Catheter angiogram in central nervous system vasculitis: still first among equals

Central nervous system (CNS) vasculitis is an inflammatory disorder with devastating morbidity. It occurs as a primary disorder limited to the CNS (childhood primary angiitis of the nervous system [cPACNS]) or secondary to systemic inflammatory disease, infection, drug exposure, and various other causes. The diagnosis of CNS vasculitis is challenging, with lack of consensus on diagnostic criteria. In the past, the criterion standard for diagnosis was brain or leptomeningeal biopsy that revealed histopathological features of angiitis in the setting of characteristic clinical features. Biopsy, however, is invasive and even when performed optimally may result in a false negative result due to the patchy nature of CNS vasculitis. Four vessel angiography or conventional angiogram has been suggested as the diagnostic modalities of choice to be used in place of biopsy. Clinical features such as headache and acquired neurological deficits combined with multifocal brain parenchymal lesions seen on brain magnetic resonance imaging (MRI) in association with typical angiographic findings on conventional angiogram have been used for diagnosis. Magnetic resonance angiography (MRA) is also useful, as it is less invasive and does not expose the child to radiation. Eleftheriou et al. report the results of MRA and conventional angiogram in a series of children with cerebral infarction secondary to suspected CNS vasculitis. They found that the sensitivity and specificity of MRA compared with conventional angiogram was 63% and 89% respectively, with most false negatives involving the posterior circulation. As MRA is typically performed before conventional angiogram, disease progression may account for the greater number of lesions seen by conventional angiogram compared with MRA. Nevertheless, the preponderance of posterior circulation lesions identified only by conventional angiogram suggests that disease progression does not account for differences in detection of vasculitic lesions. Thus, although MRA has been used increasingly to investigate childhood cerebral vasculopathies, conventional angiogram still has a role in suspected CNS vasculitis. The current report expands the findings of Aviv et al. who reviewed MRI and MRA findings in children diagnosed with cPACNS based on clinical and laboratory presentation and conventional angiogram. They found that MRI was abnormal in all cases and that the most common pattern of location for MRA abnormalities was the proximal, anterior circulation in association with multifocal parenchymal lesions on MRI within the lenticulostriate distribution. Left untreated, CNS vasculitis causes a devastating neurological disease. Treatment with potent immunosuppressive agents has significant side effects. Optimal treatment of children with CNS vasculitis requires timely and accurate diagnosis and the ability to follow disease progression radiographically as well as clinically. The study by Eleftheriou et al. is a valuable addition to our understanding of CNS vasculitis. It confirms the importance of conventional angiogram in the diagnosis of CNS vasculitis in childhood. In a child with the clinical features of CNS vasculitis and brain lesions on MRI, MRA is an appropriate initial investigation. But if MRA is not diagnostic and clinical suspicion persists, conventional angiogram is the next step, despite concerns about procedural risk and radiation exposure. Finally, both MRA and conventional angiogram fail to detect some cases of CNS vasculitis, particularly small vessel vasculitis. In these patients, brain and leptomeningeal biopsies still play a role.