Convert to ICD-10-CM: 
346.21 converts approximately to:
- 2015/16 ICD-10-CM G43.819 Other migraine, intractable, without status migrainosusOr: 
- 2015/16 ICD-10-CM G43.A1 Cyclical vomiting, intractableOr: 
- 2015/16 ICD-10-CM G43.B1 Ophthalmoplegic migraine, intractableOr: 
- 2015/16 ICD-10-CM G43.C1 Periodic headache syndromes in child or adult, intractableOr: 
- 2015/16 ICD-10-CM G43.D1 Abdominal migraine, intractable