A new editorial from Linda de Vries, (de Vries LS, Brouwer AJ, Groenendaal F: Posthaemorrhagic ventricular dilatation: When should we intervene? Archives of Disease in Childhood – Fetal and Neonatal Edition 2013.) comments on an article which has been available on-line for a couple of months. The title poses a question that many of us have struggled with. I have reviewed the data from the CNN, (and am trying to find time to write the article) which shows huge variation in the proportion of babies in different NICUs with hydrocephalus who get shunted. The article that triggered the new editorial was a study of neurophysiological recordings (flash evoked visual potentials and amplitude integrated EEG), in infants who were developing PHVD (Klebermass-Schrehof K, Rona Z, Waldhor T, Czaba C, Beke A, Weninger M, Olischar M: Can neurophysiological assessment improve timing of intervention in posthaemorrhagic ventricular dilatation? Archives of Disease in Childhood – Fetal and Neonatal Edition 2012.)
That article showed, in 17 cases of very preterm infants who had PVHD which had reached the 97th percentile, that wave latencies on the evoked potentials and aEEG suppression were both increased. When the infants had shunts inserted these features returned to normal.
The standard indication (as I noted above there is no real standardization here) is to intervene when the ventricular width is more than 4 mm above the 97th percentile, this threshold arose somewhat arbitrarily in the 1980’s, and provides a benchmark against which to compare other approaches. Ten of the patients in this new study were below that cut off, yet still showed the neurophysiologic changes, with the evoked potential changes being more reliably affected.
Dr de Vries editorial was written to address the specific issues in the Klebermass article, she notes that they have not consistently found the same aEEG changes in her unit, but that they have noted prolongation of the visual evoked potential wave latencies.
A recent more complete review article by Andy Whitelaw (Whitelaw A, Aquilina K: Management of posthaemorrhagic ventricular dilatation. Archives of Disease in Childhood – Fetal and Neonatal Edition 2012, 97(3):F229-F223.) addressed many other issues. One of which was to note that clinical signs of intracranial hypertension may be absent even when the intraventricular pressure is raised, and that other measures such as doppler resistance index calculation may be preferable.
We will hopefully soon have better information on which to base our interventions, the European study called ELVIS (early versus late ventricular intervention study) is an RCT comparing intervention at the standard threshold that I have described (which is the ‘late arm) to intervention once the ventricles are over the 97th percentile. Until those results are in it looks like visual evoked potentials may give us some idea of which babies have cerebral dysfunction from their PVHD.