Pathophysiological consideration of medullary streaks on FLAIR imaging in pediatric moyamoya disease

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Medullary streaks detected on fluid-attenuated inversion recovery (FLAIR) imaging have been considered to be reflected ischemic regions in pediatric moyamoya disease. The purpose of this study was to evaluate these medullary streaks both clinically and radiologically and to discuss associated pathophysiological concerns.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>The authors retrospectively reviewed data from 14 consecutive pediatric patients with moyamoya disease treated between April 2009 and June 2016. Clinical and radiological features and postoperative imaging changes were analyzed. In 4 patients, hyperintense medullary streaks on FLAIR imaging (HMSF) at the level of the centrum semiovale were detected.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>The HMSF were coincident with hyperintense medullary streaks on a T2-weighted image, though they were not completely coincident with the vasculature on either a T2*-weighted image or contrast-enhanced CT. Analysis revealed significantly higher values in terms of MR angiography scores, number of flow voids of the basal ganglia, and the presence of the medullary artery in the group with HMSF than in those without. In contrast, the presence of white matter damage was significantly less frequent in the HMSF group. All HMSF disappeared after surgery, and the mean apparent diffusion coefficient at the same level was significantly reduced postoperatively.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Although HMSF should be associated with collateral circulation in moyamoya disease, other factors may be involved, including stagnated cerebrospinal fluid or vasogenic edema that is relevant to the impaired state of the white matter. Findings in this study provide insight into the pathophysiological basis of the perivascular space in moyamoya disease.</jats:p></jats:sec>

Prevalence of and risk factors for enlarged perivascular spaces in adult patients with moyamoya disease

“…However, this is not true in pediatric cases with moyamoya disease, which can exhibit linear hyperintensities that extend into the perivascular space of the deep white matter in FLAIR imaging [ 39 ]. These linear hyperintensities, which have been called medullary streaks, are thought to be associated with vasculature [ 40 ] or might result in a stagnation of cerebrospinal fluid of the perivascular spaces [ 41 ]. Because of this difference in adult and pediatric patients with moyamoya disease, pediatric patients were not included in this study.…”

Atypical postoperative radiographical findings in a patient with moyamoya disease: A case report

“…Revascularization surgery for improving a patient's hemodynamics can prevent the development of strokes, but is known to be associated with perioperative cerebral infarction and cerebral hyperperfusion causing transient neurological deterioration, delayed intracerebral hemorrhage, and vasogenic edema. [1], [2], [3], [4], [5], [6], [7] In this case, radiologic examination revealed no ischemic lesion on POD 1, but within 3 days, abnormal intensity changes were noted throughout the cortical and subcortical regions.…”

Contemporary and emerging magnetic resonance imaging methods for evaluation of moyamoya disease

“…The utility of the T2 FLAIR sequence for the assessment of MMD has been extensively investigated. 21,22,28,43,48,63 The "ivy sign," an indicator of slow or retrograde flow in cortical vessels, can help characterize the origins of collateral supply, correlates with cerebrovascular reactivity (CVR), and can improve in response to revascularization surgery, or it can temporarily worsen after revascularization in the setting of hyperperfusion. 21,28,48 In the cerebral white matter, linear T2 hyperintense streaks perpendicular to the lateral ventricle, referred to as "medullary streaks," have been described.…”

“…21,28,48 In the cerebral white matter, linear T2 hyperintense streaks perpendicular to the lateral ventricle, referred to as "medullary streaks," have been described. 63 The pathophysiology of medullary streaks is incompletely understood, but is thought to be associated with ischemia and these may represent collateral vasculature, increased CSF, and edema. 63 Additionally, Komatsu et al reported that T2 FLAIR can demonstrate areas of parenchymal white matter T2 hyperintensity that variably reverse after revascularization.…”

“…63 The pathophysiology of medullary streaks is incompletely understood, but is thought to be associated with ischemia and these may represent collateral vasculature, increased CSF, and edema. 63 Additionally, Komatsu et al reported that T2 FLAIR can demonstrate areas of parenchymal white matter T2 hyperintensity that variably reverse after revascularization. 35 The appearance of T2 FLAIR images depends on the precise technique.…”