<1990 91 S. Karger AG. Basel 1016-2291/90-9I/O166-0326 $ 2.75/0 Pediatr Neurosurg 1990-91: 16:326-330 Ruptured Intracranial Aneurysm Presenting as Cerebral Infarction in a Young Child AM. Rojiania, K.J. Poskirt h, D.D. Cochranec. A.J. Macnabd. A7/. G. Normana Departments of “Pathology, ’’Radiology. "Neurosurgery and ''Pediatrics, British Columbia's Children's Hospital and University of British Columbia. Vancouver. B.C., Canada Key Words. Cerebral aneurysm * Vasospasm • Infarction Abstract. We describe a 15-month-old girl who presented with an acute hemiplegia. The sequence of events appears to have been clinically silent subarachnoid hemorrhage, vasospasm, infarction and a second lethal hemorrhage 3 months later. The old infarction was seen on computed tomography during her second illness. Autopsy confirmed the presence of a recent rupture of an intracranial aneurysm and old hemorrhage. In addition there was an unusual fibroblastic pro­ liferation in the aneurysm wall. This case demonstrates that clinically silent subarachnoid hemorrhage, vasospasm and infarction can occur as complications of aneurysms, even in very young children. The frequency of congenital aneurysms in the pediatric group ranges from 0.5 to 4.6% of aneurysms at all ages 11-5]. Congenital aneurysms in children differ from those in adults in the following respects: a higher male:female ratio: an increased number of giant aneurysms, and a higher percentage of lesions in the posterior circulation [6]. These lesions are rare and therefore infrequently con­ sidered in the differential diagnosis of subarachnoid hemorrhage (SAH). These factors were compounded in this case by an unusual presentation with right-sided hemiplegia. We report unusual histopathologic features, intense cellular proliferation and the presence of giant cells in the aneurysm wall. Case Report Our patient first presented to the emergency department of a local hospital at the age of 15 months with acute onset of painless, right hemi­ plegia. Investigations including computed tomography (CT) and elec­ troencephalography showed no cause for the hemiplegia and the differ­ ential diagnosis was either a metabolic phenomenon or a post-ictal epi­ sode. Over the next 2 months she regained almost normal function. Retrospective review of the initial CT scan after examination of the brain, disclosed decreased attenuation of the head of the caudate and was interpreted as representing a recent infarction (fig. 1). At the age of 18 months, while being breast fed, she suddenly threw her head back, arched her hack, screamed and clasped her head as if in severe pain. On arrival at the local hospital she was comatose and was transferred to British Columbia's Children’s Hospital. On admission she moved all limbs symmetrically, with diminished response to pain and little spontaneous movement. Focal neurological signs were absent. The child required assisted ventilation and was treated with anticon­ vulsants. Over the next few hours occasional seizures occurred and approximately 12 h after the initial episode she deteriorated, becoming rapidly comatose, unresponsive, with fixed, dilated pupils and died. A CT scan done at the time of deterioration showed SAH with blood in the left sylvian fissure, the posterior aspect of both lateral ventricles and in the fourth ventricle. The basal cisterns were obliterated. Cerebral edema with transtentorial herniation and possible infarction in the dis­ tribution of the left middle cerebral and both posterior cerebral arteries was present. Two focal areas of decreased attenuation representing old infarctions were identified on the left, in the head of the caudate nucleus and putamen (fig. 2). Angiography was not performed as the child was in extremis. Pathological Findings Diffuse SAH was present over the cerebral hemi­ sphere, more marked over the left frontal and anterior temporal areas and within the sylvian fissure. A moderate Downloaded by: Karolinska Institutet, University Library 130.237.122.245 - 1/18/2019 4:29:15 PM Introduction 327 Ruptured Aneurysm Presenting as Cerebral Infarction both in the wall of the aneurysm and in the adjacent paren­ chyma. Other intracranial vessels were normal on gross and microscopic examination. The left hemisphere con­ tained an old infarct in the head of the caudate and putamen which extended posteriorly to the anterior thalamus and involved a small area of the internal capsule (fig. 6). There was marked cerebral edema. The midbrain was compressed laterally; cerebellar tonsillar and uncal her­ niation were marked. Acute anoxic-ischemic changes were present, particularly in the cerebellum. Arteries else­ where in the body were normal on gross examination and were not sectioned. There was terminal bilateral bronchopneumonia with aspiration. Fig. 1. Axial contrast CT head scan performed on the initial admis­ sion to another hospital. The scan was initially read as normal. The head of the caudate nucleus is of decreased attenuation (arrowhead), repre­ senting a recent infarct. amount of blood lay over the base of the brain and ventral surface of the brainstem. An 0.8-cm diameter aneurysm arose from the left middle cerebral artery, 0.2 cm distal to its bifurcation (fig. 3). It was ovoid and contained clotted blood. It was attached to the underlying vessel by a broad neck. Microscopic examination of the aneurysm showed that it had a relatively thick wall on one side and contained a fresh blood clot and recent thrombus. Mas­ son’s trichrome and Verhoeff van Gieson elastic stains showed a small segment of normal arterial wall, and a much larger abnormal component with a dilated and expanded aneurysm wall with a sudden, sharp decrease in the smooth muscle of the media and an absence of elastic lamina (fig. 4). The intimal surface of the aneurysm near the neck showed marked proliferation of fibroblasts. Within this area of proliferation there were occasional multinucleate giant cells (fig. 5). There was hemosiderin within the macrophages and in the extracellular space. This case illustrates a number of unusual features. Our patient was only 15 months old when she had her first symptoms. Ruptured intracranial aneurysms (RIA) are a rare cause of SAH in young children, with pediatric cases ranging from less than 0.5 to 4.6% [1-5]. A recent autopsy study of 133 patients with ruptured aneurysms revealed no cases younger than 10 years and only 4 cases in the 10- to 19-year-old group [71. Crompton [8] reported 41 of 6,368 cases of RIA in the 1- to 19-year age group. The incidence of aneurysms in very young children is even more infre­ quent. Patel and Richardson [2], in their study of 58 pa­ tients in the first 2 decades of life, reported no cases in the 0- to 7-year age group, while another series [5], reviewing intracranial aneurysms in 43 children and adolescents, describes only 1 child below the age of 4 years. Children rarely present with signs and symptoms di­ rectly referable to an aneurysm; only when the aneurysm ruptures is medical attention sought [9]. The symptoms are those of a SAH, and the first consideration is hemorr­ hage from an arteriovenous malformation. Ostergaard and Voldby [5] reported that 70% of their cases presented with signs and symptoms typical of SAH. These included intense headache and meningism. Of the remaining cases, 4 had no signs of SAH, 3 presenting with oculomotor paresis and 1 a left hemiplegia. Our case had an atypical presentation, with a right hemiplegia and no clinical or radiologic evidence of SAH. Initially no cause for the hemiplegia could be identified, but a retrospective review of the first CT scan showed early focal infarction in the left basal ganglia. This was confirmed at autopsy. The importance of missed, minor bleeding episodes leading to vasospasm has also been emphasized [10]. Cerebral vaso- Downloaded by: Karolinska Institutet, University Library 130.237.122.245 - 1/18/2019 4:29:15 PM Discussion Rojiani/Poskitt/Cochrane/Macnab/Norman Fig. 2. a Axial CT head scan without contrast, obtained at the time of the second admission to hospital. The slice was obtained at the level of the inferior aspect of the sylvian fissures and documents the presence of subarachnoid blood within the left sylvian fissure. The basal cisterns are also obliterated, b Higher slice from the axial CT scan documenting evidence of old infarctions involving the head of the caudate nucleus on the left and part of the internal capsule (arrow). There are linear areas of increased attenuation within the depths of the sylvian fissure, indicating subarachnoid hemorrhage. spasm, clinical or radiographic, is common following SAH from a R1A. Its incidence varies from 30 to 70%, varying significantly with the time of angiography and the severity ofSAH [11]. Fisheretal. [ 12] showeda50% inci­ dence of delayed (after day 3) cerebral ischemia and neu­ rologic deficit associated with vasospasm in RIA. At autopsy, cerebral infarctions have been reported in 60% of adults following RIA [8|. The role of cerebral vasospasm in the outcome of RIA was assessed in 43 patients, 19 years or younger, with verified intracranial saccular aneurysms. Vasospasm was demonstrated in 53% of 19 patients who had angiographic studies performed after the 3rd day and between the 1st and 2nd week after SAH, the period most frequently associated with the development of vasospasm. None of the patients who developed vaso­ spasm had an increased mortality and no cerebral infarc­ tion was seen at autopsy ]5|. In another study 7 of 54 cases under the age of 20 years showed radiographic vaso­ spasm. Autopsies on 4 of these 7 cases showed no cerebral infarctions, despite the presence of severe radiographic vasospasm in 2 autopsied cases [2], A possible explana­ tion is the increased resilience of childhood arteries com­ pared to adults, although no evidence is provided for this hypothesis [13]. We feel that this child had a silent, minor bleeding episode which resulted in focal cerebral vaso­ spasm of the perforating branches of the middle cerebral artery. This caused an infarction which subsequently pre­ sented as hemiplegia. This hypothesis is supported by evi­ dence of an old hemorrhage in the wall of the aneurysm and adjacent parenchyma, and autopsy confirmation of the Downloaded by: Karolinska Institutet, University Library 130.237.122.245 - 1/18/2019 4:29:15 PM 328 Ruptured Aneurysm Presenting as Cerebral Infarction 329 Fig. 5. Fibroblastic proliferation in intitna showing occasional giant cells (arrows). HE. Original magnification X 100. Fig. 3. A single aneurysm is seen, arising from the left middle cere­ bral artery, with adjacent clotted blood. The frontal tip of the left tem­ poral lobe has been resected to permit visualization of the aneurysm. Fig. 4. Section through the neck and body of the aneurysm showing normal arterial wall with lamina (arrow) and expanded aneurysm wall with intimal thickening and absence of elastic lamina and smooth muscle. Verhoeff van Gieson stain. Original magnification x20. old infarction. In the absence of typical signs of SAH and angiography for detection of the aneurysm or the pre­ sumed vasospasm, interpretation of this child’s clinical presentation with hemiplegia was difficult. An unusual pathological feature of this case is the intense fibroblastic reaction with occasional giant cells seen in the intima of the vessel. Histopathologic studies of cerebral blood vessels in vasospasm related to SAH have shown changes including intimal swelling and prolifera­ tion. as well as a variety of other histopathologic features consistent with complement-dependent immune reactions [14-16]. Intimal proliferation has previously been de­ scribed in an 11-month-old infant who also showed fibro- Downloaded by: Karolinska Institutet, University Library 130.237.122.245 - 1/18/2019 4:29:15 PM Fig. 6. Old infarction involving caudate, putamen and internal cap­ sule (arrow). Subarachnoid hemorrhage is also evident in this coronal section through the frontal lobes. Rojiani/Poskitt/Cochrane/Macnab/Norman muscular hyperplasia of the renal arteries [17]. While no gross abnormalities were identified in other extracranial vessels examined in our case, both cases represent aneurysms of the ‘congenital type', with an absence of elastic lamina and smooth muscle within the media. Al­ though the giant cells seen in this case may indicate an inflammatory process, such as some form of vasculitis, other intracranial vessels examined were histologically normal. The precise etiopathogenesis of this proliferative reaction is uncertain. In conclusion, we describe a young child who suffered a clinically silent early hemorrhage, presumed cerebral vasospasm and resulting cerebral infarction, a rare presen­ tation for a ruptured intracranial aneurysm in early child­ hood. Acknowledgement We thank coroner Dennis McSweeney for permission to publish this case. 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