Surgical Management of Hydrocephalus in the Adult

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Chapter 94 Surgical Management of Hydrocephalus in the Adult

David M. Frim, Richard Penn, Maureen Lacy

Hydrocephalus, from the Greek word meaning “water in the head,” is a general term used to describe many conditions of fluid collected in the intracranial space. For the purposes of this chapter, we define hydrocephalus as an inappropriate amount of cerebrospinal fluid (CSF) within the intracranial space at an inappropriate pressure. In this way, we can include a variety of both childhood and adult syndromes of abnormal CSF flow and absorption patterns and the sequelae of their treatments. This definition excludes syndromes such as the pseudotumor cerebri syndrome,1,2 whose etiology and treatment may be somewhat different from those of hydrocephalus. Our definition would include low-pressure hydrocephalus syndromes in which the ventricles stay enlarged with relatively normal pressures, despite our lack of understanding of these syndromes.3,4

From a practical standpoint, the treatment of hydrocephalus in the adult can be divided into two broad categories: childhood onset and adult onset. The first situation revolves mostly around upkeep of shunting devices and monitoring of a care strategy already implemented to prevent or treat complications. The latter situation necessitates a standard approach of evaluation of a clinical entity, choice of intervention strategy, and then implementation of that intervention. We deal with these two situations separately.

Management of the Adult Treated for Hydrocephalus as a Child

As much as 40% of pediatric neurosurgical practice in most large centers involves the treatment of hydrocephalus. The most common etiologic factor is premature birth and intraventricular hemorrhage. The presumption is that blood in the CSF causes either scarring in the subarachnoid space or sclerosis from inflammation at the absorptive surface of the arachnoid villi. This situation decreases the absorption rate of fluid and causes hydrocephalus with four-ventricle dilatation. This condition has been referred to as communicating or absorptive hydrocephalus. Other etiologies for an absorptive defect in children can be a congenital incontinence of the arachnoid villi for a variety of etiologic reasons or an obstruction within the CSF pathways that will cause ventricular dilatation upstream from the obstruction. The most common situation that presents in this fashion is aqueductal stenosis from either scarring or a benign tectal tumor. In children, obstructive hydrocephalus is first approached with the question of whether the obstruction can be removed or bypassed. Endoscopic third ventriculocisternostomy can be performed to bypass aqueductal obstruction with a high rate of success. At this stage in our ability to treat hydrocephalus, absorptive hydrocephalus causing dilatation of all four ventricles is almost always treated by an extracranial shunting device.

Children who have been treated with a third ventriculocisternostomy bypass need to be monitored into adulthood because there is risk of the ostomy closing many years after its initial placement. The true incidence of this is not yet known but is believed to be relatively low if the ostomy has survived several years. The adult who presents with a third ventriculocisternostomy bypass from childhood can be periodically evaluated by an imaging study such as magnetic resonance imaging with a cinematic gated flow study through the ostomy.5 If the ostomy has begun to occlude, the lateral and third ventricles may slowly begin to enlarge, even in the absence of overt clinical symptoms. Options for treatment at this time include endoscopic re-exploration for reconstruction of the ostomy or placement of a shunting device.

The management of the majority of adult hydrocephalus that was first treated in childhood revolves around the upkeep of extracranial CSF shunting devices. The utility of yearly or biennially shunt checks for pediatric and adult patients is controversial. Our practice is to maintain a regimen of more or less yearly shunt check evaluations in all our adult patients with shunts to maintain contact with the patient and the patient’s family, as well as to continually review the presentation and dangers of shunt malfunction. Where the upkeep of a shunting device in a child may concern issues of growth, such as ascertaining whether the extracranial portion of the shunt tubing is of adequate length during periods of growth or the ventricular catheter does not extrude from the ventricular system due to head growth, upkeep and management of shunting devices in adults are more straightforward. Shunt longevity is much longer in older children and adults than in infants,6 presumably due to issues of growth. In the adult, as in the child, the most common overall complication of shunt placement is a malfunction due to catheter or valve occlusion or fracture.7,8 The next most common complication is shunt infection, which is generally seen in an early phase after implantation.9 Beyond that, issues of overdrainage and underdrainage may also need to be confronted.

Shunt malfunction in the adult, as generally seen in a child, presents with stereotypic symptoms more or less similar to past shunt malfunctions and consistent with the initial presentation of the hydrocephalus. In adulthood, cognitively high-functioning patients are often able to make the diagnosis on clinical grounds. The evaluation consists of the usual radiographic studies such as plain shunt radiographs and a head computed tomography scan after an adequate patient history has been taken and a physical examination has been performed. Oftentimes, the diagnosis of shunt malfunction is made due to either mechanical obstruction of the shunt tubing or enlargement of the ventricular system. In that situation, the shunt is explored operatively in the usual fashion.

We have generally opened the scalp incision first to determine the ventricular catheter patency versus malfunction of the components from the valve to the distal tubing. We then replace one portion of the shunt, either that in the brain or the extracranial space, in its entirety. Our experience, like that of others, has shown no benefit to replacing the entire shunt versus revision of the affected component.6 Usually we replace a nonfunctioning valve with a valve of a similar type if the patient had done well for some time with that same valve. This may be different from the situation in the infant or child in whom, as the child grows, drainage needs may require a change to a valve type with other characteristics.

The advent of percutaneously programmable, differential pressure valves and programmable valves with fused antisiphoning components (Table 94-1) allows some flexibility in installing a valve that can provide dynamics similar to those of the one being replaced and retains the option of changing the shunting dynamics without operative intervention. With regard to shunt revision in the adult patient, generally we recommend replacing those components that are nonfunctional but not disturbing other components that appear to be functioning adequately.

Table 94-1 Currently Available Shunting Valves

Valve Type Examples
Differential pressure (siphoning) Contour (Medtronic Neurosurgery, Minneapolis, MN)
Hakim (Integra Lifesciences, Plainsboro, NJ)
Medos nonprogrammable (Codman/Johnson & Johnson, Randolf, MA)
Nonsiphoning, combination, differential pressure Delta (Medtronic Neurosurgery)
Equiflow (Radionics/Integra Lifesciences, Plainsboro, NJ)
Novus (Integra Lifesciences)
Percutaneously programmable, differential variable pressure Codman-Hakim programmable (Codman/Johnson & Johnson)
Sophy (Sophysa, Orsay, France)
Strata NSC (Medtronic Neurosurgery)
Percutaneously programmable, nonsiphoning or gravity compensating, variable pressure Strata (Medtronic Neurosurgery)
Aesculap-Miethke proGAV (Miethke/Aesculap, Center Valley, PA)
Flow dependent Orbis-Sigma (Integra Lifesciences)
Diamond (Phoenix Biomedical, Mississauga, Ontario, Canada)

Shunt infection in the adult patient almost always presents with some sign of systemic infection such as a fever, elevated serum leukocyte count, or frank meningitis, although the risk factors for infection, as well as many commonly used approaches to reduce infection rates in CSF shunts, remain insufficiently studied to determine significance.10 The severity of symptoms depends on the infectious agent and may range from headache with minimal other signs of infection (for relatively benign organisms such as Staphylococcus epidermidis or Corynebacterium) to a more virulent picture of life-threatening meningitis (if the etiologic agent is Staphylococcus aureus or a gram-negative organism). A shunt infection needs to be treated as any foreign body infection would be in an adult, with removal of all infected foreign body material, which in general means removal of the entire shunt. Depending on the etiology of the hydrocephalus and the need for daily drainage, the shunt can be replaced with an external draining ventricular catheter or a lumbar drainage catheter for the period of the antibiotic treatment. Although the length of this period of temporary external drainage and antibiotic treatment can vary, most recommendations include at least several days of external drainage with negative CSF cultures before replacement of the shunting device in a new location, if possible.10 Depending on the terminus of the shunt, whether it is in the peritoneum, the pleura, or the cardiac atrium, the infection may spread or become loculated in those areas and require separate treatment. One other late complication of infection in the adult population that is more common than in the pediatric population is sclerosis of an absorbing surface from acute or chronic infection. In the peritoneum, this presents as a CSF pseudocyst or ascites, and in the pleural space this may present as CSF pleural effusion. In either situation, once recurrent infection is ruled out, the distal CSF catheter may be moved to another location or placed in the vascular tree through a large vein into the cardiac atrium where reabsorptive sclerosis is not present.

Shunt overdrainage and underdrainage in the adult can become a problem with age, in which presumably the brain may require lower pressure analogous to the normal-pressure hydrocephalus syndrome, which is described later. In that situation, the approach to the shunting dynamics is similar to that in the normal- or low-pressure hydrocephalus situation in that a trial of drainage at a low pressure may be appropriate or a programmable valve can be placed to allow percutaneous programming to lower pressures.

Our impression is that, in patients whom we have followed from childhood into adulthood, complications seem to be reduced as children reach adulthood. The etiologic basis for this is unclear but may have to do with cessation of growth and reduced physical activity. Upkeep and care of the adult who was treated for hydrocephalus as a child are quite rewarding and relatively straightforward.

Evaluation and Management of Hydrocephalus Presenting in Adulthood

The causes of hydrocephalus presenting in adulthood are the same and yet different from hydrocephalus presenting in childhood. Intraventricular and subarachnoid blood from aneurysmal subarachnoid hemorrhage or hemorrhage from intraparenchymal vascular malformations can cause chronic hydrocephalus via a mechanism believed to be similar to that seen in the absorptive hydrocephalus of prematurity. Similarly, bacterial meningitis can also cause inflammation and presumably scarring in the subarachnoid space or at the arachnoid villi that will cause an absorptive hydrocephalus. These entities present with four-ventricle enlargement as in childhood. Obstructive lesions such as tectal tumors or even congenital scarring at the sylvian aqueduct can cause triventricular enlargement and obstructive hydrocephalus, which present in adulthood.11 The treatment of aqueductal stenosis in an adult, similar to that in a child, is third ventriculocisternostomy to bypass the obstruction.12 Also, intraventricular tumors or large tumors abutting the ventricles can sometimes cause hydrocephalus from what is believed to be a CSF hyperprotein state that may reduce villus absorption of CSF. These causes of hydrocephalus and its presentation mirror similar situations in childhood and present with symptoms and signs of elevated intracranial pressure.

Normal-Pressure Hydrocephalus (Adult-Onset Chronic Hydrocephalus)

Unique to adults is the normal- or low-pressure hydrocephalus seen with advanced age. This syndrome, first described by Hakim and Adams13 40 years ago, has been undergoing continual reevaluation over the years. Classically, this syndrome presents as a triad of gait disorder, incontinence, and cognitive dysfunction, usually attention and short-term memory loss that can mimic a dementia.14 The patient has CSF pressures measured in the normal range on lumbar puncture, and symptoms may often be reduced by large volume removal of CSF. The diagnosis of normal-pressure hydrocephalus syndrome is a subject of considerable controversy, as is the decision to treat the syndrome by CSF shunting.3 A variety of diagnostic approaches have been described. These include imaging by computed tomography or magnetic resonance imaging, which show a characteristic pattern of ventricular enlargement with widening of the sylvian fissures and some cortical sulci.15–17 One or several large-volume lumbar taps reducing CSF pressure and volume relieving or reducing the symptomatology has been advocated as an indication for treatment. An infusion test of fluid into either the lumbar or the ventricular CSF space while monitoring pressure response to a given volume has also been advocated as a test to predict outcome from shunting for this syndrome.18 Bolus or continuous infusion can be used to measure compliance and outflow resistance. Long-term intracranial pressure measurements combined with magnetic resonance imaging to detect abnormal brain pressure waves have also been suggested.19 Better results for shunting may be possible by using a high threshold for selection, but this may miss some patients who would benefit from, but are not selected for, surgery. The combination of protocols of temporary lumbar20 or ventricular21 drainage to tonically reduce CSF pressures to even less than would be the normal range, cognitive testing before and after several days of CSF drainage, and daily physical therapy evaluations to assess gait function has also been used as a predictor of outcome from shunting in this syndrome.22 In our hands, such a protocol has had a 100% positive predictive value in 23 consecutive patients for a good outcome with shunting when clear improvement in neurocognition or gait function is observed after temporary lumbar drainage. However, the false-negative rate in our cohort has not been investigated by shunt placement when no improvement with temporary drainage is seen. The neuropsychology testing protocol used at the University of Chicago is presented in Table 94-2. Unfortunately, there are not yet universally accepted diagnostic criteria for normal-pressure hydrocephalus or an agreed-upon set of predictors of outcome after shunt placement.

Table 94-2 Testing Protocol Used to Assess Neurocognitive Responses to Long-Term Lumbar Drainage in the Patient with Normal-Pressure Hydrocephalus

Mini-Mental Status Examination
Repeatable Battery for the Assessment of Neuropsychological Status
Stroop Color–Word Test
Delis-Kaplan Executive Function System Sorting Test
Trail Making Test
Phonemic fluency
Clock-drawing test
Grooved Pegboard test
Geriatric Depression Scale (15 item)

Deciding When to Treat Hydrocephalus in the Adult

In adult hydrocephalus, symptoms are primarily due to inappropriate pressure within the ventricular system. Compression of brain tissue by ventricular enlargement may produce problems in gait due to stretching of subcortical white matter tracts. The rate of development of hydrocephalus differs significantly and affects which symptoms occur. Slow progression may lead to subtle changes in cognition; rapid progression leads to headache and loss of consciousness. These symptoms can include headache, vomiting, mental status change, gait changes, extraocular movement deficit, visual changes, or cognitive changes. Hydrocephalus presenting after aneurysmal subarachnoid hemorrhage is diagnosed in the ongoing evaluation and treatment of the lesion that has caused the bleeding. Similarly, hydrocephalus developing after meningitis is recognized as the meningitis is treated. However, the exact threshold for treatment of hydrocephalus in the adult can sometimes be difficult to define. Clearly, symptoms such as headache or cognitive changes, which are interfering with life or lifestyle, would constitute indications for initiating treatment, regardless of whether the hydrocephalus is from a process of reducing absorption or one of obstruction. Radiographic evidence of enlarging ventricles in the absence of overt symptoms may also constitute indications for intervention, although in many cases it is difficult to discern whether a process, such as an infection, has begun to cause global brain atrophy or whether inappropriate pressure within the ventricular system is causing ventricular enlargement.

Using our definition of hydrocephalus as an inappropriate amount of CSF under an inappropriate pressure, a measurement of CSF pressure either by lumbar puncture (in the setting of communicating hydrocephalus) or by direct ventricular access (in the setting of triventricular enlargement from obstruction) is diagnostic when combined with imaging. A secondary criterion when CSF pressure is measured by lumbar puncture or ventricular tap is to observe a reduction in presenting symptoms by a reduction in CSF pressure. This is the analogous situation to the large-volume CSF removal that is often performed for the diagnosis of normal-pressure hydrocephalus syndrome. The exact limits of what is considered normal CSF pressure in adults are unclear. Many would consider pressures as high as 20 cm H2O in the lumbar space with the patient in a supine position to be within the normal range. However, sometimes symptoms of elevated intracranial pressure can be witnessed when pressure is measured to be as low as 15 to 18 cm H2O, and those symptoms can be ameliorated by reduction in the CSF pressure to less than 10 or even less than 5 cm H2O. This situation begins to establish a continuum of inappropriate CSF pressures in the adult that begins in the clearly abnormal range above 20 or 25 cm H2O but can end quite squarely in the middle of what most would consider a normal-pressure value. Similarly, pressures as high as mid-20 cm H2O can be asymptomatic, with no change in ventricular size. Whether this defines compensated hydrocephalus or simply a variant of normal is unclear.

Regardless, when symptoms referable to elevated intracranial pressure in the presence of an enlarged ventricular space can be ameliorated or reduced by drainage of CSF, there exists a clear indication for treatment of hydrocephalus. In the absence of a pressure measurement, symptoms referable to elevated intracranial pressure that coincide with enlarged or enlarging ventricles also call for treatment. Precise indications for intervention are sometimes not possible, even considering ventricular size, CSF pressure, and the effect of drainage of CSF. Each case must be individually evaluated by the treating neurosurgeon. The goal of treatment is to restore a CSF pressure and dynamic that maximally reduces symptoms while maintaining the pressures within a range appropriate for cerebral profusion and reduces ventricular size to a normal range.

Choices of Techniques for Treating Hydrocephalus

The general approach to an individual presenting with symptomatic hydrocephalus or radiographic enlargement of ventricles depends on the etiology of the hydrocephalus. In practical terms, obstructive hydrocephalus should generally be considered for a bypass procedure or removal of obstruction before resorting to extracranial shunting. Hydrocephalus due to absorption or obstruction of the subarachnoid space with four-ventricle enlargement should be approached with extracranial shunting primarily. Aqueductal stenosis in a center where expertise is available should be treated by a third ventriculocisternostomy, which may avoid the need for permanently implanted hardware.23 Still, extracranial shunting is certainly an option that will adequately treat this type of hydrocephalus. Extracranial shunting for obstruction or for four-ventricle hydrocephalus provides the additional possibility of fine-tuning CSF drainage dynamics and pressures that a bypass procedure cannot accomplish.

Choices of Shunting Strategy and Shunting Hardware

Adults may be more sensitive to CSF dynamic pressure changes than children. This may be due to the decreased plasticity of the adult brain. Certainly, the existence of normal-pressure hydrocephalus syndrome in adults suggests that shunting in the adult may require obtaining a specific low CSF pressure or high flow rather than simply restoring elevated pressure to a normal range and allowing the brain to accommodate. Therefore, different shunting strategies may be of use in adult hydrocephalus.

The standard extracranial shunt operation now performed in this country is a ventricular catheter placed either frontally or occipitally and subcutaneously tunneled to an entry into the peritoneum. An intervening valve and often a tapping reservoir allow control of shunting pressure and access to the CSF space. The peritoneum provides little pressure of its own and allows drainage and reabsorption of a large volume of fluid. Alternative shunting strategies can rest on a different absorptive surface than the peritoneum. The cardiac atrium provides an egress for a very large volume of CSF. It can also handle high protein content that could cause malabsorption of spinal fluid in the peritoneal space. The pleural space also provides an alternative extracranial absorptive surface, but the pleural space generates its own negative pressure. This can be used to advantage in constructing a shunting system that provides less-than-normal pressure or even negative pressure if the valve is chosen appropriately.24 Antisiphoning components, which prevent negative pressure in the shunt tubing, can be used to counteract the negative pressure “sink” of the pleural space. The gallbladder can also be used as an absorptive surface, and it provides a positive pressure postprandially that prevents overdrainage.25 In addition, recipient sites such as the internal jugular vein in reverse orientation may be used in the adult more so than in the child because of easier access and a larger anatomy in which to place the distal shunting tube.26

Concerning placement of the catheter into the ventricular system, the larger head and larger ventricles of the adult provide better landmarks than those of the child. We have generally advocated a frontal approach in adults with small ventricles because of ease of ventricular access. An occipital approach is reasonable when the ventricles are large because it allows more catheter length to be placed within the ventricle and, particularly under endoscopic guidance, can allow the catheter tip to be placed as far as possible from the choroid plexus at the foramen of Monro.

A variety of shunting components are now available for use in constructing a shunting system. Although ventricular catheters and bur hole reservoirs are similar, shunt valves can be divided into three general groupings: differential pressure valves that siphon, differential pressure valves plus an antisiphoning or gravity-actuated resistance chamber that reduces siphoning, and valves designed to maintain constant flow of CSF called flow-control or flow-dependent valves (see Table 94-1). The differential pressure valves siphon when an adult stands upright and may cause low-pressure symptoms. However, this is a strategy that may be useful in a shunting system that drains CSF to a less-than-normal pressure. The antisiphoning shunt valves provide a more normal postural pressure dynamic but may underdrain in patients with normal-pressure hydrocephalus.27 The flow-control valves are not free of complications of overdrainage in normal-pressure hydrocephalus28 but are of value in patients who may require constant flow or flow that is more robust than that seen in the nonsiphoning combination valves. In any case, a thoughtful choice of an initial shunt system may prevent valve revision if the shunting system does not match an individual patient’s needs. However, at times, two or even all three valve types will need to be tried if a patient remains symptomatic from initial valve placement.

There are currently four percutaneously programmable, differential pressure valves available for purchase. The valve setting mechanisms range in pressure from 3 to 20 cm H2O by various increments. Only one of these valves, the Strata valve (Medtronic Neurosurgery) is manufactured with a fused antisiphoning chamber; a programmable valve from the Meithke Corporation contains a variable pressure differential component and a gravity-actuated resistance circuit in a single housing. To make the other two programmable valves (Codman-Hakim valve, Codman/Johnson & Johnson, and Sophy valve, Sophysa) into nonsiphoning valves, antisiphoning chambers need to be spliced inline distal to the valve mechanism. The Codman-Hakim valve is sold fused to a flow occlusive device; that device (called a siphon guard) can be of use in reducing the flow rate of the valve while allowing it to drain to a low pressure by a siphoning mechanism. The programmable valve can be of great use in the adult shunting system because adults may be less able to adapt to a fixed pressure than children, whose brains are more plastic.29,30 Therefore, variable pressure settings may allow fine-tuning of shunting pressures to symptoms. In addition, there is the theoretical benefit with normal-pressure hydrocephalus or hydrocephalus with large ventricles and a small cortical mantel in initially placing a shunt in a patient with a high differential pressure setting on the valve and then slowly decreasing that pressure to a more normal or even less-than-normal one. This may allow better accommodation and prevent ventricular collapse from sudden overdrainage, with the attendant risk of subdural hematoma due to rupture of bridging subdural veins. In the future, hardware cost may dictate much of the decision making in shunt system construction. For now, the many choices of shunt valves and other accompanying hardware makes selecting shunting hardware difficult, particularly because no randomized studies show any system to be clearly superior.12 Matching the shunt system to the patient’s individual needs is, therefore, somewhat of an art.

Technical Aspects in the Treatment of Adult Hydrocephalus

Technique of Endoscopic Third Ventriculocisternostomy

Endoscopic third ventriculocisternostomy is performed identically in adults and children. We recommend a coronal bur hole at the midpupillary line and dural opening to allow a 12.5- or 14-French (Fr) introducer with trocar. Once the ventricular space is entered, an endoscope, either rigid or flexible, is placed within the ventricular system and navigated through the foramen of Monro.

The landmarks for this navigation31 are the choroid plexus in the choroidal fissure, which dives into the foramen, and the septal and thalamostriate veins, which enter medially and anterolaterally into foramen of Monro. Once the foramen is traversed, navigation through the third ventricle is based on identification of the paired mammillary bodies from which the surgeon can discern the midline and anteriorly the retrochiasmatic space. Frequently, behind the retrochiasmatic space, a small red stripe that corresponds to the infundibulum is seen. In the space between the retrochiasmatic recess and the mammillary bodies is the flat and often thinned anterior floor of the third ventricle. We use a point one third of the way back from the retrochiasmatic recess for our ostomy hole. This minimizes the risk of injury to the basilar artery, which is generally positioned beneath the anterior floor in the posterior half. A blunt 1-mm probe is used to gently traverse through the floor of the third ventricle. The probe is left in place for a moment to potentially tamponade bleeding in the floor. Then a Fogarty balloon dilator of either 3 or 4 mm in size is introduced. This can be placed through a working channel of the endoscope with or without concurrent irrigation. The ostomy is gently dilated by inflating the balloon within it. An alternative technique of inflating the balloon on the inferior side of the ostomy and pulling it through the hole to tear the tissue can be successful, though it may cause bleeding. Bleeding is controlled either with warm saline irrigation or with unipolar or bipolar cautery devices available for work through the endoscope. Once the bleeding is controlled, the endoscope can be navigated through the ostomy to inspect the prepontine cistern, where it is used to fenestrate leaflets of arachnoid if that can be safely done without injury to the basilar artery. Once there is free flow of CSF throughout the prepontine cistern and through the ostomy hole, the ventriculoscope is withdrawn into the third ventricle, which is inspected for bleeding, and then withdrawn into the lateral ventricle.

In adults, we leave a ventricular catheter placed under endoscopic guidance by withdrawing the endoscope into the introducer sheath and then placing the sheath approximately 1 cm from the foramen of Monro. The ventriculoscope is then removed, and a ventricular catheter is placed so that it is (by measured length) at the tip of the introducer, which is then peeled out of the hole. The catheter is cut and connected to a blunt-ended bur hole reservoir. This catheter and tapping reservoir provide emergency access to CSF should there be sudden catastrophic occlusion of the ostomy. The patency of a third ventriculocisternostomy after several months to years is between 60% and 80%. If the ostomy provides egress of CSF for several years, even if it occludes at that time, the procedure can be repeated safely. Early failure of the ostomy generally requires extracranial CSF shunting for a permanent solution.

Techniques for the Placement of an Extracranial Shunting Device in Adults

Ventriculoperitoneal shunts are placed identically in adults and children. As a rule, connections within the shunt devices should be minimized, and whenever possible connections should be orthogonal to the direction of tube movement, such as a right angle connection from a bur hole reservoir device into the proximal end of a ventricular catheter. Ample tubing must be placed into the peritoneal or pleural space for catheter movement; however, issues of selecting a shunt catheter of adequate length for growth no longer apply in adulthood.

The procedures for placement of a ventriculoperitoneal shunt begin with the patient being placed in the supine position with the head turned from the side of the ventricular access. Usually, we place the head in the lateral position with the falx parallel to the floor and a roll under the shoulder ipsilateral to the shunt placement. Hair can be shaved or not per the surgeon’s preference.32 The entry site is chosen to be either at the coronal suture in the midpupillary line for frontal access to the ventricle or approximately 5 or 6 cm above the inion and 4 to 5 cm lateral from the midline for occipital access. The surgical prep is continuous from the frontal or occipital region and down along a track to the neck, chest, and belly. The shunting device is tested to make sure that it closes at an appropriate pressure and that all connections are secured. The abdominal incision is in the upper midline or subcostal. Care is taken to cover all skin surfaces with iodine-impregnated adhesive drapery and to minimize the exposed skin surfaces. We have infused intravenous antibiotics within 45 minutes of placement of the skin incision.

An incision is made, and then layers are divided through fascia in the midline or through fascia and muscles in a subcostal incision until the peritoneum is identified below the linea alba in the midline or below the posterior rectus fascia in the subcostal position. The peritoneum is grasped and then opened. The scalp incision is made over the selected bur hole entry site. A skin flap is then elevated and retracted. A bur hole is made with a perforator using either a power or a hand drill. Before the dura is opened, a pocket is made inferior to the bur hole and then a shunt-tunneling device is used to tunnel from the bur hole to the peritoneum. In the case of a frontal entry site, an intermediate incision behind the ear is usually required to “turn the corner” with the tunneling device. Either a tunneling sheath or a long silk tie is then used to pull the shunting components from the head to the abdominal incision. Once in place with a bur hole reservoir or other connector over the bur hole, the dura is opened with unipolar cautery and the pia is opened with bipolar cautery. The trajectory into the ventricular system can be determined either by preoperative computed tomography scanning or by estimate for an occipital approach using the contralateral medial canthus at a level in the midforehead and for a frontal approach using lines from the frontal bur hole to the medial canthus and from the bur hole to halfway between the lateral canthus and the tragus. An additional option, using a stereotactic intraoperative image guidance system for catheter placement, is now available from several companies who have constructed such systems. However, with the generally enlarged ventricles seen in adult onset hydrocephalus, ventricular access is usually easily obtained utilizing surface landmarks only. This observation should not be construed as a recommendation against the use of intraoperative navigational guidance, which can reduce reoperation for catheter malpositioning.

Once the catheter is placed and CSF egress is seen, the connection is made to the connector at the bur hole and is secured. The distal catheter is then placed in the peritoneum, and all incisions are closed in layers. For ventriculopleural access, we make an incision at the third or fourth rib off the midline in the same line that we would use for passage of the peritoneal catheter for a ventriculoperitoneal shunt. We then dissect down to the pleura through the muscles of the anterior chest wall and the intercostal muscles. Once the pleura is identified, it is not opened until the shunt is entirely connected. Analogous to the peritoneal catheter, which is placed in the peritoneum after the ventricular catheter is connected to the shunt, we also connect the ventricular catheter to the shunting device, visualize distal runoff of CSF, and then under direct vision make a pleural egress with a long hemostat and place approximately 20 cm of tubing into the pleural space. Alternatively, a trocar may be used for the catheter to be placed blindly. We recommend placement of a positive end–expiratory pressure valve in the anesthesia circuit to maintain lung inflation during placement of the pleural catheter and thus avoid pneumothorax.

For ventriculoatrial shunt placement, the procedure is best done with fluoroscopic or angiographic assistance. After the shunting device is connected either frontally or occipitally and a valve and distal tubing are in place, a tunnel is made either from the distal nipple of the valve (if placed occipitally) or from an intermediate incision behind the ear (if placed frontally) to a point over the internal jugular vein. This point is selected by placement of a “finding” needle and then a larger needle and J wire into the internal jugular vein on the neck lateral to the sternocleidomastoid muscle. The incision is enlarged with a stab wound, and adequate tubing is tunneled from the exposed distal valve nipple (or intermediate incision behind the ear) to the neck incision to allow the blunt-end catheter tubing into the cardiac atrium with an additional several centimeters for positioning. Once the wire is visualized in the cardiac atrium by fluoroscopy, a 10-Fr introducer sheath is placed over the wire, the wire is removed, and the tubing is threaded directly through the introducer sheath into the cardiac atrium under fluoroscopic guidance. If there is some kink in the venous system, a long, flexible guidance wire of a 0.038-inch diameter can be guided into the cardiac atrium and the atrial tubing can be threaded over the wire into the atrium. After wire removal, the tubing is then pulled back until it makes a straight connection to the shunting system, with the tip at the right atrium–superior vena cava junction. We have performed intraoperative cardiac angiography to confirm the placement of the catheter at the junction between the superior vena cava and the right atrium. Before connection, the atrial catheter is flushed with heparinized saline. Incisions are then closed in layers.

In our practice, other places for reabsorption of CSF, such as the gallbladder, are approached with the assistance of a general surgeon. Laparoscopic placement of peritoneal tubes also usually requires the assistance of a general surgeon until comfort is attained with that technique.

Complications of Treatment of Adult Hydrocephalus

Complications of a third ventriculostomy or other bypass procedures, whether they are fenestration of ventricular walls, cyst walls, or removal of obstructing tumors, are specific to the surgery for the bypass procedure. If the surgery proceeds without any immediate complications, the major long-term problem is whether the bypass ostomy occludes with time. This occurrence recapitulates the presenting symptoms of the hydrocephalus. If the ostomy fails, a decision needs to be made as to whether the ostomy can be reconstructed or whether the patient should proceed to placement of an extracranial shunting device.

Complications of extracranial shunting include shunt malfunction, shunt infection, and overdrainage and underdrainage of CSF, as well as complications relating to injury to the absorptive site by the distal shunting catheter.

Shunt Malfunction

Shunt malfunction is caused by occlusion or impedance to flow along the shunting device. The most common place for shunt malfunction occurs near the ventricular catheter from ingrowth of choroid plexus or other debris into the catheter, and this is true for both children and adults. Valve function can be degraded by particulate matter or protein within the CSF and necessitate valve replacement. Distal catheter occlusion in the peritoneal space can be precipitated by tissue ingrowth into the distal shunt tube. In all these situations, surgery must be performed to test the shunt components and to replace that which is malfunctioning.

The patient’s history and physical findings most often suggest elevated intracranial pressure. The symptoms often recapitulate those that occurred at the time of initial presentation with hydrocephalus. The elevation in CSF pressure can be tested by lumbar puncture in absorptive hydrocephalus or by direct shunt tap if the shunt does not communicate with the lumbar CSF space. Once the diagnosis of shunt malfunction is established, the patient needs to be brought to the operating room for exploration.

We always prepare the entire length of the shunt. The incision overlying the ventricular bur hole is first opened, and then the proximal and distal components of the shunt are disconnected and tested individually. The component that is occluded or malfunctioning is replaced. Proximally, the ventricular catheter is frequently occluded and thus needs replacement. If distal function is compromised, the valve or tubing is occluded and needs to be removed. Sometimes the manipulation of the shunting components during exploration releases a site of impedance of CSF flow. In those situations, the ventricular catheter is the most likely culprit based on clinical experience. In some cases, if shunt function was demonstrated preoperatively to be nonoptimal, the entire shunting system may need to be replaced if no specific malfunction is found at the time of surgery.

Shunt Infection

Shunt infection is treated identically in the adult and the child. Suspicion for shunt infection is based on clinical presentation and CSF cultures. In our hands, there is a higher yield for positive culture in the setting of infection from fluid obtained directly by shunt tap than for that obtained by a lumbar puncture. Once laboratory investigation data support infection either by Gram stain or culture results, the entire shunt is removed and replaced by a temporary draining ventriculostomy or, in some cases, a lumbar drainage catheter. In cases of normal-pressure hydrocephalus in which the patient has no overt or dangerous symptoms of hydrocephalus causing intracranial hypertension, the shunt may be removed in its entirety to have a period with no foreign body in the CSF space. Cultures are monitored daily from the external draining device when present. After several days of negative cultures, a new shunting device can be replaced at a site separate from the infected one. Few data provide a guideline for the length of temporary drainage before a new shunt is placed. Considerable variability in treatment of shunt infections is quite evident from the literature.9,10 It seems that the standard of care encompasses both direct replacement of shunts under antibiotic coverage with no intermediate phase of external drainage or external drainage that can be anything from a few days to several weeks under antibiotic coverage.

Other Complications

The shunting complication of overdrainage or underdrainage is one that is difficult to treat. In general, overdrainage from shunting is diagnosed by a postural headache that improves with lying down. This can be approached by insertion of an antisiphoning device, if that is not yet in the shunting system, or by changing the valve to a higher pressure. The percutaneous programmable valves are particularly useful for finding a pressure that is appropriate. In some cases, the distal shunt tubing needs to be moved to a different location that decreases drainage, such as the gallbladder or the internal jugular vein in reverse orientation. Changes of valve type from a differential pressure valve or a differential pressure valve with an antisiphoning component to a flow-dependent valve sometimes alleviates symptoms. However, overdrainage is generally a problem that causes symptoms but as yet has not been described as having long-term effects on neurologic function beyond the symptoms. Underdrainage of extracranial CSF shunting devices is a problem encountered more often in adults than in children. In particular, normal-pressure hydrocephalus, which by definition calls for CSF drainage to a less-than-normal pressure, can be inadequately treated by underdrainage. Valve changes by removing an antisiphoning component or by replacing a differential pressure valve with a flow-regulated valve may sometimes provide additional drainage. Also, revising the terminus of the shunting device from the peritoneal space to the pleural space, which generates negative pressure, can improve drainage characteristics. One particular caveat of normal-pressure hydrocephalus syndrome is that in several of our patients we have observed that, with time, the syndrome requires ever-lower-pressure drainage to achieve therapeutic results. The etiology of this change is not known, nor is the reason that it only seems to affect a subset of the population. However, eventually manipulations to provide ever-lower pressure can be exhausted.

The one acute potential complication of overdrainage, particularly in the elderly, is ventricular collapse and disruption of the subdural bridging veins, causing subdural hematoma. This is a potentially catastrophic complication in individuals who have compromised brain function. In general, when the subdural collection is small, we have advocated placing an antisiphoning device, if one is not yet in the system, and increasing the valve pressure. Although this usually resolves a small subdural collection in the situation of normal-pressure hydrocephalus, it brings back the original symptoms. Usually, patients can tolerate several weeks of no symptomatic relief to resolve the subdural hematoma before gradually lowering valve pressure. The use of a percutaneous programmable valve has greatly simplified this process.33 Another complication of overdrainage is the slit-ventricle syndrome. Thankfully, this is relatively rare in the adult population, but a variety of approaches to this problem have been advocated. They range from changes in valve pressure or the addition of an antisiphoning device to decompression of the intracranial space by craniectomy. Recently, we have found that the addition of a lumboperitoneal shunting system to the functioning ventricular shunting system can alleviate symptoms.34 The slit-ventricle syndrome can be diagnosed by high CSF pressures in the presence of slitlike ventricles and a functioning ventriculoperitoneal shunt. Several more detailed discussions of its manifestations and treatment have been published.35,36

Conclusions

The treatment of an adult with hydrocephalus is similar and yet distinct from that of a child in many respects. Much of the treatment of adult hydrocephalus is the ongoing maintenance of shunting devices placed during childhood. Diagnosis of adult-onset hydrocephalus of any type is made based on evidence of an inappropriate amount of CSF at an inappropriate pressure in the intracranial space. However, the normal-pressure hydrocephalus syndrome in the adult population makes the determination of what is an appropriate pressure confusing. Hydrocephalus from an obstructive source can be bypassed, or the obstruction can be attacked directly, thereby resolving the symptomatology. For hydrocephalus due to abnormal absorption, shunting of CSF to an extracranial absorptive surface is needed. Various shunting systems with different valve types exist, and several potential absorptive surfaces are available. The choice of the best valve and the optimal absorptive surface must be individualized. Bypassing an obstruction and extracranial shunting can result in several types of surgical complications. However, shunt malfunction, shunt infection, overshunting, and undershunting can be treated successfully if approached thoughtfully. The treatment of hydrocephalus in the adult can be a rewarding exercise in the diagnosis of the syndrome and in the use of current technology to treat it.

Key References

Aschoff A., Kremer P., Hashemi B., Kunze S. The scientific history of hydrocephalus and its treatment. Neurosurg Rev. 1999;22:67-95.

Bergsneider M., Peacock W.J., Mazziotta J.C., Becker D.P. Beneficial effect of siphoning in treatment of adult hydrocephalus [see comment]. Arch Neurol. 1999;56:1224-1229.

Borgbjerg B.M., Gjerris F., Albeck M.J., Borgesen S.E. Risk of infection after cerebrospinal fluid shunt: an analysis of 884 first-time shunts. Acta Neurochir. 1995;136:1-7.

Bret P., Guyotat J., Chazal J. 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” [see comment]. J Neurol Neurosurg Psychiatry. 2002;73:9-12.

Bruce D.A., Weprin B. The slit ventricle syndrome. Neurosurg Clin N Am. 2001;12:709-717.

el-Shafei I.L. Ventriculojugular shunt against the direction of blood flow. III. Operative technique and results. Childs Nerv Syst. 1987;3:342-349.

Frim D.M., Lathrop D., Chwals W.J. Intraventricular pressure dynamics in ventriculocholecystic shunting: a telemetric study. Pediatr Neurosurg. 2001;33:237-242.

Fukuhara T., Luciano M.G. Clinical features of late-onset idiopathic aqueductal stenosis. Surg Neurol. 2001;55:132-137.

Goumnerova L.C., Frim D.M. Treatment of hydrocephalus with third ventriculocisternostomy: outcome and CSF flow patterns. Pediatr Neurosurg. 1997;27:149-152.

Hebb A.O., Cusimano M.D. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. Neurosurgery. 2001;49:1166-1184.

Horgan M.A., Piatt J.H.Jr. Shaving of the scalp may increase the rate of infection in CSF shunt surgery. Pediatr Neurosurg. 1997;26:180-184.

Hurley R.A., Bradley W.G.Jr., Latifi H.T., Taber K.H. Normal pressure hydrocephalus: significance of MRI in a potentially treatable dementia. J Neuropsychiatry Clin Neurosci. 1999;11:297-300.

Kosmorsky G. Pseudotumor cerebri. Neurosurg Clin N Am. 2001;12:775-797.

Krauss J.K., Regel J.P. The predictive value of ventricular CSF removal in normal pressure hydrocephalus. Neurol Res. 1997;19:357-360.

Le H., Yamini B., Frim D.M. Lumboperitoneal shunting as a treatment for slit ventricle syndrome. Pediatr Neurosurg. 2002;36:178-182.

Mase M., Yamada K., Banno T., et al. Quantitative analysis of CSF flow dynamics using MRI in normal pressure hydrocephalus. Acta Neurochir Suppl. 1998;71:350-353.

Meier U., Bartels P. The importance of the intrathecal infusion test in the diagnosis of normal pressure hydrocephalus. J Clin Neurosci. 2002;9:260-267.

Meier U., Zeilinger F.S., Kintzel D. Signs, symptoms and course of normal pressure hydrocephalus in comparison with cerebral atrophy. Acta Neurochir. 1999;141:1039-1048.

Munshi I., Lathrop D., Madsen J.R., Frim D.M. Intraventricular pressure dynamics in patients with ventriculopleural shunts: a telemetric study. Pediatr Neurosurg. 1998;28:67-69.

Piatt J.H.Jr., Carlson C.V. A search for determinants of cerebrospinal fluid shunt survival: retrospective analysis of a 14-year institutional experience. Pediatr Neurosurg. 1993;19:233-242.

Qureshi A.I., Williams M.A., Razumovsky A.Y., Hanley D.F. Magnetic resonance imaging, unstable intracranial pressure and clinical outcome in patients with normal pressure hydrocephalus. Acta Neurochir Suppl. 1998;71:354-356.

Savolainen S., Hurskainen H., Paljarvi L., et al. Five-year outcome of normal pressure hydrocephalus with or without a shunt: predictive value of the clinical signs, neuropsychological evaluation and infusion test. Acta Neurochir. 2002;144:515-523.

Tisell M., Almstrom O., Stephensen H., et al. How effective is endoscopic third ventriculostomy in treating adult hydrocephalus caused by primary aqueductal stenosis? Neurosurgery. 2000;46:104-111.

Walchenbach R., Geiger E., Thomeer R.T., Vanneste J.A. The value of temporary external lumbar CSF drainage in predicting the outcome of shunting on normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry. 2002;72:503-506.

Zemack G., Romner B. Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients. Neurosurgery. 2002;51:1392-1402.

Numbered references appear on Expert Consult.

References

1. Kosmorsky G. Pseudotumor cerebri. Neurosurg Clin N Am. 2001;12:775-797.

2. Johnston I., Paterson A. Benign intracranial hypertension. I: diagnosis and prognosis. Brain. 1974;97:289-300.

3. Hebb A.O., Cusimano M.D. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. Neurosurgery. 2001;49:1166-1184.

4. Lamas E., Esparza J., Diez Lobato R. Intracranial pressure in adult non-tumoral hydrocephalus. J Neurosurg Sci. 1975;19:226-233.

5. Goumnerova L.C., Frim D.M. Treatment of hydrocephalus with third ventriculocisternostomy: outcome and CSF flow patterns. Pediatr Neurosurg. 1997;27:149-152.

6. Piatt J.H.Jr., Carlson C.V. A search for determinants of cerebrospinal fluid shunt survival: retrospective analysis of a 14-year institutional experience. Pediatr Neurosurg. 1993;19:233-242.

7. Kast J., Duong D., Nowzari F., et al. Time-related patterns of ventricular shunt failure. Childs Ner Syst. 1994;10:524-528.

8. Puca A., Anile C., Maira G., Rossi G. Cerebrospinal fluid shunting for hydrocephalus in the adult: factors related to shunt revision. Neurosurgery. 1991;29:822-826.

9. Piatt J.H.Jr. Cerebrospinal fluid shunt failure: late is different from early. Pediatr Neurosurg. 1995;23:133-139.

10. Borgbjerg B.M., Gjerris F., Albeck M.J., Borgesen S.E. Risk of infection after cerebrospinal fluid shunt: an analysis of 884 first-time shunts. Acta Neurochir. 1995;136:1-7.

11. Fukuhara T., Luciano M.G. Clinical features of late-onset idiopathic aqueductal stenosis. Surg Neurol. 2001;55:132-137.

12. Aschoff A., Kremer P., Hashemi B., Kunze S. The scientific history of hydrocephalus and its treatment. Neurosurg Rev. 1999;22:67-95.

13. Bret P., Guyotat J., Chazal J. 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” [see comment]. J Neurol Neurosurg Psychiatry. 2002;73:9-12.

14. Meier U., Zeilinger F.S., Kintzel D. Signs, symptoms and course of normal pressure hydrocephalus in comparison with cerebral atrophy. Acta Neurochir. 1999;141:1039-1048.

15. Raftopoulos C., Massager N., Baleriaux D., et al. Prospective analysis by computed tomography and long-term outcome of 23 adult patients with chronic idiopathic hydrocephalus. Neurosurgery. 1996;38:51-59.

16. Hurley R.A., Bradley W.G.Jr., Latifi H.T., Taber K.H. Normal pressure hydrocephalus: significance of MRI in a potentially treatable dementia. J Neuropsychiatry Clin Neurosci. 1999;11:297-300.

17. Mase M., Yamada K., Banno T., et al. Quantitative analysis of CSF flow dynamics using MRI in normal pressure hydrocephalus. Acta Neurochir Suppl. 1998;71:350-353.

18. Meier U., Bartels P. The importance of the intrathecal infusion test in the diagnosis of normal pressure hydrocephalus. J Clin Neurosci. 2002;9:260-267.

19. Qureshi A.I., Williams M.A., Razumovsky A.Y., Hanley D.F. Magnetic resonance imaging, unstable intracranial pressure and clinical outcome in patients with normal pressure hydrocephalus. Acta Neurochir Suppl. 1998;71:354-356.

20. Walchenbach R., Geiger E., Thomeer R.T., Vanneste J.A. The value of temporary external lumbar CSF drainage in predicting the outcome of shunting on normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry. 2002;72:503-506.

21. Krauss J.K., Regel J.P. The predictive value of ventricular CSF removal in normal pressure hydrocephalus. Neurol Res. 1997;19:357-360.

22. Savolainen S., Hurskainen H., Paljarvi L., et al. Five-year outcome of normal pressure hydrocephalus with or without a shunt: predictive value of the clinical signs, neuropsychological evaluation and infusion test. Acta Neurochir. 2002;144:515-523.

23. Tisell M., Almstrom O., Stephensen H., et al. How effective is endoscopic third ventriculostomy in treating adult hydrocephalus caused by primary aqueductal stenosis? Neurosurgery. 2000;46:104-111.

24. Munshi I., Lathrop D., Madsen J.R., Frim D.M. Intraventricular pressure dynamics in patients with ventriculopleural shunts: a telemetric study. Pediatr Neurosurg. 1998;28:67-69.

25. Frim D.M., Lathrop D., Chwals W.J. Intraventricular pressure dynamics in ventriculocholecystic shunting: a telemetric study. Pediatr Neurosurg. 2001;33:237-242.

26. el-Shafei I.L. Ventriculojugular shunt against the direction of blood flow. III. Operative technique and results. Childs Nerv Syst. 1987;3:342-349.

27. Bergsneider M., Peacock W.J., Mazziotta J.C., Becker D.P. Beneficial effect of siphoning in treatment of adult hydrocephalus [see comment]. Arch Neurol. 1999;56:1224-1229.

28. Weiner H.L., Constantini S., Cohen H., Wisoff J.H. Current treatment of normal-pressure hydrocephalus: comparison of flow-regulated and differential-pressure shunt valves. Neurosurgery. 1995;37:877-884.

29. Black P.M., Hakim R., Bailey N.O. The use of the Codman-Medos programmable Hakim valve in the management of patients with hydrocephalus: illustrative cases. Neurosurgery. 1994;34:1110-1113.

30. Zemack G., Romner B. Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients. Neurosurgery. 2002;51:1392-1402.

31. Vinas F.C., Dujovny N., Dujovny M. Microanatomical basis for the third ventriculostomy. Minim Invasive Neurosurg. 1996;39:116-221.

32. Horgan M.A., Piatt J.H.Jr. Shaving of the scalp may increase the rate of infection in CSF shunt surgery. Pediatr Neurosurg. 1997;26:180-184.

33. Kamano S., Nakano Y., Imanishi T., Hattori M. Management with a programmable pressure valve of subdural hematomas caused by a ventriculoperitoneal shunt: case report. Surg Neurol. 1991;35:381-383.

34. Le H., Yamini B., Frim D.M. Lumboperitoneal shunting as a treatment for slit ventricle syndrome. Pediatr Neurosurg. 2002;36:178-182.

35. Bruce D.A., Weprin B. The slit ventricle syndrome. Neurosurg Clin N Am. 2001;12:709-717.

36. Walker M.L., Fried A., Petronio J. Diagnosis and treatment of the slit ventricle syndrome. Neurosurg Clin N Am. 1993;4:707-714.

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