Is onabotulinumtoxinA (Botox) 155 units every 3 months medically necessary for a patient with chronic migraine without aura?

Medical Necessity Determination for OnabotulinumtoxinA 155U

Based on the available documentation, onabotulinumtoxinA 155U every 3 months is NOT medically necessary at this time because the patient has not completed adequate trials of two oral preventive medications from different classes, and the documentation does not fully establish the ICHD-3 diagnostic criteria for chronic migraine.

Critical Deficiencies in Documentation

Inadequate Preventive Medication Trials

The patient has not met the prerequisite requirement for onabotulinumtoxinA treatment:

• The American Academy of Neurology requires patients to have failed at least two oral preventive medications from different classes before initiating onabotulinumtoxinA 1
• A 60-day trial of a preventive medication at therapeutic doses is required to assess efficacy, with documentation of start and stop dates, and reason for discontinuation or failure 1

Current trial documentation is insufficient:

• Escitalopram (Lexapro): Started 2/27/25, discontinued by 6/10/25 due to abdominal discomfort. However, no documentation exists regarding trial duration, dosing adequacy, or whether the patient took it for the required 60 days 1
• Atenolol: Used for hypertension management, not specifically for migraine prophylaxis. Documentation states "unable to take every day because her blood pressure drops" and was "poorly tolerated," but no documentation of trial duration, specific dosing for migraine prophylaxis, or whether this constitutes an adequate therapeutic trial 1
• The European Headache Federation recommends patients should preferably have tried two to three other migraine prophylactics before start of onabotulinumtoxinA 2

Incomplete ICHD-3 Diagnostic Criteria Documentation

The International Headache Society diagnostic criteria require documentation of at least 2 of the following pain characteristics: unilateral location, pulsating quality, moderate-to-severe intensity, or aggravation by routine physical activity 1, 3

The current documentation fails to establish these required criteria:

• The notes mention photophobia, phonophobia, and nausea (which are present) 4
• However, there is NO documentation of any of the four required pain characteristics: unilateral location, pulsating quality, moderate-to-severe intensity, or aggravation by routine physical activity 3
• Complete documentation of ICHD-3 diagnostic criteria is necessary to establish a diagnosis of chronic migraine 1

What Would Constitute Medical Necessity

Required Preventive Medication Trials

To meet medical necessity criteria, the patient needs:

1. Two documented preventive medication trials from different classes, each lasting at least 60 days at therapeutic doses 1
2. Documentation must include: medication name, dose, start date, stop date, reason for discontinuation (inefficacy vs. intolerance), and specific adverse effects 1
3. Acceptable medication classes include 4, 1:
   • Antidepressants (e.g., amitriptyline, venlafaxine, escitalopram)
   • Beta-blockers (e.g., propranolol, metoprolol, atenolol)
   • Anticonvulsants (e.g., topiramate, valproate)
   • CGRP antagonists (e.g., Emgality - which patient is currently taking)

The patient is currently on Emgality (CGRP antagonist), which counts as one adequate trial 1

Required Diagnostic Documentation

Complete ICHD-3 criteria documentation must include 4, 3:

• Headache frequency: ≥15 days per month for >3 months (DOCUMENTED - patient meets this)
• Migraine features on ≥8 days per month (DOCUMENTED - patient meets this)
• At least 2 of 4 pain characteristics (NOT DOCUMENTED):
  • Unilateral location
  • Pulsating quality
  • Moderate-to-severe intensity
  • Aggravation by routine physical activity
• Associated symptoms: Nausea/vomiting OR both photophobia and phonophobia (DOCUMENTED - patient has all three)

Clinical Context and Considerations

Evidence Supporting OnabotulinumtoxinA Efficacy

When appropriately indicated, onabotulinumtoxinA is highly effective:

• OnabotulinumtoxinA is the only FDA-approved therapy for chronic migraine prophylaxis 4
• The PREEMPT trials demonstrated significant reduction in headache days: -8.4 days with onabotulinumtoxinA vs -6.6 days with placebo at 24 weeks 5
• In chronic migraine, botulinum toxin reduces the number of headache days per month by 1.9 days 6
• The FDA-approved dose is 155U every 12 weeks 1

Medication Overuse Consideration

This patient has multiple risk factors for medication overuse headache:

• Taking multiple acute medications (alprazolam, ibuprofen 600mg) 4
• The European Headache Federation states that patients with medication overuse should be withdrawn from the overused medication before initiation of onabotulinumtoxinA if feasible 2
• However, if withdrawal is not feasible, onabotulinumtoxinA can be initiated from the start or before withdrawal 2

Dosing Verification

The requested dose of 155U every 3 months is appropriate:

• The FDA-approved dose for chronic migraine prophylaxis is 155U every 12 weeks 1
• The PREEMPT injection protocol specifies 155U-195U to 31-39 sites every 12 weeks 2
• More than 200U is considered not medically necessary 4

Recommendation for Approval Pathway

To establish medical necessity, the following documentation is required:

1. Complete one additional adequate preventive medication trial (60 days at therapeutic dose) from a different class than Emgality, with full documentation of dates, doses, and reason for discontinuation 1
2. Document at least 2 of the 4 required pain characteristics (unilateral, pulsating, moderate-to-severe intensity, or aggravation by activity) through detailed headache history 1, 3
3. Consider formal headache diary for 28 days to comprehensively document all ICHD-3 criteria 4

Alternative consideration: If the patient has true contraindications or documented serious adverse effects to multiple medication classes that prevented adequate trials, this should be explicitly documented as justification for proceeding directly to onabotulinumtoxinA 1