Medullary streaks: Dilated medullary vessels in chronic ischemia in children

Abstract

Medullary streaks are linear structures on MRI crossing the white matter of the brain, which can be observed in aging brain or patients with moyamoya disease. 1 The increases in medullary streak diameter that accompany advancing age coincide with, and are thought to represent, age-related enlargement of fluid-filled perivascular spaces that have been shown by histology to accompany senile brain atrophy. 2 On the other hand, medullary streaks in moyamoya disease are speculatively considered to represent compensatorily dilated medullary vessels rather than the perivascular spaces. 1 In this report, we demonstrate contrast enhancement of the medullary streaks in two patients with severe chronic cerebral ischemia (advanced moyamoya disease and progeria syndrome), which supports this hypothesis. We also propose that the medullary streaks and the ivy sign (leptomeningeal enhancement on postcontrast T1-weighted images or hyperintensity on fluidattenuated inversion recovery [FLAIR] images) 3 in ischemic conditions have the same pathogenesis: compensatorily dilated medullary and pial vessels.Case reports. Case 1. A 9-year-old girl with transient alternating monoparesis several times a year for 6 years was referred to our hospital. On admission, her neurologic examination was unremarkable except for bilateral extensor plantar responses. FLAIR images (figure, A) revealed prominent medullary streaks. Postcontrast spin-echo T1-weighted images (figure, B) demonstrated enhancement of the medullary streaks and the ivy sign. Conventional angiography revealed bilateral stage 4 moyamoya disease. Subsequent studies after successful encephalo-duroarterio-synangiosis showed disappearance of medullary streaks on FLAIR images (figure, C).Case 2. An 8-year-old girl with the diagnosis of progeria syndrome (Hutchinson-Gilford syndrome) presented with transient paresthesias in her right extremities. Her neurologic examination on admission was unremarkable except for bilateral increased deep tendon reflexes and extensor plantar responses.Diffusion-weighted imaging revealed acute infarctions in the left frontal watershed region and in the right deep white matter. MR angiography revealed occlusion or severe stenosis of both internal carotid arteries, probably due to atherosclerosis associated with progeria syndrome. T2-weighted images 2 months after the onset of symptoms revealed medullary streaks, in addition to infarctions in the white matter. Postcontrast T1-weighted images (figure, D) demonstrated enhancement of the medullary streaks and the ivy sign.Discussion. Our findings support the concept that the imaging finding of medullary streaks may represent either dilated perivascular spaces or dilated medullary vessels. Perivascular spaces typically do not enhance after contrast administration unless the blood-brain barrier has been disrupted, as in patients with lymphoma or neurosarcoidosis due to infiltration of lymphoma cells or granulomatous leptomeningitis into the perivascular spaces. 4 However, such infiltration was unlikely in the pre...

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

“…Takanashi et al speculated, based on the findings of postoperative normalization, that medullary streaks are related to ischemia, which is attributable to the dilation of medullary arteries acting as collateral flow. 34 Harada et al concurred, as their data showed a postoperative decrease in the medullary streak diameter. 11 The paraventricular anastomosis should be associated either directly or indirectly with the appearance of the HMSF.…”

“…21 Basically, medullary streaks were observed as hypersignals on T2-weighted imaging, though they were recognized as hypersignals on FLAIR imaging in some pediatric patients with moyamoya disease. 34 In previous reports, these HMSF were considered an extension of the ivy sign. 16,20,31,38 Pathophysiology of HMSF Given our results, we suggest that the HMSF could be caused by at least 3 possible factors, the first of which is associated with vasculature.…”

“…15,24,36 In some pediatric cases, the linear hyperintensity on FLAIR imaging extends to the perivascular space of the deep white matter, 16,20,31,38 is referred to as "medullary streaks," and is considered to be associated with changes in vasculature. 34 The aim of this study was to investigate the characteristics of medullary streaks on FLAIR imaging in pediatric moyamoya disease and to explore the pathophysiology of the findings.…”

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.…”

Deep Medullary Vein Involvement in Neonates with Brain Damage: An MR Imaging Study

“…12,13 In these conditions, the observed DMVs are dilated. Some pediatric cases of SturgeWeber syndrome and chronic ischemia with DMV alterations have been reported, 14,15 but little information is available about the involvement of the DMV in neonates. 16,17 In this study, the patients' anatomic distributions of WM lesions along with their ventricularly converging wedgeshaped appearance make us hypothesize that these linear alterations represent pathologic DMVs.…”