Loss of Pelvic Anchor Sensation After Lateral Internal Sphincterotomy
Your loss of the deep pelvic "anchor point" sensation is caused by a 20-40% reduction in resting internal anal sphincter pressure combined with persistent pelvic floor muscle guarding—not by complete loss of IAS function—and requires specialized pelvic floor physical therapy rather than additional surgery. 1, 2
Quantifying Your Pressure Loss
Lateral internal sphincterotomy typically reduces resting anal pressure by approximately 35-45 mmHg (representing a 30-40% reduction from baseline):
- Pre-operative resting pressures in fissure patients average 95-138 mmHg (significantly elevated compared to normal controls at 66-81 mmHg) 3, 4, 5
- Post-operative pressures stabilize at 86-110 mmHg by 12 months, which remains higher than healthy controls but 20-30% lower than your pre-operative baseline 3
- Your subsequent fistulotomy likely caused additional minor pressure reduction, though this procedure primarily affects the external sphincter and perianal tissues rather than the IAS 6
Why the "Anchor" Disappeared Completely Rather Than Just Diminishing
The paradox you describe—complete loss rather than partial reduction—stems from protective pelvic floor muscle guarding that developed during your painful fissure period and persists despite sphincter healing:
- Protective guarding patterns that formed during painful defecation continue even after the acute problem resolves, creating persistent pelvic floor muscle tension 1, 7
- This myofascial tension masks the remaining IAS pressure signals that should still be present, since your post-operative pressures remain well above normal control values 3
- The warm water test failing to restore sensation confirms this is muscular guarding rather than simple sphincter relaxation—if it were purely IAS-related, warm water would allow you to perceive the remaining tone 1
Your Blunted Urinary Sensation
The urinary bluntness represents extension of pelvic floor dysfunction rather than direct surgical nerve injury:
- Your normal pudendal nerve pinprick test excludes major pudendal neuropathy 2
- Pelvic floor muscle tension commonly develops after anorectal surgery and affects multiple pelvic sensations including sexual and urinary function 1, 2
- The IAS is anatomically distinct from deep pelvic autonomic nerves, being a superficial structure confined to the anal canal level—it does not directly control deep pelvic or urinary sensations 7
Treatment Algorithm (Not Additional Surgery)
Initiate specialized pelvic floor physical therapy immediately, as additional surgical intervention would worsen rather than improve your neuropathic symptoms:
- Pelvic floor physical therapy 2-3 times weekly focusing on internal and external myofascial release, gradual desensitization exercises, and muscle coordination retraining to address the persistent guarding patterns 1, 2
- Topical lidocaine 5% ointment applied to affected perianal areas for neuropathic pain control, even in the absence of acute pain 1, 2
- Warm sitz baths to promote muscle relaxation, though you've noted limited benefit—continue these as adjunctive therapy 1
- Expected timeline: 6-12 months for significant improvement in dysesthesia and altered sensations with appropriate therapy 1
Critical Pitfalls to Avoid
Do not pursue sphincter revision, sphincter reconstruction, or any additional anal surgery:
- Additional surgical interventions would likely worsen the neuropathic component rather than restore your "anchor point" sensation 1, 2
- Your problem is primarily neuropathic/myofascial rather than mechanical sphincter failure, requiring physical therapy rather than surgical revision 2
- Manual anal dilatation is absolutely contraindicated, carrying 30% temporary and 10% permanent incontinence rates 1, 7
Why Botulinum Toxin Would Have Been Safer
For future reference, botulinum toxin injection achieves 75-95% cure rates for anal fissures with no risk of permanent incontinence or sexual dysfunction, unlike lateral internal sphincterotomy: 8, 2, 7