Role of radiological parameters in predicting overall shunt outcome after ventriculoperitoneal shunt insertion in pediatric patients with obstructive hydrocephalus

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Despite significant advances in the medical field and shunt technology, shunt malfunction remains a nightmare of pediatric neurosurgeons. In this setting, the ability to preoperatively predict the probability of shunt malfunction is quite compelling. The authors have compared the preoperative radiological findings in obstructive hydrocephalus and the subsequent clinical course of the patient to determine any association with overall shunt outcome.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>This retrospective study included all pediatric patients (age &lt; 18 years) who had undergone ventriculoperitoneal shunt insertion for obstructive hydrocephalus. Linear measurements were taken from pre- and postoperative CT or MRI studies to calculate different indices and ratios including Evans' index, frontal horn index (FHI), occipital horn index (OHI), frontooccipital horn ratio (FOHR), and frontooccipital horn index ratio (FOIR). Other morphological features such as bi- or triventriculomegaly, right-left ventricular symmetry, and periventricular lucency (PVL) were also noted. The primary clinical outcomes that were reviewed included the need for shunt revision, time interval to first shunt revision, frequency of shunt revisions, and revision-free survival.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>A total of 121 patients were eligible for the analysis. Nearly half of the patients (47.9%) required shunt revision. The presence of PVL was associated with lower revision rates than those in others (39.4% vs 58.2%, p = 0.03). None of the preoperative radiological indices or ratios showed any correlation with shunt revision. Nearly half of the patients with shunt revision required early revision (&lt; 90 days of primary surgery). The reduction in the FOHR was high in patients who required early shunt revision (20.16% in patients with early shunt revision vs 6.4% in patients with late shunt revision, p = 0.009). Nearly half of the patients (48.3%) requiring shunt revision ultimately needed more than one revision procedure. Greater occipital horn dilation on preoperative images was associated with a lower frequency of shunt revision, as dictated by a high OHI and a low FOIR in patients with a single shunt revision as compared with those in patients who required multiple shunt revisions (p = 0.029 and 0.009, respectively). The mean follow-up was 49.9 months. Age was a significant factor affecting shunt revision–free survival. Patients younger than 6 months of age had significantly less revision-free survival than the patients older than 6 months (median survival of 10.1 vs 94.1 months, p = 0.004).</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Preoperative radiological linear indices and ratios do not predict the likelihood of subsequent shunt malfunction. However, patients who required early shunt revision tended to have greater reductions in ventricular volumes on postoperative images. Therefore a greater reduction in ventricular volume is not actually desirable, and a ventricular volume high enough to reduce intracranial pressure is instead to be aimed at for long-term shunt compliance.</jats:p></jats:sec>

Overdrainage-related ependymal bands: a postulated cause of proximal shunt obstruction

“…40 Recent reports suggest that patients with greater reductions in ventricular volume tend to have a higher probability of shunt malfunction. 18,25 The endoscopic findings presented here provide further evidence of a link between imaging, catheter environment, and shunt obstruction. Specifically, we demonstrate that collapse of the ventricles and juxtaposition of the catheter surface to the ventricular wall correlate with partial or complete catheter obstruction.…”

MR Elastography demonstrates reduced white matter shear stiffness in early-onset hydrocephalus

“…Furthermore, we are not able to differentiate the numerous potential sources for this brain softening – possible candidates may be the initial insult to the brain at the time of the development of ventricular enlargement, the chronic effects of abnormal ventricular size or shunt functionality ( Del Bigio et al, 2003 ), or the pathophysiological changes known to manifest in hydrocephalus patients ( Zhang et al, 2017 , Del Bigio, 2010 , Del Bigio, 2004 , Del Bigio, 2001 , Williams et al, 2007 ). Numerous clinical studies have attempted to use ventricular size as a viable radiological marker to predict hydrocephalus severity, but the evidence to date as well as anecdotal observations from several groups indicates that ventricular size is in general a poor predictor of outcome ( Buxton et al, 1998 , Nikas et al, 2014 , Patra et al, 2016 , Kim et al, 2000 ). In contrast, Morales and colleagues have demonstrated that ventriculomegaly is correlated with changes in CSF biomarkers in patients with post-hemorrhagic hydrocephalus of prematurity ( Habiyaremye et al, 2017 , Limbrick et al, 2017 , Morales et al, 2017 ).…”

“…For the last twenty years, investigators have attempted to identify noninvasive biomarkers for gauging changes in the hydrocephalic brain as well as for guiding development of potential alternative therapies. Radiologically, the size of the lateral ventricles may not be directly or solely related to prognosis; it is well known, for example, that the ventricles will not always decrease in size following shunt surgery or ETV, even in the presence of marked clinical improvement, and may not always dilate with shunt failure ( Buxton et al, 1998 , Nikas et al, 2014 , Patra et al, 2016 , Kim et al, 2000 ). CSF flow imaging, and in particular pulsatility through the cerebral aqueduct, has received much attention although mostly in adult hydrocephalus, and even there, conclusions are mixed ( Luetmer et al, 2002 , Bradley et al, 1996 , Mouton Paradot et al, 2010 , Kahlon et al, 2007 ).…”

Frontal and occipital horn ratio is associated with multifocal intraparenchymal hemorrhages in neonatal shunted hydrocephalus

“…A recent retrospective analysis demonstrated that among children under 18 years of age the percentage of ∆FOR is correlated with a need for early shunt revision (within 90 days of placement), although the etiology of this proclivity for early shunt failure is unknown. 13 Changing the magnitude and rate of ventricular size change will require an intelligent paradigm for shunt valve selection. Measurement of ventricular opening pressure and compliance may prove useful in this regard, but the association between intracranial pressure and ventricular size and measurement indices is incompletely understood.…”