Anterior Cerebral Artery Dolichoectasia Associated with Adjacent Cortical Dysplasia

Sir, A tortuous, fusiform dilatation with frequent calcification of the anterior cerebral artery (ACA), particularly at the pericallosal and distal ACA segments, is a rare but characteristic finding. It is sometimes mistaken for arterio-venous malformation (AVM). The lesion has no arteriovenous shunting but may show adjacent cortical dysplasia, which can be subtle and asymptomatic. We present two cases, a 13-year-old girl and a 45-year-old man, who had unilateral dolichoectasia of the ACA and concurrent cortical dysplasia. A 13-year-old girl presented with recurrent right partial motor seizure and occasional headache for last one year. There was no history suggestive of head trauma, neurofibromatosis, connective tissue disorder, or homocystinuria. General physical examination and neurological examination were normal. Seizures were controlled on carbamazepine therapy. Brain MRI showed focal cortical dysplasia in the left frontal lobe. There was presence of thickened cortex appearing isointense to rest of the cortex and altered signal intensity in subcortical white matter appearing hypointense on T1W images [Figure 1a] and hyperintense on T2W [Figure 1b] suggestive of cortical dysplasia. The prominent flow void noticed on T2W images in the left frontal parasagittal region adjacent to cortical dysplasia was suggestive of ectasia of left ACA [Figure 1b]. Cerebral digital subtraction angiography (DSA) showed a tortuous, fusiform left pericallosal artery [Figure 2a]. Superselective angiogram of pericallosal artery [Figure 2b] showed absence of arteriovenous shunting. Right ACA and the remaining intracranial vessels appeared entirely normal.Figure 1: Brain MRI shows focal cortical dysplasia in the left frontal lobe. There was presence of thickened cortex appearing isointense to rest of cortex. It shows altered signal intensity in subcortical white matter appearing hypointense (down arrow) on T1W images (a) and hyperintense (down arrow) on T2W (b) suggestive of cortical dysplasia. The prominent flow void noticed on T2W images in the left frontal parasagittal region adjacent to cortical dysplasia (side arrow) is suggestive of ectasia of left ACA (b)Figure 2: Cerebral DSA shows tortuous, fusiform left pericallosal artery (a). Superselective angiogram of pericallosal artery (b) shows absence of arteriovenous shuntingA 40-year-old male had occasional right partial sensory seizures with secondary generalization for last three months. There were no comorbidities. Neurological examination was normal. Laboratory tests were unremarkable. He was treated with oxcarbazepine and seizures were controlled. Brain MRI showed focal cortical dysplasia in the right parietal lobe appearing hyperintense on T2W images and the prominent flow void adjacent to cortical dysplasia suggestive of ectasia of right ACA [Figure 3]. Cerebral DSA showed tortuous, fusiform right ACA (A1 and A2)/pericallosal artery, without arteriovenous shunting [Figure 4]. Left ACA and other intracranial arteries were normal. Informed consent was taken from both patients.Figure 3: Brain MRI shows focal cortical dysplasia in the right parietal lobe appearing hyperintense on T2W images (down arrows). The prominent flow void is noticed adjacent to cortical dysplasia suggestive of ectasia of right ACA (side arrow)Figure 4: Cerebral DSA shows tortuous, fusiform right ACA, A1 and A2/Pericallosal artery (a and b), without any arteriovenous shunting (b)Dolichoectasia is an arterial disease causing dilatation and/or tortuosity of the affected vessel. The prevalence of dolichoectasia increases with age and can be associated with other traditional cardiovascular risk factors.[1-3] Multiple pathophysiological processes lead to the development of dolichoectatic vessels. Activation of metalloproteinases and turbulent blood flow seem to cause irreversible disruption of the internal elastic lamina with subsequent weakness and deformation of the arterial wall. Histologically, the media demonstrates areas of smooth muscle atrophy and replacement with fibrous tissue showing hyaline changes, whereas the intima is concentrically thickened. Dolichoectasia of the intracranial arteries is rare and most frequently affects the vertebrobasilar system followed by the internal carotid artery.[4] There are isolated case reports of pure arterial malformations defined as dilated and tortuous coil-like dolichoectatic arteries without any associated venous component. These lesions can affect any of the intracranial arteries.[5,6] Dolichoectasia of the anterior circulation has been associated with seizures,[7,8] headache,[8] visual field defects,[9] and dementia with hydrocephalus.[10] Both congenital and acquired causes have been suggested for this condition. In reviewing their own cases and the literature, Araki et al.[11] concluded that there are two distinct causes of arterial ectasia, namely arteriosclerosis and congenital malformations. In the arteriosclerosis group, ectasia appears in adults generally over 40 years of age, more frequently male, and involves the proximal vertebrobasilar and carotid arteries. In the congenital group, affected persons are under 40 years of age, of either sex, and more frequently involve distal branches of cerebral arteries. Evidence for a congenital origin of dolichoectasia lies in the occurrence of the condition in children and young adults in the absence of other potential predisposing health problems. Our cases of dolichoectasia were most likely congenital in origin as the age of patients were 13 years and 40 years without any vascular risk factors and involvement of distal branches of cerebral arteries. In addition, the thickened cortex adjacent to dolichoectasia suggests a migrational abnormality, which provides additional evidence for a developmental cause. There are few case reports of anterior cerebral artery dolichoectasia associated with adjacent cortical dysplasia. Usually, they are bilateral, but there can be a spectrum of findings. They may be unilateral or short segment dolichoectasia. The etiology is unknown; it may be a part of “pure arterial vascular anomalies.”[5,6] Brinjikji et al.[5] reported a series of 12 patients with pure arterial malformations. In three of these cases, pure arterial malformation involved the anterior cerebral arteries (25.0%). In one patient, malformation of cortical development with an associated mildly dilated coil-like distal ACA branch was noticed. She was a 47-year-old woman with a history of thunderclap headaches. Doran et al.[12] reported a case of dolichoectasia of both anterior cerebral arteries extending distally to involve the pericallosal and calloso-marginal branches associated with neuronal migrational anomaly in a 14-year-old girl. Even though it is rare, based on the previously available literature and our cases, we can classify ACA dolichoectasia into two types: unilateral ACA dolichoectasia and bilateral ACA dolichoectasia. They can be further subdivided into (A) short-segment dolichoectasia involving a small segment of ACA and (B) long-segment dolichoectasia involving the whole of ACA. Our cases can be categorized as 1B group as both had unilateral long-segment dolichoectasia of ACA. Concurrent cortical thickening adjacent to ACA dolichoectasia suggests either a neuronal migrational abnormality or secondary changes attributable to vascular insufficiency.[12] Our patients presented with partial seizures likely due to cortical dysplasia. Anterior cerebral artery dolichoectasia has a characteristic appearance. It should not be mistaken for an arteriovenous malformation. If unsure, cerebral DSA should be done to resolve the dilemma. ACA dolichoectasia may be associated with adjacent cortical dysplasia. Thus, it is important to keenly look for it in the MRI brain as it can be a subtle finding. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.