Patterns, pearls and practical medicine

Fibromuscular dysplasia

Idiopathic segmental, non-inflammatory and non-atherosclerotic vascular disease leading to stenoses of small and medium sized vessels
A radiological diagnosis
Requires a high index of suspicion
Not as rare as once thought, or renal limited
Suspect in young or middle-aged patients without conventional CV risk factors
Epidemiology
- - 9x more common in women, often middle aged
  - Men have more severe disease and dissections
  - 4% have family hx
  - Possible link with oestrogen therapy
  - Smoking cause more aggressive disease
Described in almost every arterial bed, but most commonly in
- - Renal (75%)
  - Carotids (75%)
  - Cardiac including SCAD (Spontaneous Coronary Artery Dissection)
  - Mesenteric
  - Iliac
Presentations
- - Hypertensive crisis / difficult to control BP
    - - Renin and aldosterone may be raised
      - Can be headache and pulsatile tinnitus
  - CVA and TIAs
  - Dissections (10% of all dissections are sec to FMD)
  - Ruptured aneurysms
  - Ischemia – incl mesenteric
  - Thromboembolism
  - Middle aortic syndrome – rats tail aorta
  - Horner’s syndrome
  - SCAD
Spontaneous Coronary Artery Dissection
- - Rare cause of ACS
  - Dissection of coronaries without trauma or intervention
  - > 90% in young women without CV risk factors
  - 60% of SCAD have associated FMD, and < 5% of FMD have SCAD
  - Associated with pregnancy (15% of ACS in pregnancy is SCAD), CTD and vasculitis
  - Conservative management. Instrumentation risks propagating the dissection
  - Revascularisation only done due to left main stem dissection, ongoing ischaemia, unstable patients
  - CKD with asymmetrical kidneys on USS
Examination
- - BP
  - Bruits
Investigations
- - Bloods including HbA1c, U&Es
  - Secondary hypertension screen
  - MR renal angiogram
    - - In multifocal FMD there is a beaded appearance of renal arteries with large stenoses. Also SMA and coeliac vessels affected. Sometimes S curve – severe tortuosity of vessels, unique to FMD
      - Unifocal FMD tends to occur in men and kids, and presents with ischaemic symptoms
Management
- - Do angioplasty for renal disease
  - Avoid stents – they re-stenose and have a high chance of dissection
  - Rule out FMD mimics – migraine, SAM, NF, AV malformations, isolated carotid dissection, Ehlers Danlos, Takayasu’s, neurofibromatosis, vasculitis
  - Top to toe imaging – Look for FMD elsewhere in the body
  - Treat hypertension – any antihypertensives will do
  - Stop smoking
  - Antiplatelets