History
Most patients with craniocervical FMD are asymptomatic. Others report nonspecific problems such as headache, lightheadedness, vertigo, and tinnitus. Neck pain or carotidynia may be an initial presenting symptom due to arterial dissection. The symptoms of stroke can be varied but most often involve the anterior circulation because of the predilection of FMD to affect the extracranial carotid arteries.
Patients may provide a history of transient or permanent neurologic deficits of the face or extremities such as weakness or numbness, or they may experience visual changes or speech difficulties. No particular symptoms are pathognomonic for FMD, and any history compatible with a stroke in younger individuals may indicate underlying FMD. The family history should include information about relatives who have had vascular events at a young age.
One report notes an extremely unfortunate case of locked-in syndrome due to autopsy-proven basilar artery FMD. [16] FMD may be complicated by stroke because of direct effects of craniocervical stenosis, dissection, or intracranial aneurysm, or the indirect effects of concomitant renovascular hypertension.
Symptoms compatible with a sentinel bleed, namely a sudden explosive headache followed later by neck stiffness, may signify the existence of an aneurysm, which in turn, may be associated with FMD.
A review of symptoms may provide clues of noncraniocervical FMD. Long-standing involvement of the renal arteries may lead to a history of hypertension. Rarely, abdominal pains, and even a history of ischemic bowel, may indicate mesenteric or visceral artery involvement. Vascular compromise of the limbs by FMD lesions may cause ischemic symptoms such as intermittent leg claudication. A case of FMD associated with spinal subdural hematoma has been reported. [25]
Physical
Because of the broad possibilities of neurologic dysfunction due to stroke caused by FMD, a thorough neurologic examination should be performed. Findings may include anything from cranial nerve deficits to weakness, numbness, and coordination difficulties.
Sensitive signs of motor dysfunction such as pronator drift and plantar responses may yield deficits when formal power assessment does not. The neurovascular examination would not be complete without auscultation for carotid and vertebral artery bruits. If a headache history is provided, assessment for meningismus (eg, nuchal rigidity, Kernig sign, Brudzinski sign) may prove positive.
Because of the systemic nature of FMD, the general physical examination should include a search for signs of renal, visceral, and limb arterial involvement. These signs may include hypertension, decreased peripheral pulses, and even asymmetric limb pressures. Bruits may be found on auscultation of the renal, abdominal, iliac, or subclavian arteries.
Causes
The cause of FMD is unknown, despite some speculations related to its associations with some rare genetic conditions and predilection for young white females. Strokes can be caused by the FMD stenoses themselves, generally by thromboembolic events. Even without trauma, FMD lesions predispose the afflicted individual to arterial dissection, which in turn can cause embolic events or, rarely, local thrombosis and massive hemispheric stroke. Hypertension due to renovascular FMD may be a risk factor for lacunar and large vessel infarcts and even intracerebral hemorrhage.
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Digital subtraction angiogram of the right internal carotid artery demonstrates an irregular extracranial portion that is consistent with FMD.
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Conventional angiogram of the left carotid artery demonstrates a 1.5-cm, long, smooth, severe stenosis of the extracranial internal carotid artery. Note that the artery is not completely occluded and a thin continuous string of contrast is present along the length of the stenosis. This smooth tubular stenosis is suggestive of the intimal fibroplasia form of FMD but can be observed with any of the subtypes.
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Cerebral angiogram of the left carotid artery territory demonstrates a long, irregular stenosis with a string-of-beads appearance along the entire extracranial length of the internal carotid artery (ICA). This is consistent with the most common medial dysplasia form of fibromuscular dysplasia. Also note similar involvement of the first 3 cm of the external carotid artery (ECA). Such extensive ICA involvement, as well as ECA involvement, is atypical. Note sparing of the carotid bulb.
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Lateral view of a right carotid angiogram demonstrates multiple stenoses of FMD of the internal carotid artery. The string of beads appearance is suggestive of the medial dysplasia form of FMD.
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Anteroposterior view of a right carotid angiogram demonstrates FMD of the extracranial portion of the right internal carotid artery.
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Angiogram of the descending aorta demonstrates the stenoses of FMD in the renal arteries bilaterally.
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Angiogram of the right vertebral artery demonstrating irregular stenoses of fibromuscular dysplasia at the level of C2-3.
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Illustration of the operative approach of graduated dilatation of the internal carotid artery (ICA). The common carotid and external carotid arteries are cross-clamped, and the superior thyroid artery is clipped while the ICA is isolated, opened, and dilated with progressively larger dilators. This technique has been shown to be successful in the management of medically refractive FMD stenoses.
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Illustration depicts the intraluminal appearance of graduated dilatation of the stenoses of FMD. The dilator is passed into the vessel and opens the bandlike narrowings.
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Illustration depicts the locations of FMD lesions, which differentiate regions with typical and atypical angiographic appearances of this disease.
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Digital subtraction angiography of the left internal carotid artery distribution demonstrates a large 1.5-cm-diameter aneurysm of the right anterior communicating artery. Aneurysms may be associated with systemic vasculopathies such as FMD.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery. Dissected vertebral artery.
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Small infarct in woman with fibromuscular dysplasia from dissected vertebral artery. An incidental aneurysm, or ovoid diverticula, is noted in the supraclinoid left internal carotid artery. Internal carotid angiogram.
