What are the initial recommendations for managing constipation in a patient with multiple sclerosis (MS) on an InterStim (Interstim) bowel regimen?

Management of Constipation in Multiple Sclerosis Patients with InterStim

For patients with multiple sclerosis (MS) on an InterStim bowel regimen, the initial management of constipation should begin with polyethylene glycol (PEG) as first-line pharmacological treatment, which can be combined with psyllium fiber supplements for enhanced effect. 1, 2

First-Line Interventions

Dietary Modifications

• Increase fluid intake to ensure adequate hydration
• Add dietary fiber (aim for >10g/day for at least 4 weeks)
• Consider fractionating meals for patients with muscular fatigue 2

Pharmacological Management

1. Polyethylene Glycol (PEG)

   • First-line pharmacological treatment with strong recommendation and moderate evidence 1
   • Can be used alone or combined with fiber supplements
   • Shows durable response over 6 months
   • Monitor for side effects: abdominal distension, loose stool, flatulence, and nausea

2. Fiber Supplements

   • Psyllium is the most effective fiber supplement (strong recommendation) 1
   • Ensure adequate hydration when using fiber to prevent worsening constipation
   • Can be used as first-line therapy, particularly for those with low dietary fiber intake

Second-Line Interventions

If first-line treatments are ineffective:

1. Osmotic Laxatives

   • Magnesium oxide (conditional recommendation)
     • Start at lower dose and increase if necessary
     • Avoid in patients with renal insufficiency due to risk of hypermagnesemia 1
   • Lactulose (conditional recommendation)
     • Be aware of common side effects: bloating and flatulence 1

2. Stimulant Laxatives

   • Bisacodyl 10-15 mg daily to TID (strong recommendation)
     • Goal: one non-forced bowel movement every 1-2 days
     • Good option for occasional use or rescue therapy 1, 2
   • Senna (conditional recommendation)
     • Start at lower dose and increase if no response
     • Monitor for abdominal pain and cramping with higher doses 1

Advanced Options for Refractory Constipation

If constipation persists despite above measures:

1. Prescription Medications

   • Linaclotide (strong recommendation)
     • For patients who don't respond to osmotic laxatives 1
   • Plecanatide (strong recommendation)
     • For patients who don't respond to osmotic laxatives 1
   • Lubiprostone (conditional recommendation)
     • Consider for patients who don't respond to osmotic laxatives 1
   • Prucalopride (strong recommendation)
     • Can be used as replacement or adjunct to OTC agents 1

2. Rectal Interventions

   • Glycerine suppository ± mineral oil retention enema
   • Bisacodyl suppository (one rectally daily-BID)
   • Manual disimpaction (if necessary, following pre-medication with analgesic ± anxiolytic) 1

3. Special Considerations for MS with InterStim

   • Optimize InterStim settings if possible, as sacral neuromodulation has shown benefits for both urinary and bowel symptoms in MS patients 3
   • Consider abdominal functional electrical stimulation (ABFES) as an adjunctive therapy, which has shown promise in treating constipation in MS patients 4

Monitoring and Adjustment

• Rule out impaction or mechanical obstruction before escalating therapy
• Assess for other causes of constipation: hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus, medication side effects 1, 2
• Monitor response to treatment and adjust as needed based on symptom control and side effects
• Discontinue any non-essential constipating medications 1

Common Pitfalls to Avoid

1. Failing to ensure adequate hydration when increasing fiber intake
2. Using magnesium preparations in patients with renal insufficiency
3. Not recognizing that constipation in MS is often multifactorial (neurological pathways impairment, polypharmacy, behavioral disorders, loss of autonomy) 5
4. Delaying escalation to more effective therapies when initial treatments fail
5. Overlooking the impact of constipation on quality of life and bladder function in MS patients 6, 5

Remember that effective management of constipation can significantly improve quality of life and may reduce the incidence of bladder disorders in MS patients 5.