ENTRICULOPERITONEAL (VP) shunt placement inpatients with hydrocephalus is one of the mostcommonly performed operations in neurological

surgery. Despite the relative simplicity of this procedure,the complication rate can be significant. Surgical tech-nique, from proper tissue handling to accurate catheterplacement, plays a major role in reducing complicationsassociated with VP shunts. Improper placement of theventricular catheter may result in neurological injury fromthe misplaced catheter or early proximal shunt obstruc-tion. Thus, to obtain optimum shunt function and mini-mize morbidity, proper placement of the proximal catheteris mandatory.

The incidence of misplaced catheters varies anddepends on a number of factors, including the experienceof the surgeon; the size of the targeted ventricle; the sur-gical approach (frontal versus parietooccipital); and theuse of intraoperative guidance such as fluoroscopy, ultra-sound, or endoscopy. Few data are available on this topic,although, in a retrospective series, Albright, et al.,1 foundaccurate catheter placement in only 55% of frontal shuntsand 33% of parietooccipital shunts. Although four casesof ophthalmic injury following ventricular catheter inser-

tion were reported recently10 and intracerebral hemor-rhages secondary to misplacement have appeared in iso-lated clinical reports,5,7 the rate of such complications isnot known. Endoscopic placement of ventricular catheterswith an accurate placement rate of 90% has recently beenreported.9 The disadvantages of this technique are the costof the instrumentation, the added operative time, and thetime required for the surgeon to become familiar with thetechnique.

An accurate, rapid, and inexpensive tool to aid incatheter placement has been successfully developed byGhajar6 for placement of frontal ventricular catheter. Thisinstrument capitalizes on the anatomical observation thata line passing perpendicular to the skull at the coronalsuture will intersect the lateral ventricle. Unfortunately,such an anatomical relationship does not apply in the pari-etooccipital region.

We report a new device to aid in parietooccipitalcatheter placement. The posterior ventricular guide (PVG)uses a simple mechanical concept to orient a posteriorguide tube toward an anterior target. Catheter placementaccuracy using the PVG was assessed and compared toprevious results obtained without the guide.

J Neurosurg 82:300–304, 1995

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A guide to placement of parietooccipital ventricular catheters

Technical note

MATTHEW A. HOWARD III, M.D., JAYASHREE SRINIVASAN, M.D., CARL G. BEVERING, B.S.,H. RICHARD WINN, M.D., AND M. SEAN GRADY, M.D.

Division of Neurological Surgery, Department of Surgery, University of Iowa, Iowa City, Iowa; andDepartment of Neurological Surgery, University of Washington, Seattle, Washington

U Accurate placement of parietooccipital ventricular catheters can be difficult and frustrating. To minimize the morbidi-ty of the procedure and lengthen the duration of shunt function, the catheter tip should lie in the ipsilateral frontal horn.The authors describe a posterior ventricular guide (PVG) for placement of parietooccipital catheters that operates bymechanically coupling the posterior burr hole to the anterior target point. In a series of 38 patients who underwent ven-triculoperitoneal shunting with the assistance of the guide, postoperative computerized tomography (CT) scanning re-vealed that 35 (92.0%) had accurate catheter placement. In comparison, a retrospective review of free-hand posteriorcatheter placement revealed good catheter position in only 22 of 43 patients (51.1%). The use of the guide added less than5 minutes to the entire procedure, and there were no complications related to its use. The PVG is a simple and useful toolthat aids in the placement of parietooccipital ventricular catheters.

KEY WORDS • hydrocephalus • ventriculoperitoneal shunt • guide • placement

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Description of the Ventricular Guide

The PVG is a simple mechanical assembly in which anadjustable catheter guide tube is oriented along a line thatintersects a fixed target point. The guide tube and the tar-get point are mechanically coupled so that a catheterpassed through the guide tube with a rigid stylet will havethe optimum orientation toward the target point.

Lightweight aluminum guides were manufactured inthe University of Washington and University of Iowa sci-entific instrument shops and can be used on all patientsregardless of head circumference (Fig. 1A and B). Theguides were sterilized by autoclave prior to each use.

Surgical Technique

The patient is positioned and prepped for a standardparietooccipital VP shunt with one exception: the fore-head is covered by transparent adhesive drapes to allowvisualization of the frontal target site, which is located inthe midline 1 cm above the supraorbital rim. A modifiedBovie cleaning pad,* with an approximately 5 3 5-mmsquare cut in the center, is placed on the forehead with thehole directly over the target site. The correct location ofthe burr hole is imperative for successful use of the PVG;

in adults and older children, the burr hold is placed 7 cmabove the inion and 3 cm lateral to the midline. In infants,the burr hole is made 3 to 4 cm above the inion and 2 to3 cm lateral to the midline. A preoperative computerizedtomography (CT) scan is used to identify anatomicalanomalies and to estimate the depth of catheter placementneeded to reach the frontal horn of the lateral ventricle.

Once the burr hold is made and the dura opened, thePVG is positioned with the anterior target indicator rest-ing on the opening in the Bovie pad and the adjustableguide tube positioned several millimeters above the burrhole so that the pial surface is still visible (Fig. 1C and D).A standard 25-cm ventricular catheter over a long straight-wire stylet is passed through the guide tube to the desireddepth. The stylet is removed to confirm ventricular entry,the guide tube withdrawn, and the PVG removed from thepatient’s head. The remainder of the operation is complet-ed according to standard surgical protocol.

Clinical Studies

Under institutional review board approval, a prospec-tive clinical study of the PVG was initiated at theUniversity of Washington–affiliated hospitals. Over an18-month period, all patients with hydrocephalus whowere on the authors’ (H.R.W., M.S.G.) clinical servicesunderwent parietooccipital VP shunt placement using thePVG, unless there were contraindications to this route,

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Posterior ventricular catheter guide

FIG. 1. A and B: Photographs depicting elements of the posterior ventricular guide (PVG). The adjustable catheterguide tube is inserted into the main assembly and secured by tightening the guide screw, and the modified square cauterycleaning pad is secured to the frontal target site. During catheter placement, the conical nosepiece of the main assemblyrests on the frontal target site (A). The adjustable catheter guide tube is in position and a ventricular catheter has beenpassed through the tube using a metal stylet. The catheter follows a straight trajectory toward the frontal target site (B).C and D: Schematic drawings showing the guide technique. The PVG is positioned for right occipital catheter placement,and the adjustable guide tube positioned close to the burr hole so that the catheter is visible as it exits the guide tube andenters the brain (C). The surgeon has passed the stylet and catheter through the tube and into the ipsilateral lateral ven-tricle. Note the straight trajectory of the ventricular catheter toward the frontal target site (D).

* Bovie cleaning pad supplied by Baxter Healthcare Corp.,Deerfield, Illinois.

such as recent occipital surgery. All patients with hydro-cephalus were included, regardless of ventricular size.The trial was continued at the University of Iowa by oneauthor (M.A.H.) who moved to that institution. The oper-ative records documented the number of attempts made toachieve good catheter placement and any intraoperativedifficulties encountered. A postoperative CT scan wasobtained prior to discharge to identify the position of theventricular catheter. A correct placement was classified asone in which the tip of the catheter lay in the anterior hornof the ipsilateral lateral ventricle.

The accuracy of free-hand parietooccipital catheterplacement was determined by a retrospective review ofall patients undergoing parietooccipital VP shunt place-ment over a recent 2-year period at both the Universityof Washington and the University of Iowa. Forty-threepatient charts were reviewed, with particular attentionpaid to operative reports and postoperative studies to doc-ument shunt placement. On review, we found that theoperative notes often did not take note of the number ofpass attempts made, making it difficult to compare to thePVG data. Either anteroposterior and lateral skull radio-grams or CT scans were obtained postoperatively in allpatients; good placement, as observed on radiogram, con-sisted of catheter tip placement in the ipsilateral frontalhorn. The CT criteria for judging placement were thesame for the PVG and free-hand data.

Clinical Results

Patient Population

A total of 38 patients underwent parietooccipital VPshunt placement with the assistance of the PVG. Theseindividuals ranged in age from 7 to 82 years of age, withan average age of 59.6 years. Presumed etiologies ofhydrocephalus included subarachnoid hemorrhage, nor-mal-pressure hydrocephalus, trauma, and miscellaneouscauses (Table 1).

Operative Technique

In 34 of 38 operations (89.5%), the catheter was placedon the first pass; poor flow of cerebrospinal fluid (CSF) intwo patients and no flow in two others was noted. Two ofthese shunts were placed early in the series and the poor

CSF flow resulted from incorrect placement of the poste-rior burr hole; this was corrected by placement of a secondburr hole. The catheter was inadvertently deflected on adural edge within the burr hole in one case; this was easi-ly corrected by retracting the dural leaves with bipolarcautery. The fourth case occurred later in the series in ayoung patient with small ventricles and elevated intracra-nial pressure. Following placement of the catheter, a smallvolume of fluid was released under high pressure, afterwhich spontaneous flow ceased. The catheter was re-moved and replaced by a second catheter without alteringthe position of the PVG, on the assumption that thecatheter had become obstructed. The flow remained poorthrough the second catheter, but an intraoperative pneu-moencephalogram revealed good catheter position and itwas left in place. A postoperative CT scan confirmed theaccurate position and the patient made an uneventfulrecovery.

Postoperative Results

Postoperative CT scans demonstrated good catheterplacement in 35 of 38 patients (92.0%), with the tip of thecatheter being in the ipsilateral frontal horn of the lateralventricle. In two cases (5.3%), the catheter crossedthe midline and ended in the contralateral ventricle. Inone case (2.6%), a small hematoma developed along thecatheter tract in the parietal lobe, although the catheterwas in the correct position (Table 2).

Three patients died (7.9%): one, the first patient of theseries, from a myocardial infarction 3 days followingshunt placement and two from complications of theirunderlying diagnosis of subarachnoid hemorrhage. Therewere no shunt infections or malfunctions during this brieffollow-up period.

A total of 43 patients who had undergone free-handparietooccipital VP shunt placement at both institutionswere reviewed. Patient age distribution (mean 53 years)and etiologies of hydrocephalus did not differ significant-ly from the PVG group (p . 0.05) (Table 1). Accurateoperative data were not available for these patients, but allhad postoperative radiographic studies to determinecatheter position: 37 (86%) had CT scans and six (14%)had anteroposterior and lateral skull radiograms. Twenty-two patients (51.1%) had accurate placement of the ven-tricular catheter, although 21 (48.9%) did not. In 17 ofthese latter patients (39.5% of all patients), the cathetercrossed the midline to rest in the contralateral anteriorhorn. In one patient, the catheter traversed the ipsilateral

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basal ganglia to end in the frontal horn, and in another, thecatheter was passed too far, with the tip in the periventric-ular frontal lobe. A single catheter was also not placeddeeply enough and ended at the foramen of Munro (Table2). None of these patients suffered any immediate clinicalconsequences from the positions of the catheters; howev-er, long-term follow-up is not available.

The frequency of optimal catheter placement was com-pared between the PVG group and the free-hand group.By chi-square analysis, the difference in accurate place-ment in the PVG group (92.0%) versus the free-handgroup (51.1%) was statistically significant (x2 = 14.31,p , 0.001).

Discussion

In the placement of a VP shunt, the ventricle may becannulated by one of two approaches: frontal or parieto-occipital. Each approach has its advantages and disadvan-tages.1,3 The frontal approach is technically simpler fortwo reasons: the landmarks are easier to identify and thetarget distance is shorter. These reasons also make the pos-terior approach more hazardous; however, there are otherfactors that counterbalance these shortcomings. The pari-etooccipital site, for example, is optimally situated for acontinuous subcutaneous path to the abdomen, thus avoid-ing an additional incision. Furthermore, there is evidencethat suggests that the parietooccipital shunt carries lessrisk of epilepsy than a frontal one: Dan and Wade4 foundan incidence of 6.6% for parietooccipital shunts and54.5% for frontal shunts, although the number of patientsin the frontal group was significantly smaller and othershave not found any difference.8,11

With a frontal approach, the nose and the ear providesimultaneous spatial references for the surgeon and bothare visible during catheter placement. With the posteriorapproach, the target in the glabellar region is not visible tothe surgeon during catheter placement or, conversely, ifthe surgeon is situated anteriorly, the burr hole andcatheter are hidden. The catheter trajectory must be esti-mated and is thus subject to inaccuracy.

The distance separating the tip of a misplaced catheterand its intended target depends both on the error in the tra-jectory angle and the distance the catheter travels. For agiven error angle, the absolute distance by which thecatheter tip misses the intended target increases linearlywith the increasing length of the catheter pass. For exam-ple, a parietooccipital catheter 10 cm in length passed ina straight line with a trajectory error angle of 5˚ will havea final catheter tip position twice as far from the target asa frontal catheter 5 cm in length with the same angle oferror (Fig. 2). Thus, the angular trajectory of a posteriorcatheter is crucial for proper placement.

The PVG is designed to resolve the difficulty in choos-ing the correct catheter trajectory. By mechanically cou-pling a guide to target point indicator, the catheter is ori-ented in the optimum direction toward the target. Thistechnique was successfully used by a number of surgeonsin this trial and resulted in accurate catheter placementwhile adding less than 5 minutes to the procedure.Postoperative CT scans demonstrated correct catheterplacement in 35 of 38 cases (92%), a significantly higher

percentage than noted in a retrospective series of free-hand posterior catheter placement, in which only 51.1% ofpatients had accurate catheter placement (p , 0.001).

Although these differences are very significant, thereare certain facts to be considered. The first is that accura-cy of catheter placement depends on the surgeon’s experi-ence with posterior shunt placement. This variable is notcontrolled in this study; several surgeons performed oper-ations in each group (PVG versus free hand) and not allwere involved in both groups. Second, the clinical conse-quences of poor catheter placement are not discussed inthis paper. Becker and Nulsen2 first noted the importanceof the frontal horn position for parietooccipital shunts in1968 and Albright, et al.,1 found a statistically significantdifference in duration of shunt function between properlyplaced frontal and parietooccipital catheter and those thateither crossed the midline or ended in parenchyma. Themost common free-hand placement error noted in thisseries occurred when the catheter tip crossed the midlineto enter the anterior horn of the contralateral ventricle. Thelong-term significance of this type of error has not beenreported and may not be clinically important. Third,although the PVG is simple to use, meticulous surgicaltechnique is still necessary. The guide’s only function is toprovide the correct catheter trajectory. It will not, forexample, correct for errors in burr-hole selection. Both thebone and the dural edge may deflect the catheter from itsintended course, so care must be taken to ensure that thecatheter is free from impingement at the pial surface. Thestylet must not be bent, as this will cause the catheter todeviate from the target.

The simplicity of use and the high degree of accuracyare compelling arguments for the PVG. In a free-handplacement, once the entrance and target sites are selected,the surgeon must rely on visual-spatial skills to orientthe catheter properly. The PVG eliminates the chanceassociated with this and provides consistent and accuratecatheter placement; furthermore, it does so in an inexpen-sive and rapid manner, adding less than 5 minutes to the

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Posterior ventricular catheter guide

FIG. 2. Graphs demonstrating how an error in trajectory anglehas a greater effect with increasing distance. The distance thecatheter has been passed is represented in the x-axis and the errorangle is calculated from this axis. The y-axis represents the error indistance from target point for a given angle of error.

entire procedure. For these reasons, we believe that it is avaluable asset in parietooccipital shunt procedures andwill help minimize the morbidity secondary to this com-mon neurosurgical procedure.

Disclosure

The authors have no financial interest in the instrumentation ormethodology described in this report.

References

1. Albright AL, Haines SJ, Taylor FH: Function of parietal andfrontal shunts in childhood hydrocephalus. J Neurosurg 69:883–886, 1988

2. Becker DP, Nulsen FE: Control of hydrocephalus by a valve-regulated venous shunt: avoidance of complications in pro-longed shunt maintenance. J Neurosurg 28:215–226, 1968

3. Bierbauer KS, Storrs BB, McLone DG, et al: A prospective,randomized study of shunt function and infections as a functionof shunt placement. Pediatr Neurosurg 16:287–291, 1991

4. Dan NG, Wade MJ: The incidence of epilepsy after ventricularshunting procedures. J Neurosurg 65:19–21, 1986

5. Derdeyn CP, Delashaw JB, Broaddus WC, et al: Detection of

shunt-induced intracerebral hemorrhage by postoperative skullfilms: a report of two cases. Neurosurgery 22:755–757, 1988

6. Ghajar JBG: A guide for ventricular catheter placement: techni-cal note. J Neurosurg 63:985–986, 1985

7. Kuwamura K, Kokunai T: Intraventricular hematoma sec-ondary to a ventriculoperitoneal shunt. Neurosurgery 10:384–386, 1982

8. Leggate J, Baxter P, Minns RA, et al: Epilepsy following ven-tricular shunt placement. J Neurosurg 68:318–319, 1988(Letter)

9. Manwaring KH: Endoscope-guided placement of the ventricu-loperitoneal shunt, in Manwaring KH, Crone KR (eds): Neu-roendoscopy. Vol 1. New York: Mary Ann Liebert, 1992, pp29–40

10. Shults WT, Hamby S, Corbett JJ, et al: Neuro-ophthalmic com-plications of intracranial catheters. Neurosurgery 33:135–138,1993

11. Venes JL, Dauser RC: Epilepsy following ventricular shuntplacement. J Neurosurg 66:154–155, 1987 (Letter)

Manuscript received January 27, 1994.Accepted in final form June 3, 1994.Address reprint requests to: Matthew A. Howard III, M.D.,

Department of Surgery, Division of Neurosurgery, 200 HawkinsDrive, Iowa City, Iowa 52242–1061.

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