Why does a patient with a history of anal fissure repair surgery experience pelvic tension and altered sensation, changing from pleasurable to tense and numbing, despite no observed damage 3.5 years post-surgery?

Chronic Pelvic Pain Syndrome After Anal Fissure Surgery

Your patient likely has developed chronic pelvic floor dysfunction with altered sphincter mechanics and neuropathic pain following surgical sphincterotomy, despite the absence of visible structural damage on endoscopy. 1, 2

Understanding the Pathophysiology

The change from pleasurable to tense and numbing sensation represents a complex interplay of altered sphincter dynamics and nerve dysfunction that can persist long after surgical healing:

• Sphincter denervation injury occurs even without visible damage, as direct or denervation injury to pelvic floor musculature increases stress on fascia and leads to weakening of the pelvic floor 1
• The bulbocavernosus muscle (BCM) is anatomically part of the external anal sphincter, and surgical disruption of sphincter mechanics can affect erectile and sensory function in this region 2
• Internal sphincterotomy permanently alters sphincter tone and pressure dynamics, which were previously elevated in fissure patients (132 ± 21 cmH2O vs 81 ± 14 cmH2O in controls) 3

Why Sensation Changed Post-Surgery

The transition from pleasurable to tense/numbing sensation has a clear physiological basis:

• Pre-surgery hypertonic sphincter created increased pressure that some patients experience as pleasurable stimulation during anal activities 2, 3
• Post-sphincterotomy, the reduced sphincter tone (which is the therapeutic goal) eliminates this pressure dynamic, fundamentally changing sensory feedback 3
• Anal pain can radiate to pelvic structures and is exaggerated during activities involving the pelvic floor, creating a pain-tension cycle even after fissure healing 2
• Altered slow wave activity and sampling function persist in some patients even after successful surgical treatment, indicating ongoing sphincter dysfunction 3

Clinical Assessment Framework

Your patient needs evaluation for chronic pelvic floor dysfunction, not just fissure recurrence:

• Normal endoscopy at 3.5 years excludes recurrent fissure but does not rule out functional pelvic floor disorders 1
• Pelvic floor dysfunction affects 25-33% of patients and often involves multiple compartments simultaneously, including defecatory dysfunction and altered sensation 1
• MRI of the pelvic floor with dynamic maneuvers (not standard MRI) can reveal occult pelvic floor abnormalities not detected on physical examination 1
• Anal manometry would demonstrate whether sphincter pressures have normalized or remain abnormal, and can identify persistent ultra slow waves that correlate with ongoing dysfunction 3

Management Approach

The tense and numbing sensation represents chronic pelvic floor dysfunction requiring multimodal treatment, not surgical revision:

• Pelvic floor physical therapy is the cornerstone treatment, as the goal is to improve quality of life in this primarily morbidity-causing (not life-threatening) condition 1
• Avoid repeat sphincterotomy, as patients with persistent symptoms after initial surgery who underwent additional sphincterotomy showed the same pathological features, and further surgery risks permanent incontinence 3
• Consider referral to pelvic floor specialist for comprehensive evaluation including dynamic pelvic floor MRI and anal manometry to characterize the specific dysfunction 1

Critical Pitfalls to Avoid

• Do not assume normal endoscopy means normal function – visible healing does not equal functional recovery of sphincter mechanics 1, 3
• Never perform manual anal dilatation, which carries 10-30% permanent incontinence rates and will worsen pelvic floor dysfunction 4, 5
• Recognize this is likely permanent altered sensation from changed sphincter dynamics, not a correctable surgical complication 2, 3

The absence of visible damage confirms successful fissure healing but does not address the permanent alteration in sphincter mechanics and sensory feedback that surgery intentionally created. 3 The patient's symptoms represent adaptation to new pelvic floor dynamics rather than surgical failure. 1, 2