Abnormal Migration and Extrusion of Abdominal End of Ventriculoperitoneal Shunt: An Experience of Eight Cases.

BACKGROUND: Ventriculoperitoneal (VP) shunt is commonly used in the treatment of hydrocephalus. Migration and extrusion of the distal end of the VP shunt are relatively rarely occurring complications. AIM: To retrospectively analyze patients with extrusion of the abdominal end of ventriculoperitoneal shunts and evaluate the possible etiology and outcome. SETTINGS AND
DESIGN: All patients presenting with extrusion of lower end of the shunt were included. The variables collected were age, sex, site of extrusion, time duration of extrusion, presence of local infection, meningitis, shunt dependency, and treatment received. Contrast-enhanced computed tomography of brain was carried out in all patients to rule out retrograde migration of infection in the cranial cavity.
MATERIALS AND METHODS: Eight patients of abnormal migration and extrusion of lower end of VP shunt were included.
RESULTS: The distal end of VP shunt was extruded from the anus (n = 3), vagina (n = 2), and anterior abdominal wall (n = 3). In five of these patients, shunt catheter was draining cerebrospinal fluid (CSF), the children were afebrile and CSF was sterile. In three children with extrusion of the shunt through the abdominal wall, the shunt tract was infected. Two of these patients had abscess in the shunt tract, which required incision and drainage. Both these patients had meningitis with a growth of Streptococcus species from CSF. Seven patients required further CSF diversion such as endoscopic third ventriculostomy (n = 3) or placement of VP shunt (n = 4).
CONCLUSION: Distal tip migration of VP shunt may prove to have potentially serious complications such as meningitis. A prompt and aggressive protocol of management is recommended.

INTRODUCTION

Ventriculoperitoneal (VP) shunt is commonly used in the treatment of hydrocephalus. Complications associated with VP shunt are reported in about 24%–47% cases. The reported incidence of abdominal complications is 10%–30%.[12] The common complications include shunt infections and malfunction. Migration and extrusion of the distal end of the VP shunt are relatively rarely occurring complications. Colon is the most commonly involved site of visceral perforation by VP shunt catheter, and extrusion through rectum is reported in less than 0.1%–2.5% of the cases.[2] Transvaginal protrusion of a VP shunt catheter is exceedingly unusual, and has been reported very few times in literature.[3] This paper reports eight patients with extrusion and abnormal migration of the distal end of the VP shunt. The presenting features and management are highlighted.

MATERIALS AND METHODS

This study was carried out at our center between July 2014 and October 2016, and data from July 2011 was retrospectively analyzed as well. All patients presenting with extrusion of lower end of the shunt, either operated previously for the first surgery at our hospital or operated outside were included in the study. The variables collected were age, sex, site of extrusion, time duration of extrusion, presence of local infection, meningitis, shunt dependency, and treatment received. Contrast-enhanced computed tomography (CT) of brain was carried out in all the patients to rule out retrograde migration of infection in the cranial cavity.

RESULTS

Eight patients of communicating and noncommunicating hydrocephalus who had undergone VP shunt, as a procedure for cerebrospinal fluid (CSF) diversion, presented with abnormal migration or extrusion of the lower end of the shunt.

Three of these patients had undergone the VP shunt surgery in our institute and five were referred from other centers. The age of these patients ranged from 6 months to 7 years and the time of extrusion or migration ranged from 2 to 10 months (average, 4.25 months). The distal end of the shunt came out of the anus in three patients, from the vagina in two patients, and from the anterior abdominal wall in three patients [Figure 1].

Figure 1

(A) Transanal extrusion of abdominal end of the shunt with free flow of CSF. (B) Transvaginal extrusion of abdominal end of the shunt with free flow of CSF. (C) Extrusion of the shunt through anterior abdominal wall not draining CSF with inflamed shunt tract. (D) Shunt chamber obstructed with pus

In five of these children with transvaginal and transanal extrusion, the shunt catheter was draining CSF; the children were afebrile and the CSF culture was sterile. The patients with anal extrusion of shunt would complain of intermittent herniation of the tube at the anal verge while straining during defecation. In two patients with anal extrusion, the extruded part of catheter was soiled and discolored because of feces.

These patients without shunt infection were managed by initial removal of the whole shunt assembly. To prevent catheter track contamination and ascending infections, shunt was divided just below the chamber and pulled out through the lower incision. None of these patients had any complications pertaining to the site of extrusion or internal organ perforation.

These patients were observed for shunt dependency and all five required further CSF diversion such as endoscopic third ventriculostomy (ETV) or placement of shunt. After ensuring negative CSF examination and culture, ETV was performed successfully in two patients and VP shunt placement in three patients.

In three children with extrusion of the shunt through the abdominal wall, the shunt tract was infected, inflamed, and the catheter was not draining CSF. Two of these patients presented with signs of raised intracranial pressure and had abscesses in the shunt tract, which required incision and drainage. Both these children with abscess had meningitis with a growth of Streptococcus spp. from CSF culture.

The three patients with infected shunt tract were managed by shunt removal, incision and drainage of pus from the tract, and intravenous antibiotics according to culture and sensitivity of the organism. Simultaneously antibiotic was started for meningitis as well. Oral acetazolamide therapy was administered in the interim. In the meantime, intermittent CSF drainage was carried out with external ventricular drain (EVD) placement. Two of these three patients showed features of shunt dependency, and a shunt was inserted on the opposite side in one of them and ETV was carried out in other after ensuring clearance of infection from CSF. The patient in whom shunt was inserted, however, did not improve and expired.

The third patient remained asymptomatic from hydrocephalus after removal of shunt and did not require any further CSF diversion procedure [Table 1].

Table 1

Summary of eight cases

DISCUSSION

The reported incidence of extrusion or migration of VP shunt is rare but its occurrence may be fatal because of risk of ascending bacterial meningitis.

The review of literature revealed several reports regarding extrusion or abnormal migration of distal end of shunt.[45678910] Although most common type of migration is within the peritoneum but extrusion through anus, vagina, urethra, umbilicus, into congenital inguinal hernial sac, through anterior abdominal, chest, or from cervical region have also been occasionally reported.[145678910] The other common extraperitoneal sites are migration into thorax through the diaphragm resulting in CSF hydrothorax.[4]

Postulations for migration/extrusion of VP shunt

Although none of the authors in the literature have been able to identify a specific cause of migration accurately, Akyüz et al.[10] hypothesized that the catheter tip adheres to the visceral wall, a local inflammatory process weakens the bowel wall, and then the tip erodes into the lumen over a period.[11] A constant pressure abutting the tip of catheter with the viscera or the extruding surface usually accompanies this kind of setting. This favors tip migration through the abnormal site.

The ventricular end of the VP shunt is likely to be extruded if it is insecurely anchored to the pericranium.

Another factor responsible for the occurrence of this complication is extensive subcutaneous dissection at the time of primary surgery. Vuyyuru et al.[12] reported that malnutrition and former abdominal surgery may increase the risk of migration because of adhesions that arose from infection.[613] In children because of weak musculature of bowel, they are more susceptible to intestinal perforation.[1415]

We have seen that in cases of tuberculous meningitis (TBM), there is a risk of extrusion of catheter through anterior abdominal wall because of malnutrition, which leads to severe weight loss and decreased soft tissue cover over the shunt catheter. Also, prolonged treatment course with long-term steroids for vasculitis leads to thin and fragile skin, which can further add to risk of extrusion of shunt.

Some factors that may be postulated to be responsible for the migration of the distal end of the VP shunt are:

Intestinal peristalsis

Continuous water hammer effect of the pulsation of the CSF

Intermittent rise in the intra-abdominal pressure (in one of our patient with transabdominal extrusion, there was CSF loculation intraperitoneally [Figure 2])

Figure 2

CT abdomen image showing paraumbilical CSF loculation with traversing shunt tube 2 weeks before the extrusion of the shunt

Presence of a congenital hernial sac can be a predisposing factor for the migration of the VP shunt into the scrotum

Stiffness and length of catheter, age, and sex of the patient may be also culprit in the occurrence of this complications

Use of trocar for placing abdominal catheter is a blind procedure and also may be a causative factor[1]

Management protocol

In our view, the management principles in such patients should be prompt removal of the entire shunt assembly.

Three factors that will determine the further course of action are the following:

Presence of local shunt tract infection

Presence of meningitis

Shunt dependency

Broad-spectrum intravenous antibiotics should be started prophylactically and pus should be drained, if present. A sufficient recovery period is then allowed to lapse in cases of meningitis so that the CSF culture is sterile on two successive occasions. In the meantime, CSF may be drained intermittently if patient shows signs of raised intracranial pressure by EVD or regular taps. Simultaneously, we assess for the requirement of CSF diversion with the help of serial clinical and radiological examinations. The subsequent CSF diversion, if required, is by either ETV or replacement of shunt, provided the CSF examination and culture are normal. In one patient of TBM, ETV was performed for CSF diversion. ETV can be considered as the first surgical option for CSF diversion in patients with TBM hydrocephalus.[15] Repositioning of the lower end of the shunt can be done in cases such as migration of the lower end in a congenital inguinal hernial sac.

In cases where the shunt tract shows infection, it is advisable to place the VP shunt from the opposite side.

We have also seen that in cases of transvaginal or transanal extrusion, generally no local infection or obvious signs of peritonitis is reported as the inflammation is usually a localized phenomenon and is reversible as soon as the shunt tube is removed. Hence, the shunt assembly can be removed without addressing the site of perforation in bowel. Even in our series, it was seen that none of these patients had any complications because of the perforation of internal organs.

CONCLUSION

In conclusion, although distal tip migration of VP shunt is not a usual complication, it may lead to serious problems.

Presence of local shunt tract infection, presence of meningitis, and shunt dependency are the main factors, which determine the management of these patients.

In cases of TBM, malnutrition leading to weight loss along with long-term steroid therapy for vasculitis leading to thin fragile skin are predisposing factors for transabdominal shunt extrusion.

In cases of transanal and transvaginal extrusions, in the absence of frank signs of peritonitis, we recommend direct removal of shunt assembly without any further abdominal exploratory procedure to address the site of internal organ perforation.

A prompt and aggressive protocol of management as advised in this study can be lifesaving and decrease the morbidity and mortality associated with this complication.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.