The MRI brain scans of 28 SIDS infants were compared with 14 controls at the Neuropathology Unit, University of Sydney, and the Department of Radiology, Royal Prince Alfred Hospital, New South Wales, Australia. The amount of myelin assessed by densitometer in 21 of 26 sites showed no changes in 15 sites, and a higher rate of myelination in 6 sites, but only in infants older than 8 months. No focal white matter abnormalities were detected. [1]

COMMENT. This MRI investigation failed to confirm the histopathological evidence of delayed myelination in SIDS victims reported from the University of Toronto [2]. See Progress in Pediatric Neurology I, 1991, pp309-310, for a review of mechanisms of SIDS. It was concluded that a central type of respiratory failure or cardiac dysrythmia was involved. A delayed development of the vagus nerve, similar to the finding in an infant with Ondine’s curse, was described in the Canadian study.

The Steering Committee of Collaborative Home Infant Monitoring Evaluation reports on a multi-center study aimed at correlating events in infants at increased risk for SIDS, including siblings of prior SIDS victims [3]. It concluded that siblings are at increased risk for SIDS, and monitoring is cost-effective in sibs of prior SIDS infants.

INTERLEUKIN-6 CSF LEVELS were increased in 20 infants dying of SIDS in a study reported from the Institute of Forensic Medicine, National Hospital, Oslo, Norway [4]. The authors suggest that immune activation plays a role in SIDS, and cytokines in the CNS may cause respiratory depression in vulnerable infants.

An increased postneonatal mortality in lower social groups was explained by an association with SIDS in a study from the Department of Epidemiology, National Institute of Public Health, Oslo, Norway. [5]

A series of articles and an editorial in a recent issue of JAMA address the roles of sleeping position and passive smoking and tobacco exposure through breast milk in the etiology of SIDS. A major factor relating to a decline in SIDS in Tasmania was a reduction in the prevalence of prone sleeping position of infants [6]. In contrast, routine prone sleeping position was not associated with an increased risk of SIDS in a Southern California study population [7]. Passive smoking in the same room as infants increased the risk for SIDS in a study at the University of California, San Diego [8]. An editorial by Willinger M [9] advises that caregivers should follow AAP recommendations, and parents should be counselled that back or side sleep position is one measure to protect their infant from SIDS, but it is not fool-proof.