FINAL DIAGNOSIS - THROMBOSIS OF INTERNAL CEREBRAL VEINS
Venous thrombosis is a clinically underrecognized cause of lethargy or coma as well as seizures in the neonatal period (1-3). The dural venous sinuses are most commonly affected (1, 3), but the internal (Galenic) venous system may also be involved - either in conjunction with the dural sinuses, or in isolation as in the present case. In some cases, neonatal cerebral venous thrombosis may have a favorable outcome with normal subsequent neurodevelopment (2), however a poor outcome is more likely when the internal venous system is involved (3).
The pathogenesis of perinatal cerebral venous thrombosis was discussed thoroughly by Ehlers and Courville in their classic article published in 1936 (3). They classified intracranial venous thrombosis into primary (marantic), secondary (infectious), and combined types, and reported that whereas thrombosis of the dural sinuses is most often secondary to a suppurative process such as meningitis, thrombosis of the internal venous system is usually of the primary or combined type. In infants, important factors associated with primary thrombosis of the internal cerebral veins include diarrhea, vomiting, and dehydration (3); any factors causing increased coagulability of the blood may also contribute.
The presence of hemorrhagic venous infarcts bilaterally in the deep hemispheres is characteristic of thrombosis of the internal cerebral venous system (3). In normal anatomy, blood from the deep structures drains via bilaterally paired internal cerebral veins into the unpaired midline vein of Galen, which in turn drains into the straight sinus. Thus, thrombosis of the vein of Galen or straight sinus leads to bilateral congestion of internal cerebral veins and retrograde spread of thrombosis, followed by hemorrhagic infarction. Thrombosis of the internal cerebral venous system should be considered in the differential diagnosis of neonatal intraventricular hemorrhage and periventricular leukomalacia, particularly when the infant is near term and has bilateral hemorrhagic lesions.
The present case illustrates a close correlation between the postmortem brain specimen and the pattern of lesions as seen by ultrasound exam. MRI methods that reveal the absence of blood flow are also useful for diagnosing intracranial venous thrombosis (2).
Contributed by Robert Hevner, MD and Raymond A. Sobel, MD