Treatment for Decreased Anal Sphincter Tone
The primary treatment for decreased anal sphincter tone focuses on identifying and addressing the underlying cause, with pelvic floor rehabilitation through biofeedback therapy being the cornerstone of management, while avoiding interventions designed to reduce sphincter tone (such as calcium channel blockers or sphincterotomy) which would worsen the condition. 1
Initial Diagnostic Approach
Digital rectal examination is essential to confirm decreased sphincter tone and identify associated conditions such as pelvic floor dyssynergia, rectal prolapse, anal stricture, or rectocele. 1 The examination should assess both resting tone (internal anal sphincter function) and squeeze pressure (external anal sphincter function). 2
- Anorectal physiology testing combined with balloon expulsion should be performed to confirm the diagnosis and characterize the specific dysfunction, particularly in patients not responding to initial therapies. 1
- Consider defecography with barium or MRI if structural etiologies such as pelvic organ prolapse or rectal intussusception are suspected. 1
Primary Treatment Strategy
Pelvic Floor Rehabilitation
Biofeedback therapy is the primary treatment modality for patients with decreased anal sphincter tone, particularly when associated with functional defecation disorders or dyssynergic defecation. 1 This approach helps retrain the pelvic floor muscles and improve coordination.
Management of Contributing Factors
- Address fecal impaction if present, as a large fecal load in the rectum can relax the sphincter muscle and contribute to incontinence. 1
- Optimize bowel habits with dietary modifications including increased fiber intake (25-30g daily) and adequate fluid consumption to prevent both constipation and diarrhea. 1
- Treat underlying constipation which is frequently associated with sphincter dysfunction and may contribute to the problem. 1
Critical Pitfalls to Avoid
Never use treatments designed to reduce sphincter tone in patients with decreased tone, as this would be contraindicated:
- Avoid calcium channel blockers (diltiazem, nifedipine) which reduce internal anal sphincter tone. 1
- Avoid nitrates (glyceryl trinitrate) which decrease sphincter pressure. 1
- Never perform manual dilatation, which carries a 30% risk of temporary incontinence and 10% risk of permanent incontinence. 1
- Avoid sphincterotomy procedures which would further compromise sphincter function. 1
Underlying Etiology Considerations
The treatment approach must be tailored to the underlying cause:
- Lower motor neuron lesions causing hypotonia most commonly lead to fecal incontinence and require specialized neurological management. 3
- Structural damage from obstetric trauma, prior surgery, or other injuries may require surgical reconstruction in severe cases. 4
- Age-related sphincter weakness may benefit from conservative management with bowel regulation and pelvic floor exercises. 4
When to Refer
Referral to a colorectal surgeon or pelvic floor specialist is indicated for patients with: