 5
Critical Pitfall to Avoid
Do not pursue additional surgical interventions, as this would likely worsen the neuropathic component 1, 2. The dysfunction is not from cut nerves that need repair—it's from pain-induced muscle dysfunction that requires physical therapy, not surgery.
The Real Incontinence Risk from LIS
While not directly related to sexual function, it's important to note that LIS does carry significant continence risks:
- 45% of patients experience some degree of fecal incontinence at some point postoperatively, though most cases are minor and transient 6
- Permanent alterations in continence occur in a minority, with closed sphincterotomy showing better outcomes than open technique 7
- Women experience higher rates of incontinence (53.4%) compared to men (33.3%) 6
Alternative to Avoid These Complications
Botulinum toxin injection should be strongly considered instead of LIS, achieving 75-95% cure rates with no risk of permanent incontinence or sexual dysfunction 3, 2. This provides temporary sphincter relaxation without permanent damage, avoiding the neuropathic complications that can affect sexual function 2.