Role of Radiological Parameters in Predicting Overall Shunt Outcome After Ventriculoperitoneal Shunt Insertion in Pediatric Patients With Obstructive Hydrocephalus

Devi Prasad Patra, MD, MCh; Shyamal C. Bir, MD, PhD; Tanmoy K. Maiti, MD, MCh; Piyush Kalakoti, MD; Hugo Cuellar, MD, PhD; Bharat Guthikonda, MD; Hai Sun, MD, PhD; Christina Notarianni, MD; Anil Nanda, MD, MPH

Disclosures

Neurosurg Focus. 2016;41(5):e4 

In This Article

Results

A total of 273 patients were treated for pediatric hydrocephalus at our institute between January 2004 and January 2016. Of this total, 172 patients had obstructive hydrocephalus from various etiologies. Forty-seven patients were excluded because comparative radiological studies were unavailable, and 4 patients were excluded for inadequate clinical data; thus, 121 patients were included in our analysis. Demographics on the patients and their outcomes have been listed in Table 2. All patients underwent VP shunt placement as the primary procedure. Postoperative CT or MRI studies were available at various intervals (median interval 5 days, range 1–60 days, approximately 90% of the scans had been obtained within 1 month). Postoperative indices were calculated, including the critical frontooccipital horn ratio (FOHR). Reduction of the FOHR was calculated as a percentage of the initial FOHR (Table 1).

Factors Affecting Shunt Revision

Nearly half of the patients (47.9%) required shunt revision. The presence of PVL on the preoperative images was significantly associated with lower revision rates in the univariate analysis (39.4% vs 58.2% in the presence or absence of PVL, respectively, p = 0.03), though it failed to reach a significant level in the multivariate analysis (p = 0.11; Table 3). Triventricular and symmetric ventricular enlargements more commonly led to shunt revision, though the difference was not statistically significant (p = 0.19 and 0.059, respectively). There was no significant difference between shunt revision rates among the different etiologies (p = 0.09). Similarly, the type of shunt did not show any influence on shunt revision rates (p = 0.33). None of the preoperative radiological indices or ratios showed any correlation with subsequent shunt revision in both univariate and multivariate analyses (Table 4). The postoperative reductions of FOHR were found to be similar in patients with or without shunt revision (13% vs 12.1% respectively, p = 0.39).

Factors Affecting the Shunt Revision Interval

The median interval to the first shunt revision from the primary surgery was 99.5 days (range 12 days–7.7 years, approximately 90% of revisions occurred within 2 years). The shunt revision interval was stratified into 2 groups: early revision (within 90 days) or late revision (after 90 days). Nearly half of the patients with shunt revision required early revision. None of the factors such as etiology, bi- or triventricular dilation, ventricular symmetry, presence of PVL, or shunt type significantly affected the shunt revision interval (Table 3). Interestingly, preoperative FOHR had a significant association with the shunt revision interval (mean FOHR 0.58 in patients with early shunt revision vs 0.53 in those with late shunt revision, p = 0.049; Table 5). However, the parameter with the most significant association with the shunt revision interval was the reduction in FOHR (20.16% in patients with early shunt revision vs 6.4% in patients with late shunt revision, p = 0.009). This significant difference held true in the multivariate analysis too (p = 0.037).

Factors Affecting the Frequency of Shunt Revision

Nearly half of the patients (48.3%) requiring shunt revision ultimately needed more than one revision procedure (Table 1). Preoperative OHI and FOIR had significant associations with shunt revision frequency (p = 0.029 and 0.009, respectively) in the univariate analysis but not in the multivariate analysis (p = 0.38 and 0.095, respectively; Table 6). The mean preoperative OHI in those patients requiring a single shunt revision was 0.73, compared with 0.65 in patients with multiple shunt revisions. In contrast, the mean FOIR value was lower (0.74) in patients with a single shunt revision as compared with that in patients with multiple revisions (0.84). Other factors did not have any significant association with shunt revision frequency (Table 3).

Factors Affecting Shunt Revision–Free Survival

The mean follow-up was 49.9 months (range 1–144 months). Age was a significant factor affecting shunt revision–free survival (Fig. 2). Patients younger than 6 months had significantly less revision-free survival than the patients who were older than 6 months (median survival 10.1 vs 94.1 months, p = 0.004). Similarly, other factors associated with increased revision-free survival were biventriculomegaly, asymmetrical ventriculomegaly, and the presence of PVL on preoperative images; however, the differences were not statistically significant (p = 0.27, 0.11, 0.15, respectively).

Figure 2.

Kaplan-Meier curves showing differences in revision-free survival in different groups based on age (A), presence of PVL (B), bi- or triventriculomegaly (C), and ventricular symmetry (D).

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