Methods and Complications in Surgical Cerebrospinal Fluid Shunting

Ventricular Catheter Insertion on the Occipital and Parietooccipital Bone: A Nonmetric Complementary Technique

Background and Study Aim Hydrocephalus is a common disease of the pediatric population, with cerebrospinal fluid diversion as the management of choice. All current insertion techniques require craniometrics calculation that may not be applicable for pediatric patients, due to significant variation in head circumference. We describe a complementary method of inserting ventricular catheters, devoid of craniometrics.

Materials and Methods The insertion site is based on two imaginary lines on the sagittal plane (superior and inferior limits) and four imaginary lines on the axial plane of a computed tomography/magnetic resonance imaging. The insertion point is chosen based on the shortest location from the outer table of the bone to the ventricle. The length of catheter insertion is calculated based on the distance between the calvarial outer table and the foramen of Monro.

Results Two case examples of ventricular catheter insertions, in pediatric patients with noncommunicating hydrocephalus, are described. External ventricular drain and ventriculoperitoneal shunt were inserted using this technique, with no required craniometrics measurements.

Conclusion This complementary method of inserting ventricular catheters can be easily tailored and implemented by junior neurosurgical residents to senior neurosurgeons as it precludes the measurement of the catheter insertion points.

Predicting the Ideal Ventricular Freehand Pass Trajectory Using Osirix Software and the Role of Occipital Shape Variations

BACKGROUND

Cannulation of lateral ventricles via a posterior approach is a common neurosurgical procedure. It is often believed that a single entry and fiducial point applies to all. No importance is given to skull shape variations, which can lead to wrong shunt positions and revisions.

OBJECTIVE

A virtual-reality study was conducted to find the ideal entry point, ideal forehead fiducial point, and ideal angulation of the ventricular catheter and variations in these with changes in skull shapes.

METHODS

Fifty human cadaveric skulls were used to measure anteroposterior (AP) diameter and width and to classify shape of skulls into 4 types. Hydrocephalus (100 cases) and normal magnetic resonance images (50 cases) were studied from a PACS (Picture Archiving and Communication System) database. An Osirix DICOM Viewer (3.9.4) was used to reconstruct the images and estimate the ideal, 90°, and midline shunt trajectory and correlate the same with AP/width ratios and skull shapes.

RESULTS

Contrary to popular practice, the vertical distance from the inion for ideal trajectory placement was <6 cm and >4 cm in all shapes and ratio groups for hydrocephalus and nonhydrocephalus cases, respectively. As the AP/width ratio increases, the fiducial needs to be placed at a higher distance from the nasion and the distance of the entry point also increased from the inion. A rounder or more dolichocephalic skull dictates a 90° approach to be better, especially as the first pass.

CONCLUSIONS

No magical external entry point uniformly applicable for all cases exists. Hence, there is a need to classify skulls according to shapes/ratios and to use a tailored approach for a freehand pass to cannulate the ventricles.

Development of robust biocompatible silicone with high resistance to protein adsorption and bacterial adhesion

A new biocompatible silicone comprising a carboxybetaine (CB) ester analogue, 3-methacryloxypropyltris(trimethylsiloxy)silane (TRIS) and an organic silicone macromer (bis-α,ω-(methacryloxypropyl) polydimethylsiloxane) has been developed using photo-polymerisation. Following interfacial hydrolysis of the CB ester, the resulting zwitterionic material became significantly more hydrophilic and exhibited high resistance to both non-specific protein adsorption and bacterial adhesion. Moreover, the stability of these non-fouling properties was dramatically improved by using a slow and controlled rate of ester hydrolysis of the original protective hydrophobic matrix. The subsequent ability to maintain the original optical and mechanical properties of the bare silicone following surface activation makes this material an ideal candidate for preparing contact lenses and other medical devices.

Optimization of ventricular catheter placement via posterior approaches: a virtual reality simulation study

BACKGROUND

This study aimed to evaluate 2 commonly used posterior approach entry points for ventricular cannulation and the ideal trajectories using 3-dimensional virtual reality technology.

METHODS

Magnetic resonance imaging data of 10 patients without gross ventricular dilatation or distortion were retrieved and reconstructed. A stereoscopic 3-dimensional preoperative planning system was used to designate the entry points. Various trajectories were simulated. The ideal trajectory was determined as the one that provided direct entry into the atrium or body of the lateral ventricle en route to the ipsilateral frontal horn.

RESULTS

Magnetic resonance imaging data sets from 10 patients were used. For the entry point 6 cm above and 4 cm lateral to the inion (Frazier's point), ideal cannulation was achieved for all 10 patients when the selected target was 4 cm above the contralateral medial canthus. When the contralateral medial canthus was targeted, 5 patients had successful outcomes. There were only 3 satisfactory outcomes each when the ipsilateral medial canthus and glabella were targeted. The target 2 cm above the glabella yielded 2 satisfactory outcomes. The entry point 3 cm above and 2 cm lateral to the inion (Dandy's point) had 10 satisfactory outcomes when the target point was 2 cm above the glabella. All the other target points, namely, ipsilateral medial canthus, contralateral medial canthus, 4 cm above the contralateral medial canthus and glabella yielded poor results.

CONCLUSIONS

For satisfactory placement when entering via Frazier's point, the best trajectory target would be 4 cm above the contralateral medial canthus. When entering via Dandy's point, the best target would be 2 cm above the glabella.

Accelerated progression of kaolin-induced hydrocephalus in aquaporin-4-deficient mice

Hydrocephalus is caused by an imbalance in cerebrospinal fluid (CSF) production and absorption, resulting in excess ventricular fluid accumulation and neurologic impairment. Current therapy for hydrocephalus involves surgical diversion of excess ventricular fluid. The water-transporting protein aquaporin-4 (AQP4) is expressed at the brain-CSF and blood-brain barriers. Here, we provide evidence for AQP4-facilitated CSF absorption in hydrocephalus by a transparenchymal pathway into the cerebral vasculature. A mouse model of obstructive hydrocephalus was created by injecting kaolin (2.5 mg/mouse) into the cisterna magna. Intracranial pressure (ICP) was approximately 5 mm Hg and ventricular size <0.3 mm(3) in control mice. Lateral ventricle volume increased to 3.7+/-0.5 and 5.1+/-0.5 mm(3) in AQP4 null mice at 3 and 5 days after injection, respectively, significantly greater than 2.6+/-0.3 and 3.5+/-0.5 mm(3) in wildtype mice (P<0.005). The corresponding ICP was 22+/-2 mm Hg at 3 days in AQP4 null mice, significantly greater than 14+/-1 mm Hg in wildtype mice (P<0.005). Brain parenchymal water content increased by 2% to 3% by 3 days, corresponding to approximately 50 muL of fluid, indicating backflow of CSF from the ventricle into the parenchymal extracellular space. A multi-compartment model of hydrocephalus based on experimental data from wildtype mice accurately reproduced the greater severity of hydrocephalus in AQP4 null mice, and predicted a much reduced severity if AQP4 expression/function were increased. Our results indicate a significant role for AQP4-mediated transparenchymal CSF absorption in hydrocephalus and provide a rational basis for evaluation of AQP4 induction as a nonsurgical therapy for hydrocephalus.

Non-shaved ventriculoperitoneal shunt in Thailand

The objective of this study was to determine whether non-shaved patients undergoing ventriculoperitoneal shunt operations would experience a significantly increased shunt infection rate as compared to shaved patients. Clinical trials of non-shaved scalp preparation were performed in ventriculoperitoneal shunt procedures at Songklanagarind Hospital from January 1994 to December 1999. Exclusion criteria were poor scalp condition, previous shunt procedures and immunocompromised hosts. Statistical analysis using univariate, multivariate and logistic regression was used. One hundred and nineteen patients were included in the study. Thirty-six cases were in the non-shaved group. Thirty-eight of 119 cases were less than one year of age and congenital hydrocephalus was the most common problem. The only notable risk factor for shunt infection was an operation lasting more than 59 min. The shunt infection rate in the non-shaved and shaved groups was 6.25% and 14.94%, respectively (p>0.05). In conclusion, leaving the hair intact for ventriculoperitoneal shunt surgery is safe and not associated with increased risk of shunt infection. The non-shaved method may encourage quicker restoration of the patients' self-image and facilitate their early return to normal life.

Failure rate of frontal versus parietal approaches for proximal catheter placement in ventriculoperitoneal shunts: revisited

Early studies on ventriculoperitoneal shunt malfunctions demonstrated that proximal catheter obstruction was the most common cause for shunt malfunction and choroid plexus was the primary culprit for catheter obstruction. Subsequently, several studies were performed using stereotactic and endoscopic guidance systems to assist with optimal placement of proximal shunt catheters. Surgeons collectively agree that optimum placement of the proximal catheter tip is away from choroid plexus in the frontal horn. To achieve this catheter placement, neurosurgeons typically choose a frontal or parietal approach. Two previous studies comparing parietal and frontal shunt failure rates in the pediatric population have different conclusions. Thus, we decided to compare proximal catheter failure rates of frontal versus parietal approaches on 117 patients (ages ranging from 1 month to 80 years) who had undergone ventriculoperitoneal shunt placement at our institution. Statistical analysis demonstrated a significantly higher malfunction rate in the patients less than 3 years of age and a lower overall malfunction rate in patients shunted for normal pressure hydrocephalus. Surprisingly, there was no significant difference between the two surgical approaches. Thus, we concluded after reviewing the literature, that regardless of the initial surgical approach, the most important variable in shunt malfunction appears to be the final destination of the catheter tip in relation to the choroid plexus.

Preassembled method for insertion of Ommaya reservoir

OBJECTIVE

Present a revised neurosurgical technique for insertion of the Ommaya reservoir that we have routinely utilized and found to have fewer complications that the standard approach.

EXPERIMENTAL DESIGN

Randomized retrospective study of 20 patients who underwent insertion of Ommaya reservoir with the preassembled technique.

SETTING

Major university hospital.

PATIENTS OR PARTICIPANTS

Twenty patients who underwent Ommaya reservoir placement within the last 5 years were randomly selected for chart and computed tomography review.

INTERVENTIONS

A new preassembled technique for Ommaya reservoir placement was utilized in all 20 patients.

MEASURES

Retrospective review of the patient records and computed tomography scans of 20 patients undergoing Ommaya placement were performed to assess ventricular catheter placement and any postoperative complications.

RESULTS

In all 20 patients, we had consistent ipsilateral right frontal horn placement of ventricular catheter and had no postoperative morbidities, reoperations for ventricular catheter positioning or mortalities.

CONCLUSIONS

This technique reduces overall operative time, decreases risk for intraoperative infection, and poor ventricular catheter placement by eliminating the manipulation step of connecting the reservoir to the catheter in vivo.

Surgical treatment of intracranial hypertension in encephalic cryptococcosis

The incidence of cryptococcosis has risen sharply together with the growing number of patients with Acquired Immunodeficiency Syndrome (AIDS). Cryptococcal meningitis is nowadays the most common intracranial non-viral infection in such cases. One of its most serious complications is intracranial hypertension (ICH), a situation that can lead either to early death, or disabling sequelae. The authors analyse a series of 10 cases of encephalic cryptococcosis with ICH, and describe the clinical course, diagnosis, medical and surgical treatment, and evolution. The physiopathology of ICH in these patients is discussed, proposing placement of a ventriculo-peritoneal shunt as the primary and emergency treatment, even when ventricular enlargement might be absent. Although the present series is certainly small, from the preceding discussion and according to an extensive bibliographical review, our conclusion is that patients with encephalic cryptococcosis and uncontrollable ICH should receive surgical treatment, consisting of an emergency diversion of the CSF, because serial lumbar punctures are not enough to improve the clinical course, that if left to its natural evolution would lead to a fatal outcome in a short time. In spite of the fact that CSF shunts were carried out on immunocompromised patients, no superinfections occurred.

Medical Devices of the Head, Neck, and Spine

There are many medical devices used for head, neck, and spinal diseases and injuries, and new devices are constantly being introduced. Many of the newest devices are variations on a previous theme. Knowing the specific name of a device is not important. It is important to recognize the presence of a device and to have an understanding of its function as well as to be able to recognize the complications associated with its use. The article discusses the most common and important devices of the head, neck, and spine, including cerebrospinal fluid shunts and the Codman Hakim programmable valve; subdural drainage catheters, subdural electrodes, intracranial electrodes, deep brain stimulators, and cerebellar electrodes; coils, balloons, adhesives, particles, and aneurysm clips; radiation therapy catheters, intracranial balloons for drug installation, and carmustine wafers; hearing aids, cochlear implants, and ossicular reconstruction prostheses; orbital prostheses, intraocular silicone oil, and lacrimal duct stents; anterior and posterior cervical plates, posterior cervical spine wiring, odontoid fracture fixation devices, cervical collars and halo vests; thoracic and lumbar spine implants, anterior and posterior instrumentation for the thoracic and lumbar spine, vertebroplasty, and artificial disks; spinal column stimulators, bone stimulators, intrathecal drug delivery pumps, and sacral stimulators; dental and facial implant devices; gastric and tracheal tubes; vagus nerve stimulators; lumboperitoneal shunts; and temperature- and oxygen-sensing probes.