Of the four known cases, only this one illustrates the double origin PICA’s potential for right-sidedness. The double origin PICA should not be confused with the common anterior inferior cerebellar artery-PICA configuration that Icardo et al ( 11) refer to as “duplication in the origin” of the PICA. The rostral component of the double origin is the PICA proper, which derives embryologically from a hypertrophied radiculopial artery. Originating lateral to the medulla, the lateral spinal artery, which forms the caudal component of the double origin PICA, typically arises from either the PICA or the intradural VA. The double origin PICA represents a persistent anastomosis of the normal lateral spinal artery ( 1). On the contrary, other vascular curiosities such as the duplicated basilar artery are exceedingly rare ( 10). These variants, including the duplicated or anomalous posterior cerebral arterial origin of the superior cerebellar artery, present daily in the catheter laboratory. In this unique case, the fenestration was located on the anterior medullary segment of the PICA in a patient with nonaneurysmal subarachnoid hemorrhage.Īnomalous and duplicated intracranial arteries are frequently revealed by angiography. Of interest, only one instance of PICA fenestration has been reported ( 9). The incidence of basilar artery fenestration ranges from 0.04% to 6% ( 5– 7), whereas VA fenestrations are found in 0.3% to 2% of the population ( 6, 8). Nevertheless, based on autopsy and angiography series, cerebral arterial fenestration occurs more commonly in the vertebral and basilar arteries than in the middle cerebral, anterior cerebral, and internal carotid arteries ( 5, 6). The incidence rate of fenestration is, in general, greater at postmortem examination than at angiographic examination ( 4, 5). Duplication, on the other hand, requires two distinct arteries with separate origins and no distal arterial convergence. Fenestration or “partial duplication” is defined as a division of a vessel lumen, resulting in two distinct endothelium-lined channels that may or may not share an adventitial layer ( 4, 5). The double origin PICA might appear to represent, at least initially, a hybrid of all three.įenestration and duplication are terms that are frequently but mistakenly used interchangeably in the literature ( 3). The most recognizable oddities include the fenestrated, duplicated, and anomalous origin arteries. Before a complete workup could be performed, the patient left the hospital against medical advice and was subsequently lost to follow-up.ĭevelopmental variations of the cerebral vasculature are familiar findings in the angiography suite. With the exception of cervical carotid atherosclerosis, the remaining angiographic findings were normal. The right PICA was clearly identified as a double origin variant in that both the distal and proximal PICA component vessels originated from the right V4 segment and fused at the midportion of the anterior medullary PICA segment ( Fig 1A and B). Standard biplane digital subtraction angiography of the bilateral VA and carotid arteries showed a dominant left VA with faint reflux into the distal aspect of a hypoplastic right VA ( Fig 1C). As a result, cerebral conventional angiography was performed to exclude vasculitis as a cause of seizures. Cerebral MR angiography showed major vessel patency, but the peripheral cerebral vasculature detail was limited. Mediastinal lymphadenopathy and a 2-cm right lung mass were also discovered with the use of CT. Diffuse periventricular leukoencephalopathy was shown by cranial CT. Blood cultures and lumbar puncture CSF evaluation were negative. Left-sided pulmonary crackles were heard on auscultation. Neurologic evaluation revealed left blepharospasm, upper extremity rigidity greater on the right side, bilateral lower extremity weakness, and generalized absent deep tendon reflexes. Physical examination revealed an awake but intermittently attentive elderly gentleman. A 66-year-old right-handed Caucasian man with emphysema and a medical history of paraplegia secondary to remote motor vehicle accident presented with new onset seizures.
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