The use of the Codman-Medos Programmable Hakim valve in the management of patients with hydrocephalus: illustrative cases

From Shunt to Recovery: A Multidisciplinary Approach to Hydrocephalus Treatment in Severe Acquired Brain Injury Rehabilitation

Background: Hydrocephalus among Severe Acquired Brain Injury (SABI) patients remains overlooked during rehabilitation. Methods: A retrospective cohort study was carried out of traumatic and non-traumatic SABI patients with hydrocephalus, consecutively admitted over 9 years in a tertiary referral specialized rehabilitation hospital. Patients were treated with ventriculoperitoneal shunt before or during inpatient rehabilitation and assessed using the Level of Cognitive Functioning Scale and Disability Rating Scale. Logistic regression models were used to identify predictors of post-surgical complications. Linear regression models were used to investigate predictors of hospital length of stay (LOS), disability, and cognitive function. Results: Of the 82 patients, 15 had post-surgical complications and 16 underwent cranioplasty. Shunt placement complication risk was higher when fixed vs. when programmable pressure valves were used. A total of 56.3% achieved functional improvement at discharge and 88.7% improved in cognitive function; of the 82 patients, 56% were discharged home. In multiple regression analyses, higher disability at discharge was related to cranioplasty and longer LOS, while poorer cognitive function was associated with cranioplasty. Increase in LOS was associated with increasing time to shunt and decreasing age. Conclusions: A significant improvement in cognitive and functional outcomes can be achieved. Cranioplasty increased LOS, and fixed pressure valves were related to poorer outcomes.

Programmable Shunt Valves for Pediatric Hydrocephalus: 22-Year Experience from a Singapore Children's Hospital

(1) Background: pediatric hydrocephalus is a challenging condition. Programmable shunt valves (PSV) have been increasingly used. This study is undertaken to firstly, to objectively evaluate the efficacy of PSV as a treatment modality for pediatric hydrocephalus; and next, review its associated patient outcomes at our institution. Secondary objectives include the assessment of our indications for PSV, and corroboration of our results with published literature. (2) Methods: this is an ethics-approved, retrospective study. Variables of interest include age, gender, hydrocephalus etiology, shunt failure rates and incidence of adjustments made per PSV. Data including shunt failure, implant survival, and utility comparisons between PSV types are subjected to statistical analyses. (3) Results: in this case, 51 patients with PSV are identified for this study, with 32 index and 19 revision shunts. There are 3 cases of shunt failure (6%). The mean number of adjustments per PSV is 1.82 times and the mean number of adjustments made per PSV is significantly lower for MEDTRONIC™ Strata PSVs compared with others (p = 0.031). Next, PSV patients that are adjusted more frequently include cases of shunt revisions, PSVs inserted due to CSF over-drainage and tumor-related hydrocephalus. (4) Conclusion: we describe our institutional experience of PSV use in pediatric hydrocephalus and its advantages in a subset of patients whose opening pressures are uncertain and evolving.

Disappearance of a Distal Shunt Catheter: A Case Report of an Unusual Cause of Shunt Malfunction

Shunt malfunction is a common complication in patients who undergo ventriculoperitoneal shunt (VPS) placement for the treatment of hydrocephalus. A plethora of reports regarding shunt malfunctions due to distal catheter migration have been demonstrated in the literature. However, to our knowledge, there have been no reports thus far of shunt malfunctions caused by the complete disappearance of a distal catheter. A 70-year-old man was admitted to our hospital for progressive gait disturbance beginning approximately 5 months ago. He received a VPS for posthemorrhagic hydrocephalus and was doing well over the course of 18 months of follow-up. Since no increase in the size of the ventricle was observed on brain computed tomography taken at the outpatient clinic, we tried to readjust the pressure setting of his programmable shunt valve to relieve his symptoms. Without any progression, we discovered later by chance that the distal shunt catheter was missing. Shunt revision surgery was performed. At the 2-year follow-up, a slight improvement in gait was observed. Although it is very rare, the distal catheter can disappear without any noticeable symptoms. If shunt malfunction is suspected, it is important to check whether the entire shunt system is structurally intact.

Use of programmable versus nonprogrammable shunts in the management of normal pressure hydrocephalus: A multicenter retrospective study with cost-benefit analysis in Turkey

Ventriculoperitoneal shunt systems that are used in the treatment of normal pressure hydrocephalus are often associated with drainage problems. Adjustable shunt systems can prevent or treat these problems, but they may be expensive. The aim of our study is to compare the complications and total cost of several shunt systems.Patients with normal pressure hydrocephalus who underwent ventriculoperitoneal shunting between 2011 and 2016 were included in the study. The study involves patient consent and the informed consent was given. Complications and the average cost per person were compared between patients with adjustable and nonadjustable shunts. Shunt prices, surgical complications, and revision costs were taken into account to calculate the average cost.Of the 110 patients who were evaluated, 80 had a nonadjustable shunt and 30 had an adjustable shunt. In the group with adjustable shunts, the rates of subdural effusion and hematoma were 19.73% and 3.29%, respectively. In the group with nonadjustable shunts, these rates were 22.75% and 13.75%, respectively. One patient in the adjustable group underwent surgery for subdural hematoma, while 8 patients in the nonadjustable group underwent the same surgery. Ten patients required surgical intervention for subdural effusion and existing shunt systems in these patients were replaced by an adjustable shunt system. When these additional costs were factored into the analysis, the difference in cost between the shunt systems was reduced from 600 United States dollars (USD) to 111 USD.When the complications and additional costs that arise during surgical treatment of normal pressure hydrocephalus were considered, the price difference between adjustable and nonadjustable shunt systems was estimated to be much lower.

Feasibility Analysis for Treatment of Giant Intracranial Benign Tumor by Delayed Operation in Infancy

OBJECTIVE

The survival rate and prognosis in infants with giant intracranial tumors are significantly worse than in older children. This study aimed to analyze the feasibility of delayed operation for infants with giant intracranial benign tumor by evaluating the initial clinical presentations, expectant treatment measures, perioperative vital signs, and recuperation after surgery.

PATIENTS AND DATA

We reviewed 3 infant patients (average age, 9.33 months; range, 5-12 months) with giant intracranial benign tumors during January 2015 and April 2016. The maximum sections of tumors were 38 × 50 mm, 57 × 39 mm, and 55 × 67 mm, respectively. All clinical presentations, neuroimaging, and laboratory examinations were recorded.

RESULTS

Obstructive hydrocephalus was observed in 2 infants; ventriculoperitoneal shunts were placed in both before the delayed tumor resection. The disease progressed rapidly in the infant with teratoma and surgery was performed 4 months after placement of the ventriculoperitoneal shunt. The other 2 patients had experienced a 12-month growth and developmental phase and later underwent operations. Gross total resection was achieved in all patients. The pathologic results were consistent with the preoperative diagnosis. During a period of high-quality postoperative care, they remained stable and were discharged without any complications or neurologic deficits, and continued to improve toward their baseline.

CONCLUSIONS

Delayed operation enabled infant patients to gain a better physical state, with a stage of full preoperative preparation that may reduce intraoperative/postoperative morbidity and mortality.

Shunt Overdrainage Caused by Displacement of the Pressure Control Cam after Pressure Adjustment

Although the Codman-Hakim programmable valve is one of most popular shunt systems used in the clinical practice for the treatment of hydrocephalus, malfunctions related with this system have been also reported which lead to underdrainage or overdrainage of the cerebrospinal fluid. While obstruction of the ventricular catheter by tissue materials or hematoma and catheter disconnection are relatively common, the malfunction of the valve itself is rare. Herein, we report on a rare case of shunt overdrainage caused by displacement of the pressure control cam after pressure adjustment. A 57-year-old female, who underwent a ventriculoperitoneal shunt eight years ago, experienced aggravating symptoms of shunt overdrainage after pressure adjustment. Displacement of the pressure control cam was revealed on the X-ray, and a shunt revision was performed. The purpose of this report is to provide a working knowledge of the valve structure and to enhance the ability to interpret the valve setting on an X-ray for diagnosis of valve malfunction.

Ventricular Shunts

Ventricular shunts are mechanical devices used in the treatment of hydrocephalus, by means of which cerebrospinal fluid (CSF) is diverted from the ventricles to other low-pressure body cavities. Over the last 50 years, mechanical shunting has become the cornerstone for the treatment of hydrocephalus with shunt valves evolving from simple differential valves to complex programmable valves. The chief complications of ventricular shunting include obstruction, infections, and overdrainage causing subdural hematomas and slit-ventricle syndrome. As the number of commercially available valve designs continues to grow, each new generation aims at reducing the likelihood of complications, especially those resulting from overdrainage. Several studies aimed at establishing the superiority of any valve design have been conducted. All have highlighted the advantages and shortcomings of most models without conclusively providing evidence for choosing one over another. As a result, choices still rest on individual and institutional preferences.

Is there an ideal shunt? A panoramic view of 110 years in CSF diversions and shunt systems used for the treatment of hydrocephalus: from historical events to current trends

OBJECT

The goal of this study is to evaluate whether an "ideal shunt" exists.

METHODS

This is a retrospective analysis based on original papers in the field of Hydrocephalus and Shunts. Patients of all age groups, who had hydrocephalus, and underwent some form of CSF diversion were included. The study has been divided into four stages: from 1900 to 1949, 1950 to 1974, 1975 to 1999, and from 2000 to 2010.

RESULTS

In stage 1 (historical era): Saphenous vein grafts, rubber conduits, and other materials were used in CSF diversions. In 1949, the first implantable shunt tube was developed by Nulsen. In stage 2 (experimental stage): the Holter valve was developed. Newer innovations were developed in relation to the ventriculo-atrial shunt, which was the preferred CSF diversion. In stage 3 (developmental stage), a large number of different design shunt systems were developed, with the aim of reducing complications. The ventriculo-peritoneal shunt had become the preferred CSF diversion. Also, the programmable valve was born. In stage 4 (era of programmable valve, there is a preference for the use of programmable shunt systems. However, shunt failure rate at 1 year being around 25 to 40%, and shunt survival at 1 and 2 years are 50-70 and 47-53% in most series.

CONCLUSION

Every shunt is an ideal shunt provided the choice of the shunt used should be made by the matching performance of the shunt system to the altered profile of CSF dynamics of a given patient. The most important factor being the opening pressure.

Programmable shunt valves for the treatment of hydrocephalus: a systematic review

OBJECTIVE

To evaluate the clinical effectiveness of programmable valves compared with non-programmable valves of hydrocephalus.

METHODS

In this paper, the authors report a systematic review and meta-analysis of complications and revision rate for programmable valves and non-programmable implantation. Randomized or non-randomized controlled trials of hydrocephalus treated by programmable and non-programmable valves were considered for inclusion.

RESULTS

Seven published reports of eligible studies involving 1702 participants meet the inclusion criteria. Compared with non-programmable, programmable valves had no significant difference in catheter-related complications [RR = 0.88, 95%CI (0.66,1.19), p = 0.10] and infection rate [RR = 1.25, 95%CI (0.92,1.69), p = 1.00]. There were significant differences in overall complications [RR = 0.80, 95%CI (0.67,0.96), p < 0.01], over-drainage or under-drainage complications [RR = 0.44, 95%CI (0.31,0.63), p < 0.01] and revision rate [RR = 0.56, 95%CI (0.45,0.69), p < 0.01] in favor of programmable valves.

CONCLUSION

Although the studies seem to demonstrate a small advantage for the programmable shunts, the probable bias and the difficulties in patient selection are too important to make a general conclusion.

A randomised trial of high and low pressure level settings on an adjustable ventriculoperitoneal shunt valve for idiopathic normal pressure hydrocephalus: results of the Dutch evaluation programme Strata shunt (DEPSS) trial

BACKGROUND

In treating idiopathic normal pressure hydrocephalus (INPH) with a shunt there is always a risk of underdrainage or overdrainage. The hypothesis is tested whether patients treated using an adjustable valve preset at the highest opening pressure leads to comparable good clinical results with less subdural effusions than in a control group with an opening pressure preset at a low pressure level.

METHODS

A multicentre prospective randomised trial was performed on a total of 58 patients suspected of INPH. Thirty patients were assigned to (control) group 1 and received a Strata shunt (Medtronic, Goleta, USA) with the valve preset at a performance level (PL) of 1.0, while 28 patients were assigned to group 2 and received a Strata shunt with the valve preset at PL 2.5. In this group the PL was allowed to be lowered until improvement or radiological signs of overdrainage were met.

RESULTS

Significantly more subdural effusions were observed in the improved patients of group 1. There was no statistically significant difference in improvement between both groups overall.

CONCLUSIONS

On the basis of this multicentre prospective randomised trial it is to be recommended to treat patients with INPH with a shunt with an adjustable valve, preset at the highest opening pressure and lowered until clinical improvement or radiological signs of overdrainage occur although slower improvement and more shunt adjustments might be the consequence.

Rapid resolution of an acute subdural hematoma by increasing the shunt valve pressure in a 63-year-old man with normal-pressure hydrocephalus with a ventriculoperitoneal shunt: a case report and literature review

Introduction

Symptomatic subdural hematoma development is a constant concern for patients who have undergone cerebrospinal fluid shunting procedures to relieve symptoms related to normal-pressure hydrocephalus. Acute subdural hematomas are of particular concern in these patients as even minor head trauma may result in subdural hematoma formation. The presence of a ventricular shunt facilitates further expansion of the subdural hematoma and often necessitates surgical treatment, including subdural hematoma evacuation and shunt ligation.

Case presentation

We present the case of a 63-year-old North American Caucasian man with normal-pressure hydrocephalus with an adjustable valve ventriculoperitoneal shunt who developed an acute subdural hematoma after sustaining head trauma. Conservative treatment was favored over operative evacuation because our patient was neurologically intact, but simple observation was considered to be too high risk in the setting of a low-pressure ventriculoperitoneal shunt. Thus, the valve setting on the ventriculoperitoneal shunt was increased to its maximum pressure setting in order to reduce flow through the shunt and to mildly increase intracranial pressure in an attempt to tamponade any active bleeding and limit hematoma expansion. A repeat computed tomography scan of the head six days after the valve adjustment revealed complete resolution of the acute subdural hematoma. At this time, the valve pressure was reduced to its original setting to treat symptoms of normal-pressure hydrocephalus.

Conclusions

Programmable shunt valves afford the option for non-operative management of acute subdural hematoma in patients with ventricular shunts for normal-pressure hydrocephalus. As illustrated in this case report, increasing the shunt valve pressure may result in rapid resolution of the acute subdural hematoma in some patients.

Initial experience with the Codman Certas adjustable valve in the management of patients with hydrocephalus

Background

A new adjustable valve, the Codman Certas^TM valve for treatment of hydrocephalus was introduced into clinical practice in January 2011. It has 8 different settings with an opening pressure varying from 36 to over 400 mm H₂O at a flow rate of 20 mL/h. The 8th setting is designed to provide a "virtual off" function. The objective of this report is to describe the initial clinical experience with the Certas^TM valve and evaluate clinical usage with the main focus on the portable adjustment device - Therapeutic Management System (TMS), the “virtual off” setting and compatibility with magnetic resonance imaging (MRI).

Findings

Forty-two patients with hydrocephalus from different etiologies were treated with the Certas^TM adjustable shunt system. Data regarding implantation procedures, the use of the TMS system, x-ray imaging, and MRI procedures were recorded prospectively. All patients had clinical follow-up at four weeks after implantation and every three months until a stable clinical condition was obtained.

The mean time for follow-up was 8.6 months (1–16.6). Seventy-one adjustments were performed with the TMS, 12 were problematic. Twenty-nine MRI procedures were performed and did not cause accidental resetting. Five patients were treated with the "virtual off" function for a period.

Conclusions

We found the Certas^TM valve valuable in the treatment of hydrocephalus, usability of the TMS was high because it is small and portable, but in some cases we experienced adjustment problems with the first procedures performed by a surgeon, indicating that there is a learning curve. The "virtual off" function provided a possibility of treating over-drainage without the need for shunt ligation or other invasive procedures.

The combination of a programmable valve and a subclavicular anti-gravity device in hydrocephalus patients at high risk for hygromas

OBJECTIVES

In order to avoid occurrence of post-operative hygromas in specific hydrocephalus patients being at high risk of overdrainage, a combination of programmable valve and anti-gravity device is widely recommended. We analyzed our series of hydrocephalus patients implanted with such a shunt configuration focusing on complications in relation to over-/underdrainage and neurological outcome.

METHODS

In 28 hydrocephalic patients (14 women and 14 men; mean age 65 years, range from 14 to 82 years; 11 normal pressure, 7 post-traumatic, and 4 post-hemorrhagic hydrocephalus), a Codman Medos programmable valve combined with a Miethke shunt assistant (SA) was implanted at the Department of Neurosurgery of the Academic Teaching Hospital Feldkirch. Implantation was performed simultaneously in 20 patients during the primary procedure: in five patients, SA was placed during revision surgery, and in three patients, the patent system was completed by additional implantation of an SA.

RESULTS

Subdural hematoma occurred in one out of 20 patients with SA implantation during primary procedure and in two out of eight patients with SA implantation as secondary procedure, respectively. Shunt occlusion occurred in one patient out of the patients with SA implantation during primary procedure, but was seen in three patients with pre-existing shunt without SA. Shunt infection occurred in one case.

DISCUSSION

Our results suggest the combination of an adjustable valve and SA as an effective treatment for a specific group of hydrocephalus patients being at high risk for overdrainage.

A pressure adjustment protocol for programmable valves

OBJECTIVE

There is no definite adjustment protocol for patients shunted with programmable valves. Therefore, we attempted to find an appropriate method to adjust the valve, initial valve-opening pressure, adjustment scale, adjustment time interval, and final valve-opening pressure of a programmable valve.

METHODS

Seventy patients with hydrocephalus of various etiologies were shunted with programmable shunting devices (Micro Valve with RICKHAM(R) Reservoir). The most common initial diseases were subarachnoid hemorrhage (SAH) and head trauma. Sixty-six patients had a communicating type of hydrocephalus, and 4 had an obstructive type of hydrocephalus. Fifty-one patients had normal pressure-type hydrocephalus and 19 patients had high pressure-type hydrocephalus. We set the initial valve pressure to 10-30 mmH(2)O, which is lower than the preoperative lumbar tapping pressure or the intraoperative ventricular tapping pressure, conducted brain computerized tomographic (CT) scans every 2 to 3 weeks, correlated results with clinical symptoms, and reset valve-opening pressures.

RESULTS

Initial valve-opening pressures varied from 30 to 180 mmH(2)O (mean, 102 +/- 27.5 mmH(2)O). In high pressure-type hydrocephalus patients, we have set the initial valve-opening pressure from 100 to 180 mmH(2)O. We decreased the valve-opening pressure 20-30 mmH(2)O at every 2- or 3-week interval, until hydrocephalus-related symptoms improved and the size of the ventricle was normalized. There were 154 adjustments in 81 operations (mean, 1.9 times). In 19 high pressure-type patients, final valve-opening pressures were 30-160 mmH(2)O, and 16 (84%) patients' symptoms had nearly improved completely. However, in 51 normal pressure-type patients, only 31 (61%) had improved. Surprisingly, in 22 of the 31 normal pressure-type improved patients, final valve-opening pressures were 30 mmH(2)O (16 patients) and 40 mmH(2)O (6 patients). Furthermore, when final valve-opening pressures were adjusted to 30 mmH(2)O, 14 patients symptom was improved just at the point. There were 18 (22%) major complications : 7 subdural hygroma, 6 shunt obstructions, and 5 shunt infections.

CONCLUSION

In normal pressure-type hydrocephalus, most patients improved when the final valve-opening pressure was 30 mmH(2)O. We suggest that all normal pressure-type hydrocephalus patients be shunted with programmable valves, and their initial valve-opening pressures set to 10-30 mmH(2)O below their preoperative cerebrospinal fluid (CSF) pressures. If final valve-opening pressures are lowered in 20 or 30 mmH(2)O scale at 2- or 3-week intervals, reaching a final pressure of 30 mmH(2)O, we believe that there is a low risk of overdrainage syndromes.

Endoscopic third ventriculostomy in the treatment of shunt-related over-drainage: Preliminary experience with a new approach how to render ventricles navigable

OBJECTIVE

Endoscopic third ventriculostomy (ETV) is increasingly used for the treatment of shunt-related complications in hydrocephalic patients, particularly if the etiology of the underlying hydrocephalus is of obstructive nature.

PURPOSE

Due to the slit-like configuration of the ventricles, ventricular dilatation must be achieved prior to ETV in patients with problems due to over-drainage. This has been accomplished by ligating or explanting the shunt. Here we present an alternative procedure using a gravitational antisiphon device.

MATERIALS AND METHODS

In two patients with over-drainage due to shunted occlusive hydrocephalus ventricles were dilated by integrating an antisiphon device (Miethke ShuntAssistant, Aesculap AG, Tuttlingen, Germany) into their shunt systems. The resistance of the antisiphon device, which is available in configurations from 10 to 35 cm H2O was chosen 10 cm H2O higher than necessary to prevent siphoning in the individual patient.

RESULTS

Both patients gradually recovered from their over-drainage symptoms and the ventricles enlarged enough to allow access with an endoscope. Using a standard procedure, ETV was performed 7 days and 1 month later, respectively. In the same operative session the shunts were occluded. Shunts were removed within 6 weeks after ETV. During follow-up of more than 3 years, both patients remained free of symptoms.

CONCLUSION

The incorporation of an antisiphon device with resistance level selected 10 cm H2O higher than needed to prevent anti-siphoning into a pre-existing shunt system in patients suffering from shunt-related over-drainage is a safe and effective technique to render ventricles large enough to allow endoscopic access for ETV.

Comparison of programmable shunt valves vs standard valves for communicating hydrocephalus of adults: a retrospective analysis of 407 patients

BACKGROUND

The aim of the present study was to clarify whether programmable shunt valves are advantageous in the treatment of adults with communicating hydrocephalus with respect to valve-related shunt complications and surgical shunt revisions, in comparison with standard valves.

METHODS

Adult patients with communicating hydrocephalus treated with Codman Hakim programmable (CHP) valves or Hakim (H) standard valves during 12 years were retrospectively studied. Patients were analyzed for demographic data, implantation diagnosis, valve type, opening pressure at implantation, opening pressure adjustments, and incidence of shunt complications, especially valve-related complications. The end point of the study was a surgical shunt revision.

RESULTS

In 407 patients, 247 CHP valves and 160 H valves were implanted. Median opening pressure of CHP at implantation was 110 mm H(2)O, while 3 low-pressure, 153 medium-pressure, and 4 high-pressure H valves were implanted. Opening pressure adjustments were performed in 39% of CHP patients--1.44 adjustments per adjusted valve. Overall complication rate as well as the rate of surgical revisions for infections and catheter- and valve-related problems did not show any significant difference between CHP and H valves. The incidence of nontraumatic subdural hematomas and hygromas was significantly higher in the CHP group; however, the rate of surgical decompressions did not differ.

CONCLUSIONS

The advantage of reprogramming of CHP did not translate into a reduction in surgical shunt revisions. Therefore, in conjunction with the present data, we believe it is still justified to implant H standard valves in adult patients with communicating hydrocephalus.

Decreases in ventricular volume correlate with decreases in ventricular pressure in idiopathic normal pressure hydrocephalus patients who experienced clinical improvement after implantation with adjustable valve shunts

OBJECTIVE

This retrospective study examined whether changes in ventricular volume correspond with changes in adjustable valve pressure settings in a cohort of patients who received shunts to treat idiopathic normal pressure hydrocephalus. We also examined whether these pressure-volume curves and other patient variables would co-occur with a positive clinical response to shunting.

METHODS

We selected 51 patients diagnosed with idiopathic normal pressure hydrocephalus who had undergone implantation of a Codman Hakim programmable valve (Medos S.A., Le Locle, Switzerland). Clinical data were gathered from the patients' records and clinical notes by an investigator blinded to patients' ventricular volumes. Ventricular volume was measured using 3D Slicer, an image analysis and interactive visualization software package developed and maintained at the Surgical Planning Laboratory at Brigham and Women's Hospital.

RESULTS

Eighty-six percent of patients with gait disturbance at presentation showed improvement of this symptom, 70% experienced improvement in incontinence, and 69% experienced improvement in dementia. For the group showing 100% clinical improvement, the correlation coefficient of average changes in valve pressure over time (delta P/delta T) and average changes in ventricular volume over time (delta V/delta T) were high at 0.843 (P < 0.05). For the group experiencing no or only partial improvement, the correlation coefficient was 0.257 (P = 0.32), indicating no correlation between average delta V/delta T and average delta P/delta T for each patient.

CONCLUSION

This was a carefully analyzed modeling study of idiopathic normal pressure hydrocephalus treatment made possible only by adjustable valve technology. With careful volumetric analysis, we found that changes in ventricular volume correlated with adjustments in valve pressure settings for those patients who improved clinically after shunting. This suggests that positive clinical responders retained parenchymal elasticity, emphasizing the importance of dynamic changes in this cohort.

Effect of Vagus Nerve Stimulator Magnet on Programmable Shunt Settings

OBJECTIVE

Vagus nerve stimulators and programmable shunt valves are used in the operative care of epilepsy and hydrocephalus, respectively. Both devices use magnetic fields to activate and program their various settings and functions. The authors conducted several ex vivo trials to better elucidate any interplay between the two systems.

METHODS

A pulse generator controller (Cyberonics Corp., Houston, TX) was brought to within 4 cm of Strata programmable shunt valves (Medtronic Neurosurgery, Goleta, CA). Each of five valves was preset to either a low- or high-pressure setting and then challenged with the vagus nerve stimulator generator. Each valve was challenged 20 times, for a total of 100 trials.

RESULTS

In 100 trials, 78 inadvertent pressure setting adjustments were recorded. In 46 attempts, the valve pressure was increased, and in 34 attempts, the pressure was decreased.

CONCLUSION

This study provides some support to the anecdotal reports of inadvertent adjustments of programmable shunt valves by the external magnetic field created by vagus nerve stimulator pulse generator controllers. Further trials and a double-blind study are necessary to illustrate more clearly the possible relationship of these magnetically controlled neurosurgical devices.

Clinical experience with the use of a shunt with an adjustable valve in children with hydrocephalus

OBJECT

The goal of this study was to assess the value of making adjustments in the opening pressure of a shunt valve and to determine shunt survival in children and young adults in whom an adjustable valve was used to manage cerebrospinal fluid drainage.

METHODS

The authors conducted a single-center retrospective study of 158 children and young adults who had received 199 Codman Hakim programmable valves (noninvasively adjustable to settings in the range of 30-200 mm H2O). The mean age at which the patients underwent shunt implantation was 4.4 years (median 0.4 years, maximum 18 years); 94 patients were younger than 2 years of age, including 14 patients with a gestational age younger than 38 weeks at the time of implantation. In 84 (53.2%) of the 158 patients, valve pressure adjustment was required at least once (mean 1.3 times, maximum 16 times). Among the 202 adjustments made in patients the reason for adjustment was underdrainage in 74 adjustments (36.6%) and overdrainage in 119 (58.9%). The clinical status of the patient improved after 121 (69.1%) of 175 adjustments and after 58 (73.4%) of 79 minor adjustments (less than or equal to +/- 20 mm H2O). The shunt infection rate was 13 (10.9%) of 119 patients. Shunt survival was 60.5% at 1 year, 47.1% at 2 years, and 43.9% at 3 years of follow-up review.

CONCLUSIONS

Adjustment of the valve's opening pressure further improves outcome in pediatric patients.

Ventriculoperitoneal shunt dysfunction during rehabilitation: prevalence and countermeasures

OBJECTIVE

We examined the prevalence of shunt dysfunction (e.g., overdraining or underdraining malfunctions) in patients with a ventriculoperitoneal shunt and elucidated effective countermeasures of a programmable valve shunt system in treatments for shunt dysfunction during rehabilitation therapy.

SUBJECTS

Among 114 patients with a ventriculoperitoneal shunt for normal pressure hydrocephalus, underdraining appeared in eight patients during hospitalization for rehabilitation therapy, and seven patients experienced overdraining.

RESULTS

We could treat underdraining noninvasively for all six patients with a programmable valve shunt system by decreasing the opening pressure, whereas the other two patients with a fixed valve pressure system required surgical replacement of the valve unit. We could also treat overdraining noninvasively in two cases with programmable valve shunt system by increasing the opening pressure. In two cases with fixed valve pressure system, however, chronic subdural hematomas had to be surgically treated. Either dysfunction interfered with a better functional outcome in rehabilitation therapy. Barthel index after the countermeasures and continuous rehabilitation therapies was significantly larger than the index before the countermeasures in both overdraining and underdraining groups.

CONCLUSIONS

Shunt dysfunction appeared in approximately 13.2% of patients with a ventriculoperitoneal shunt during hospitalization for rehabilitation. The ventriculoperitoneal shunt using programmable valve shunt system was convenient and valuable for treating both overdraining and underdraining malfunctions in the rehabilitation ward.

Is normal pressure hydrocephalus a valid concept in 2002? A reappraisal in five questions and proposal for a new designation of the syndrome as "chronic hydrocephalus"

The authors question the current validity of the traditional concept of normal pressure hydrocephalus (NPH) as it was described by Adams and Hakim in 1965. The classic features of the disease are addressed. It is concluded that most of the historical statements made three decades ago need to be revised. Especially, the term "normal pressure" hydrocephalus probably does not match the actual manometric profile of patients with NPH. Similarly, the terms"curable"and "reversible" dementia are inadequate to designate the mental alterations of NPH. That NPH is non-specific to the adult population is also stressed, since it may be not uncommonly encountered in paediatrics, especially in an implanted shunt malfunction. The term "chronic hydrocephalus" without reference to cerebrospinal fluid pressure and to the age of the patient is proposed instead of NPH, which seems out of step with current knowledge of the pressure profile and with the diagnosis and decision making context in patients with so called NPH.

Volumetric measurements in the detection of reduced ventricular volume in patients with normal-pressure hydrocephalus whose clinical condition improved after ventriculoperitoneal shunt placement

OBJECT

The syndrome of normal-pressure hydrocephalus (NPH) refers to the clinical triad of gait disturbance, dementia, and urinary incontinence in association with idiopathic ventriculomegaly and normal intracranial pressure. Ventriculoperitoneal (VP) shunt placement often yields significant clinical improvements, sometimes without apparent reduction of ventricular size. The authors hypothesized that careful volumetric measurements would show a decrease in ventricular volume in these patients.

METHODS

Twenty consecutive patients with NPH underwent placement of VP shunts equipped with programmable valves. In 11 patients pre- and postoperative neuroimaging was performed, which allowed volumetric analysis. Volumetric measurements of the lateral ventricles were calculated in triplicate by National Institutes of Health image-processing software to assess standard computerized tomography (CT) scans (eight patients) or magnetic resonance (MR) images (three patients) obtained before and after shunt placement. Ventricular volumes were also assessed by an independent neuroradiologist. Postoperative studies were performed at a time of clinical improvement, between 1 and 9 months postsurgery (mean 5 months). Preoperative and postoperative Unified Parkinson's Disease Rating Scale evaluations were performed in four patients. Significant clinical improvement occurred in all patients after shunt placement (mean follow-up period 17.5 months). Although 10 (91%) of 11 patients demonstrated a calculable decrease in volume in the lateral ventricles (mean decrease 39%), formal interpretation of neuroimages indicated a definite decrease in lateral ventricular volume in only three (27%) of 11 patients.

CONCLUSIONS

Volumetric measurements obtained to compare preoperative and postoperative CT or MR studies obtained in patients with NPH in whom clinical improvement was seen after shunt placement surgery show a demonstrable decrease in ventricular size. Volumetric measurements may be helpful in clinical assessment postoperatively and in guiding programmable valve pressure settings.

Electromagnetic field hazards involving adjustable shunt valves in hydrocephalus

OBJECT

Standard therapy for hydrocephalus involves shunts and valves, which are frequently adjustable. Because of increasing "electromagnetic smog" (for example, that generated by cellular phones), these valves are often exposed to electromagnetic fields.

METHODS

Various magnetic fields were tested for their effects on two different kinds of adjustable valves. The minimum magnetic flux density affecting the adjustment of the valve was determined. Results were compared with magnetic fields found in contemporary everyday life. In homogeneous magnetic fields the adjustment of one valve (Sophysa model SM8) was changed at 5 mT, whereas the second valve (Codman Hakim model CM) was not affected. In nonhomogeneous fields the SM8 valve was affected at 25 mT and the CM valve at 15 mT. Thus, these valves may be affected by headphones and telephone receivers. Surroundings such as the Japanese magnetic suspension railway and the lead cabin of electrical railway engines, in which critical levels of magnetic flux may be present, may also affect adjustable valves. The high-frequency fields of cellular phones, however, have no effect on these valves.

CONCLUSIONS

Every surgeon who implants these valves and every patient who receives them should know the possible hazards. The valve selection should be adapted to the environment of the patient. Devices with critical levels of electromagnetic flux that are used in the homes of patients should be replaced by ones with lower magnetic fields. The future construction of these valves should be modified in such a way that their adjustment requires a higher magnetic flux density, so that the valves become less sensitive to unwanted effects from environmental magnetic fields.

Management of hydrocephalus with programmable valves after traumatic brain injury and subarachnoid hemorrhage

Programmable shunt valves are a recent technological advance that enhance the management of most patients with hydrocephalus secondary to subarachnoid hemorrhage or traumatic brain injury. An improved understanding of the intracranial pressure dynamics occurring both before and after a cerebrospinal fluid diversionary shunt has provided a more scientific basis for the application of these valves.

Seven years of clinical experience with the programmable Codman Hakim valve: a retrospective study of 583 patients

OBJECT

The goal of this study was to assess the value of the Codman Hakim programmable valve to settings in the range of 30 to 200 mm H2O. This valve can be adjusted noninvasively for cerebrospinal fluid (CSF) drainage.

METHODS

The authors conducted a single-center retrospective study of 583 patients (421 adults and 162 children) suffering from hydrocephalus of various causes (379 patients), normal-pressure hydrocephalus (174 patients), arachnoid cyst (14 patients), and pseudotumor cerebri (16 patients). In all cases a Codman Hakim programmable valve was implanted; in 82.8% of cases it was included during the patient's first shunt implantation. In 42.4% of the cases valve pressure adjustment was required at least once (mean number of adjustments 1.2, maximum 23). The patients' clinical status improved after 64.6% of pressure adjustments. Accidental resetting of opening pressure, other than that caused by magnetic resonance (MR) imaging, was uncommon. Because MR imaging caused resetting in 26.8% of cases in which it was used, it was deemed mandatory to obtain an x-ray film after MR imaging. Valve malfunction, blockage, or adjustment difficulties occurred in 2% of valves implanted, and nontraumatic subdural fluid collections were demonstrated in 5.1% of patients (13 of whom were treated by valve pressure adjustment alone). Five-year shunt survival was 53.1% for first-time shunt implantations. The shunt infection rate was 8.5% of valve implantations. Catheter-related complications and shunt-related infections were the main reasons for surgical revision and the major cause of shunt failure. At follow-up review, 97% of children and 90% of adults had improved.

CONCLUSIONS

Because one cannot know in advance which case will turn out to be complicated, the authors' preference is to use the Codman Hakim programmable valve for all conditions in which CSF should be drained.

In vivo intracranial pressure dynamics in patients with hydrocephalus treated by shunt placement

OBJECT

With the commercial availability of a variety of shunt systems, there is considerable controversy over the choice of the most appropriate shunt valve for each individual with hydrocephalus. Although the performance characteristics of all shunt systems are well documented in the laboratory setting, there is little description of the in vivo dynamics of intracranial pressure (ICP) after implantation of commonly used shunt systems in humans. The authors coupled telemonitoring devices to several different shunt systems to measure the performance characteristics of these valve systems with respect to intraventricular pressure (IVP) at increments of head elevation.

METHODS

Twenty-five patients with different shunt systems and three control patients without shunts were studied for IVP at 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 90 degrees of head elevation, and the resultant curves were analyzed for the best-fit regression coefficient. For purposes of analysis the authors grouped shunt valve systems by design characteristics into three groups: differential-pressure valves (r = -0.321 +/- 0.061; 11 patients), nonsiphoning systems (r = -0.158 +/- 0.027; 10 patients), and flow-regulated valves (r = -0.16 +/- 0.056; four patients); there were three control patients without shunts (r = -0.112 +/- 0.037).

CONCLUSIONS

The authors found that differential-pressure valves always caused ICP to drop to 0 by 30 degrees of head elevation, whereas all other valve systems caused a more gradual drop in ICP, more consistent with pressures observed in the control patients without shunts. Not surprisingly, the differential-pressure valve group was found to have a significant difference in mean regression coefficient when compared with those in whom nonsiphoning shunts (p < 0.023) or no shunts were placed (p < 0.049). These data provide a basis for evaluating shunt valve performance and for predicting valve appropriateness in patients in whom characteristics such as pressure and flow dynamics are weighed in the choice of a specific valve for implantation.

A randomized, controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus. Hakim-Medos Investigator Group

OBJECTIVE

A multicenter prospective randomized controlled study was performed to assess the safety and efficacy of a Codman Hakim programmable shunt valve (Codman/Johnson & Johnson, Raynham, MA) versus a conventional valve system of the surgeon's choice for the treatment of patients with hydrocephalus.

METHODS

Enrollment was stratified on the basis of whether the patient was undergoing initial shunt insertion or revision of an existing valve system at study entry. Study end points were: 1) valve explantation, and 2) shunt failure (surgical intervention for any component of the shunt). A total of 377 patients were enrolled onto the study, with 235 undergoing first shunt insertion (119 experimental, 116 control) and 142 undergoing revisions (75 experimental, 67 control).

RESULTS

During a follow-up interval of 104 weeks after the first implantation on-study, explantation of the valve was required in 62 (32%) of 194 experimental valves, compared with 71 (39%) of 183 control valves. Two-year survival rates of the original shunt without revision of any component were 52% (62 of 119) and 50% (58 of 116) in experimental and control patients, respectively, who underwent initial shunt insertion, and 43% (32 of 75) and 43% (29 of 67) in experimental and control patients, respectively, who underwent replacement of an existing valve. No statistically significant difference was observed between experimental and control patients in the survival of either the valve or the overall shunt system. Control of hydrocephalus as assessed symptomatically and by imaging was comparable in the two treatment groups. Although problems related to inability to achieve the desired pressure setting were reported in 22 experimental valves, in all but four instances no additional programming was attempted because the patients were functioning well clinically. The most common reasons cited for valve explantation and shunt revision were infection (9.8% frequency in the overall cohort) and proximal shunt malfunction, which occurred with comparable frequency in the experimental and control groups.

CONCLUSION

Safety and efficacy of the Codman Hakim programmable shunt valve is comparable to conventional valves in the overall population of patients with hydrocephalus. However, the current study was not designed to assess the efficacy of programmable versus conventional valves in the management of individual hydrocephalus problems, and it had insufficient statistical power to support such comparisons. This study provides a rationale for examining whether the theoretical advantages of a programmable valve for managing challenging hydrocephalus problems can translate into meaningful improvements in shunt and valve survival.

Endoscopic aqueductoplasty: technique and results

OBJECTIVE

The purpose of this study was to determine the safety and efficacy of endoscopic aqueductoplasty in patients with hydrocephalus caused by aqueductal stenosis. The controversy of third ventriculostomy and aqueductoplasty is discussed.

METHODS

A series of 17 patients who underwent endoscopic aqueductoplasty is reported. Rigid rod-lens scopes were used for inspecting the aqueductal entry and performing balloon aqueductoplasty. With the aid of a 2.5-mm flexible endoscope, the aqueduct and fourth ventricle were explored and aqueductal membranous obstructions were perforated. Third ventriculostomies were performed simultaneously in nine patients. One aqueductal stent was inserted. In six patients, frameless computerized neuronavigation was used for an accurate approach to the aqueduct. The average duration of the endoscopic procedures was 59 minutes (range, 25-100 min).

RESULTS

There was no endoscopy-related mortality. Surgical complications included an asymptomatic fornix contusion and two injuries to the aqueductal roof, which resulted in permanent diplopia due to dysconjugate eye movement (one patient) and transient trochlear palsy (one patient). In addition, two patients developed transient dysconjugate eye movements, and one patient had an asymptomatic epidural hematoma. Eleven patients showed improvement in their symptoms. The conditions of five patients were unchanged. One patient died of stroke 1 month after the operation. No patient required shunting. The ventricles decreased in size in nine patients and were unchanged in the remaining eight patients.

CONCLUSION

Endoscopic aqueductoplasty is an effective alternative to third ventriculostomy for the treatment of hydrocephalus caused by short aqueductal stenosis. However, longer follow-up periods are necessary to evaluate long-term aqueductal patency after aqueductoplasty.

Contralateral extradural haematoma after insertion of a programmable-valve ventriculoperitoneal shunt

Images

Experience with a programmable valve shunt system

OBJECT

The goal of this study was to clarify the efficacy of the Codman Hakim programmable valve. Clinical data obtained in 179 patients with hydrocephalus or other intracranial fluid-accumulating diseases were analyzed.

METHODS

Shunt placement operations were effective in 168 patients, approximately one half (50.6%) of whose devices required reprogramming of opening pressure postoperatively. This was a significantly larger number of shunts than the authors had thought would need reprogramming. Extremely narrowed ventricles observed on computerized tomography scans, as well as clinical symptoms related to inadequate or excessive cerebrospinal fluid drainage, improved in patients after shunt reprogramming. Shunt reprogramming frequently was necessary in patients with posthemorrhagic acute hydrocephalus; the programmable valve proved particularly beneficial for such patients. Subdural effusion and arachnoid cyst also proved to be good indications for use of the valve. Twelve patients (7%) suffered complications postoperatively. The most common complication was valve obstruction, which occurred in five patients, most of whom had brain tumors.

CONCLUSIONS

The programmable valve was beneficial for the treatment of hydrocephalus and other intracranial fluid-accumulating diseases. It is important to be careful in selecting patients for treatment with the programmable valve, because complications involving the valve seem more likely in brain tumor cases. The valve proved to be poorly resistant to magnetic fields; therefore, it is essential to confirm opening pressure after every magnetic resonance imaging examination. The authors recommend that an identification system for patients be developed so that medical personnel will be aware of the presence of the valve and the previous setting of opening pressure.

CSF dynamics in a patient with a programmable shunt

The Codman-Medos programmable shunt system was designed by Drs. Hakim to relieve under and over drainage problems. The system allows for non-invasive post-implantation adjustment of the opening pressure of the valve through a range of 30 to 200 mmH2O in 10 mm differentials. However, its wide adjustability does not simplify determination of the optimal pressure setting. The bolus injection method was used to study the intracranial pressure environment of nine adult hydrocephalic patients treated with the Codman-Medos programmable shunt. Changes in CSF hydrodynamics with manipulation of the pressure valve setting, and the effectiveness of the bolus injection method to determine the optimum valve pressure setting were investigated. Initial valve pressure setting at shunt implantation was determined on the basis of preoperative CSF dynamics test. Another CSF dynamics test was carried out after surgery, and the pressure setting was revised in necessary. The new setting was the maximum obtained within normal CSF hydrodynamics. If shunt overflow was suspected, pressure was set at a higher level. After resetting of the shunt, no patient encountered serious shunt-related problems in the follow-up period. This method was considerably useful for understanding of the intracranial pressure environment of patients with a programmable shunt, and determination of a better shunt setting.

Dutch Normal-Pressure Hydrocephalus Study: randomized comparison of low- and medium-pressure shunts

OBJECT

The goal of this prospective study was to compare outcome after placement of a low- or medium-pressure shunt in patients with normal-pressure hydrocephalus (NPH).

METHODS

Ninety-six patients with NPH were randomized to receive a low-pressure ventriculoperitoneal shunt (LPV; 40 +/- 10 mm H2O) or medium high-pressure ventriculoperitoneal shunt (MPV; 100 +/- 10 mm H2O). The patients' gait disturbance and dementia were quantified by applying an NPH scale, and their level of disability was evaluated by using the modified Rankin scale (mRS). Patients were examined prior to and 1, 3, 6, 9, and 12 months after surgery. Primary outcome measures were determined by differences between preoperative and last NPH scale scores and mRS grades. The LPV and MPV shunt groups were compared by calculating both the differences between mean improvements and the proportions of patients showing improvement. Intention-to-treat analysis of mRS grades yielded a mean improvement of 1.27 +/- 1.41 for patients with LPV shunts and 0.68 +/- 1.58 for patients with MPV shunts (p = 0.06). Improvement was found in 74% of patients with LPV shunts and in 53% of patients with MPV shunts (p = 0.06) and a marked-to-excellent improvement in 45% of patients with LPV shunts and 28% of patients with MPV shunts (p = 0.12). All outcome measures indicated trends in favor of the LPV shunt group, with only the dementia scale reaching significance. After exclusion of serious events and deaths unrelated to NPH, efficacy analysis showed the advantage of LPV shunts to be diminished. Reduction in ventricular size was also significantly greater for patients in the LPV shunt group (p = 0.009). Subdural effusions occurred in 71% of patients with an LPV shunt and in 34% with an MPV shunt; however, their influence on patient outcome was limited.

CONCLUSIONS

Outcome was better for patients who had an LPV shunt than for those with an MPV shunt, although most differences were not statistically significant. The authors advise that patients with NPH be treated with an LPV shunt.