Spontaneous aortic dissection and rupture in a patient with neurofibromatosis☆☆☆
Article Outline
Abstract
Vascular involvement in neurofibromatosis type I is a well-recognized but rare feature of the disease. This case report is the first such describing acute aortic dissection and rupture in a patient who also had incidental aneurysms of his carotid and iliac arteries. A review of the literature about pathogenesis and management strategies is also presented. (J Vasc Surg 2001;34:364-6.)
Neurofibromatosis (NF) is a common genetic disease with an autosomal dominant mode of inheritance. Several subtypes have been characterized, although types I and II are the most well defined. NF type II describes the association of bilateral vestibular schwannomas with café-au-lait spots and neurofibromata. Involvement of the vascular system has mainly been described in NF type I (NF-I), which is the focus of this paper.
NF-I, or classic von Recklinghausen's disease, results from a mutation in a tumor-suppressor gene located on the long arm of chromosome 17 (17q11.2).1 This is the most common subtype of NF, with a prevalence of approximately one in 3000 births.2 Although the gene is dominantly inherited and almost completely penetrant, its clinical expression is highly variable. As many as 50% of cases occur sporadically in patients without a family history of the disease. The disease affects tissues of neural crest and mesodermal origin; therefore, the clinical features are diverse.3 Most patients manifest the cutaneous stigmata: café-au-lait spots, pedunculated skin lesions (fibroma molluscum), and neurofibromata, which are clues to the diagnosis. Other features include Lisch nodules (harmatoma of the iris), kyphoscoliosis, dysplasia of the sphenoid, bowing and pseudarthrosis of the tibia, and an increased incidence of neoplasia (eg, acoustic neuroma, meningioma, neurofibrosarcoma, astrocytoma, glioblastoma, malignant schwannoma, pheochromocytoma).
Vasculopathy in NF-I is well described in the literature but is rarely encountered clinically. The true incidence of this entity is unknown because many lesions may be asymptomatic. Although the renal artery is most frequently involved, any vessel may be affected. The lesions may be occlusive or cause aneurysmal degeneration of the blood vessel. Hence, the clinical presentation can be indolent (eg, hypertension) or dramatic (arterial rupture). We report a case of acute aortic dissection and rupture in a patient with NF-I, highlighting the potentially catastrophic complications resulting from arterial involvement. To our knowledge, this is the first case of acute aortic dissection caused by NF reported in the literature.
Case report
A 34-year-old man with a positive family and personal history of NF-I came to the emergency department with a 2-day history of midabdominal and low back pain. On admission, the pain had increased in severity and was associated with vomiting. His past history was significant for scoliosis, seizures, and a known fusiform aneurysm of the left internal carotid artery. On examination, he had multiple cutaneous neurofibromata and café-au-lait spots. During the examination, his blood pressure dropped to 60/40 mm Hg, and his heart rate increased to 150 bpm, with an increase in abdominal tenderness. He was resuscitated with intravenous fluids and taken immediately to the operating room. When the abdomen was entered, free blood was encountered and a large left-sided retroperitoneal hematoma was seen. Supraceliac clamping of the aorta followed by medial visceral rotation was performed. A 3-cm longitudinal aortic tear with rupture was noted just above the aortic bifurcation. The clamp was relocated to the infrarenal position, and distal control of both iliac arteries was secured. At this point, it was apparent that the aortic pathology was that of dissection, with separation of the media and adventitia. Because of the patient's hemodynamic instability, local repair of the dissected aorta was performed with a continuous running 4-0 polypropylene suture, reinforced with pledgets in areas of friable tissue. Intraperitoneal packing and rapid closure of the abdomen were then performed, and he was taken to the intensive care unit for further resuscitation. A second procedure was performed the next day to remove the packing. No further bleeding or additional pathologic condition was found, and the aortic closure was secure. The patient's subsequent postoperative course was uneventful, and he was discharged on postoperative day 10. Local aortic dissection of the distal infrarenal aorta (Figure) and an incidental small aneurysm of the left common iliac artery were confirmed by means of a computed tomographic angiogram performed before his second exploration.
Computed tomographic angiogram of the abdominal aorta showing localized dissection with intimal flap (arrow ).
Discussion
Involvement of the vascular system in NF-I is a known, albeit under-recognized, feature of this disease. Perhaps the silent nature of most lesions and the inaccessibility of involved vessels to clinical examination have resulted in an underappreciation of its occurrence. An autopsy series of NF-I patients who died from other causes found vascular abnormalities in eight of 18 cases (44%).4 Reubi5, 6 suggested that vascular lesions could be seen in all cases of NF if a careful search were made. As illustrated in this case, vascular involvement can be life threatening, particularly in the setting of major arterial rupture. Screening of all patients with NF-I for arterial disease should be performed. Noninvasive imaging modalities, such as duplex ultrasound scanning, magnetic resonance angiography, and computed tomography scanning, are useful means of visualizing vessels that are less accessible to clinical examination.
The renal artery is the most frequently affected vessel, and its involvement usually results in hypertension in a young patient.4 However, reports of involvement of almost every major artery can be found in the literature, and no vessels (including veins7) are spared.
Vascular lesions are more often stenotic, but aneurysmal dilatation is not infrequent. The natural history of such aneurysms is likely one of progressive enlargement and rupture,8 although the actual size criteria for intervention are unknown because of the rarity of this disease. Clinical judgment is required, and treatment should be individualized. Involvement of the abdominal aorta is usually in the form of coarctation,9 but, as illustrated by means of this case, acute dissection can also occur.
Small, medium, and large arteries can be affected by the disease. There is evidence, however, to suggest that the pathologic condition in small vessels may differ from that in larger ones.10 Reubi6 was the first to classify the arterial lesions in vessels less than 1 mm in diameter. He divided the lesions into pure intimal, intimal aneurysmal, and nodular forms. Feyrter11 added an advanced intimal form. Changes seen in a specimen often straddle more than one category. In these small vessels, there is intimal proliferation of spindle cells with secondary degenerative changes (eg, fibrosis, loss of media smooth muscle, and elastin fragmentation). These cells have been shown by means of immunohistochemical and ultrastructural studies to likely originate from smooth muscle rather than neural elements, alluding to a mesodermal dysplastic process in patients with NF.10, 12 Although these proliferative lesions often obliterate the lumen of the vessel, advanced degeneration of the arterial wall can lead to aneurysm formation. Although this mechanism likely accounts for most aneurysms in small- and medium-size arteries, affliction of larger arteries, such as the common carotid, has also been described.13
A second mechanism of aneurysm formation is often seen in larger vessels in which neurofibromatous or ganglioneuromatous tissue invades and weakens the arterial wall.7, 8, 14 These cells do not have malignant features but are part of the generalized process in NF, affecting nerve fibers in the adventitia of the vessel wall.
Surgical repair and reconstruction of vessels affected by NF should be undertaken with caution because of the fragility of the vessel wall and extreme vascularity of the surrounding neurofibromatous tissue. Reports of massive hemorrhage and perioperative mortality when surgery is attempted highlight the technical difficulty of these cases.7, 8, 14 Our experience with this case confirms the poor quality of the vessel wall, necessitating the use of pledgeted sutures for secure closure. Endovascular techniques, such as selective embolization of aneurysms and stenting for stenotic disease, should be used whenever such an option is feasible. When open surgery is required, ligation and bypass grafting of an aneurysm, rather than direct aneurysm resection (to avoid the vascular infiltrating neurofibromatous tissues), and use of pledgeted sutures may be helpful.
Conclusion
Vasculopathy in NF-I is a well-recognized, albeit rare, feature that may have potentially catastrophic consequences. A detailed clinical examination supplemented by the use of vascular imaging modalities should be performed in these patients to detect occult disease. Although the renal artery is most commonly involved, no vessel is immune. Two distinct pathogenetic mechanisms have been identified: smooth muscle (mesodermal) dysplasia and direct vascular invasion by neurofibromatous tissue. Lesions manifest as stenosis, dissection, aneurysm formation, or rupture of the affected vessel. When surgical reconstruction is required, ligation and bypass grafting of aneurysms and the use of pledgeted sutures may facilitate handling of the involved tissues, which are often friable and vascular. Endovascular treatment remains an attractive option when anatomically feasible.
References
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☆ Competition of interest: nil.
☆☆ Reprint requests: David K. W. Chew, MD, Division of Vascular Surgery, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115 (e-mail: dchew@partners.org ).
PII: S0741-5214(01)52706-8
doi:10.1067/mva.2001.116141
© 2001 Society for Vascular Surgery and The American Association for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
