20.2.1 Endoscope-Assisted Ventricular Catheter Placement

Techniques aimed at reducing the rate of proximal shunt obstruction include placement of the ventricular catheter tip away from the choroid plexus and ependymal wall and the use of neuronavigation for ventricular catheter placement.9,10,11 Moreover, reports have shown that endoscope-assisted ventricular catheter placement reduces the rate of proximal obstruction.12,13,14 The main indication for endoscope-assisted ventricular catheter placement has been in the setting of multiloculated hydrocephalus, where the endoscope is used to fenestrate and establish communication between isolated CSF compartments.15,16,17

However, in a landmark prospective well-controlled study, routine endoscope-guided placement of ventricular catheters did not seem to decrease the rate of shunt failure or proximal shunt malfunction over other techniques.1 Similarly, selective use of endoscopy for ventricular catheter placement improved accuracy but did not seem to reduce the rate of proximal malfunction.18 Other limitations of endoscope-assisted ventricular catheter placement are its cost, prohibiting widespread application; possible additional set-up time for each procedure; increased risk of infection with the introduction of more hardware onto the operative field; and the need for specialized trained personnel to assist in this procedure.

20.2.2 Endoscopy and Shunt Obstruction

For over 25 years, endoscopic third ventriculostomy (ETV) has been the primary alternative to shunting procedures in the treatment of hydrocephalus. Today, ETV is the procedure of first choice for patients with aqueductal stenosis and obstructive hydrocephalus. Indications for ETV are constantly being reviewed, revised, and expanded, driven by the ease of the procedure, the more physiologic solution to hydropcephalus, the relatively high success rates, and the opportunity to avoid shunt hardware placement.19

Further advantages of ETV compared with VP shunt placement (or revision) (Video 20.1) are decreased infection rates (0–2% versus 5–10%2,20,21,22,23), avoidance of shunt-specific complications such as slit-ventricle syndrome and CSF overdrainage, and ability to treat hydrocephalus in the setting of abdominal malabsorption of CSF.24

Subsequently, the usage of ETV for shunt malfunction has been gaining popularity, with proven outcomes19,20,25,26 (Table 20.1). Bilginer et al19 report the overall success rate for ETV after shunt malfunction was 80% in a series of 45 patients shunted as infants for a variety of etiologies—aqueductal stenosis, neonatal meningitis, tumor, intraventricular hemorrhage (IVH) of prematurity, myelomeningocele, and trauma. When the authors analyzed the subgroup of patients with aqueductal stenosis, the success rate of ETV after shunt malfunction improved to 85.7%. Cinalli et al reported a 90% success rate for this cohort of patients in their series.5

Siomin et al27 published a success rate of 64.3% for patients with a history of infection, and 60.9% for patients with intraventicular hemorrhage (IVH) in a multicentered study. In patients with a history of hemorrhage, the multivariate analysis revealed that a history of VP shunt placement before ETV was a positive predictive factor for ETV success (OR 18.139, p = 0.01). O’Brien et al20 demonstrated 75% and 71% success rate for the infection and IVH groups, respectively. Bilginer et al19 showed a 77.8% success rate for the infection group and 100% for the IVH group.

The possible complications of ETV should not be underestimated when performing it for shunt malfunction or infection. In acute ventricular dilation secondary to an obstructed shunt, the third ventricular floor is often distorted and thicker than that seen in chronically dilated hydrocephalus. This results in poor visibility of the critical neurovascular structures of the interpeduncular cistern, particularly the apex of the basilar artery, and a greater risk of potentially fatal arterial injury.5 Also ventricular enlargement in patients at the time of shunt malfunction is often smaller than in patients with newly diagnosed obstructive hydrocephalus.28 Hypothalamic dysfunction and cranial nerve injury are exclusive to ETV as a CSF diversion procedure.

Hader et al28 reported the outcomes of 131 patients who underwent ETV as a primary procedure or at the time of shunt malfunction. Despite a high success rate in both groups, serious complications after ETV occurred more frequently in patients who presented at the time of shunt malfunction (14 of 45, 31%) compared with patients undergoing primary ETV (7 of 86, 8%) (p = 0.02). Previously shunted patients with a history of two or more revisions (p = 0.03) and those who had a serious complication such as meningitis at the time of ETV (p = 0.01) were more likely to require shunt replacement.

20.2.3 Endoscopy and Shunt Infection

Infection of a VP shunt has been recognized as one of the most serious (and morbid) problems for patients with hydrocephalus, especially in the pediatric population.29,30,31 However, a standardized strategy for managing an infected VP shunt has not been established.32 Part of the management strategy may include eradication of the infection, control of the hydrocephalus, and the insertion of a new shunt system. Unfortunately, several studies have reported a high rate of reinfection—14.8 to 26%—of newly inserted shunt systems.29,33,34 Because complete removal of the shunt system results in a better prognosis,34 performing an ETV for the patient’s hydrocephalus during infected shunt removal may be a reasonable option. A VP shunt infection usually does not lead to communicating hydrocephalus, as in neonatal meningitis. The pre-existence of a functioning shunt in patients with shunt infections may lead to secondary aqueductal stenosis. This scenario makes the likelihood of ETV success greater after removal of the infected shunt.20

Shimizu et al32 analyzed 45 children with shunt infection who underwent either shunt reinsertion (27.8% reinfection rate) or ETV at the time of infected shunt removal (11.1% reinfection rate). The authors conclude that there is a small preventive effect of ETV against CSF reinfection.