Use of Intracranial Pressure Monitoring in the Management of Childhood Hydrocephalus and Shunt-related Problems

Intracranial pressure monitoring in pediatric and adult patients with hydrocephalus and tentative shunt failure: a single-center experience over 10 years in 146 patients

OBJECT In patients with hydrocephalus and shunts, lasting symptoms such as headache and dizziness may be indicative of shunt failure, which may necessitate shunt revision. In cases of doubt, the authors monitor intracranial pressure (ICP) to determine the presence of over- or underdrainage of CSF to tailor management. In this study, the authors reviewed their experience of ICP monitoring in shunt failure. The aims of the study were to identify the complications and impact of ICP monitoring, as well as to determine the mean ICP and characteristics of the cardiac-induced ICP waves in pediatric versus adult over- and underdrainage. METHODS The study population included all pediatric and adult patients with hydrocephalus and shunts undergoing diagnostic ICP monitoring for tentative shunt failure during the 10-year period from 2002 to 2011. The patients were allocated into 3 groups depending on how they were managed following ICP monitoring: no drainage failure, overdrainage, or underdrainage. While patients with no drainage failure were managed conservatively without further actions, over- or underdrainage cases were managed with shunt revision or shunt valve adjustment. The ICP and ICP wave scores were determined from the continuous ICP waveforms. RESULTS The study population included 71 pediatric and 75 adult patients. There were no major complications related to ICP monitoring, but 1 patient was treated for a postoperative superficial wound infection and another experienced a minor bleed at the tip of the ICP sensor. Following ICP monitoring, shunt revision was performed in 74 (51%) of 146 patients, while valve adjustment was conducted in 17 (12%) and conservative measures without any actions in 55 (38%). Overdrainage was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. The ICP wave scores, in particular the mean ICP wave amplitude (MWA), best differentiated underdrainage. Neither mean ICP nor MWA levels showed any significant association with age. CONCLUSIONS In this cohort of pediatric and adult patients with hydrocephalus and tentative shunt failure, the risk of ICP monitoring was very low, and helped the authors avoid shunt revision in 49% of the patients. Mean ICP best differentiated overdrainage, which was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. Underdrainage was best characterized by elevated MWA values, indicative of impaired intracranial compliance.

The use of abdominal binders to treat over-shunting headaches

OBJECT

Headaches are common in children with shunts. Headaches associated with over-shunting are typically intermittent and tend to occur later in the day. Lying down frequently makes the headaches better. This paper examines the efficacy of using abdominal binders to treat over-shunting headaches.

METHODS

Over an 18-year period, the senior author monitored 1027 children with shunts. Office charts of 483 active patients were retrospectively reviewed to identify those children with headaches and, in particular, those children who were thought to have headaches as a result of over-shunting. Abdominal binders were frequently used to treat children with presumed over-shunting headaches, and these data were analyzed.

RESULTS

Of the 483 patients undergoing chart review, 258 (53.4%) had headache. A clinical diagnosis of over-shunting was made in 103 patients (21.3% overall; 39.9% of patients with headache). In 14 patients, the headaches were very mild (1-2 on a 5-point scale) and infrequent (1 or 2 per month), and treatment with an abdominal binder was not thought indicated. Eighty-nine patients were treated with a binder, but 19 were excluded from this retrospective study for noncompliance, interruption of the binder trial, or lack of follow-up. The remaining 70 pediatric patients, who were diagnosed with over-shunting headaches and were treated with abdominal binders, were the subjects of a more detailed retrospective study. Significant headache improvement was observed in 85.8% of patients. On average, the patients wore the binders for approximately 1 month, and headache relief usually persisted even after the binders were discontinued. However, the headaches eventually did recur in many of the patients more than a year later. In these patients, reuse of the abdominal binder was successful in relieving headaches in 78.9%.

CONCLUSIONS

The abdominal binder is an effective, noninvasive therapy to control over-shunting headaches in most children. This treatment should be tried before any surgery is considered. It is suggested that the abdominal binder may modulate abnormally increased intracranial pulse pressures associated with over-shunting. Interactions with the cerebrovascular bed are suspected to account for persistent headache relief after the binder is discontinued.

Intraoperative assessment of endoscopic third ventriculostomy success

OBJECT

The authors' aim in this study was to determine if standardizing the evaluation of intraoperative findings during endoscopic third ventriculostomy (ETV) could predict patients with hydrocephalus in whom endoscopic treatment will fail and require ventriculoperitoneal shunt treatment. The creation of a uniform scale with predictive outcomes may reduce returns to the operating room for shunt treatment and reliance on postoperative externalized ventricular monitoring and MR imaging.

METHODS

The authors evaluated the preoperative history, intraoperative findings, and postoperative monitoring and imaging findings in 109 consecutive patients undergoing 112 consecutive attempted ETVs for obstructive hydrocephalus. A 5-grade scale was developed to assess preoperative risk factors and intraoperative evaluation to unify criteria that have been suspected to influence outcome independently. A grade of 0 was assigned to patients with no negative predictors, whereas increasing scores were assigned to patients who had multiple preoperative and intraoperative risks identified. Patients' grades were compared with outcome of the procedure, utility of externalized ventricular monitoring, and results of postoperative MR imaging.

RESULTS

Of 112 ETVs, 77 were successful and 35 were unsuccessful. Fifty-nine patients received a grade of 0, 27 received a grade of 1, 11 received a grade of 2, and 15 received a grade of > or = 3. In all 15 patients receiving a grade > or = 3 attempted ETV procedures failed, and the patients required a ventriculoperitoneal shunt. Postoperative monitoring with externalized ventricular drains and MR images demonstrating radiographic evidence of flow was independently less reliable than intraoperative grading in predicting success. Patients with a grade of 0 almost uniformly had successful surgery, independent of MR imaging findings. Patients with a grade of 1 or 2 who had successful surgery almost always lacked negative intraoperative predictive findings.

CONCLUSIONS

Despite reliance in recent years on post-ETV MR images and externalized ventricular monitoring, these modalities, although often useful adjuncts, appear less reliable as predictive tests than a simple assessment at the time of endoscopic fenestration. By using a uniform grading scale, the authors have introduced a novel means through which intraoperative and postoperative decision making can be aided, with the goal of reducing unnecessary procedures and tests and preventing unnecessary returns to the operating room.

Experience with the Strata valve in the management of shunt overdrainage

OBJECT

The overdrainage of cerebrospinal fluid (CSF) in children with shunt-treated hydrocephalus may cause chronic disabling symptoms and require repeated surgery. Externally adjustable valves offer a noninvasive way of altering the valve opening pressure. The authors report on their experience with using the Strata valve in the management of symptomatic CSF overdrainage.

METHODS

The authors treated 24 patients with symptomatic CSF overdrainage by inserting a Strata valve. The severity of symptoms was graded, and the frequency of hospital visits and shunt operations was recorded before and after insertion of the valve. Additionally, results of brain imaging and intracranial pressure monitoring were reviewed. Nineteen patients (79.2%) had severe symptoms at the time of the insertion; 1 year after Strata valve insertion only one patient (4.17%) still suffered severe symptoms. The number of hospital admissions was 3.38/patient/year before placement and 1.21 for the 1st year, 1 for the 2nd, and 0.4 for the 3rd postoperative year. The number of operations was 3.42/patient/year during the year before placement of the valve, and then 0.71 for the 1st, 0.56 for the 2nd, and 0.25 for the 3rd postoperative years. During the 1st year after placement of the Strata valve, the settings were changed 2.79 times/patient/year, 1.29 for the 2nd, and 1.33 times/patient/year for the 3rd year.

CONCLUSIONS

The Strata valve was effective in improving the symptoms of overdrainage in the majority of patients in this series. The number of hospital admissions and operations for valve malfunction was reduced.

Is intracranial pressure waveform analysis useful in the management of pediatric neurosurgical patients?

BACKGROUND

We have reported casuistic observations that intracranial pressure (ICP) waveform analysis may be useful in the management of pediatric patients.

METHOD

We here report our whole patient material of 65 children undergoing ICP monitoring with storage of their ICP raw data files during the years 2002-2005. We retrospectively explored the clinical symptoms/findings and radiological cerebral ventricular size before ICP monitoring. Mean ICP was the actively treated ICP parameter. Using an algorithm for identification of cardiac-beat-induced pressure waves we retrospectively determined the mean ICP wave amplitude and latency, in addition to mean ICP. Outcome with regard to change in symptoms/findings during a 1-year period was determined in 55 children.

RESULTS

The material includes children with hydrocephalus, craniosynostosis, shunt failure, benign intracranial hypertension and others. The ICP recordings gave wrong diagnostic information due to bad signal quality in 5 of 65 patients (7.7%). The mean ICP wave amplitude was increased in those with papilledema, lethargy and nausea. The main observations were that the mean ICP wave amplitude (not mean ICP) was increased in those that improved from clinical symptoms/findings after treatment and in those that were unchanged/worse after not being treated.

CONCLUSIONS

Waveform analysis with computation of the mean ICP wave amplitude was more useful by providing information about the quality of the ICP recording, by comparing better with the symptoms/findings at the time of ICP monitoring and by best predicting outcome. Most significantly, 14 of 55 patients (25%) with high amplitudes and left untreated did not recover spontaneously.

Assessment of childhood intracranial pressure recordings using a new method of processing intracranial pressure signals

BACKGROUND

Intracranial compliance may be more reliably predicted by the pulsatile component (pulse pressure) than the steady (mean pressure) component of intracranial pressure (ICP). A new method of processing continuous ICP signals assessing both components of ICP is described and applied to the ICP recordings of 6 pediatric cases.

METHOD

The new method was applied to each subsequent 6-second time sequence window of a continuous ICP signal. For time sequence windows including single ICP waves, the following time sequence (TS.x)-related parameters were computed: (a) mean ICP (i.e. TS.MeanP) was computed according to the currently used and known technology; (b) the mean ICP wave was computed according to the new method, characterized by mean wave amplitude (i.e. TS.MeanWavedP) and mean wave latency (i.e. TS.MeanWavedT). Cases No. 1-4 were treated for hydrocephalus and cases No. 5 and 6 for craniosynostosis.

RESULTS

In 5 children, clinical intracranial hypertension was associated with elevations of mean ICP above 15-20 mm Hg of variable durations. The ICP recordings of the 5 children with intracranial hypertension and successful outcome after surgery revealed mean wave amplitude values above 5 mm Hg. Mean wave latency was more variable, ranging between 0.10 and 0.25 s.

CONCLUSIONS

In the children with intracranial hypertension and successful outcome after surgery, mean wave amplitude was variably above 5 mm Hg. It is suggested that mean wave amplitude may be a useful parameter by more directly predicting cerebral compliance than mean ICP.