Abnormal migration of the Distal Catheter of Ventriculoperitoneal shunts in Pediatric Age Group: Case SeriesAhmed A.M. Ezzat1, Mohamed A.R. Soliman1, Amr A. Hasanain1, Mohamed A. Thabit1, Hesham Elshitany1, Hitham Kandeel 1, Sameh H Abdel-Bari1, Ahmed Abdullah 1, Mohamed F.M. Alsawy 1, Ammar Ali 1, Ahmed Al Menabbawy 1, Ahmed A. Marei 1, Bassante Abd El Razik 1, Henry W.S.Schroeder 2, Sascha Marx 2, Ahmed Zohdi 1, Ehab El Refaee 1,2 1 Department of Neurosurgery, Cairo University2 Department of Neurosurgery, University Medicine Greifswald AbstractObjectVentriculoperitoneal (VP) shunting is the most commonly performed procedure in the treatment of hydrocephalus, bypassing the normal CSF pathway to allow absorption of the CSF in the peritoneal cavity. VP shunt migration can occur at different sites. The aim of the study was to present different sites of abnormal distal shunt migration and the management in each situation.MethodsBetween 2014 and 2017 all patients with hydrocephalus in the department of neurosurgery, Cairo University, were gathered in a prospective database. All pediatric patients below the age of 12 years with an abnormal shunt migration of the distal end of the VP shunt were identified.ResultsOf 1092 patients operated upon by V-P shunt between 2014 and 2017, 15 presented shunt dysfunction because of abnormal distal shunt migration (6 anal, 3 scrotal, 1 colon, 1 peroral, 1 upper lumbar extrusion, 1 paraspinal, 1 penile, 1 umbilical). Especially upper lumbar extrusion and para-spinal shunt migration are extremely rare. All the 15 patients were treated successfully with VP shunts and prospectively followed until they presented with complications on different occasions.ConclusionAbnormal shunt migration did occur in 1.4% in the present series of 1092 prospectively collected pediatric patients with hydrocephalus. Thus, abnormal shunt migration needs to be considered in patients presenting with shunt dysfunction. We recommend to avoid insertion of VP shunts using trocars & silicone firm tipped shunts in malnourished children.Keywords: Ventriculoperitoneal shunt, Cerebrospinal fluid, Hydrocephalus, Distal end migration, Bowel perforation.IntroductionVentriculoperitoneal (VP) shunting is the most commonly performed procedure in the treatment of hydrocephalus, bypassing the normal CSF pathway to allow absorption of the CSF in the peritoneal cavity (6). VP shunt migration can occur at different sites. The aim of the present study was to analyze site and management of abnormal distal VP shunt migration. Of 1092 patients, 15 presented with shunt dysfunction because of abnormal distal shunt migration (6 anal, 3 scrotal, 1 colon, 1 peroral, 1 upper lumbar extrusion, 1 paraspinal, 1 penile, 1 umbilical). Especially para-spinal (11) & Lumbar extrusion (17) shunt migration is extremely rare. All the 15 patients were treated successfully with VP shunts and prospectively followed until they presented with complications on different occasions. Methodology:Between 2014 and 2017 all patients with hydrocephalus in the department of neurosurgery, Cairo University, were gathered in a prospective database. All pediatric patients below the age of 12 years with an abnormal shunt migration of the distal end of their VP shunt were identified. The German Academic Exchange Service (DAAD) supported this database (30). Patients collected data were; diagnosis, age at initial presentation, age at abnormal migration, site of abnormal migration and it’s management. All the collected data were analyzed (Table 1 & 2). Results:Routes of abnormal shunt migrationOut of 1092 patients, 15 (1.4%) presented with an abnormal shunt migration. Here of were one case of peroral migration (figure 1A), one case of upper lumbar region extrusion (figure 1B), one case of penile migration (figure 1C), six cases of anal migration (figure 1D), one case of umbilical migration (figure 1E), one case that was explored for intestinal obstruction, in which the distal end of the shunt was found in the intestine (figure 1F), two cases of scrotal migration (figure 1G), in addition to one case of retroperitoneal migration into the paraspinal area (figure 1H). Patient characteristics:The mean age of patients was 1.5 years (range from 1 months to 9 years). 13 patients were males and 2 patients were females.The commonest symptom at the time of presentation due to shunt malfunction was vomiting (in ten cases = 66.7%), followed by bulging anterior fontanel that was noticed either by the relatives or during the routine follow up (in six cases = 40 %), and the appearance of abnormal morphology as the shunt tube extruding from the anus (in six cases = 40%) or scrotal swelling (in three cases = 20%).Ten cases (66.7%) showed ventriculomegaly in the radiological workup and in one case only (6.7%) there was multi-loculated hydrocephalus.In 13 cases (86.7%), the abnormal migration occurred after the first time insertion of the VP shunt without revisions, but in one case (6.7%), it occurred after three revisions & in one case (6.7%) after one revision.In 11 cases (73.3 %), the distal end was inserted using a trocar and in 4 cases (26.7 %) was inserted by a laparotomy. The shunt inserted in 13 cases (86.7%) was chabbra, one case was Integra (6.7%) and one case was Medtronic (6.7%).In two cases, the follow up of the patients were lost. The first was an 8 years old child with an extruded distal shunt end through the penis and the other patient was 9 years old boy with an extruded distal end from the umbilicus with CSF leak. Management of the abnormal shunt migration:In the anal migration group, the shunt tube was removed from an anal route (cutting the distal end in the peritoneum before penetrating the viscus), followed by repair of the intestinal defect and CSF was externally diverted for one week. Then a VP shunt was re-inserted after exclusion of peritoneal inflammation. On the contrary, the patient with the posterior lumbar migration had performed a previous distal revision at which a connector was implanted to accomplish lengthening of the distal end which is required in some shunt materials that have a slit end release. The laparoscopic revision was performed at which the connector was found implanted within the posterior lumbar muscles where the distal end was retracted from the posterior lumbar area and reinserted in the peritoneal cavity. The laparoscopic revision was performed in all cases with scrotal migration with a favorable outcome. Direct repair of the intestinal wall was performed in the case with intestinal migration where the CSF was externally diverted for one week. Then a VP shunt was re-inserted after exclusion of peritoneal inflammation. In the upper lumbar extruded shunt patient, the shunt was removed from the back and CSF was externally diverted for a week and the VP shunt was re-inserted. While the peroral shunt migration patient the distal end was removed from the oral route (cutting the distal end at the scalp incision distal to the reservoir) and the CSF was also externally diverted for one week to exclude any inflammation & then a VP shunt was re-inserted. Discussion: Introduction and Pathophysiology: Although hydrocephalic patients can be treated successfully by VP shunts, they remain to have a significant risk of long-term complications. The most frequent complication is shunt malfunction, which occurs in more than 50% of the children within 2 years post-shunt surgery and at least 80% of lifetime risk. (9) VP Shunt related complications are common and the abdominal complications related to shunts reported as 10-30%. (21) An unusual complication of less than 0.1%- 0.7% of cases has bowel perforation and anal extrusion of a distal peritoneal shunt. (38) The rate of abnormal shunt migration in the present study is 1.4% and, thus, comparable with these reported rates.It is reported that every hollow viscus has been perforated by the distal shunt catheter (38) associated with 15% mortality (8,37). These include the small & large bowel, stomach, with extrusion of distal shunt tube through the rectum (14,35) or the mouth (36), vagina and fallopian tubes (27), urinary bladder (31), and scrotum (25).Various shunt factors had been suggested for perforation such as a long abdominal end of the catheter, sharp abdominal tip, shunt components bio-reactivity, consistency of the shunt is relatively stiff, silicon allergy and barium coating of the shunt. (32)Multiple peritoneal catheter types have been associated with perforation. (32) In 13 out of the 15 patients in the present study, Chhabra shunt® was used. Its valve is “Slit n Spring” with a distal catheter 75 cm, silicone plug closing the distal end, and has two pairs of the slit valve. The valve of this type of shunt is made of silicone rubber that has slight tendency to stick when it is in a dry state (32), which can be an explanation for the high amount of abnormal shunt migration in this type of shunt. Upper lumbar region extrusionExtrusion of the shunt from the upper lumbar region has never been reported. There was only one reported case of extrusion of the shunt from the mid-lumbar region. (17) The certain causes of such extrusion are still not clearly understood. This might be due to the firmness of the tip of the chabbra shunt that may cause tissue necrosis and advancement of the tip of the shunt through the muscle and skin. Paraspinal Migration Migration to the para-spinal region is a very rare and has been reported in only two case reports (11,24). The certain causes of such migration to the para-spinal region are still not clearly understood. Many theories have been mentioned in the literature as migration due to repeated shunt revisions, obesity, and chronic constipation. The most convenient theory for such migration could be obesity and increased intra-abdominal pressure especially with abdominal movements and contractions that increase the friction between the distal end of the shunt and the peritoneum inducing fibrosis around the shunt’s connector facilitating its own way to the paraspinal muscles and the subcutaneous tissue (1). In our study, it worth to say that this patient performed a previous surgery with distal revision, where a connector was used to help in shortening of the shunt tube without losing the slit valve release within the distal end. Intestinal migration In regards to viscus perforation, the exact reason for the distal catheter perforation is unknown. It could be because of the break in continuity of epithelium at contact site with the silicon in shunt tube, which can lead to local inflammation and fibrosis leading to distal shunt tube adherence to the bowel wall. The cerebrospinal fluid pulsations lead to continuous water hammering effect that can perforate the bowel wall. Once the distal end reaches the bowel lumen, shunt tube is pushed forward and downward by peristaltic waves. (15,16) However, upward migration of the distal catheter through the gastroesophageal junction against the normal peristalsis toward the oral cavity. This can occur either due to repeated vomiting or abnormal peristalsis. (2,12) Peroral extrusion is a very rare complication and has been reported in only 21 cases reports.(3) Patients with spinal dysraphism and congenital hydrocephalus have weak innervation of the intestinal wall, which can predispose to bowel perforation. Long peritoneal tubing, surgical technique, and poor host immunity are contributing factors to shunt extrusion. Severe ventriculitis, encephalitis, and meningitis can result from the presence of the shunt tube for a long time in gastrointestinal lumen. (5,34) Scrotal migration: Scrotal migration has been previously reported in 30 cases according to the English literature. (20) Most cases occurred in the pediatric age group in the first six months after VP catheter insertion. (22) The high incidence of patent processus vaginalis in this age group goes with the high incidence of shunt migration into the scrotum in comparison to the adult where the majority has obliterated ones. (19) Processus vaginalis remains patent in 90% of the population at 0 months, 50–60% at 12 months, 40% between 24 months and 16 years, and 15–30% in older adults at necropsy. (13,33) Patency of processus vaginalis could be hypothetically prolonged by the high intra-abdominal pressure induced by the constant inflow of fluid from the VP shunt. (13,18) One of the mentioned theories explaining such migration is that residual peritoneal cavity volume is directly proportionate to the body surface area, that’s why infants have a higher tendency to have distal catheter migration into the scrotum due to both non-obliterated processus vaginalis and smaller peritoneal cavity. (20) Urinary Bladder Migration: To our knowledge, shunt migration into the bladder is an extremely rare complication of VP shunt surgery (28). Passage of the catheter from the peritoneum into extra-peritoneal space and then perforation of the bladder make the shunt migration to the bladder is highly unlikely. (29) Migration of the shunt into the bladder has been reported in several studies and reports. The mechanism by which peritoneal catheters may perforate the bladder is the same way of perforation of the bowel. Prasad et al. suggested that perforation occurs via a series of stepwise events, namely catheter fixation or anchoring, penetration, perforation, entry into the urethra, and finally extrusion (29) Umbilical migration: With respect to migration of the shunt to the umbilicus, there are few case reports of umbilical CSF fistula post-ventriculoperitoneal shunt insertion. (4,7) This kind of abnormal shunt migration would be attributed to possible infection or congenital umbilical defects. (10,23,39) CSF leak or extrusion of the shunt from the umbilicus may be due to distal tip irritation and/or mechanical pressure of VP shunt to anterior abdominal wall structures which could result in adhesion of the shunt tube to the persistent omphalomesenteric tract /urachal remnant. Risk Factors:The risk factors of VP shunt catheter migration and extrusion is not fully understood till now. When we reviewed our results we found that all of our patients were less than years with a mean age of 1.5 years. The most accepted theory for this is that the children have more vigorous peristaltic activity and weaker bowel muscles especially if they are malnourished. (26) The Type of shunt is an important risk factor for VP migration. In 13 out of the 15 patients with shunt migration, Chabbra shunts were used. These shunts are made of silicone that might cause silicone allergy or local inflammation that leads to mechanical irritation. (15,16) Firm tipped and long type of catheter has been associated with increased risk of bowel perforation.(2) The last risk factor that was observed in our cases is the mode of insertion of the distal end. In 11 out of the 15 patients with shunt migration, trocar was used to insert the peritoneal end. The exact mechanism is not understood. Visceral injury at the time of surgery is unlikely as the migration incident was around 5 months after surgery. Management: The management of the shunt-extruded patients includes removal of the shunt, external CSF drainage, intravenous antibiotics, and re-insertion of a VP shunt after clearance of infection or endoscopic third ventriculostomy (ETV).(2) The bowel perforation heals spontaneously after removal of shunt tube due to presence around the shunt track chronic fibrous sheath. Patients presenting with an acute abdomen is the only indication for emergency laparotomy. (2) In the anal migration group, the shunt tube was removed from anal route the peroral extrusion patient, the shunt tube was removed from the oral route (cutting the distal end in the peritoneum before penetrating the viscus), Exploration of the perforation site is always done which can be treated by direct closure in small perforations especially in the small intestine. This is done to decrease the risk of potential infection from the exposed peritoneal end. CSF was externally diverted for one week and then a VP shunt was reinserted after exclusion of peritoneal inflammation. In the colonic case, abdominal exploration was done; the distal end was removed, and then re-insertion of a new distal end in the right iliac fossa one week later. In the upper lumbar extrusion patient, the shunt tube was removed from the lumbar wound cutting the distal end in the peritoneum, CSF was externally diverted for one week and then a VP shunt was reinserted after exclusion of peritoneal inflammation. In the scrotal cases, the shunt was extracted and re-inserted it into the peritoneum using a laparoscopic approach. Also in the para-spinal shunt migration, the revision was performed laparoscopically. The peroral patient the shunt tube The follow-up data of and the penile and umbilical cases data was unfortunately lost. Conclusion:This case series identifies the rare complication of abnormal shunt migration in large patients population. Abnormal shunt migration did occur in 1.4% in the present series of 1092 prospectively collected pediatric patients with hydrocephalus. Thus, abnormal shunt migration needs to be considered in patients presenting with shunt dysfunction. The management of abnormal shunt migration is according to the site of migration and should be done in an interdisciplinary approach. We recommend to avoid insertion of VP shunts using trocars & silicone firm tipped shunts in malnourished children.