Patient Concern Validity and Documented Sensory Changes After IAS Tone Reduction
The patient's worry about losing deep pelvic fullness sensation is not a documented or validated symptom in the anal fissure treatment literature, and the concern appears to conflate anal canal sensation with sexual arousal mechanisms that operate through entirely separate neurophysiologic pathways. 1, 2
Anal Sensation Is Not Critical for Continence or Documented Sexual Function
Topical anesthesia studies demonstrate that complete abolition of anal canal sensation does not impair fecal continence and actually improved saline retention in subjects who previously could not retain full rectal volumes, proving that anal sensation is not a critical sensory modality for sphincter control. 2
The internal anal sphincter (IAS) generates resting tone through involuntary smooth muscle contraction and does not provide conscious sensory feedback; reducing IAS tone with calcium channel blockers or sphincterotomy targets the pain-spasm-ischemia cycle, not sensory perception. 1, 3
No guideline or research evidence documents "pelvic fullness sensation" as a recognized symptom affected by IAS tone reduction in the treatment of anal fissure with topical nifedipine, diltiazem, or lateral internal sphincterotomy. 4, 1, 3, 5
Sexual Function and Anal Fissure: The Evidence Shows the Opposite Pattern
One older study reported that erectile dysfunction occurred in men with untreated anal fissure due to pain and increased IAS tone, and that ED resolved after successful fissure treatment (conservative therapy for acute fissures, sphincterotomy for chronic fissures) in 94% of cases. 6
The mechanism proposed was anal pain radiating to the penis and exaggerated during erection, not loss of a "fullness sensation"; treatment that reduced IAS tone restored normal erectile function, contradicting the patient's concern. 6
This single 2000 study is the only evidence linking anal pathology to sexual function, and it demonstrates that reducing IAS hypertonicity improves rather than impairs sexual function. 6
What IAS Tone Reduction Actually Does
Topical nifedipine 0.3% with lidocaine 1.5% blocks L-type calcium channels in IAS smooth muscle, lowering resting anal pressure from the pathologic range (≈114 cm H₂O) toward normal (≈73 cm H₂O), which increases anodermal blood flow and permits fissure healing in 95% of cases. 1, 3
Lateral internal sphincterotomy divides a portion of the IAS to permanently reduce resting tone, achieving >95% healing with 1–3% recurrence; the documented risks are minor flatus incontinence in 1–10% of patients, not loss of pelvic sensation. 1, 5
Neither pharmacologic nor surgical IAS tone reduction is reported to alter conscious sensory perception in the pelvis or affect arousal pathways, which depend on pudendal nerve afferents, pelvic autonomic innervation, and central processing—none of which are targeted by fissure therapies. 1, 2
Clinical Pitfalls and Counseling Points
Do not validate unfounded sensory concerns that lack any evidence base, as this may reinforce health anxiety and delay effective treatment of a painful, highly treatable condition. 1, 7
Emphasize that 50% of acute fissures heal with conservative measures alone (fiber 25–30 g/day, hydration, sitz baths) within 10–14 days, and that topical therapy is the next step if conservative care fails. 1, 5
The documented risk of IAS-targeted therapy is minor incontinence (primarily flatus), not sensory loss; if the patient had normal continence before the fissure, the risk of any permanent deficit after topical therapy is essentially zero. 1, 5
Untreated chronic anal fissure causes ongoing pain, potential progression to sentinel tag or fistula, and—per the one relevant study—may itself impair erectile function through pain mechanisms, making treatment medically indicated. 1, 6
Recommended Management Algorithm
Confirm the fissure is in the typical posterior midline location; atypical (lateral or multiple) fissures require urgent evaluation for inflammatory bowel disease, infection, or malignancy before any therapy. 1
Initiate conservative management: fiber supplementation 25–30 g/day, adequate hydration, warm sitz baths 2–3 times daily, and topical lidocaine for pain. 1, 5
If no improvement after 2 weeks, add compounded 0.3% nifedipine with 1.5% lidocaine applied three times daily for 6–8 weeks; pain relief typically occurs after 14 days. 1, 3, 5
Reassure the patient that reducing IAS tone is the therapeutic mechanism and that no evidence supports loss of "pelvic fullness" or arousal sensation; the single relevant study shows the opposite effect (improved erectile function after fissure treatment). 1, 6
If the fissure remains unhealed after 6–8 weeks of comprehensive medical therapy, refer for lateral internal sphincterotomy, which has >95% healing rates and a small risk of minor flatus incontinence, not sensory deficits. 1, 5