in-depth view: how to perform a lumboperitoneal csf shunt · rhage secondary to head trauma,...

In-Depth View: How to Performa Lumboperitoneal CSF Shunt

Soumya Mukherjee and Paul D. Chumas

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2History of the Lumboperitoneal Shunt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Patient Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Communicating Hydrocephalus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Idiopathic Intracranial Hypertension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Cranial Base or Spinal Cerebrospinal Fluid Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Pseudomeningocele . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Normal Pressure Hydrocephalus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Occlusion of Major Intracranial Venous Sinuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Growing Skull Fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Contraindications to Lumbar-Peritoneal Shunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Description of the Shunt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

The Valve Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Lumbar Catheter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Peritoneal Catheter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Suture Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Preoperative Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Operative Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Anesthetic Considerations and Patient Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Checking the Valve for Patency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Introduction of the Lumbar Catheter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Mini-laparotomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Tunneling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Final Shunt Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Postoperative Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

S. Mukherjee • P.D. Chumas (*)The General Infirmary at Leeds, Leeds, UKe-mail: [email protected]

# Springer International Publishing AG 2017C. Di Rocco et al. (eds.), Textbook of Pediatric Neurosurgery,DOI 10.1007/978-3-319-31512-6_29-1

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mailto:[email protected]

Complications of Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Key Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Introduction

Lumboperitoneal shunting necessitates careful patient selection as it is associatedwith unique complications, in addition to those seen with other forms of CSFdiversion. In addition to the need for attention to detail at time of insertion,consideration regarding the choice of the most appropriate shunt system (andpossible valve inclusion) is required.

History of the Lumboperitoneal Shunt

Diversion of lumbar cerebrospinal fluid (CSF) into the peritoneal space wasattempted as early as 1898 by Ferguson (1898), who removed the arch of the fifthlumbar vertebra, pulled the cauda equine aside, and drilled a hole through the bodyof the vertebra. He passed a loop of silver wire bent inferiorly in the thecal sac,toward the peritoneum to act as a conduit for CSF flow. Three such cases did poorly.Subsequently in 1905, Nichol drew the free edge of the omentum into a defect in thespinal dura (Nicholl 1905). At around the same time, Cushing anastamosed thespinal subarachnoid space with the peritoneal or retroperitoneal spaces through acombined laminectomy and laparotomy using a silver cannula (Cushing 1905). Of12 such patients, he experienced three deaths. Heile experimented with severaldifferent anastomotic techniques, including intestinal serosa, silk strands, saphenousvein, a rubber catheter, and a direct anastomosis of the kidney pelvis followingnephrectomy (Heile 1914). All these early attempts at CSF diversion, althoughheroic, were associated with very high mortality and disastrous complications.Indeed Cushing wrote, “among the first of my patients – as will probably havebeen true of most young men entering this particular field – were infants with what isknown as essential hydrocephalus, for which a greater number of treatments have asyet been advocated than successes recorded – if indeed there are any clear-cutsuccesses at all recorded.”

The next phase was the introduction of a polyethylene catheter as a conduit.Using such a catheter, Matson standardized the technique of lumbar-ureteralshunting, which required a nephrectomy (Matson 1949). The major disadvantagesof the procedure were unregulated over-drainage of CSF, the need to resect onekidney, electrolyte imbalance, diarrhea, and bowel intussusception. Arachnoiditis,cracking, kinking, and obstruction of the shunt – thought to be the consequence ofthe polyethylene tubing – resulted in loss of favor with this form of shunting.

In 1949, Cone et al. performed the first successful modern lumboperitoneal shuntinsertion procedure (Jackson 1951). Soon after, Jackson and Snodgrass (1955) were

2 S. Mukherjee and P.D. Chumas

the first to report the outcomes of a sizeable series of lumboperitoneal as well asventriculoperitoneal shunts, and introduced the percutaneous technique on thesuggestion of Dr George Ehni. Following the introduction of silicone elastomersin shunt manufacture in 1967 there was a dramatic decline in shunt obstruction andfracture rates (Kestle et al. 2000; Spetzler et al. 1975), and this together with theintroduction of the percutaneous technique later popularized by Spetzler et al.(1975), led to a resurgence of LP shunting in the 1980s. The subsequent advent ofone-way valves that opened at predetermined pressures also signaled a majorbreakthrough.

Throughout the 1980s and early 1990s, LP shunting was popular and was evenperformed in very small babies using a limited laminotomy and insertion of a T-tube(Jea et al. 2007). However, problems with shunt migration, difficulty in knowingif the shunt was working, over-drainage causing headaches and acquired Chiarimalformation (ACM), and overall high failure rates all led to reappraisal of this formof shunting. These issues have since dictated the technical detail of the revisedoperative technique – the need for secure ties to prevent migration and the use todayof valve systems to prevent over-drainage.

Patient Selection

The general indication for a lumboperitoneal (LP) shunting procedure is the presenceof obstruction to the cerebrospinal fluid (CSF) absorptive mechanism with resultantincreased intracranial pressure, ventriculomegaly, or both. It should be noted, how-ever, that the role of these mechanisms in idiopathic intracranial hypertension, forwhich LP shunting can be used, is less clear. Effective LP shunting necessitates freecommunication between the ventricular system and the spinal subarachnoid path-ways. If an obstruction within the ventricular system exists (“obstructive hydroceph-alus”), LP shunting is contraindicated because it may result in catastrophic caudalherniation of brain stem structures.

LP shunting is largely reserved for adults and is very rare in children. Todemonstrate this point, case volume data from our own unit in the UK, a busytertiary referral institution for pediatric neurosurgery, show that during the last10 years, over 1000 CSF diversion procedures were performed in pediatric patients,85% of which were VP shunting procedures (two-fifths new insertions; three-fifthsrevisions). Only 16 cases (1.6%) were LP shunting procedures (six new insertions,two-thirds of which were for idiopathic intracranial hypertension; ten revisions).Several other centers’ experience reflect a similar rarity of pediatric LP shunting(Aoki 1990; Chumas et al. 1993a, b; Kulkarni et al. 1999). Indeed national data fromthe United Kingdom indicate that of more than 2200 CSF diversion (includingexternal ventricular drain) procedures performed in 2015 for children under theage of 16 years, only 14 (0.6%) were LP shunt operations, and of these only3 were new insertions, the remainder explorations or removals (British PaediatricNeurosurgery Group Audit Chair – personal communication). We will discuss allindications for both adult and pediatric LP shunting but concentrate on the latter.

In-Depth View: How to Perform a Lumboperitoneal CSF Shunt 3

Communicating Hydrocephalus

Communicating hydrocephalus, resulting from inadequate CSF absorption, washistorically the most common primary indication for LP shunting in children in the1990s, representing more than three-quarters of patients in the majority of studies inthe literature (Chumas et al. 1993a, b; Kulkarni et al. 1999). However, LP shuntingsubsequently became less commonly performed for communicating hydrocephalusonce its complications became more widely understood. A variety of etiologies areimplicated including previous acute or chronic meningitis and subarachnoid hemor-rhage secondary to head trauma, ruptured aneurysm, or arteriovenous malformationor an operative procedure. Prior to considering LP shunting, it is imperative to ensurevia adequate brain imaging that there is no loculation within the ventricular systemfrom ventriculitis and that there is no obstruction at the foramen of Monro or theaqueduct of Sylvius. It is also imperative to confirm that any active infectiousprocess has resolved; repeated negative cultures and normalization of cell countshould be documented. If the cerebrospinal fluid contains debris and/or a largenumber of cells, LP shunting should be delayed. In such instances, it may even bebeneficial to install temporary ventricular or lumbar drainage for several days toallow clearing of the fluid; occasionally this maneuver alone may eliminate the needfor a permanently implanted shunt.

Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) also known as pseudotumor cerebri his-torically represented up to 10% of pediatric LP shunt cases in the 1990s (Chumaset al. 1993a, b; Kulkarni et al. 1999). However since then, with LP shunting lesscommonly used for communicating hydrocephalus, IIH may now represent the mostcommon indication and this has certainly been the experience borne out at ourinstitution over the last decade. In the majority of instances it is a self-limited diseasewhich responds to the use of steroids, acetazolamide, repeated lumbar punctures, andelimination of any obvious risk factors. However, in some cases the syndromeremains intractable to therapy. The two major symptoms that dictate surgical therapyare progressive visual failure from papilledema due to increased intracranial pressureand intractable generalized headaches. In this small subset of patients who do notrespond to conventional medical therapy, surgical options should be considered.Patients with intractable headaches and visual failure are candidates for lumbar-peritoneal shunting. Alternatives include optic nerve heath fenestration orventriculo-distal shunting (Spitze et al. 2014). The former is outside the scope ofthis review but has been shown to be of particular use in patients with risk to visionrather than headaches (Wall 2008; Banta and Farris 2000). There have been nocontrolled trials comparing either of these alternatives with LP shunting. AlthoughVP shunting is likely to yield comparable results, the small size of the ventricles mayrender ventricular access technically difficult (and usually needs image guidedinsertion of the ventricular catheter). Other drawbacks with VP shunts for this


condition include the risk of epilepsy and the high chance of proximal shuntblockage. On the other hand, studies have shown relatively high rates of LP shuntmalfunction for pediatric IIH with revision rates in the range of 50–75% (Chumaset al. 1993a; Johnston et al. 1988; Sainte-Rose et al. 1989) – low-pressure symptomsfrom over-drainage represent a particular problem, for which horizontal-verticalvalve placement has been advocated.

Cranial Base or Spinal Cerebrospinal Fluid Leaks

An LP shunt can be used to treat CSF rhinorrhea following either cranial injury, skullbase surgery, or of unknown etiology. CSF leak can also occur following spinalsurgery or penetrating trauma. Such fistulas are sometimes refractory to direct repair,external drainage, and blood patches. An LP shunt can be effective in these difficultsituations (Aoki 1990; James and Tibbs 1981) and represents up to 10% of pediatricLP shunt procedures (Yadav et al. 2004; Deen et al. 2003).

Pseudomeningocele

About 5–10% of pediatric LP shunt cases are indicated for postoperative pseudo-meningocele, most commonly following posterior fossa surgery (Chumas et al.1993a, b; Kulkarni et al. 1999), although the majority of such cases will resolvewith initial conservative management or temporary CSF diversion.

Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (NPH, largely an “adult condition”) isanother potential indication for lumboperitoneal shunting, although stringent criteriashould be used in patient selection. There may be advantages of LP over VP shuntingfor the treatment of communicating and normal pressure hydrocephalus, includingthe fact that since the cortical mantle is not penetrated, there is no risk of develop-ment of a seizure focus, and the risk of bleeding related to penetration of the cortex,white matter, and deeper structures is eliminated. A recent prospective study com-paring LP shunting using a programmable valve with VP shunting found similarefficacy and safety rates (Miyajima et al. 2016). Similarly, a recent retrospectivereview found LP shunting using a horizontal-vertical valve to be effective in treatingNPH with a low rate of over-drainage, and a 27% shunt failure rate requiring revisionsurgery which is comparable to that borne out in the literature for VP shunting(Bloch and McDermott 2012).


Occlusion of Major Intracranial Venous Sinuses

Occlusion of major intracranial venous sinuses such as the distal part of the superiorsagittal sinus, the dominant transverse sinus, or the jugular bulb may result inincreased venous pressure with a consequent increase in cerebrospinal fluid pressure.With the advent of magnetic resonance venography, this syndrome is being recog-nized more frequently. Patients using contraceptive pills and patients with a hyper-coagulative state from the presence of high levels of C protein are susceptible to thisproblem. Although endovascular procedures and/or anticoagulation are a possibility,it is difficult to maintain the patency. Lumbar-peritoneal shunting in such instances isan alternative therapeutic option.

Growing Skull Fractures

LP shunting has also been used in growing skull fractures which are difficult to treatby conventional methods such as when the dural defect extends deep in the cranialbase or across venous sinuses and in recurrent cases after conventional surgery. LPshunting should be considered when bulging disappears after the lumber puncture(Yadav et al. 2004; Yadav 2005). VP shunting is an alternative option but is difficultwhen the ventricles are not dilated.

Contraindications to Lumbar-Peritoneal Shunting

LP shunting must be avoided in patients with obstructive hydrocephalus as it mayresult in disastrous caudal herniation of brain stem structures. The shunting proce-dure requires the introduction of a large 14-gauge Tuohy needle into the lumbarsubarachnoid space. This may not be feasible in some clinical situations. Patientswith advanced lumbar degenerative arthropathy with marked spinal stenosis have avery narrow spinal canal with crowding of cauda equina roots, and a spinal tap or thesatisfactory advancement of the lumbar catheter may not be technically possible.Patients with an advanced degree of congenital kyphoscoliosis with rotationaldeformities may also present a similar problem. Patients with documented evidenceof adhesive arachnoiditis or with radiologic evidence of an extensive posteriormidline fusion of the lumbar spine are not suitable candidates for LP shunting.

Very small infants will not accommodate the 14-gauge needle that is required forthe percutaneous introduction of the catheter. In these cases, limited laminotomy andinsertion of a T-tube (Codman Corp., Randolph, MA) – originally designed byHarold Hoffman (Jea et al. 2007) – should be performed. Patients with a low-lyingcord, meningomyelocele, or lipomeningocele are obviously not suitable for an LPshunt. Likewise, it is probably best to avoid LP shunts in patients who already havehindbrain herniation such as in Chiari malformation. Patients with infection or skinbreakdown in the lumbar area, with chronic infection from any cause, or withvertebral osteomyelitis or discitis are not suitable candidates for lumbar-peritonealshunting due to relatively higher risk of meningitis.


Description of the Shunt System

A variety of shunt systems are available based on surgeon’s preference and indica-tion for shunting, and their composite parts therefore vary. Commercially availablesystems include Spetzler, Codman, Medtronics, Aesculap, and Chhabra. However,the mainstay component of all these is the lumbar catheter. This can have distal slitsacting as a valve, and it can be used as a unishunt tunneled from the lumbarsubarachnoid space into the peritoneum if long enough relative to patient’s bodyhabitus. Alternatively, the lumbar catheter can be attached via a “step-down” con-nector to a peritoneal catheter, for intraperitoneal entry. An optional valve unit – ofwhich there are many choices outlined below and which many surgeons nowadaysinsert due to concerns of over-drainage – can be inserted and connected to the lumbarcatheter and peritoneal catheter using “step-down” and straight connectors, respec-tively. If the pressure setting of a fixed pressure shunt proves to be a mismatch aftersurgery, causing underdrainage or over-drainage complications, the patient mustundergo a shunt revision. This is a limitation of all fixed pressure shunts. Neverthe-less, there is no convincing data in the literature to date as to which specific shunt orvalve system is associated with the highest efficacy and safety or lowest failure rates.A suture clamp can be used for fascial anchoring of the shunt tubing.

The Valve Unit

The valve unit (schematic diagram shown in Fig. 1) provides controlled drainage ofthe CSF fluid from the lumbar subarachnoid space into the peritoneal cavity whilemaintaining the intracranial pressure in the physiologic range. A variety of fixedpressure and programmable valves are commercially available including CodmanHakim, Medtronics, Aesculap, Phoenix, and Integra. Though specific designs vary,the valve generally has a bimodal mechanism to compensate for varying hydrostaticpressures in the recumbent and upright positions. On the inlet side is the lower-pressure mechanism which typically consists of a spring-activated valve. The ten-sion in the spring determines the valve opening pressure. On the outlet side is the

Fig. 1 Schematicrepresentation of the valveunit (if used). 1 Inletconnecting to the lumbarcatheter. 2 Outlet connectingto the peritoneal catheter.3 Low-pressure chamber.4 High-pressure chamber.5 Switch for toggling betweenpressure chambers dependingon the patient’s position


higher-pressure, gravity-activated mechanism consisting generally of a number offreely rolling steel balls or other such structure that will descend vertically due togravity in the upright position. The combined weight of the balls/structure deter-mines the opening pressure. In the horizontal position, only the lower valve isfunctional. In the upright position, both the spring-activated and gravity-activatedmechanisms are functional; thus, in the upright position, spinal fluid flow remainsconstant despite the higher hydrostatic pressure.

An appropriate range of valve pressures should be chosen based on the ventricularsize and the height of the patient. An exemplary range of values pertaining specificallyto lumboperitoneal shunting is shown in Table 1 (Drake and Sainte-Rose 1995a). Therange of opening pressure for the horizontal valve is chosen based on the ventricularsize. A lower opening pressure range should be chosen for patients with extremeventricular enlargement and a standard opening pressure range for patients withmoderate ventricular enlargement. The opening pressure of the vertical valve ischosen according to the patient’s height. Tall children with moderate ventricularenlargement may require a higher opening pressure range than small children withextreme ventricular enlargement. However, there are no conclusive data supportingany specific pressure ranges for any specific groups of patients. In our practice we tendto use a fixed pressure valve with various settings although most commonly horizon-tal/vertical 10/40 cm H2O (corresponding to patient height 160–180 cm).

Lumbar Catheter

The lumbar catheter is a narrow radiopaque silicone catheter (0.7 mm internaldiameter) with multiple small perforations at its lumbar end. The lumbar end isinserted into the lumbar subarachnoid space through a Tuohy needle, and the distalend is connected to the inlet side of the valve unit (if used) or tunneled into theabdomen.

Table 1 Example of pressure ranges (mm H2O) of the horizontal and vertical valves inlumboperitoneal shunting based on patient’s height and extent of ventricular enlargement

Patient’s heightVentricularenlargement

Horizontalclosing pressure

Vertical closingpressure

Large adults (>180 cm) Not significant 85–125 325–445

Large adults (>180 cm) Extreme 50–80 290–400

Large children and normal-sizedadults (160–180 cm)

Not significant 85–125 265–365

Large children and small adults(160–180 cm)

Extreme 50–80 230–320

Small children (<160 cm) Not significant 250–285

Small children (<160 cm) Extreme 50–80 170–240


Peritoneal Catheter

If there is no valve used, the distal end is inserted into the abdomen and may haveslits which act as a valve mechanism. The narrowness (0.7 mm internal diameter) ofthe catheter and length of the distal tubing both add resistance to the system.However, if a valve is utilized then a larger radiopaque silicone peritoneal catheter(1.2 mm internal diameter) is required. Its proximal end is connected to the outletside of the valve unit using a straight connector. The distal end has several staggeredrows of slits which provide multiple routes of drainage and may function as valves.

Connectors

A short plastic step-down connector is used to attach the lumbar catheter to the inletside of the valve unit. The smaller side connects to the catheter, and the larger sideconnects to the valve unit. A short plastic straight connector is used to attach theperitoneal catheter to the outlet side of the valve unit.

Suture Clamp

A butterfly suture clamp made of silicone is used to anchor the lumbar catheter to thelumbodorsal fascia near the entry site of the catheter to prevent migration of thecatheter during movements of the back (Fig. 3e).

Preoperative Preparation

A diagnostic workup should include brain imaging with an MRI or CT study toconfirm the clinical diagnosis and to rule out obstruction within the ventricularpathways. A plain radiograph of the lumbar spine may be considered in patientswith suspected spinal abnormalities that might make the surgery technically difficult.In a patient who has undergone multiple previous abdominal procedures withsignificant abdominal adhesions, the help of a general surgeon may be sought toassist in the laparotomy component of the procedure.

Operative Technique

Anesthetic Considerations and Patient Positioning

General anesthesia is routinely used for this procedure. Good muscle relaxation willhelp during the laparotomy. The operation is always done in the lateral decubitusposition (Fig. 2a). It can be either the right or the left lateral decubitus positiondepending on the surgeon’s preference. The patient is rolled over in the lateral


decubitus position with the hip and knee flexed on the downside and extended on theupside. All the pressure points are additionally padded, especially those under thegreater trochanter and the right arm. A rolled sheet is placed under the axilla toprevent compression of the axillary artery and vein and minimize the risk of brachialplexus injury. The free left arm is held over in a suspended arm rest as is generallyused in thoracotomy procedures. The patient may lie over an inflatable bean bagmattress which helps to retain the lateral decubitus position throughout the proce-dure. The head should be supported on sheets or pillows to maintain its neutralposition, in line with the spine. The chest and the knee are flexed to maximize theinterspinous space, but there should be sufficient room in front for laparotomyaccess. In patients in whom the CSF pressure is low to normal, the operating tablemay be tilted into a head up position to promote good flow of CSF.

Fig. 2 (a) Patient positioning in left lateral decubitus; 2 cm midline linear incision. (b) Dissectionto lumbodosral fascia; insertion of Tuohy needle. (c) Intra-spinal position and orientation of Tuohyneedle. (d) Stylet removed, lumbar catheter advanced cranially into spinal subarachnoid space.(e) Tuohy needle removed. (f) Securing of catheter to fascia using butterfly suture clamp


Checking the Valve for Patency

Before implantation of the valve unit, the valve is “primed” with saline. This is doneby connecting the valve unit temporarily to the lumbar and peritoneal catheters. Theinlet (lumbar) tubing is submerged in a sterile saline solution. A syringe is attachedto the distal (peritoneal) end of the tubing through a blunt 18-gauge needle. Saline isslowly aspirated through the system, purging out all of the air. The syringe is thendisconnected, and the distal end is allowed to hang freely. Patency is proven if salinedrips from the distal end.

Introduction of the Lumbar Catheter

A small 2 cm lumbar incision is made at the L3–L4 or L4–L5 level (Fig. 2b). The topof the iliac crest generally corresponds to the L3–L4 interspinous space. In difficultcases, it may be necessary to use fluoroscopy briefly to identify the appropriateinterspace and the midline with a marker. Then dissection is performed down to thelumbar fascia, before palpating the interspinous space. In the unlikely event thatthe lumbar puncture is not successful, one may have to go to a space higher or lower.A 14-gauge, thin-wall Tuohy needle is then passed parallel to the plane of the floorand directed 10–15� cephalad. The needle should be advanced in small incrementsand the stylet removed periodically to ascertain whether the subarachnoid space hasbeen entered. The bevel of the needle is directed horizontally until the dura ispenetrated. In many instances, a “pop” may be felt as the dura is penetrated. Thiscareful approach prevents going to deep and hitting the ventral dural venous plexus.Once the arachnoid has been pierced and the stylet has been removed, a gush ofspinal fluid escapes because of the size of the needle. In some instances the fluidflows well initially but then stops abruptly because of the tamponading of the tip ofthe needle by a nerve root. In such instances, gently turning the needle by 30–50�

will change the direction of the distal aperture of the needle and thus will facilitatebetter flow. If one is in doubt whether the subarachnoid space has been penetratedproperly, a small quantity of a water-soluble contrast agent may be injected throughthe needle and an anteroposterior radiograph taken with a lateral beam which willshow the contrast agent in the subarachnoid space.

After placement of the needle into the lumbar subarachnoid space, the bevel of theneedle is turned cephalad to direct the catheter (Fig. 2c). The stylet is removed andthe thin radiopaque lumbar catheter, which has multiple perforations at the end, isinserted through the needle and advanced into the lumbar subarachnoid space(Fig. 2d). The insertion is generally easy although the catheter typically hesitates abit as it maneuvers the curve at the tip of the needle before passing on with relativeease. In no circumstance should the catheter be withdrawn through the needle or theneedle advanced over the catheter because the sharp end of the needle may shear thecatheter. If the catheter must be withdrawn for any reason then the needle should bewithdrawn along with it. It is not necessary to insert more than 8 or 10 cm of thecatheter tube into the lumbar subarachnoid space. In fact, a catheter longer than this


may tend to irritate the cauda equina roots because of its entanglement within theroots. If the CSF is bloody, the lumbar catheter insertion of the catheter should bedelayed until the fluid is clear. When the catheter has been passed to the desiredlength, the needle is then withdrawn over the catheter (Fig. 2e); the surgeon shouldhold the catheter at the skin puncture so it does not get pulled out. A small hemostatprotected with rubber sleeves is used to clamp the tip of the catheter. Near the entrysite of the lumbar catheter into the spine, the catheter is anchored to the lumbodorsalfascia with a butterfly suture clamp (Fig. 2f).

Mini-laparotomy

A horizontal incision is made about 3 cm above the umbilical level, extending fromthe midline to the lateral border of the rectus abdominis muscle (Fig. 3a). The skin,subcutaneous tissue, and anterior rectus sheath are incised horizontally, and self-retaining retractors are inserted (Fig. 3b). Subcutaneous bleeders are coagulated. Therectus abdominis muscle fibers are gently separated using a hemostat or any otherappropriate blunt instrument (Fig. 3c). The posterior rectus sheath is exposed, and itis grasped with hemostats and lifted up. Using dissecting scissors (or alternativelya No. 15 blade knife), it is incised followed by careful incision of the parietalperitoneum. Fatty tissue extrudes out of the opening (Fig. 3d), and this should be

Fig. 3 (a) The skin incision used for the minilaparotomy. (b) Incision of the anterior rectus sheath.(c) Longitudinal blunt separation of the rectus abdominis fibres. (d) Incision of the posterior rectussheath and the peritoneum; a portion of the oentum extrudes out. (e, f) Tunnelling of lumbar catheterfrom the lumbar to abdominal wound. (g) Attachment and securing of the valve and peritonealcatheter (if used). (h) Insertion of the catheter into the peritoneal cavity


inspected to check that it represents omentum and not pre-peritoneal fat. If theperitoneal cavity has been entered, one should be able to insert almost three-fourthsthe length of a blunt Freer elevator or McDonald dissector (about 5 in.) easily andwithout any resistance. Due to the patient’s lateral positioning, care is required to notenter the retroperitoneal space. An aqueous Betadine-soaked swab and sterile towelare then laid out around the wound.

Tunneling

The distal end of the lumbar catheter is then tunneled from the lumbar wound throughthe subcutaneous space and brought into the abdominal wound (Fig. 3e, f). Werecognize that according to surgeon’s preference, some may use an additional flankincision, although this is unlikely in pediatric rather than adult patients. If so, ahorizontal 2 cm flank incision can be made midway between the costal margin andthe top of the iliac crest. The incision is deepened through the subcutaneous fatty layeruntil the fascia covering the external oblique muscle is exposed. The lumbar catheteris tunneled from the lumbar wound to the flank wound, where a valve can be placed ifused and followed by tunneling of the peritoneal catheter to the abdominal wound.Some surgeons advocate use of the flank incision to facilitate uncomplicated tunnel-ing from the lumbar to abdominal wounds and allow placement of the valve awayfrom the abdominal wound.

Final Shunt Assembly

The valve unit, if used, should be filled with saline to remove the air pocket from thevalve, through a blunt needle attached to the inlet side (clear) tubing. The lumbartubing is trimmed to the desired length and connected to the inlet side of the valveunit with the step-down connector, which is only needed if a valve is in place(Fig. 3f). The connection is secured with 3-0 silk ligatures. The clamp on the lumbarcatheter is released. The valve is then orientated in the correct position and CSF flowout of the outlet side of the valve is checked.

The proximal end of the peritoneal catheter is then connected to the outlet side ofthe valve unit using a straight connector secured with 3-0 silk ligatures (Fig. 3f). Foroptimal functioning of the valve unit, it should be oriented with its long axis parallelto the long axis of the trunk of the patient, and the arrow on the inlet valve shouldpoint toward the patient’s feet. The shunt assembly is now complete. CSF flow fromthe distal end of the peritoneal catheter should be checked.

The distal end of the peritoneal catheter, which has a tapered tip, is then insertedinto the peritoneal cavity using a bayonet forceps, and the catheter is directed towardthe subhepatic space (Fig. 3g). The peritoneal catheter has two or three slits near theend. These slits are designed to open in case the tip of the catheter gets plugged andact as additional ports. The valve is secured to the fascia overlying the external


oblique muscle by passing fine nonabsorbable sutures through the available holes inthe valve housing. Finally, lumbar and abdominal wounds are closed in layers usingabsorbable sutures. Subcuticular skin sutures are used.

Postoperative Management

The patient is maintained on intravenous fluids for about 24 h until active bowelsounds are heard and bowel activity is established. The patient is then started on clearliquids, progressing to a regular diet. Adequate narcotic analgesics are administered.To ensure that the patient gets acclimatized to the shunt, the head of the bed isgradually elevated in increments, after which gradual mobilization to independentambulation is encouraged with input from the physiotherapist. This managementfacilitates the patient getting used to the new CSF dynamics. Usually the patient isready to be discharged by the second or third postoperative day.

Postoperative anteroposterior and lateral lumbar spine and abdominal radio-graphs are obtained to confirm satisfactory positioning of the lumbar catheter withinthe spinal canal and peritoneal tubing within the peritoneal cavity, respectively. Afollow-up CT or MRI study is normally obtained within 1 month to assess satisfac-tory shunt functioning. In patients with ventriculomegaly, imaging may confirmnormalization of ventricular size. However, ventricular size has been correlatedpoorly with LP shunt function (Kulkarni et al. 1999). More usefully and certainlyin patients with IIH, cranial imaging may confirm closure or reduction of the basalcisterns, the so-called “absent cistern” sign (Fig. 4), which has a quoted sensitivity of75% and specificity of 57%, and is considered to reliably rule out a completelyblocked shunt, but less reliably detect a normal or partially obstructed shunt(Kulkarni et al. 1999). Patients with IIH also are monitored serially with visualfield testing, visual acuity measurements, and fundoscopy.

Complications of Surgery

Like any shunt, the most common complication of lumbar-peritoneal shuntingis blockage with reported rates at 4–14% of cases in the first year postoperatively(Aoki 1990; Yadav et al. 2004; Duthel et al. 1996). Studies have demonstrated 5-yearLP shunt failure rates of approximately 50%, with percutaneous worse performingthan T-tube usually due to early migration of the former (Chumas et al. 1993a). Ifshunt blockage is suspected, it can be confirmed by CT brain which in patients withcommunicating hydrocephalus will show ventriculomegaly whilst in patients withIIH loss of obliteration of the perimesencephalic cisterns may be demonstrated.Lumbar puncture in conjunction with manometer testing may also show raisedCSF pressure indicating shunt underdrainage. Other investigations of the shuntsystem include radionuclide study, in which the radionuclide is injected into thelumbar subarachnoid space and the flow of the nuclide through the shunt into theperitoneal cavity is monitored. If the shunt is patent, the radionuclide should escape


into the peritoneal cavity within minutes after injection otherwise underdrainage isinferred, and the shunt should be revised.

As with all shunts, LP shunts are susceptible to infection, at a rate between 1%and 9% in various series (Yadav et al. 2004; Duthel et al. 1996; Sood et al. 2005;Wang et al. 2007). LP shunt infection rate may possibly be lower than that for VPshunting, and one explanation may be that a smaller area of skin exposure andsubcutaneous tunneling is involved in LP versus VP shunting (Chumas et al. 1993a).

Shunt migration after LP shunt procedures can occur upward into the spinalsubarachnoid space and downward into the abdominal cavity. Cranial migrationsare less common than downward migration into the abdominal cavity. Failure toadequately anchor the shunt system is considered the main cause. Raised abdominalpressure and a strong force produced by lumbar movements may cause upwardmigration (Yoshida et al. 2000; Kanai et al. 1999). Shunt migration has an increasedtendency to occur in the growing child (Sainte-Rose et al. 1989).

Acquired Chiari malformation (ACM) following LP shunting is common whenno valve is utilized but is often asymptomatic – although when symptomatic(approximately 5% of cases) it may manifest as neck pain, with increasing uppercervical cord and lower brainstem compression leading to lower cranial nervedysfunction. In such symptomatic cases, revision surgery to insert a valve (if notpreviously used) may be effective, and if not or if already a valve system, thenconverting to a VP shunt should be considered. Obstruction of the normal flow ofCSF at the foramen magnum can result in syringomyelia, leading progressively to

Fig. 4 “Absent cistern” sign following successful lumboperitoneal shunting (a, black arrows)versus preoperatively (b, present ambient cisterns, black arrows)


scoliosis and neurological dysfunction of the upper or lower limbs. The incidence ofACM post-LP shunting varies in the literature but has been found to be as high as70% in some studies (Aoki 1990; Chumas et al. 1993b; Yadav et al. 2004; Payneret al. 1994). Its incidence has been shown to decrease significantly with the use ofadjustable or programmable valves (Rekate and Wallace 2003). Low-pressure head-ache may also be a significant problem – particularly in patients being treated for IIH– although fortunately the headaches often resolve as the patient “acclimatizes.”Overall, most recent publications indicate that over-drainage complications, whichhave a general reported incidence of approximately 15% of patients (Aoki 1990;Duthel et al. 1996; Wang et al. 2007), including ACM, may be limited by utilizing avalve in the system (Wang et al. 2007; Riffaud et al. 2008; Nadkarni et al. 2008).

Arachnoiditis with fibrosis can lead to a stiff back, loss of range of lumbar flexion,sciatica, and even bladder dysfunction and paraplegia. Arachnoiditis was a particularproblem with the early polyethylene shunts, and although the subsequent introduc-tion of silastic shunts has largely eliminated this problem, it still occurs at anincidence of 5–10% (Drake and Sainte-Rose 1995b).

About 1–2% of the patients present with manifestations of cauda equina rootirritation. In most instances, this is transient and resolves with time. If this persists,the lumbar catheter will need to be replaced.

Key Points

• Lumboperitoneal shunting is rare in children but can play an important rolein treating a variety of conditions including communicating hydrocephalus,idiopathic intracranial hypertension, and cerebrospinal fluid leak.

• Potential advantages of LP shunting include avoiding parenchymal cannulationand the risk of proximal obstruction by choroid plexus, and the ability of insertionin the presence of small/slit ventricles.

• Although there are various techniques described for LP shunting, the mainstaycomponent is the lumbar catheter which can be used as a unishunt tunneleddirectly from the lumbar subarachnoid space into the peritoneum or can beattached via a “step-down” connector to a peritoneal catheter, for intraperitonealentry. An optional valve unit can be inserted to reduce the risk of over-drainage.

• Although there are no conclusive data supporting the use of a valve in LPshunting, it may be beneficial in reducing the risk of over-drainage and itscomplications including low-pressure headache, acquired Chiari malformation,and subdural hemorrhage.

• The “absent cistern” sign on CT or MRI is often very useful in confirming LPshunt function in valveless systems, although its reliability in shunts employing avalve is less clear.

• The most common complications of LP shunting, in similarity to VP shunting, areblockage and infection. Unique complications include acquired Chiari malfor-mation, arachnoiditis, and nerve root irritation.


Conclusion

Lumboperitoneal shunting represents an important although rarely indicated tech-nique in the neurosurgeon’s armamentarium for the treatment of children withcommunicating hydrocephalus, idiopathic intracranial hypertension and cerebrospi-nal fluid leak. Diversion of lumbar cerebrospinal fluid into the peritoneal space wasattempted over a century ago with high mortality. Since then numerous technicaladvances have led to reliable lumboperitoneal shunt systems with minimal morbid-ity. The mainstay component of all available LP shunt systems is the lumbar catheter,with an optional valve unit that has data supporting its use in reducing the risk ofover-drainage. LP shunting avoids parenchymal cannulation and the risk of proximalobstruction by choroid plexus, but in similarity with ventriculoperitoneal shunting, ismost commonly complicated by blockage and infection, and uniquely by acquiredChiari malformation, arachnoiditis and nerve root irritation.

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