Elevated midline head positioning of extremely low birth weight infants: effects on cardiopulmonary function and the incidence of periventricular–intraventricular hemorrhage

Abstract

To the Editor: We would like to thank Dr. Viraraghavan for his interest in our study published in the Journal of Perinatology and his pertinent comments and questions. Your description of the close relationship between germinal matrix/intraventricular hemorrhage (GMH/IVH) and periventricular hemorrhagic venous infarction (PHVI) is consistent with previous studies noting: (1) that the vast majority of PHVI lesions are associated with a large asymmetrical GMH–IVH, (2) the PHVI lesions are generally on the same side as a large GMH/IVH, and (3) often the PHVI develops and progresses after the occurrence of the GMH/IVH [1]. Previous neuropathological studies have shown that PHVI is a hemorrhagic infarction of the white matter and not a simple extension of the GMH/IVH [2]. Taken together, these studies suggest that obstruction of the deep venous drainage of the periventricular white matter by the GMH/IVH leads to PHVI. Subsequent clinical studies using magnetic resonance imaging emphasize the findings of deep medullary vein engorgement, congestion, and thrombosis in infants with white matter injury [3]. The relationship between GMH/IVH and PHVI is certainly not an “all or none” phenomena, as not all large GMH/IVH lead to PHVI and the ultrasound features of PHVI can be quite variable not only in terms of size but also location (i.e., anterior, parietal, occipital, or temporal locations). This suggests that the site and degree of medullary venous obstruction can be variable as well. An important question, applicable to our study is, “can the venous congestion associated with moderate to severe GMH/IVH be mitigated or modified in some way to lessen the occurrence or severity of the venous infarction?” Although there is not a great deal of research to date looking at the physiological effects of altering head position on cerebral circulation, we were particularly interested in two studies from 1983 documenting significant changes in intracranial pressure associated with head position [4, 5]. A third study from that same year showed that simply compressing the jugular vein in the lower neck of a newborn resulted in a significant drop in blood flow velocity in the superior sagittal sinus [6]. If the results of our study hold up in future research, we feel the reduction in PHVI in infants maintained in an elevated midline position may be related to improved jugular venous return mitigating the congestive and obstructive effects of GMH/IVH on various portions of the deep medullary veins. Unfortunately, we did not systematically look for cerebellar hemorrhage in our study patients. In a review of our data, we found four cases of cerebellar hemorrhage ipsilateral to a PHVI in our FLAT group, and three cases ipsilateral to two PHVI and one Grade 3 IVH; however, lateral ultrasound views were not obtained on all study infants.