Patients are referred to neurosurgeons specialized. Pure arterial malformation of the posterior cerebral artery: importance of its recognition

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1 J Neurosurg 119: , 2013 AANS, 2013 Pure arterial malformation of the posterior cerebral artery: importance of its recognition Case report Nancy McLaughlin, M.D., Ph.D., 1 Radoslav Raychev, M.D., 2 Gary Duckwiler, M.D., 2 and Neil A. Martin, M.D. 1 Departments of 1 Neurosurgery and 2 Radiology, Neurointerventional Radiology, David Geffen School of Medicine at UCLA, Los Angeles, California The finding of dilated, elongated, and tortuous vessels on brain imaging should prompt clinicians to determine what vascular anomaly is present. Importantly, not all suspicious serpentine flow voids are manifestations of arteriovenous malformations or arteriovenous fistulas. Other types of intracranial vasculopathies should also be considered. The authors report a rare case of dilated, tortuous, and redundant left posterior communicating artery and left P 2 segment of the posterior cerebral artery identified in a young healthy adult that remained stable over a 30-year period. Dynamic and 3D images were critical for determining the type of vascular anomaly and for guiding appropriate management. The authors propose that this case represents a pure arterial malformation and discuss its distinguishing features. ( Key Words arterial malformation developmental anomaly dilatative arteriopathy dolichoectasia cerebral artery ectasia posterior cerebral artery cerebral aneurysm vascular disorders Patients are referred to neurosurgeons specialized in cerebrovascular pathologies following the identification of dilated vessels on brain CT scans, CT angiograms, MR images, or MR angiograms. Not all suspicious serpentine flow voids are manifestations of arteriovenous malformations or arteriovenous fistulas. Other entities that should be considered are purely arterial anomalies or malformations (dolichoectasia, 2,8 fusiform aneurysm, dissections) or purely venous anomalies or malformations (venous varix, developmental venous anomaly, or venous angiomas). However, differentiating between arteries and veins on these static 2D imaging modalities is difficult and often impossible. Dynamic imaging modalities such as a catheter angiogram and 3D Abbreviations used in this paper: ACA = anterior cerebral artery; CTA = CT angiography; ICA= internal carotid artery; MRA = MR angiography; PCA = posterior cerebral artery; PCoA = posterior communicating artery. J Neurosurg / Volume 119 / September 2013 images such as those obtained with 3D angiography may be essential to determine the type of vascular anomaly or malformation present and, ultimately, to guide management. We report a rare case of dilated, elongated, and redundant left PCoA and left P 2 segment of the PCA that remained stable over 3 decades, based on detailed radiographic documentation (reports and images), in an otherwise healthy individual. The catheter angiogram and the 3D images were critical in characterizing this vascular malformation. We propose that this case represents a pure arterial malformation, emphasizing the importance of clinical history and appropriate imaging with longterm follow-up for safe counseling and management. Case Report History. A 54-year-old woman in good health was 655

2 N. McLaughlin et al. referred to our clinic for evaluation of a possible arteriovenous malformation. At age 24, she had undergone brain imaging prompted by the development of more frequent headaches. Head CT scanning and catheter angiography showed the presence of abnormal vessels in the suprasellar and prepeduncular cisterns, interpreted as an arteriovenous malformation. No treatment had been recommended. At age 37, she was brought to the emergency department after suffering an acute episode of dizziness that spontaneously resolved. Brain MRI at the time revealed a small cystic pituitary lesion and again showed the abnormal vessels in the same region. She was also discovered to be pregnant at this visit, and regular imaging follow-up was recommended for a supposed Rathke cleft cyst. Recently, while gardening, the patient sprayed an insecticide product in her face and eyes. She later developed diplopia, unsteadiness, and myalgia. Symptoms improved within the following 7 hours and were completely resolved within 24 hours. She did not note any headaches throughout this episode. Brain MRI and MRA showed again the infracentrimetric pituitary cystic lesion, as well as the abnormal vessels in the left suprasellar and prepeduncular cisterns (Fig. 1). There was no evidence of acute or chronic ischemia or of recent or remote hemorrhages. She was referred to a neurosurgeon who recommended embolization of the abnormal vessels. She presented to our clinic for a second opinion. She did not have any recurrence of her symptoms and remained free of headaches. Examination and Investigation. The patient s neurological examination was completely normal. Notably, she had normal external ocular movements and neither conjunctival injection nor proptosis. Auscultation of the ocular globes and temporal regions did not reveal a bruit. When reviewing her most recent brain MR images, the cystic pituitary lesion had in fact slightly decreased in size and was not exerting any pressure on the optic chiasm (Fig. 1). The abnormal vessels did not seem to have changed over time on the MR images, and no cortical dysplasia was noted. Catheter angiography with 3D images was requested to better evaluate the anatomy of this vascular anomaly and to evaluate if any risk for future bleeding was present (Figs. 2 4). The catheter angiogram showed a dilated, tortuous, and redundant left PCoA and left P 2 segment of the PCA. The redundant vascular loops formed a compact purely arterial mass. A 6-second frame acquisition allowed following the tortuous and redundant loops of the involved PCoA and P 2 arteries (Fig. 3). A small wide-necked aneurysm at the origin of the left PCoA measuring 2.6 mm (dome) and 3.4 mm (neck) was visualized. Reviewing her most recent MRA images acquired 3 months before the angiograms, although this aneurysm was already present, it was very difficult to separate from all vessel loop superpositions. It had not changed in size and morphology. The vascular anomaly was consistent with a dilated, elongated, and redundant left PCoA and P 2 segment, which, based on the detailed radiographic description of the prior angiogram, had not changed in appearance for 3 decades. The absence of a nidus and early venous drainage were noted. Management. Given the circumstances in which the recent symptoms occurred, it was not believed that these symptoms were related to the arterial anomaly. No treatment was recommended for this vascular anomaly. The patient was, however, counseled to undergo a follow-up MRA in 6 months to reevaluate the small PCoA aneurysm. If this examination documents stability of the left PCoA aneurysm, catheter angiography will be recommended in 2 years to evaluate for an interval aneurysm change (size, morphology, or both) or for a new aneurysmal formation that could potentially be obscured by the vessel loop superposition. Discussion Distinction From Arteriovenous Malformations or Fistulas Accurate characterization of the architecture of abnormal vessels is essential prior to discussing any avenues of management. Appropriate characterization of the vasculopathy is important because treatment and prognosis vary depending on the type of the vascular anomaly. Arteriovenous malformations represent abnormal connections between arteries and veins that would irrigate and drain normal brain, respectively. This transition can occur through an intervening network, a nidus, or be a direct process, termed fistulous arteriovenous malformation. If the abnormal vessels are extraparenchymal, the abnormal communication may form directly between pial arteries and pial veins, termed a pial arteriovenous fistula, Fig. 1. Serial sagittal T1-weighted MR images obtained in 2005 (A), 2008 (B), and 2011 (C). 656 J Neurosurg / Volume 119 / September 2013

3 Pure arterial malformation of the posterior cerebral artery Fig. 2. A E: Left ICA injection angiograms, lateral projection, 6-second frame. Images represent sequential frames. or directly between dural arteries and dural veins, termed a dural arteriovenous fistula. Recognizing these two vascular abnormalities and detailing their angioarchitecture is important, as associated findings may increase the risk of hemorrhage or of treatment. The absence of a nidus and a venous component makes this reported case distinct from cases of arteriovenous malformations or fistulas. Distinction From Dilatative Arteriopathy However, abnormal vessels visualized with a brain CT, CTA, MRI, or MRA do not always imply abnormal arterial to venous connections (Fig. 5). Indeed, dilated vessels seen with these imaging modalities can be purely arterial or purely venous. The most common entity presenting as elongated, tortuous, and dilated arteries at the base of the brain is an intracranial dilatative arteriopathy (dolichoectasia). 2,7,8 This acquired subtype is more common, affecting adults over 40 years of age, and is most often diagnosed in the 6th and 7th decades of life. It most commonly involves the vertebrobasilar artery and ICA. 7,8 Recent studies have proposed that the acquired subtype of dilatative arteriopathy may be part of a systemic ectatic vasculopathy as larger diameters in thoracic aortas and coronary arteries have been noted in these patients Congenital intracranial dilatative arteriopathy is less frequent, affects children and young adults, and J Neurosurg / Volume 119 / September 2013 frequently involves branches of the ICA. 3,4,6 Genetic, infectious, inflammatory, immunological, and degenerative factors may all cause or contribute to the formation and/ or progression of dilatative arteriopathy. 2 The present case was distinct from dilatative arteriopathy (dolichoectasia), which presents as a dilated and elongated vessel along the course of a recognizable artery (Fig. 5B). In pure arterial malformations, in addition to being overlapping, dilated, and tortuous, the involved vessels are redundant to the point of looking like a mass of arterial loops with a coil-like appearance. In addition, although children, adolescents, and young adults diagnosed with dilatative arteriopathy generally have genetic, infectious, inflammatory, immunological, or degenerative predisposing factors that may cause or contribute to the formation and/or progression of dilatative arteriopathy, 2 these were all absent in our patient. Distinction From Developmental Arterial Anomaly (or Arterial Vascular Dysplasia) Similar to developmental venous anomalies, there have been few reports of cases of arterial vascular dysplasia or of developmental arterial anomaly. 1,4,13 Reported developmental arterial anomalies most often involve distal branches of intracranial vessels and present as a network-like cluster of small dilated and ectatic arteries 657

4 N. McLaughlin et al. Fig. 3. A C: Left ICA angiograms, anteroposterior projection, 6-second frame. Images represent sequential frames. Note the small saccular aneurysm at the origin of the PCoA. (Fig. 5D). 1,4,13 They appear to some extent as collections of small dilated veins clustered in one area around a larger vein characteristic of developmental venous anomalies. Dysembryogenesis may occur not only in intracranial veins but also in intracranial arteries, which may be linked to structural defects in the arterial wall and migrational abnormalities. 1,4,12,13 Magnetic resonance images should be reviewed attentively to search for a possible associated cortical dysplasia, which has been described for developmental vascular anomalies. 1,4,13 The configuration of pure arterial malformation differs from developmental arterial anomalies, with the former involving more proximal dilated vessels featuring redundant arterial loops forming a compact mass of overlapping vessels instead of a network-like cluster of small distal vessels. 1,4,13 Unlike in other reported cases of developmental arterial anomaly, no cortical anomaly was found in this patient. 1,4,13 Distinction From Intracranial Arterial Dissections The lesion in the present case was distinct from an intracranial dissection because the walls of the dilated vessel remained parallel along the entire course of the tortuous segment. 5 The dilation and tortuosity not only involved the left PCoA but also extended beyond the junction of the PCoA with the PCA to involve the P 2 segment. Both of these features are not typically seen in intracranial dissec- Fig. 4. Angiogram of the posterior circulation. Left vertebral artery injection angiograms in anteroposterior (A) and lateral (B) projections. Right vertebral artery injection angiograms in anteroposterior (C) and lateral (D) projections. Right vertebral artery injection angiograms with manual compression of the right ICA in anteroposterior (E) and lateral (F) projections. 658 J Neurosurg / Volume 119 / September 2013

5 Pure arterial malformation of the posterior cerebral artery tions. Brain MRI showed no evidence of previous intramural signal intensity suggestive of an intramural thrombus. No chronic infarct was noted in the diencephalic and mesencephalic territories supplied by medial perforating arteries arising from the PCoA. Although vessel irregularity, focal dilation, or focal stenosis is not always noted in intracranial dissections, the catheter angiography also failed to document an ovoid shape, an aneurysmal outpouching along the dilated segment, tapering at the extremities, a double lumen, or an intimal flap (Fig. 5C). 5 Proposed Terminology: Pure Arterial Malformation To our knowledge, this represents the first angiographically verified case of a pure arterial malformation involving the PCoA and PCA. Although this terminology was evoked by Thompson and colleagues in their report on a patient with a dolichoectatic ACA presenting with seizures, the vascular anomaly described by Thompson et al. was an example of intracranial dilatative arteriopathy. 14 Doran and colleagues reported a patient with bilateral dilated and tortuous ACAs described as dolichoectasia of the ACAs. 1,4,13 However, considering the present case and the distinctions described previously, the vascular anomaly reported by Doran and colleagues represents, in our opinion, a case of pure arterial malformation involving the ACAs, as the vessels were not only dilated and elongated but also redundant, with arterial loops taking on a coil-like appearance. 1,4,13 Over the past 25 years, the senior author (N.A.M.) has encountered 2 other cases of developmental arterial anomalies compatible with purely arterial malformations. One patient was referred to our institution following a subarachnoid hemorrhage. Investigation revealed a distal ICA aneurysm with what was thought to be an arteriovenous malformation. Careful review of the angiogram showed a tangle of dilated arteries with no draining veins. Although the aneurysm and the tangle of arteries were in close proximity, it was not felt that both were related. The patient was brought to surgery for clipping of the ruptured supraclinoid ICA aneurysm. During the procedure, a mass of redundant arteries originating from the middle cerebral artery/lenticulostriates with macroscopically normal appearing vessel walls (no evidence of atherosclerosis) was observed. The second case was a patient referred for evaluation of a possible arteriovenous malformation involving the M 1 segment. The dilated and tortuous middle cerebral artery showed no venous component. This patient was not brought to the operating room and was managed conservatively. In summary, recognizing the presence of abnormally dilated vessels on images from brain CT, CTA, MRI, or MRA should initiate a differential diagnosis, including rarer entities such as purely arterial and purely venous anomalies. As illustrated in the present case, dynamic and 3D imaging may be required to determine the nature of the vascular anomaly and to guide appropriate management. The diagnosis of a purely arterial malformation should be raised in the presence of dilated, overlapping, and tortuous arteries forming a mass of arterial loops with a coil-like appearance in the absence of any venous component. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Author contributions to the study and manuscript preparation include the following. Conception and design: Martin, McLaughlin. Acquisition of data: McLaughlin. Analysis and interpretation of data: all authors. Drafting the article: McLaughlin, Raychev. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: McLaughlin. Study supervision: Martin. Fig. 5. Schematic representation of intracranial arterial vasculopathies. A: Pure arterial malformation (present case). B: Dilatative arteriopathy or dolichoectasia. 14 C: Arterial dissection. 5 D: Developmental arterial anomaly or arterial vascular dysplasia. 13 J Neurosurg / Volume 119 / September 2013 References 1. Abe T, Singer RJ, Marks MP, Kojima K, Watanabe M, Uchida M, et al: Arterial vascular abnormality accompanying cerebral cortical dysplasia. AJNR Am J Neuroradiol 18: , Caplan LR: Dilatative arteriopathy (dolichoectasia): what is known and not known. Ann Neurol 57: , Chao KH, Riina HA, Heier L, Steig PE, Gobin YP: Endovascular management of dolichoectasia of the posterior cerebral artery report. AJNR Am J Neuroradiol 25: , Doran SE, Deveikis JP, Chandler WF: Dolichoectasia of the anterior cerebral arteries in an adolescent. AJNR Am J Neuroradiol 16: , Duncan IC, Terblanché JM: Spontaneous isolated posterior communicating artery dissection in a young adult with hyperhomocysteinemia. AJNR Am J Neuroradiol 26: ,

6 N. McLaughlin et al. 6. Kawahara I, Morofuji Y, Takahata H, Toda K, Tsutsumi K, Baba H, et al: Dolichoectasic anterior cerebral artery and hemodynamics. J Stroke Cerebrovasc Dis 21:907.e5 907.e8, Kwon HM, Lee YS: Dolichoectasia of the intracranial arteries. Curr Treat Options Cardiovasc Med 13: , Lou M, Caplan LR: Vertebrobasilar dilatative arteriopathy (dolichoectasia). Ann N Y Acad Sci 1184: , Pico F, Biron Y, Bousser MG, Amarenco P: Concurrent dolichoectasia of basilar and coronary arteries. Neurology 65: , Pico F, Jacob MP, Labreuche J, Soufir N, Touboul PJ, Benessiano J, et al: Matrix metalloproteinase-3 and intracranial arterial dolichoectasia. Ann Neurol 67: , Pico F, Labreuche J, Cohen A, Touboul PJ, Amarenco P: Intracranial arterial dolichoectasia is associated with enlarged descending thoracic aorta. Neurology 63: , Sacks JG, Lindenburg R: Dolicho-ectatic intracranial arteries: symptomatology and pathogenesis of arterial elongation and distention. Johns Hopkins Med J 125:95 106, Shankar JJ, Banerjee ST, Hogan M, terbrugge K, Lasjaunias P, dos Santos MP: A rare case of cerebral cortical dysplasia with arterial vascular dysplasia. Can J Neurol Sci 36: , Thompson JR, Weinstein PR, Simmons CR: Cerebral arterial dolichoectasia with seizure. Case report. J Neurosurg 44: , 1976 Manuscript submitted July 12, Accepted April 25, Please include this information when citing this paper: published online June 7, 2013; DOI: / JNS Address correspondence to: Neil A. Martin, M.D., Department of Neurosurgery, David Geffen School of Medicine at UCLA, Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Suite 6236, Los Angeles, CA neilmartin@mednet.ucla.edu. 660 J Neurosurg / Volume 119 / September 2013