Reconsidering Ventriculoperitoneal Shunt Surgery and Postoperative Shunt Valve Pressure Adjustment: Our Approaches Learned From Past Challenges and Failures

Treatment for idiopathic normal pressure hydrocephalus (iNPH) continues to develop. Although ventriculoperitoneal shunt surgery has a long history and is one of the most established neurosurgeries, in the 1970s, the improvement rate of iNPH triad symptoms was poor and the risks related to shunt implantation were high. This led experts to question the surgical indication for iNPH and, over the next 20 years, cerebrospinal fluid (CSF) shunt surgery for iNPH fell out of favor and was rarely performed. However, the development of programmable-pressure shunt valve devices has reduced the major complications associated with the CSF drainage volume and appears to have increased shunt effectiveness. In addition, the development of support devices for the placement of ventricular catheters including preoperative virtual simulation and navigation systems has increased the certainty of ventriculoperitoneal shunt surgery. Secure shunt implantation is the most important prognostic indicator, but ensuring optimal initial valve pressure is also important. Since over-drainage is most likely to occur in the month after shunting, it is generally believed that a high initial setting of shunt valve pressure is the safest option. However, this does not always result in sufficient improvement of the symptoms in the early period after shunting. In fact, evidence suggests that setting the optimal valve pressure early after shunting may cause symptoms to improve earlier. This leads to improved quality of life and better long-term independent living expectations. However, in iNPH patients, the remaining symptoms may worsen again after several years, even when there is initial improvement due to setting the optimal valve pressure early after shunting. Because of the possibility of insufficient CSF drainage, the valve pressure should be reduced by one step (2–4 cmH2O) after 6 months to a year after shunting to maximize symptom improvement. After the valve pressure is reduced, a head CT scan is advised a month later.

Neuromonitoring During Cardiac Surgery in a Patient with Ventriculo-Caval Shunt Migration: Case Report

Ventricular shunting is a well-recognised and commonly practiced method of reducing increased intracranial pressure in patients with neurologic pathology. There are possible complications related to shunt implantation, where the rarest is intracardiac migration of the distal shunt catheter. We present a case where the distal catheter migrated into the right ventricle, causing extrasystoles and was complicated with acute right ventricle failure during the endovascular shunt evacuation procedure.

Pioneer shunt implantation surgery in Brazil

One of the first experiences of shunt implantation in the world occurred in 1949, by Nulsen and Spitz, who implanted a rubber catheter with a ball valve system, from the lateral ventricle to the internal jugular vein [1]. In the 1950s, the shunt systems had great development, especially the Spitz-Holter system, first used in 1956, consisting of the first system produced on a large scale. The second patient who benefited from this new system was Holter's son Casey, who had myelomeningocele [2,3]. From these first American reports, the shunt surgery had great worldwide dissemination in the 1960s. One of the first CSF shunts in Brazil and Latin America occurred in 1966, in the city of Uberaba, Minas Gerais, by Prof. Francisco Mauro Guerra Terra, founder of the Chair of Neurosurgery at Triângulo Mineiro Medical School, today part of Federal University of Triângulo Mineiro (UFTM). The procedure was performed at the Children's Hospital of Uberaba, at the time one of University Hospitals, and the patient was a 7-month-old baby named Maria Beatriz. The child suffered from hydrocephalus, as a complication of tuberculous meningitis, and was diagnosed by pneumoventriculography, a procedure described by Dandy, and widely used in the era before tomography [4] (Fig. 1). The child was submitted to a ventriculo-atrial shunt (Figs. 2, 3 and 4), with implantation of a catheter without a valve, an option widely used at the time. Besides Prof. Guerra, the surgical team was composed by the then medical students Jaime Olavo Marquez, later titular of the Neurology Department of UFTM, Antônio Luiz da Costa Sobrinho, later a neurosurgeon, who later settled in Presidente Prudente, São Paulo, Brazil Carlos Antunes de Paula, also later a neurosurgeon, who settled in the city of Santos, São Paulo, Brazil and the anesthesiologist Dr. Newton Camargo Araújo, from Uberaba (Fig. 5). There is a postoperative image of the case, showing the success of the procedure (Fig. 6). The surgery had great repercussion in the national media at the time (Fig. 7).

A case of endophthalmitis following needling procedure after PRESERFLO® Micro Shunt implantation

Purpose: To report a case of endophthalmitis following bleb needling in a patient previously implanted with a PRESERFLO® MicroShunt. Methods: Case report. Results: A 40-year-old woman with bilateral malformative glaucoma repeatedly operated on in childhood underwent PRESERFLO® MicroShunt implantation in her right eye and six needling revisions (NRs) and a surgical revision due to unsatisfactory intraocular pressure (IOP) control due to bleb encapsulation. About 3 months after the surgical revision the bleb encapsulation relapsed and she underwent a further NR with betamethasone. About 4 days after the last NR, she experienced visual acuity reduction and was therefore advised to come immediately to the hospital for an unscheduled visit, showing up with hypopyon and diffuse vitreous haze. A clinical diagnosis of endophthalmitis (later confirmed by bacteria culture tests) was made and she was treated with pars-plana vitrectomy with silicone oil and intravitreal antibiotics. Preoperative visual function was luckily completely restored. Conclusions: Endophthalmitis can occur after NR in an eye with PRESERFLO® MicroShunt implant which therefore does not prevent reflux of bacteria from a filtering bleb to the anterior chamber.

Change in Corneal Endothelial Cell Density after Baerveldt Shunt Implantation in Glaucoma Patients

Objective: To evaluate changes in corneal endothelial cells density (EDC) at 1 one, six, and twelve months after Baerveldt shunt implantation. Materials and Methods: This prospective study included 24 patients who underwent Baerveldt shunt implantation for refractory glaucoma, and who had one full year of post-surgical follow-up. Best corrected visual acuity (BCVA), intraocular pressure (IOP), number of glaucoma medications, central corneal thickness (CCT), corneal endothelial cell density (EDC), and morphology in central, inferior, and superotemporal (stEDC) areas were recorded at baseline, and 1, 6, and 12 months after surgery. Distance between the tip of tube to corneal endothelium (TTC) was measured using optical coherence tomography at one month after surgery. Results: Twenty-four eyes from 24 patients were analyzed. Sixty-two percent were primary open-angle glaucoma, and 73.1% of patients had previous trabeculectomy. Mean BCVA was not significantly changed. The mean IOP at six months (12.2±4.35 mmHg) and at one year (11.1±4.31 mmHg) was significantly lower than baseline (20.1±9.24 mmHg) (p<0.001 and p<0.001 respectively). Median (min, max) number of anti-glaucoma medications significantly decreased from 4 (1, 6) at baseline to 1 (0, 3) and 1 (0, 3) at six months and one year after surgery (p<0.001 and p<0.001, respectively). Mean baseline stEDC was 1,527±644 cells/mm2. From linear mixed model, stEDC showed the most significantly decreasing slope (y=1365.54 – 18.6125t, p=0.014), and CCT showed a significant increase over time (y=533.65 + 1.8853t). Pearson’s correlation coefficient between TTC and stEDC change at one year was not statistically significant (-0.403, p=0.172). Conclusion: After Baerveldt shunt implantation, EDC loss over time was found in the area closest to where the tube was placed in addition to increasing CCT. Distance from tip of tube to cornea is not the only factor that can cause EDC loss after shunt implantation. Additional study to identify other possible mechanisms is warranted.

Hydrocephalus and shunts: a comparative flow-pressure study

Introduction: Differential Pressure Shunts (DPS) for hydrocephalus work through a pressure differential between the proximal and the distal inlet. Neurosurgeon’s reference is extra-low, low, medium, normal or high-pressure valves, symbolizing the shunt’s resistance against the downstream flow. The Brazilian manufacturing process for all shunts is regulated by ISO 7195 version 2006, revised in 2016, and it allows a lot of flexibility in the determination of shunt resistance and flow characteristics. Methods: This article compares the pressure-flow characteristics of some hydrocephalus shunts available in Brazil based on their information brochures Results: Six shunt information brochures were compared regarding to CSF flow-control manufacturing graphs and/or pressure work range tables. Based on the data obtained of each valve, authors propose and introduce a comparative table that can be helpful if used as a guide to the neurosurgeon when one considers either a first time shunt implantation or a shunt revision Conclusion: There is no standardization regarding the pressure which defines the different models of shunts available in Brazil and neurosurgeon must be aware when choosing a specific shunt and even more when, in a shunt review, choose another manufacturer.