Introduction
Fibromuscular dysplasia (FMD) is a rare, idiopathic, non-atherosclerotic, and non-inflammatory vascular disorder characterized by abnormal cell growth within the walls of medium-sized arteries, leading to stenosis, aneurysm formation, tortuosity, or dissection.1,2 FMD is seen mainly in the renal, extracranial, and vertebral arteries but has been found in all atrial beds.1 FMD is now classified Internationally as Focal or Multi-focal FMD, down from a prior 4-type classification.2–4 Multifocal is known as the “string of beads” appearance and is the most common in 90%, followed by focal, constituting the remaining 10%.3 Patients with focal FMD were, on average, 10 years younger, male, with less prevalence of bilateral vessel disease.3 The clinical features vary by which artery is being affected; hypertension is the most common feature when the renal artery is involved.
Signs and symptoms in the carotid or vertebral arteries may include dizziness, pulsatile tinnitus, headache, transient ischemic attack, intracerebral hemorrhage, carotid and vertebral arterial dissection, Horner’s syndrome, or stroke.1,3,4 FMD is considered systemic, multi-site, and may involve arterial sites distal from the stenotic arteries or even present with subclinical alterations in non-affected arterial segments.2,3,5 Many of the signs and symptoms of FMD are non-specific, which is 1 reason there can be a 4 to 9-year delay in diagnosis. The true prevalence of FMD in the asymptomatic population is suspected to be approximately 3-6%.6 The cause of FMD is also unknown, but there is a theory that an imbalance in hormones drives it and, as such, is 90% more prevalent in women than in men.1,7,8
While looking at other considerations, lifestyle may play a role, such as the history of current smoking, but there is no known etiology. A genetic association has been correlated associating autosomal dominant inheritance with variants in arterial specific regulation of the actin cytoskeleton and intracellular calcium homeostasis.4,6–8
The differential diagnosis for these types of patients can be atherosclerotic stenosis, large vessel vasculitis, monogenic and inflammatory arterial disease, arterial spasms, Marfan syndrome, stenoses associated with Ehlers-Danlos and Williams’ syndromes, type 1 neurofibromatosis, and segmental arterial mediolysis.3,4,6,9 The management of FMD, once diagnosed, can range from simple medical management, including blood pressure control and antiplatelet agents, to interventional therapies, including angioplasty, stents, endovascular coils, and surgery.3,7 FMD is a rare disease and most of the data is derived from international registries such as the United States, French-Belgian, and the European International FMD registry and initiative.2,4 The first international consensus statement on FMD was not published until 20194
This paper discusses a 35-year-old male with generalized lower back pain, radiculopathy, and a sensation of weakness and fatigue in the leg after activity.
Case Report
A 35-year-old male with a one-year history of worsening lower back pain with intermittent radiating pain to his left lower extremity came for care. Initially mild and achy, the pain increased to 8/10 on the Visual Analog Scale (VAS) with physical activities such as jogging. He was recently training for a 5k and had been increasing mileage progressively. He also experienced weakness and fatigue in the left lower extremity, worse towards the end of his jogging sessions at mile 2 of his training. His medical history was unremarkable, with no significant comorbidities or previous surgeries. He was not taking any medications, was a non-smoker, and had no history of trauma.
The initial physical examination revealed bilateral tenderness in the lower lumbar region without any deformities or neurological deficits. The pain was non-reproducible with orthopedic assessment, although he had tight hamstrings with reduced active flexion of the lumbar spine. All other ranges of motion were within normal limits. Blood pressure measured 130/80. Lower extremity pulses were present with no edema, color change, or varicosities. A lumbar spine X-ray and a non-contrast MRI of the lumbar spine were unremarkable. However, due to the persistence of symptoms, additional imaging was pursued.
A CTA of the aorta with runoff revealed a consistent appearance of fibromuscular dysplasia (FMD) of the renal arteries. He was then referred for a head CTA to evaluate other regions. The imaging revealed that the left vertebral artery was hypoplastic and terminated in the posterior inferior cerebellar artery (PICA). No aneurysms were identified.
The imaging findings led to the diagnosis of FMD. The patient was referred to a specialist for further evaluation and co-management of this condition. Following this patient’s diagnosis of FMD, his father suffered a brain aneurysm.
Discussion
This case shows the importance of advanced imaging and a co-management approach to care for the chiropractic patient. The presenting problem of low back pain with radiculopathy is a common condition, but for most providers, the addition of exacerbation with physical activity and a feeling of fatigue should alert the provider of something more significant; FMD as a diagnosis should be a differential diagnosis in patients with neurological or vascular symptoms. When determining differential diagnosis, FMD should be considered in women aged 20-60; however, this case demonstrates that it can also occur in young men.
The history and physical exam play a vital role in diagnosing generalized FMD and in which arteries could be affected. Renal FMD affects up to 72% of all cases and presents with flank pain, hematuria, renal infarct, and abdominal bruit.7 Cranio-cervical FMD presenting with headaches, pulsatile tinnitus, dizziness, neck pain, stroke, Horner syndrome, and carotid bruit. Mesenteric FMD presents with weight loss, fatigue, abdominal pain, and epigastric bruit; Subclavian FMD presents with upper arm weakness, paresthesia, claudication, and Steal syndrome.3 Lower limb FMD presents with claudication, cold legs, and ischemic feet. Coronary FMD presents with chest pain, shortness of breath, and acute coronary syndrome.9–11
Differentiating FMD from other diagnoses can be problematic, as it can present with radiculopathy or nerve impingement. Another differential diagnosis to consider would be fibromyalgia. Fibromyalgia (FM) tends to present with fatigue-related pain and symptoms more common in women ages 30-50 like FMD.12 Differentiating the 2 can be aided with determining if the pain and fatigue are relieved with rest. FMD ischemia-related pain will be relieved with rest, whereas FM pain will not. FM may also be associated with cognitive tiredness and overall body fatigue versus the isolated fatigue of the affected limb or region in FMD.12
The pathology of FMD involves dysplasia of the arterial wall, leading to alternating areas of stenosis and dilatation, which produce the characteristic’ string of beads’ appearance on imaging. This appearance, resembling a string of beads, is due to the alternating narrowing and widening of the artery. Although this pattern is most commonly seen in the renal arteries, it can also affect the carotid, vertebral, and other arteries. In this patient, the bilateral involvement of the renal arteries, combined with the abnormality in the left vertebral artery, highlights the systemic and multi-site nature of FMD. The presence of symptoms during exercise suggests possible exercise-induced ischemia. This also raises concerns about potential cerebral implications if not effectively managed.5,7
One of the significant challenges in managing FMD is the risk of complications such as arterial dissection, aneurysm formation, renovascular hypertension, limb ischemia, or peripheral ulcerations.1,5,10,11,13 Proper early referral of this patient for advanced imaging allowed for appropriate medical intervention and disease monitoring.
FMD management typically involves medical therapy, lifestyle modification, and interventional procedures.7 Antihypertensive medications are often prescribed to control blood pressure, particularly in patients with renal artery involvement, as seen in this case.6,9 Additionally, antiplatelet agents may be considered to reduce the risk of thromboembolic events in patients with carotid or vertebral artery involvement.6,9 Smoking cessation is recommended if the patient is a smoker, as it is shown to increase the risk of aneurysm in FMD.6,9 Exogenous hormone therapy is a concern for women due to the theoretical risk. However, there is no data to support this.6 Long-term follow-up care is highly recommended due to the long-term effects of FMD4,9 The patient is also to avoid the use of fluoroquinolones, a type of antibiotic recommended by the FDA as it is an increased risk factor of aortic ruptures or dissections in patients with FMD.2
In this case, the decision to co-manage the patient with a vascular specialist and a chiropractor was appropriate, given the nature of the patient’s symptoms. Chiropractic care relieves musculoskeletal pain and improves functional mobility, while vascular management monitors the underlying vascular disease. The patient continued musculoskeletal treatment with the mobilization of the thoracic and lumbopelvic light force drop technique. Soft tissue mobilization was provided to the hamstrings, gastrocnemius, and Iliotibial bands as needed, bilaterally to release myofascial adhesions and promote circulation and symmetrical movement patterns. The patient was provided with home stretching and exercises to support a regular jogging routine and core stabilization. The vascular physician determined that no medications or surgical intervention was necessary. He was to monitor his blood pressure and to follow up regularly for imaging yearly. Such a multidisciplinary approach is often required when managing complex cases of FMD, where the causation of symptoms may overlap across different medical specialties.7,9 Knowledge of contraindications for FMD in cervical manual manipulation should be considered.13 The patient’s cervical spine was avoided for manual manipulation. Continuing to monitor the patient’s blood pressure and cholesterol and providing a vascular examination regularly were added to the management plan.
Patient education is another crucial aspect of FMD management. In this case, the chiropractor and the vascular physician educated the patient on the importance of regular blood pressure monitoring. He was advised on dietary modifications and supplementation for overall cardiovascular health. These lifestyle interventions are vital in managing FMD and preventing disease progression.1,7
The long-term prognosis of FMD varies depending on the extent of vascular involvement and the presence of complications such as hypertension or stroke. The prognosis depends on the extent of vascular changes or damage and to what region. The patient’s health depends on current atherosclerotic changes, smoking habits, and activity level. Cardiovascular manifestations are essential to investigate as sudden death associated with FMD changes to the coronary arteries have been found in 2% of the population with unexplained sudden cardiac death.14
The case also raises important considerations regarding the screening and monitoring of FMD in individuals with a family history of the disease. Although FMD is not classified as a hereditary condition, evidence suggests a familial predisposition, particularly among first-degree relatives.2 The prevalence is as high as 41.7% for aneurysms and dissections in family members of those with FMD.7 The family history of vascular disease in this patient shows the importance of a thorough history, although the diagnosis of aneurysm was not present until after the patient’s diagnosis.
Conclusion
This paper demonstrates the importance of ordering advanced imaging and making proper referrals when conditions are appropriate. The patient’s presentation of low back pain with radiculopathy, a common condition, is complicated by the symptoms of leg fatigue with activity. Differential diagnosis of FMD that may not be considered in daily practice should be, with these uncommon symptoms. Contraindications and continued vascular evaluation should be considered in the management plan in these cases.