A rare case of fibromuscular dysplasia involving the cervicocephalic arterial tree highlighting the neuropathological findings

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To the Editor: We present a rare case of a 27-year-old woman with fibromuscular dysplasia (FMD) primarily affecting the vascular network within the cervicocephalic arterial tree, also more commonly known as the circle of Willis. While there is a multitude of medical literature surrounding the clinical and radiographic findings associated with systemic FMD outside of the CNS, there is an insufficient number of detailed studies that simultaneously discuss and illustrate the neuropathological findings associated with intracranial involvement of FMD within the circle of Willis. FMD is a non-atherosclerotic, non-inflammatory arteriopathy that involves the muscular walls of small- and medium-sized arteries that may result in serious complications, such as vascular narrowing, occlusions, aneurysms, or dissections (1). FMD was first described in the renal arteries of a 5-year-old boy in 1938 by Leadbetter and Burkland (2), and later in the cervicocephalic arterial tree by Palubinskas and Ripley (3). The most common arteries affected by FMD in the circle of Willis involve the midportion of the cervical internal carotid artery (ICA), the extradural segment of the vertebral arteries, and intracranial arteries (4). Neurologic symptomatology can vary in severity with more subtle, nonspecific manifestations including headaches, visual changes, lightheadedness, dizziness, pulsatile tinnitus, or audible carotid bruits (5). More severe neurologically related events can involve cerebrovascular arterial dissections, intracranial saccular aneurysms, transient ischemic attacks (TIAs), ischemic stroke, subarachnoid hemorrhages, and intracerebral hemorrhages (5). Magnetic resonance angiography (MRA) helps to elucidate FMD pathophysiology by showing the arterial luminal narrowing with alternating aneurysmal dilation, which endows FMD with its classic “string-of-beads” appearance (4). The majority of FMD patients are able to be managed pharmacologically with a daily low-dose aspirin (75–100 mg) being a clinically reasonable choice to help prevent thromboembolic complications (5). Hypertension is often observed concurrently with FMD, which calls for a more multidisciplinary approach to treatment, particularly if the renal arteries are also involved (5). For more complicated cases concerning FMD-related sequela (e.g. unruptured cranial aneurysms, TIAs, and ischemic strokes), endovascular stenting, clipping, or bypass surgery may be required (5). This is a case of a 27-year-old Caucasian woman with a past medical history significant for drug-resistant migraines who presented to the emergency department (ED) complaining of a constant, incurable migraine with associated nausea and generalized body weakness. During her initial presentation, she was prescribed migraine medications and a head computed tomography (CT) was performed, which demonstrated unremarkable findings at the time. Due to the patient’s history of chronic migraines and no new neurologic symptomatology, a differential diagnosis of intracranial FMD was not considered and further work-up was deemed unwarranted. Her ED treatment included an intravenous liter of lactated Ringer solution and a cocktail of diphenhydramine, ketorolac, and metoclopramide. She was subsequently discharged home and returned to her normal activities. Two weeks later, while at a local shopping center, she experienced a severe headache, right-sided weakness, ataxia, lethargy, and slurred speech resulting in loss of consciousness. After regaining consciousness, she stated that her intractable migraine from 2 weeks prior had never dissipated, and that it had gradually increased in pain and intensity. The patient was immediately taken for a brain magnetic resonance imaging (MRI), which revealed a focal acute infarct located in the left pons (0.1 cm in greatest dimension). A computed tomography angiogram (CTA) of the brain and neck showed narrowing in the bilateral V3 segments and a nonocclusive thrombosis located in the basilar artery with significant associated luminal stenosis (Fig. 1A–C). The telestroke neurology team was then consulted on the patient’s case. Thrombolytic therapy was discussed and treatment with tissue plasminogen activator (tPA) was electively pursued. Shortly after the visit with the telestroke neurology team, the patient became extremely somnolent with decreased mental status leading to the inability to follow commands or answer questions. At this point, the clinical team subsequently intubated the patient for airway protection, administered tPA, and transferred her to the intensive care unit. Angiographic imaging of the circle of Willis. (A) CTA shows a diminutive right V3 segment compatible with thrombus/dissection. (B) CTA shows diminutive left V3 segment compatible with thrombus/dissection. (C) CTA shows thrombus/dissection in the basilar artery. (D) Repeat CTA a few days later shows worsening narrowing and irregularity in the bilateral V3 segments. (E) MRA shows markedly narrowed luminal irregularities in the distal vertebral and basilar arteries. Shortly following intubation, a repeat brain MRI was performed that revealed worsening numerous acute ischemic infarcts involving the entirety of left pons with extension into the right pons (2.0 cm in greatest dimension), left thalamic nucleus (1.8 cm in greatest dimension), left anterior medial occipital cortex (2.0 cm in greatest dimension), and the left posterior medial temporal cortex (2.0 cm in greatest dimension). A repeat CTA showed marked worsening of the bilateral V3 segments compatible with dissection (Fig. 1D). MRA demonstrated significant multifocal luminal narrowing in the basilar artery, pre-communicating segment (P1) of the left posterior cerebral artery, and bilateral cervical vertebral arteries (left ≫ right) with associated eccentric intrinsic longitudinal relaxation time (T1) signal and mild enhancement, which is typically indicative of a dissection rather than vasculitis (Fig. 1E). The patient was started on a heparin drip and was successfully extubated after regaining consciousness. During the inpatient hospitalization interval, the patient was placed on apixaban for anticoagulation therapy and made significant strides toward clinical improvement while simultaneously working with the clinical team to arrange future placement into a stroke rehabilitation facility. Approximately 1 week later, the patient experienced a rapid decline with altered mental status, nausea, and emesis. Given the patient’s known history of stroke and bilateral cervical vertebral dissections extending into the basilar artery, stroke protocol was initiated, and she was rushed to have a non-contrast helical head and neck CT performed. Head and neck non-contrast CT showed an occlusion of the distal right vertebral artery, occlusion of basilar artery with extension up into the basilar terminus, and a left vertebral artery dissection. The patient was intubated due to decreased mental and Glasgow Coma Scale status. She was emergently taken to interventional radiology where she had a thrombectomy performed on her basilar artery and a stent placed in her right vertebral artery. She returned with her pupils remaining fixed and dilated despite the re-establishment of excellent blood flow being achieved during the procedure. Unfortunately, her neurologic and respiratory status continued to deteriorate, and she was ultimately transitioned to comfort care. She died shortly thereafter on day 18 of post-hospital admission. At neuroautopsy, the unfixed brain weighed 1160.0 g. On external gross examination of the brain, the cerebral and cerebellar hemispheres were symmetric and unremarkable with no overt signs of hemorrhage or other abnormalities. The cerebral and cerebellar hemispheres were then serially sectioned into coronal sections consisting of 0.5- to 1.0-cm intervals in the anterior-to-posterior direction. Examination of the coronal sections revealed an area of focal yellowish discoloration

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