Numerous neuroimaging studies describe the presence of brain lesions in the preterm infant, using cranial ultrasound (cUS) and/or term equivalent age MRI (TEA-MRI). These studies however focus on germinal matrix-intraventricular hemorrhage (GMH-IVH) and white matter injury. Studies regarding perinatal arterial ischemic stroke (PAIS) or cerebral sinovenous thrombosis (CSVT) in the preterm infant are very limited. Several large cohort studies on neuro-imaging in preterm infants do not mention neonatal stroke. The majority of the studies about PAIS exclude preterm infants. Thus a recent study provides an update on neonatal stroke in the preterm infant, with a focus on neuroimaging findings.
Perinatal arterial ischemic stroke-
These centrally located infarcts become apparent after the first postnatal week. They are typically wedge-shaped and mostly do not involve the posterior limb of the internal capsule (PLIC). ‘Cortical sparing’ can be seen in the preterm infant either partial or complete, with complete sparing seen only in infants with a GA<32 weeks and partial sparing in infants with a GA of 33–37 weeks.
Periventricular hemorrhagic infarction
GMH-IVH can convert to PVHI due to impaired venous drainage of the medullary veins into the terminal vein. The area of echogenicity can be globular and continuous with the lateral ventricle and may spread over several lobes, even causing a midline shift. A sagittal plane view can describe the involvement of the trigone. Follow-up scans can reveal the globular lesion evolving into a single cyst communicating with the lateral ventricle (porencephaly) while a triangular-shaped lesion developing multiple cysts which are often not or partly communicating with the lateral ventricle and therefore misdiagnosed as c-PVL.
Neonatal cerebral sinovenous thrombosis Neuroimaging
Neonatal CSVT frequently involves the superficial venous system and can also show thrombosis of multiple sinuses of both the superficial and deep venous system.
Preterm infants often have extensive white matter injury that resembles that of periventricular leukomalacia, which may develop into extensive white matter cysts. This often presents beyond the immediate neonatal period and emerges in combination with late-onset IVH. Thus considering the diagnosis of CSVT in a preterm infant presenting with late-onset white matter injury and unexpected late-onset IVH is important.
Using Color Doppler cUS can demonstrate partial or a total absence of flow in combination with partial or complete occlusion of the affected sinus(es). Also, cUS can show associated brain lesions in the form of (late-onset) IVH and white matter injury.
Magnetic resonance imaging
Since the symptoms of neonatal CSVT can be non-specific, MR venography (MRV) should also be included in all infants who undergo MRI because of seizures and/or an unusual presentation of (late-onset) IVH or white matter injury.
SOURCE- Steggerda SJ, de Vries LS. Neonatal stroke in premature neonates, Seminars in Perinatology, 2021;45(7). https://doi.org/10.1016/j.semperi.2021.151471.