Cerebrospinal fluid shunting protocol for idiopathic intracranial hypertension for an improved revision rate

J Neurosurg 136:1790–1795, 2022

Cerebrospinal fluid (CSF) shunting in idiopathic intracranial hypertension (IIH) is associated with high complication rates, primarily because of the technical challenges that are related to small ventricles and a large body habitus. In this study, the authors report the benefits of a standardized protocol for CSF shunting in patients with IIH as relates to shunt revisions.

METHODS This was a retrospective study of consecutive patients with IIH who had undergone primary insertion of a CSF shunt between January 2014 and December 2020 at the authors’ hospital. In July 2019, they implemented a surgical protocol for shunting in IIH. This protocol recommended IIH shunt insertion by neurosurgeons with expertise in CSF disorders, a frontal ventriculoperitoneal (VP) shunt with an adjustable gravitational valve and integrated intracranial pressure monitoring device, frameless stereotactic insertion of the ventricular catheter, and laparoscopic insertion of the peritoneal catheter. Thirty-day revision rates before and after implementation of the protocol were compared in order to assess the impact of standardizing shunting for IIH on shunt complications.

RESULTS The 81 patients included in the study were predominantly female (93%), with a mean age of 31 years at primary surgery and mean body mass index (BMI) of 37 kg/m2. Forty-five patients underwent primary surgery prior to implementation of the protocol and 36 patients after. Overall, 12 (15%) of 81 patients needed CSF shunt revision in the first 30 days, 10 before and 2 after introduction of the protocol. This represented a significant reduction in the early revision rate from 22% to 6% after the protocol (p = 0.036). The most common cause of shunt revision for the whole cohort was migration or misplacement of the peritoneal catheter, occurring in 6 of the 12 patients. Patients with a higher BMI were significantly more likely to have a shunt revision within 30 days (p = 0.022).

CONCLUSIONS The Birmingham standardized IIH shunt protocol resulted in a significant reduction in revisions within 30 days of primary shunt surgery in patients with IIH. The authors recommend standardization for shunting in IIH as a method for improving surgical outcomes. They support the notion of subspecialization for IIH shunts, the use of a frontal VP shunt with sophisticated technology, and laparoscopic insertion of the peritoneal end. https:

Shunt age-related complications in adult patients with suspected shunt dysfunction

Acta Neurochir (2017) 159:1421–1428

Patients admitted for suspicion of shunt dysfunction (SD) often show unspecific symptoms and require timeconsuming, expensive and even invasive diagnostics involving significant radiation exposure. The purpose of this retrospective study was to analyse the current diagnostic procedures and to propose a process optimisation.

Method: As all patients admitted for suspicion of SD receive imaging studies, we searched for adult patients receiving neuroimaging in the period from January 2010 to July 2013, analysing referring diagnosis, clinical signs, products, diagnostic process and final diagnosis. Recursive partitioning was used to define time intervals for differentiating types of SD.

Results A total of 148 patients, aged 18–89 (mean, 54) years, were studied. Forty-two percent were referred by a hospital or rehabilitation centre, 30% by general practitioners and 24% were self-referrals. The admission diagnosis was in the majority “shunt dysfunction” only. Further differentiations were rarely made. An SD was confirmed in 46% of the patients. In 17%, the symptoms were based on another cause and in 37% they could not be clearly attributed to any specific disorder. Abdominal dislocations (2%) and shunt infections (5%) were found within the first 6 months. Over- (3%) and underdrainage (14%) were the most frequent complications during the first 4 years. Disconnections (13%) occurred generally 4 years or more after implantation. Only shunt obstruction (9%) showed no temporal pattern.

Conclusions: Symptoms of SD remain mostly unspecific. This study showed that the type of SD depends on the time interval from implantation.We propose a workup strategy for patients with SD based on the temporal profile.

Comparison of anti-siphon devices—how do they affect CSF dynamics in supine and upright posture?

Acta Neurochir (2017) 159:1389–1397

Three different types of anti-siphon devices (ASDs) have been developed to counteract siphoning induced overdrainage in upright posture. However, it is not known how the different ASDs affect CSF dynamics under the complex pressure environment seen in clinic due to postural changes. We investigated which ASDs can avoid overdrainage in upright posture best without leading to CSF accumulation.

Methods Three shunts each of the types Codman Hakim with SiphonGuard (flow-regulated), Miethke miniNAV with proSA (gravitational), and Medtronic Delta (membrane controlled) were tested. The shunts were compared on a novel in vitro setup that actively emulates the physiology of a shunted patient. This testing method allows determining the CSF drainage rates, resulting CSF volume, and intracranial pressure in the supine, sitting, and standing posture.

Results The flow-regulated ASDs avoided increased drainage by closing their primary flow path when drainage exceeded 1.39 ± 0.42 mL/min. However, with intraperitoneal pressure increased in standing posture, we observed reopening of the ASD in 3 out of 18 experiment repetitions. The adjustable gravitational ASDs allow independent opening pressures in horizontal and vertical orientation, but they did not provide constant drainage in upright posture (0.37 ± 0.03 mL/min and 0.26 ± 0.03 mL/min in sitting and standing posture, respectively). Consequently, adaptation to the individual patient is critical. The membrane-controlled ASDs stopped drainage in upright posture. This eliminates the risk of overdrainage, but leads to CSF accumulation up to the volume observed without shunting when the patient is upright.

Conclusions While all tested ASDs reduced overdrainage, their actual performance will depend on a patient’s specific needs because of the large variation in the way the ASDs influence CSF dynamics: while the flow-regulated shunts provide continuous drainage in upright posture, the gravitational ASDs allow and require additional adaptation, and the membrane-controlled ASDs show robust siphon prevention by a total stop of drainage.

Aspirin is associated with an increased risk of subdural hematoma in normal-pressure hydrocephalus patients following shunt implantation

Subdural Hematoma

J Neurosurg 123:423–426, 2015

In this paper the authors investigate whether shunt-treated patients with normal-pressure hydrocephalus receiving aspirin therapy are at increased risk of developing subdural hematoma (SDH).

Methods Records from 80 consecutive patients who had undergone implantation of a cerebrospinal fluid shunt for the treatment of normal-pressure hydrocephalus were retrospectively reviewed.

Results Eleven cases of symptomatic SDH occurred, all among patients receiving aspirin or clopidogrel. The 5-year survival estimate was 0.3 (p < 0.0001) for users of aspirin and the hazard ratio was 12.8 (95% CI 3.1–53).

Conclusions Patients on an aspirin therapy regimen have a markedly increased risk of SDH after a shunt has been implanted for the treatment of normal-pressure hydrocephalus. Users of clopidogrel may have an even greater risk.

Morbidity of Ventricular Cerebrospinal Fluid Shunt Surgery in Adults: An 8-Year Study

Neurosurgery 68:985–995, 2011 DOI: 10.1227/NEU.0b013e318208f36

Cerebrospinal fluid (CSF) shunt procedures have dramatically reduced the morbidity and mortality rates associated with hydrocephalus. However, despite improvements in materials, devices, and surgical techniques, shunt failure and complications remain common and may require multiple surgical procedures.

OBJECTIVE: To evaluate CSF shunt complication incidence and factors that may be associated with increased shunt dysfunction and infection rates in adults.

METHODS: From January 1999 to December 2006, we conducted a prospective surveillance program for all neurosurgical procedures including reoperations and infections. Patients undergoing CSF shunt placement were retrospectively identified among patients labeled in the database as having a shunt as a primary or secondary intervention. Revisions of shunts implanted in another hospital or before the study period were excluded, as well as lumbo- or cyst-peritoneal shunts. Shunt complications were classified as mechanical dysfunction or infection. Follow-up was at least 2 years. Potential risk factors were evaluated using log-rank tests and stepwise Cox regression models.

RESULTS: During the 8-year surveillance period, a total of 14 275 patients underwent neurosurgical procedures, including 839 who underwent shunt placement. One hundred nineteen patients were excluded, leaving 720 study patients. Mechanical dysfunction occurred in 124 patients (17.2%) and shunt infection in 44 patients (6.1%). These 168 patients required 375 reoperations. Risk factors for mechanical dysfunction were atrial shunt, greater number of previous external ventriculostomies, and male sex; risk factors for shunt infection were previous CSF leak, previous revisions for dysfunction, surgical incision after 10 AM, and longer operating time.

CONCLUSION: Shunt surgery still carries a high morbidity rate, with a mean of 2.2 reoperations per patient in 23.3% of patients. Our risk-factor data suggest methods for decreasing shunt-related morbidity, including peritoneal routing whenever possible and special attention to preventing CSF leaks after craniotomy or external ventriculostomy.

Adjustable shunt valve–induced magnetic resonance imaging artifact: a comparative study

J Neurosurg 113:74–78, 2010. (DOI: 10.3171/2009.9.JNS09171)

In this paper, the authors’ goal was to compare the artifact induced by implanted (in vivo) adjustable shunt valves in spin echo, diffusion weighted (DW), and gradient echo MR imaging pulse sequences.

Methods. The MR images obtained in 8 patients with proGAV and 6 patients with Strata II adjustable shunt valves were assessed for artifact areas in different planes as well as the total volume for different pulse sequences.

Results. Artifacts induced by the Strata II valve were significantly larger than those induced by proGAV valve in spin echo MR imaging pulse sequence (29,761 vs 2450 mm3 on T2-weighted fast spin echo, p = 0.003) and DW images (100,138 vs 38,955 mm3, p = 0.025). Artifacts were more marked on DW MR images than on spin echo pulse sequencse for both valve types.

Conclusions. Adjustable valve–induced artifacts can conceal brain pathology on MR images. This should influence the choice of valve implantation site and the type of valve used. The effect of artifacts on DW images should be highlighted pending the development of less MR imaging artifact–inducing adjustable shunt valves.