Cerebrospinal Fluid Shunts

Transcription

1 Refer to: Sells CJ, Shurtleff DB: Cerebrospinal fluid shunts. West J Med 127:93-98, Aug 1977 Cerebrospinal Fluid Shunts CLIFFORD J. SELLS, MD, and DAVID B. SHURTLEFF, MD, Seattle Cerebrospinal fluid (CSF) shunt technology has undergone rapid advances in the past two decades. As a result, pediatricians and other primary care physicians are being asked with increasing frequency to provide care for persons with CSF shunts. Familiarity with the more common shunts is a prerequisite to intelligent management of shunt related problems. Physicians providing daily care must have carefully documented hospital records and operative notes available to them as well as information detailing the safe evaluation of shunt patency and function if they are to manage patients with CSF shunts properly. In addition, parents and guardians must be alerted to signs and symptoms related to shunt malfunction. CEREBROSPINAL FLUID (CSF) shunting systems and shunt technology have undergone rapid advances over the past two decades.'-9 Pediatricians and other primary care physicians are being asked with increasing frequency to care for children with CSF shunts. The differentiation of shunt complications from non-shunt related problems and the management of acute shunt obstruction and infection, particularly when neurosurgical colleagues are unavailable, requires pediatricians and other physicians to understand CSF shunt mechanisms. Newly developed shunt systems include several externally similar but structurally and functionally different devices.*2 Some devices can be safely From the Department of Pediatrics, the Child Development and Mental Retardation Center and the Division of Congenital Defects, University of Washington School of Medicine, and the Children's Orthopedic Hospital and Medical Center, Seattle. Submitted September 23, Supported in part by the National Foundation March of Dimes Grants C#112 and CA#25, and in part by Maternal and Child Health Services, Bureau of Community Health Services, Health Services Administration, Department of Health, Education and Welfare, Project #913. *Devices or elements are sometimes used as synonyms for valves, pumps, or reservoirs. In this article, device and element are used as general terms. The use of the word valve is restricted to describing a device or element with internal parts providing oneor two-way flow. Reprint requests to: Clifford J. Sells, MD, Child Development & Mental Retardation Center Clinical Training Unit, WJ-10, University of Washington School of Medicine, Seattle, WA punctured by a small gauge needle for aspiration for diagnosis, for the injection of antibiotics or radioisotopes and for pressure measurements; but other devices cannot. Some shunts have bidirectional flow and allow access to both the cerebral ventricle and the distal limb, while others provide unidirectional flow only and allow access only to a portion of the shunt mechanism. Familiarity with the more common shunts and an understanding of the potential of reservoirs, pumps and valves is a prerequisite to appropriate management of acute shunt obstruction and infection. The purpose of this article is to provide primary care physicians with basic technical information about cerebrospinal fluid shunting systems. Types of Systems Cerebrospinal fluid shunt systems may be divided into six groups depending upon their physically palpable parts. Reservoirs (Figure 1) are devices without internal parts with no shunting capabilities unless converted. They provide access to the cerebral ventricle for drug injection, aspiration or pressure recordings, but have no palpable distal tubing. They may have side-arm THE WESTERN JOURNAL OF MEDICINE 93

2 B If j: A, - j 0t _., i! i' :1 1 ;.1w Figure 1.-Reservoirs. These elements have neither internal parts nor cerebrospinal fluid shunting capabilities unless converted and are safely perforable. A, Rickham Reservoir-Metal reservoir with soft cap without side-arm. B, Convertible Ommaya Reservoir- All soft parts reservoir with optional side-arm for later connection to a shunt system. " B "..i _ 1. attachments for later coupling to a distal device, thereby allowing for continuous CSF drainage. A second group of systems consist of a single dome-shaped device and a single palpable distal tube leading to the neck (Figure 2). These devices, as are all Heyer systems, are used with Pudenz one-way distal slit valve catheters (Figures 2-6). The Pudenz One-Way Flushing Reservoir (Figure 2A) and the Mishler Pudenz Double Lumen Reservoir (Figure 2B) are two members of this group. The Pudenz One-Way Flushing Reservoir allows CSF aspiration from the proximal end and distal flushing either by injection or external dome pressure. Needle puncture of the inner, or lower chamber may result in valve incompetency. The Mishler Pudenz Double Lumen Reservoir has two chambers. The outer chamber permits aspiration from the cerebral ventricle only. Injection into the outer chamber or slight dome compression forces CSF simultaneously toward both proximal and distal shunt limbs, toward the cerebral ventricle with distal limb occlusion or obstruction* or toward the distal shunt limb with proximal limb obstruction. The inner chamber of the Mishler Pudenz Double Lumen Reservoir permits aspiration from both chambers as well as from the proximal limb and cerebral ventricle. Injection into the inner chamber or firm dome pressure will push CSF distally only. A firm or resistant outer chamber indicates distal and either inner chamber or proximal limb obstruction. A firm or resistant inner chamber indicates distal limb obstruction only. Failure of the outer chamber to refill after compression in- *Occlusion implies csf blockage by external manual compression while obstruction implies intratubing blockage to csf flow. Figure 2.-Single Dome Devices with Palpable Distal Tube (Pictured with Pudenz One-Way Distal Slit Valvethe distal tip of either cardiac or peritoneal catheters). A, Pudenz One-Way Flushing Reservoir. B, Mishler Pudenz Double Lumen Reservoir. This unit combines an inner distal direction pumping device surrounded by an outer proximal direction pumping device. Both reservoirs are safely perforable. dicates proximal limb obstruction, while failure of the inner chamber to refill after compression indicates either outer to inner chamber or proximal limb obstruction. Intermittent external pressure (pumping) on the inner chamber of the Mishler Pudenz Double Lumen Reservoir or on the Pudenz One-Way Flushing Reservoir will result in distal CSF flow. The devices shown in Figures 1 and 2 lie over or partially in a cranial burr hole. A third group of systems has a proximal tube leading from the cranial burr hole to a single dome element as well as a distal tube leading to the neck. These single dome devices may or may not have a one- or two-way valve with or without cerebral access. Members of this group may be difficult to differentiate clinically from each other. The Foltz To and Fro Flushing Reservoir (Figure 3A) and the Mishler Pudenz Double Lumen Reservoir with flat bottom (Figure 3B) are two examples of this group. The Foltz Reservoir with proximal tube occlusion or obstruction allows access to the distal limb during injection into or pressure on the dome, causing CSF to flow distally. With occlusion of the distal limb, injection into or pressure on the dome forces CSF!I 94 AUGUST 1977 * 127 * 2

3 A w si, --K:"t-.iii.i ----;6? -AK - -. ^P F. n ;.j.st;E Figure 3.-Single Dome Devices with Two Palpable Shunt Tubes (Pictured with Pudenz One-Way Distal Slit Valve). A, Foltz To and Fro Flushing Reservoir. This device is safely perforable. B, Mishler Pudenz Double Lumen Reservoir with Flat Bottom. Both chambers are safely perforable. flow proximally and may "blow out" a ventricular end obstruction. Repetitious finger pressure first on the proximal tubing and then simultaneously on the dome causes CSF to flow distally. A firm dome with occlusive pressure on either limb indicates obstruction in the other limb. A firm, noncompressible dome indicates distal and proximal tube occlusion. The Mishler Pudenz Double Lumen Reservoir with the flat bottom and the standard Mishler Pudenz Double Lumen Reservoir have similar palpable and functional characteristics except for the palpable proximal tube with the flat bottom device which can be occluded, therefore assuring CSF flow distally with dome compression. A fourth group of systems has two round dome elements, may or may not have valves and is capable of occlusion and pumping functions. The Braden Reservoir (Figure 4A) and the Coe-Schulte Flushing Reservoir (Figure 4B) are two members of this group. A fifth group consists of cylindrical spring and slit-sleeve or ball valves. They are tubular to palpation, are of variable size and have hard metal ends. The Holter valve (Figure 5A) and the Hakim valve (Figure 5B) are two members of this group. They may be attached to perforable antechambers or reservoirs if inserted after The addition of an antechamber or reservoir allows for perforation for injection, aspiration or pressure recordings from the cerebral ventricles. Figure 4.-Double Dome Systems (Pictured with Pudenz One-Way Distal Slit Valve). A, Braden Reservoir. This unit has two soft compressible domes mounted on a palpable oblong platform and functions similarly to the Foltz To and Fro Flushing Reservoir. By occluding the inlet/outlet domes access is gained to the distal or proximal end of the system. Both domes are safely perforable. B, Coe-Schulte Flushing Reservoir. This unit has a proximal soft and a distal firm compressible dome. Constant pressure on the distal dome occludes forward flow, allowing ventricular access with injection into or pressure on the proximal dome. Repetitive pressure on the distal dome pumps cerebrospinal fluid distally. Although cerebrospinal fluid may be aspirated from either dome, perforation of the inner distal device (dome) may cause damage. Perforation of the tubular valve itself, however, may lead to leakage or damage to the valves and subsequent malfunction. With occlusive finger pressure on the valve, injection into or pressure on the reservoir or antechamber results in retrograde CSF flow toward the cerebral ventricle. Repetitive finger pressure on the soft midsection of these tubular valves pumps CSF toward the distal limb. Neither valve, if competent, allows CSF to flow retrograde toward the cerebral limb. A valve that depresses with difficulty indicates obstruction distal to the point of pressure. Recently, the most complex and most easily distinguishable valve, the Heyer-Schulte Multi- Purpose Valve, has been introduced (Figure 6). It consists of four devices and includes an occluder, a device designed to prevent loss of proximal limb occlusion by external compression when bony overgrowth occurs, a reservoir, a differential pressure valve (Miter) with an on-off control, and an antisiphon device. The antisiphon device is a valve that prevents the excessive drainage of CSF during negative pressures and is particularly important in patients with inspiratory air- THE WESTERN JOURNAL OF MEDICINE 95

4 B -4 Figure 5.-Tubular One-Way Valves with Reservoirs. The reservoir and antechamber are safely perforablethe valves are not. A, Holter Valve with Rickham Reservoir. B, Hakim Valve and Antechamber. ECSEREIR VLE D SEVO'N DEVICE RESERVOIR VALVE NSFCOF NT2II _. -=-=T _T = = I Figure 6.-Heyer-Schulte Multi-Purpose Valve. (Pictured with Pudenz One-Way Distal Slit Valve). The reservoir is safely perforable while the antisiphon device is not. The occluder prevents cerebrospinal fluid flow in both directions with external pressure and is more effective than tube compression. The Miter differential pressure valve as opposed to the Heyer distal slit valves is protected from changes secondary to body fluids. The on-off control is radiopaque. External pressure engages the button occluding cerebrospinal fluid flow. Finger pressure on the occluder with simultaneous pressure on the reservoir will "pop up" the button, thus allowing cerebrospinal fluid flow. way obstruction and an intrathoracic distal shunt tip. Partial largyngeal nerve paralysis, resulting in inspiratory airway obstruction, is a frequent complication of the Arnold-Chiari malformation associated with the myelodysplasia-hydrocephalus complex.10 It seems reasonable to expect that components of the "multipurpose" valve of the Heyer system, such as the occluder and antisiphon device, will be used in combination with other Figure 7.-Common CSF Shunt Systems. A, Foltz To and Fro Flushing Reservoir (two inlets) with MPF Ventricular and Raimondi Spring Peritoneal Catheters. The two inlet device is used when shunting from two areas is indicated. The MPF (multiperforated flange) ventricular catheter with its flanges and numerous perforations minimizes the chances of clogging while the embedded spring in the Raimondi catheter is designed to reduce kinking. B, Pudenz One-Way Flushing Reservoir with Standard Pudenz Ventricular and Infant Cardiac Catheters for use in infants with very small veins. C, Heyer-Schulte Multi-Purpose Valve with Standard Pudenz Ventricular and Peritoneal Catheters. D, Holter Valve and Rickham Reservoir with Standard Ventricular and Pudenz Infant Cardiac Catheters. E, Hakim Valve and Antechamber with radiopaque Curved Ventricular and Straight Drainage Catheters. reservoirs and valves of various future. Some of the more common fluid shunt systems are pictured in types in the cerebrospinal Figure 7. General Principles of CSF Shunt Systems The various CSF devices are designed to (1) allow unidirectional CSF flow, (2) allow flushing of the distal shunt using increased pressure, (3) allow retrograde (ventricular) flushing of shunts, (4) allow intra-ventricular injections of therapeutic or diagnostic agents, (5) allow graded levels of CSF flow, (6) limit CSF flow during times of negative intrathoracic or intra-abdominal pressure and (7) allow for intermittent CSF drainage. The one-way flow slit valves such as the Holter and Pudenz were originally developed to assure unidirectional CSF flow without reflux of blood or other body fluids. The Hakim ball-spring oneway distal flow valve was later developed to handle high protein and cell conitaining fluids, fluids not as well handled by the Holter and Pudenz valves. A number of devices have been 96 AUGUST 1977 * 127 * 2

5 developed to allow for proximal or cerebral flushing or injection and are, therefore, safely perforable using a 25 gauge or smaller needle with strict aseptic technique. They include some Heyer units (Figures 2B, 3, 4, 6), the Rickham Reservoir attached proximally to the Holter system, and the "antechamber" portion of the Hakim valve system. Pressure gradients have been modified by altering spring strength (Hakim) or tubing thickness and compliance (Heyer, Holter and Miter) to allow high, medium or low pressure shunt valve openings.2-3'7 A recent ingenious addition to shunt devices consists of a bottom plug which can shut off CSF drainage without operation (Figure 6). The evaluation of shunt function is dependent upon the specific device. A firm or resistant chamber or dome generally indicates obstruction in one or both limbs depending upon the particular device. A dome that compresses but does not refill indicates flow of CSF distally or proximally, or both, but no or poor CSF flow from the cerebral ventricle toward the dome. A dome that returns to a full position with proximal occlusion indicates that the distal valve is incompetent, there is a leak in the device or tubing and the defect is surrounded by fluid, or proximal occlusion is not complete. A malfunctioning shunt per se, however, in the absence of clinical symptoms is not an indication for shunt revision as a significant number of persons with CSF shunts may be asymptomatic with "nonfunctioning" shunts. Sudden death, however, has been observed in a few of our teenage patients with an acute illness and a nonfunctioning shunt in an otherwise asymptomatic patient. A clinician cannot always distinguish by palpation the type of device encountered since with time bone and connective tissues tend to obscure the distinguishable characteristics. In addition, certain materials used in devices tend to harden with time,'1 making identification and evaluation of function by palpation even more difficult. Barium impregnated catheters, tips and tubing, as well as the metal parts of certain devices make the identification by x-ray of certain devices possible2'3'7"12 (Figure 8). Documentation of certain physical measurements may at times facilitate identification of certain devices.18 Discussion Although comparative studies of the various shunt mechanisms have not been reported, the diagnosis, treatment and management of shunt obstruction and infection have been greatly facilitated by the development and improvement of such devices. The advantage of proximal shunt access allows for the direct installation of anti- Figure 8.-Radlographs of Common Shunt Systems. Holter Valve (left) without Rickham Reservoir, Pudenz One- Way Flushing Reservoir with MPF Catheter (center)-tubing connectors are palpable but radiolucent, and Hakim Valve and Antechamber with right angle (proximal) and straight (distal to valve units) metal tubing connectors (right). All components are subcutaneous except the three partially radiopaque ventricular catheters. The radiolucencies in the center and right roentgenographs are due to small volume air contrast studies now generally replaced by safer and more informative computerized tomography and combined pressure and radionucleotide studies. THE WESTERN JOURNAL OF MEDICINE 97

6 biotics into the ventricular system resulting in notably increased recovery rates from shuntrelated infections.'4"5 Ventricular and distal shunt system access also allows for direct CSF pressure recordings and more recently for the evaluation of shunt patency and shunt dependency using radioisotope techniques.'v'8 The advantages gained by the use of the various shunt mechanisms available, however, must be weighed against the mechanical problems inherent in the more complex devices. Our policy is to use the simplest, softest available device that allows both direct cerebral ventricular access and distal access, as well as bidirectional shunt flushing. Acute shunt obstruction and shunt-related infections can rapidly be fatal if unrecognized, untreated or improperly managed. The physician responsible for the care of children with CSF shunts must be familiar with these devices if he is to manage these patients intelligently. Intefligent management of shunt-related problems by primary care physicians, in addition to familiarity with shunt mechanisms, requires the availability of carefully documented and transcribed operative notes and hospital records of the exact type of shunt system involved. Physicians responsible for the daily care of these children should receive from the neurosurgeon full explanations for safely evaluating shunt patency and function. Parents and other persons concerned with the child's well-being should also be fully informed regarding the signs and symptoms of shunt-related CEREBROSPINAL FLUID SHUNTS problems as well as the function of the patient's device. Also, patients with CSF shunts should wear identification tags stating the type of their device. REFERENCES 1. Coe JE, Rivet JR, Hargest TS: Twin reservoir flushing device for hydrocephalus. J Neurosurg 28:85-86, Heyer-Schulte Systems for the Treatment of Hydrocephalus. Randolph, MA, Codman and Shurtleff, Inc, Control of hydrocephalus using the Holter ventriculoatrial shunt system. Extracorporal Medical Specialties, Inc, Matthews ES, Becker MH, Nelson KM, et al: Metrically marked radiopaque tubing for in vivo use. Radiology 91: , Ojemann RG: Initial experiences with the Hakim valve for ventriculovenous shunt. J Neurosurg 28: , Pudenz RH: Experimental and clinical observations on the shunting of cerebrospinal fluid into the circulatory system. Clin Neurosurg 5:98-115, The Cordis-Hakim Valve System for Ventricular Shunting, 4th Ed. Miami, FL, Cordis Corp, Rickham PP, Penn IA: The place of the ventriculostomy reservoir in the treatment of myelomeningoceles and hydrocephalus. Develop Med Child Neurol 7: , Raimondi AJ, Matsumato S: A simplified technique for performing the ventriculo-peritoneal shunt. J Neurosurg 26: , Peach B: The Arnold-Chiari malformation: Morphogenesis. Arch Neurol 12: , Leininger RI, Mirkovitch V, Peters A, et al: Change in properties of plastic during implantation. Trans Amer Soc Artif lnt Organs 10: , Altman J, James AE Jr: Ventriculo-venous cerebrospinal fluid shunts-roentgenologic analysis: Am J Roentgen 112: Shurtleff DB: Characteristics of CSF shunt systems. Clin Pediatr (In Press) 14. Morrice JJ, Young DG: Bacterial colonization of Holter valves: A ten-year survey. Dev Med Child Neurol (Supp 32) 16:85-90, Shurtleff DB, Foltz EL, Weeks RD, et al: Therapy of staphylococcus epidermidis: Infections associated with cerebrospinal fluid shunts. Pediatrics 53:55-61, Hayden PW, Rudd TG, Dizmang D, et al: Evaluation of surgically treated hydrocephalus by radionuclide clearance studies of the cerebrospinal fluid shunt. Develop Med Child Neurol (Supp 32) 16:72-78, Hayden PW, Shurtleff DB, Foltz EL: Ventricular fluid pressure recordings in hydrocephalic patients. Archive Neurol 23: , Rudd TG, Shurtleff DB, Loeser JD, et al: Radionuclide assessment of cerebrospinal fluid shunt function in children. J Nucl Med 14: , AUGUST 1977 * 127 * 2