Post-Sphincterotomy Loss of Sexual Arousal Anchor Sensation
Yes, even a modest reduction in internal anal sphincter (IAS) resting pressure after lateral sphincterotomy and trans-sphincteric fistulotomy can completely eliminate the inner-rectal pressure sensation that serves as a sexual arousal anchor, because this phenomenon is primarily neuropathic and myofascial rather than purely mechanical. 1
Understanding the Mechanism
The loss of this "anchor feeling" does not require complete sphincter destruction or major incontinence to occur:
Resting IAS pressure drops significantly after lateral sphincterotomy—from approximately 112 mmHg pre-operatively to 66 mmHg post-operatively, representing a 41% reduction in baseline tone 2
The sexual dysfunction after LIS is primarily neuropathic dysesthesia and altered sensations, not structural sphincter failure, which explains why patients maintain continence yet lose specific sensory anchors 1
Protective pelvic floor muscle guarding patterns that developed during the painful fissure period persist after surgery, creating ongoing tension and altered proprioceptive feedback that disrupts the normal sensory experience 1, 3
Why Modest Pressure Changes Cause Complete Sensory Loss
The apparent contradiction—that the patient cannot feel arousal without masturbation yet describes a "missing" sensation—actually makes physiological sense:
The IAS provides most of the resting anal pressure (approximately 70-80% of baseline tone), and this continuous low-level tension creates the baseline proprioceptive "anchor" 4
Even partial IAS tone reduction can eliminate the threshold sensation required for sexual arousal, because the sensory receptors in the anal canal are calibrated to detect specific pressure ranges 1
The puborectalis muscle and external anal sphincter (EAS) contribute to squeeze pressure but not to the continuous resting tone that creates the baseline sensory anchor 5
Anoreceptive intercourse studies demonstrate that resting pressures of 70 mmHg (similar to post-sphincterotomy levels) are associated with altered sensation, even when squeeze pressures and continence remain normal 6
The Neuropathic Component
Your patient's experience reflects a dual problem:
The surgical disruption created both a mechanical pressure reduction AND a neuropathic sensory disturbance 1
Pelvic floor muscle tension commonly develops after anorectal surgery and contributes to altered sensations during sexual activity, creating a paradoxical situation where muscles are hypertonic yet the patient perceives "missing" pressure 1, 3
The dysesthesia and altered sensations typically improve significantly over 6-12 months with appropriate pelvic floor therapy and neuropathic pain management 3
Treatment Algorithm
Initiate specialized pelvic floor physical therapy immediately:
Schedule 2-3 sessions weekly focusing on internal and external myofascial release to address the protective guarding patterns 1, 3
Apply topical lidocaine 5% ointment to affected areas for neuropathic pain control 1, 3
Implement gradual desensitization exercises guided by a physical therapist to help restore normal sensory processing 1
Prescribe warm sitz baths to promote muscle relaxation and reduce symptoms 1, 3
Focus on muscle coordination retraining to reduce protective guarding patterns that developed during the painful fissure period 1, 3
Critical Pitfalls to Avoid
Do not pursue additional surgical interventions, as this would likely worsen the neuropathic component rather than restore the missing sensation 1, 3
Recognize that this is a neuropathic/myofascial problem, not mechanical sphincter failure—the patient has intact continence, which confirms the sphincters are structurally adequate 1
Avoid the assumption that "some pressure should still be felt"—the sensory threshold for sexual arousal anchoring may be higher than the threshold for continence, meaning the patient can be continent yet lack the specific sensation needed for arousal 1, 2