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Ventriculo-epiplooic shunt for Hydrocephalus

Posted Feb 06 2012 7:19am
                                                        CAUTION: GRAFIC PICTURES

Hydrocephalus is a world wide problem with 1 in every 1,000 children born are born with this condition. In developed countries  100,000 procedures are done every year.

I have may distal in my heart it is considered a VA shunt because  I have too much scar tissue in my abdomen. I would much rather have this procediure than in my heart. Although I am a great fan of the VA shunts.

The surgeries are so much easier than opening up my abdomen...



External ventricular drainage is only a temporary solution. Extracranial ventricular drainages are mainly represented by ventriculoperitoneal shunt, ventriculoatrial shunt and lumboperitoneal shunt. Other, very rarely used, extracranial ventricular drainage systems are ventriculopleural shunt, ventriculo-gallbladder shunt, ventriculoureteral shunt, lumboureteral shunt, ventriculomastoid drainage, and drainage into the thoracic duct.

Nowadays, the most common treatment for hydrocephalus is ventriculoperitoneal shunt, used in more than 90% of patients. The first ventriculoperitoneal shunt was done by Kausch in 1908, but the procedure became widely performed 50 years later, and since 1960, the technique has not changed much.

We propose a new surgical technique, ventriculo-epiplooic shunt, for treatment of hydrocephalus. In ventriculo-epiplooic shunt the distal end of the catheter can be placed between the layers of the great omentum, performed classical (technique 1) or laparoscopic (technique 3) or intravascular into an epiplooic vein (technique 2). We present three experimental cases, required equipment, surgical technique, indications, advantages compare to other classic shunt procedures (ventriculoperitoneal and ventriculocardiac shunts), and possible complications.

MATHERIAL & METHODS

We performed experiment ventriculo-epiplooic shunts on three pigs. The experiment was performed into the Center of Experimental Medicine, University of Medicine and Pharmacy Iuliu Hatieganu, Cluj-Napoca. On each pig we performed one of the three surgical techniques of ventriculo-epilooic shunts. The experiment was done according to the laws in force.

REQUIRED EQUIPMENTS:

  • Standard tray for brain surgery
  • Standard tray for laparoscopic surgery
  • Shunt tubes (ventricular catheter, peritoneal catheter, atrial catheter), valve (high, medium, low or programmable valve)

SURGICAL TECHNIQUE:

Technique 1:
  • Step 1. Cranial step.
Subcutaneous tunneling is carried from the retromastoidian region, to the lateral neck, and over the anterior thorax and abdomen and the distal tube is inserted into this subcu ta ne ous tun nel.
Several variants of ventricular shunt placement can be performed. The most common used sites for ventricular catheter placement are described below. We perform a skin incision, 3 cm posterior and superior of the highest point of the helix of the ipsilateral ear for temporo-parietal shunt placement, 4 cm laterally and 6 cm superior of inion for parieto-occipital location, and 1 cm anterior of the coronal suture and 2 cm laterally of the midline for frontal shunt insertion. A burr hole is performed in the above reminded locations. After a minimal dural opening, and coagulation of dural margins the right ventricle is catheterized. Intraoperatory CSF pressure is measured using a manometer and samples of CSF are collected for laboratory examinations.
Ventricular catheter is connected with the distal catheter by means of a pressure valve; pressure is adapted according to the intraventricular pressure. The presence of CSF flow (drops) through the distal catheter attests the adequate shunt functioning.
In the retromastoidian area, galea aponeurotica is dissected, achieving a subgaleal cavity, in which the valve will be placed.
The cranial step is ended by hemostasis and wounds closure. (Fig.1)



  • Step 2. Abdominal step.
We perform a midline laparotomy, 15 cm long.
After greater omentum identification, careful dissection between the two epiplooic layers is performed. The distal end of the abdominal catheter is placed between the two layers of the great omentum and fixed by means of suture thread.
A safety epiplooic fenestration is made, for allowing drainage of an eventually excessive amount of CSF into the abdominal cavity.
The distal end of the abdominal catheter is fixed in a declive position.
Careful hemostasis and parietoraphy (in anatomical layers) are done (fig. 2,3,4,5,6).

Technique 2:
  • Step 2. Abdominal step.
A similar midline laparotomy, 15 cm long is performed.
After greater omentum identification, finding of a large vein, tributary to the portal system (epiplooic, gastroepiplooic veins, etc.) is mandatory. The vein is dissected and encircled with two slings. After distal vein ligation, the distal end of catheter is placed intravenous through a minimal venotomy, followed by proximal vein ligation around the catheter. For this technique, which requires an intravascular placement of the distal shunt, we use an atrial catheter that has a thinner end.
Hemostasis and parietoraphy (in anatomical layers) are done (fig.7).


Fig. 7. Placement of the distal end of the catheter into a bigepiplooic vein.

Technique 3:
  • Step 2. Abdominal step.
The peritoneal cavity is insufflated with CO2.
Three standard ports for laparoscopic surgery of the supramesocolic space are placed (the first one, measuring 10 mm diameter, is the optical port, placed on the midline just under the umbilicus, and two ports having 5 mm diameter placed within the iliac fossa).
The distal end of the peritoneal catheter is inserted into the abdominal cavity. The distal end of the tube is identified intraperitoneal.

Colo-epiplooic laparoscopic dissection is performed, in order to create an opening between the layers of the great omentum. The distal end of the peritoneal catheter is placed and fixed into this newly created space. We perform a safety fenestration on the visceral layer of the great omentum. The catheter is fixed to the omental layers by two suture threads with intracorporeal knot.
Hemostasis, peritoneal exsufflation, and skin closure are done.

RESULTS

We had no early or late postoperative complications following experimental ventriculo-epiplooic shunt on pigs. The pigs had favorable short and long time outcome, and presented no neurological deficits.

DISCUSSIONS

Particular intraperitoneal placement of distal catheter
Classically, the ventriculoperitoneal shunt surgical technique consists in inserting the distal catheter lateral to the umbilicus, on the right midclaviculary line, into the peritoneal cavity, through a minimal peritoneal breach, and then the tube is pushed inside, between intestinal loops.
Picasa performed lumboperitoneal shunt, draining CSF into the posterior peritoneal space. Several authors reported drainage of the CSF into the omental bursa. In transthoracic transdiaphragmatic ventriculoperitoneal shunt, used in patients with difficult access into the anterior abdomen, secondary to extensive adhesions following repeated revisions of the peritoneal catheter, the distal tube is inserted subdiaphragmatic suprahepatic, into a space free of adherences.

Peritoneal and great omentum capacity of absorption
Daily CSF flow is 250-500 ml/day. The peritoneal cavity is most appropriate for CSF absorption. Great omentum has a good absorption capacity, especially in children. It can absorb a good amount of CSF, leaving only a small quantity to flow into the peritoneal cavity. If the amount of CSF overwhelms the capacity of absorption of the great omentum the surplus of CSF can flow into the peritoneal cavity through the fenestration made into the visceral layer.

Indications of ventriculo-epiplooic shunt
Main indications for ventriculo-epiplooic shunt are hydrocephalus in patients with history of abdominal surgery, multiple shunt revisions, multiple previous abdominal complications (multiple CSF pseudocysts, CSF ascites, visceral perforations, etc.), extensive peritoneal adherences, high friability of visceral wall and low visceral mobility (associated neural tube defects - myelomeningocele, colagenosis).

Indications for intravascular shunt are extensive peritoneal adherences, multiple shunt dysfunctions secondary to various abdominal complications, cirrhosis, impairment of peritoneal capacity of absorption, refractory ascites.

Perioperatory issues
Before intravascular ventriculo-epiplooic shunt performing CSF must be tested for cellularity and germ growth. Three consecutive sterile CSF culture and cell number/mm3 beneath 5/mm3, allows placement of an intravascular shunt. Patients with intravascular shunts must receive prophylactic treatment for sepsis.

Advantages of ventriculo-epiplooic shunt
During standard ventriculoperitoneal shunt procedure, the distal end of the catheter is free into the peritoneal cavity and may be displaced by bowel movements. Avoiding the direct contact between bowel loops and catheter lowers the frequency of catheter migrations, exteriorization and torsion. Fixation of the catheter to the omental layer with suture threads also contributes to this consideration.

CSF has an irritative effect on the peritoneum, causing a local inflammatory response process, important peritoneal congestion and inflammatory adhesions between viscera and viscera and abdominal wall. Placing the distal catheter between the great omental layers avoids direct contact of catheter and bowel, and adherences occurrence, preventing ileus, bowel voluvulation and visceral perforations.

Bowel obstruction is a rare ventriculoperitoneal shunt-related complication. Mechanical ileus may occur in shunted patients due to bowel volvulus around intraperitoneal catheter and adherences between catheter and viscera, secondary to the local inflammatory process as a response to a foreign body or irritative CSF, causing intraperitoneal extensive adherences.

Visceral perforations are rare, but severe complications following standard ventriculoperitoneal shunt, which can occur up to 10 years after initial operation. The mortality in patients with visceral perforation following ventriculoperitoneal shunt is high, reaching 15%. Early perforations are purely due to intraoperatory errors, when a viscus is mistaken for peritoneum, usually in patients with adherences. Late visceral perforations are assumed to be the result of local inflammatory process, as a response to a foreign body (silicone tube) or to irritant CSF. Persistent local inflammatory process and vicinity of tube and viscus favors catheter adherence to viscera, then visceral wall is thinned and finally perforated by repeated movements (bowel movements, respiratory movements). Most likely visceral perforation occur into small bowel and colon (transverse colon), but may also occur into gallbladder, stomach, urinary bladder, scrotum, vagina, etc. Patients with central nervous system malformations, such as neural tube defects (myelomeningocele) and associated hydrocephalus, are prone to visceral perforations, because of the low visceral mobility and high friability of visceral wall.

Placement of distal tube between the layers prevents direct contact between catheter and viscera, adherence and progressive perforation is hindered. By lowering the incidence of visceral perforations, we diminish the morbidity related to shunt surgery and septic complications. Following visceral perforation occur: ventriculitis, meningitis, meningoencephalitis, cerebral abscesses or empyema and local or generalized peritonitis, involving gram negative bacteria (Escherichia coli). History of visceral perforation with secondary generalized peritonitis causes important intraperitoneal adherence syndrome, which may raise the frequency of further abdominal shunt-related complications. In cases with recurrent abdominal complication, important intraperitoneal adherence syndrome or multiple abdominal surgeries, putting the distal end into the great omentum prevents all of the above.

Shunt infections are the most common cause of shunt malfunction, occurring in 0.17-30% of cases. Shunt infections may early, occurring immediately after surgery due to intraoperatory contamination and late, occurring after a period of time longer than 9 month. Late infections are seeding from an abdominal site. Pathogenesis usually involves direct erosion of a viscus by the distal catheter and translocation of intestinal bacteria along the tube.

Predisposal factors for shunt infection are: low birth weight, prematurity, age under 1 year old, history of multiple shunt malfunctions, CSF leaks, history of intraventricular hemorrhage or central nervous system infections, previous abdominal surgery, myelomeningocele, hyperproteinnorrachia, immunosuppression, and prolong hospital stay. Septic process leads to adherences, straps and fibrous reshuffling between abdominal viscera and predispose to distal shunt dysfunctions and pseudocysts formation in the future. Isolating the distal end of the catheter diminishes shunt infections occurrence.

Epiplooic nods become the first stop for any shunt infection, limiting infection spreading. Liver is the second station in stopping infection spreading.
During the first phase of any abdominal sepsis of various etiology (peritonitis, bowel perforation, abscesses, inflammatory process of abdominal viscera, etc.), the great omentum limits the direct contact of the distal catheter with infection.

CSF pseudocysts occur in 1-4.5% cases with standard ventriculoperitoneal shunts. Pathophysiology of CSF pseudocysts is still unclear, but some predisposal factors for CSF pseudocysts had been reported: shunt infections with microaerophilic or anaerobic bacteria, low grade sepsis, mute clinical peritonitis, history of multiple shunt revisions, history of multiple abdominal complications, prior CSF pseudocysts, history of prior abdominal surgery, hyperproteinnorrachia, impaired absorption of the peritoneum, and silicone allergy.

Infection seems to pay a central role in CSF pseudocysts pathophysiology. Pseudocysts may be result of a self-limited shunt infection with microaerophilic or anaerobic bacteria, that cause infraclinical peritonitis. Peritoneum and abdominal viscera response to this infraclinical shunt infection by isolating the distal end of the catheter by fibrous tissue, forming pseudocysts.
Cystic “walls” are formed by fibrous tissue without epithelial lining, proving that the pseudocyst is a consequence of the local inflammatory response. Gaskill et al. reported acute shunt infections in 16% patients with pseudocysts, and history of shunt infections in 41.6% cases. Rainov et al. found active shunt infection in 30% cases with CSF pseudocysts. Adherence syndrome may be the result of low, prolonged local inflammatory response of the peritoneum to CSF, which can be highly irritating for peritoneum.

In patients with CSF pseudocysts important changes into the peritoneal cavity occur, with extensive adherences, straps fibrous reshuffling between abdominal viscera that shown that these people are prone for developing recurrent pseudocysts. By placing the distal end into the great omentum, the irritating CSF in not drained any more into the peritoneal cavity, preventing adherence formation.
CSF ascites is a rare complication of ventriculoperitoneal shunts. Ascites is a life-threatening complication, leading to shock, sepsis, respiratory failure, and hepatorenal failure. Although the pathopysiology of CSF ascites is unclear, some pathogenic factors were described: impaired absorption of the peritoneum, excessive production of CSF (choroid plexus papilloma, choroid plexus hypertrophy), hyperproteinnorrachia (optic nerve gliomas, craniopharyngiomas, suprasellar tumors), shunt infections and peritoneal tumoral seeding secondary to central nervous system tumors. Ascites may be a nonspecific, chronic inflammatory reaction to degradation of silicon rubber. Most likely CSF ascites is the result of impairment of CSF absorption of the peritoneum, secondary to either an increased CSF volume, rare, found in patients with choroid plexus papilloma or choroid plexus hypertrophy which overwhelms the peritoneal capacity of liquid absorption or secondary to a peritoneal pathology, which do not allow proper absorption. Intraperitoneal CSF accumulation provides a similar local condition as ascites of different etiology to become infected. Spontaneous bacterial peritonitis can be found in patients with CSF ascites.

Placing the tube into the great omentum, limits the quantity of CSF that reaches the peritoneum. By absorbing a good amount of CSF by the great omentum, it lowers the frequency of ascites. In refractory CSF ascites intravascular ventriculo-epiplooic shunt is recommended. By placing the distal catheter into an epipoolic vein, the entire quantity of CSF flows into the portal system, being a good therapeutic option in refractory ascites.

Inguinal hernia occurs with a frequency of 3.8-16.8% in patients with ventriculoperitoneal shunt, predominantly in infants, toddlers and young children. Predisposal factors for occurrence of inguinal hernias are: persistence of processus vaginalis (patent processus vaginalis can be present in 60-70% infants during the first 3 months, in 50-60% children 1 year old and up to 40% in children 2 years old), increased abdominal pressure, impaired absorption of the peritoneum and secondary peritoneal tumor seeding from central nervous system tumors. In 50% cases hernias are bilateral. Persistence of processus vaginalis is mandatory for inguinal hernia occurrence. Processus vaginalis can be entirely permeably, or it can have septum or cysts. Patent processus vaginalis can close with aging. Age pays is a central role in inguinal hernia occurrence, 30% of inguinal hernias develop in infants 0-3 month old, and 10% in children 1 year old. Permanent increased abdominal pressure, may maintain its patency, by keeping a pressure gradient and does not allow closure of the vaginalis. By placing the distal catheter into the great omentum all, or almost all, quantity of CSF is absorbed, canceling the pressure gradient, allowing procesus vaginalis closing with age. Ventriculo-epiplooic shunt lowers the intraperitoneal pressure, diminishing the incidence inguinal hernia, in patients with persistent processus vaginalis.
Advantages of intravascular ventriculo-epiplooic shunt compare with ventriculoatrial shunts.

Intravascular shunts carry high morbidity.
Complications specific to ventriculoatrial shunts such as arrhythmias, ventricular wall perforations, valvular lesions, rupture of subvalvular apparatus (chordae tendineae), endocarditis, pulmonary thromboembolism, pulmonary hypertension, cor pulmonale, right heart failure are avoided by intravascular ventriculo-epiplooic shunt.

Sepsis is a consequence of shunt infection. For ventriculoatrial shunt the rate of this complication is 10-15%. Sepsis is usually caused by coagulase-negative Staphylococci, especially Staphylococcus aureus and Staphylococcus epidermidis. Sepsis with Staphylococcus aureus is acute or fulminant, while sepsis with Staphylococcus epidermidis is indolent. The incidence of sepsis is lowered because the epiplooic nods and liver are two important stations in stopping infection spreading.
Shunt nephritis, an immune-complex-mediated glomerulonephritis, is a rare complication of ventriculocardiac shunts. Germs known to cause shunt nephritis are: Staphylococcus epidermidis, Staphylococcus aureus, Corynebacterium bovis, Lysteria monocytogenes, Pseudomonas aeruginosa, Propionibacterium acnes, etc. These bacteria strongly adhere to the silicone tube, escaping the immune defense system. Their presence produces a continuous antigenic stimulation, with antigen-antibody complexes, secondary activation of the complement system and deposits of C3 and antigen-antibody complexes (IgM and IgG) in the glomerular capillary walls. Shunt nephritis has dramatic consequences, such as progressive renal failure, massive proteinuria, hematuria, azotemia, hypoproteinemia, anemia, low levels of the complement protein C3, modestly elevated levels of C-reactive protein and cryoglobulins, high blood pressure, edema, recurrent fever, enlarged liver and spleen, arthritis, and skin rash.

By placing the catheter into an epiplooic vein, draining the CSF into the portal circulation, and passing through the liver the incidence of shunt nephritis can be diminished.
Laparoscopic treatment decreases risks of open surgery, diminishes adherence formation, allows peritoneal cavity exploration, viscerolisis and treatment of associated lesions.

CONCLUSIONS

Ventriculo-epiplooic shunt is a new surgical technique for treatment of hydrocephalus. The surgical technique is safe, easily performed, with surgical steps without significant morbidity, and with favorable postoperatory outcome on short and long term. Complications specific to other shunt systems, ventriculoperitoneal and ventriculoatrial, can be successfully avoided by this technique. In ventriculo-epiplooic shunt, by preventing the direct contact between the distal catheter and bowel, visceral perforations, bowel obstruction, shunt infection, and CSF pseudocyst occurrence is avoided. In intravascular ventriculo-epiplooic shunt, by draining CSF into the portal circulation, and passing through the liver, the incidence of a serious complication, shunt nephritis, can be diminished. Ventriculo-epiplooic shunt has multiple advantages compared to other classic shunt techniques, ventriculoperitoneal and ventriculoatrial, with no additional stipulated complications.
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