Vesical calculi formation on the slit valves of a migrated distal end of ventriculoperitoneal shunt.

Various complications of distal end of the ventriculoperitoneal (VP) shunt have been described in the literature. We present, here, an extremely rare and potentially severe complication of vesical calculi formation on the slit valves of distal end of VP shunt which erosively migrated into the urinary bladder. Suprapubic cystolithotomy performed, peritoneal end of the tube found to be eroding and entering into the bladder with two calculi firmly stuck to slit valves in the distal end of the tubing were removed. Shunt was functional, therefore, it was pulled out and repositioned on the superior aspect of the liver; the urinary bladder was repaired. Patient did well postoperatively. This complication was revealed 1.5 years after the shunt was implanted. Although there were symptoms of dysuria and dribbling of urine of short duration, the patient did not show obvious peritoneal signs; suggesting that, penetration of a VP shunt into the urinary bladder can remain asymptomatic for a long period of time, disclosed late and can lead to considerable morbidity. Careful follow-up is important and management should be individualized.

Introduction

Ventriculoperitoneal shunt (VP) introduced in 1908, is one of the most common neurosurgical procedures performed for patients with hydrocephalus.[1] The distal (peritoneal) end of the VP shunt has been associated with complications such as infection, shunt blockage, cerebrospinal fluid (CSF) pseudocyst formation, intestinal obstruction or volvulus, perforations of hollow viscus, penetration into solid organs and abdominal wall and protrusion outside body particularly through the abdominal incision, neck, chest, umbilicus, vagina, anus, and oral cavity.[2345] However we report an extremely rare case of vesical calculi formation on the slit valves of distal end of a VP shunt which erosively migrated into the urinary bladder. To the best of our knowledge, less than fifteen cases of erosive migration of distal end of the VP shunt into the normal (nonaugmented) urinary bladder have been reported so far, only three cases with formation of vesical calculus have been reported and none with presence of two calculi stuck with slit valves of shunt tubing in the English literature till date.[678910]

Case Report

A 3-year-old boy had VP shunt (Chhabra-slit-in-spring silicone shunt) surgery done for posttubercular meningitic hydrocephalus 1.5 years back. The child had learning disabilities with delayed milestones. Antitubercular treatment was compliant by the patient. This time he presented with dysuria and dribbling of urine for the last few days. There were no signs to suggest shunt malfunction (vomiting, headache, fever, etc.) and patient was hemodynamically stable. Except for the subcostal scar of previous operation, abdomen was unremarkable. Laboratory investigations revealed polymorphonuclear leucocytosis (12,700/mm3). Urine culture was sterile. Radiographs revealed two radio opaque bladder calculi. On careful analysis of X-rays, shunt tubing was seen intact, reaching the pelvis along with the two vesical calculi near the tip of the shunt [Figure 1]. This condition was new to our experience and decision for suprapubic cystolithotomy was taken after preoperative preparation.

Figure 1

Two radio-opaque shadows (vesical calculi) are seen along with distal end of ventriculoperitoneal shunt (blue arrow) reaching the pelvis in close relation to them

Intraoperatively, during the removal of stones, peritoneal end of the shunt tube came out of the incision from the bladder along with the two calculi firmly stuck to the points of slit valves at the distal end of the tubing [Figure 2]. The peritoneal end of the tube was found to be eroding bladder wall and entering into the bladder via right posterosuperior aspect of fundus. On compressing the reservoir, clear CSF was coming out from slit valves, indicating that the shunt was functioning. Stones were separated [Figure 2]; peritoneal end of the tube and interior of bladder was irrigated with normal saline. In view of shunt being functioning well and absence of shunt infection, a decision to reimplant it and avoid replacement was taken. A right subcostal skin incision was given and from there the peritoneal end was pulled out and repositioned on the superior aspect of the liver. The urinary bladder was repaired and procedure was completed. Antibiotic therapy was continued for 2 weeks and the postoperative period was uneventful. Patient is doing well and is under follow-up.

Figure 2

Intraoperative photograph showing two vesical calculi stuck at the slit valves at the distal end of shunt tubing. Inset image shows calculi after removal

Discussion

VP shunt complications are common. They are classified as early or late and also as mechanical, infective and functional complications. Although rare, migration of the peritoneal end into virtually every abdominal organ (thoracic cavity, heart, liver, large bowel, vagina, gallbladder, scrotum, umbilicus, and inguinal hernia) has been reported in the literature.[2345] Review of literature suggests that there are only handful cases of erosive migration of the VP shunt into the urinary bladder.[5678910] The exact cause of shunt perforation into the lumen of body cavities particularly the bladder is not fully clear yet. The possible factors responsible for visceral perforation in VP shunt patients are sharp and stiff end of the VP shunt,[3] thin visceral wall in children, strong peristaltic waves in children, chronic irritation and inflammation by the shunt which may lead to adhesions followed by perforation, previous surgery, infection, increased intrabdominal pressure, abdominal musculature contraction, silicone or latex (chemical components of the shunt) allergy, and long abdominal part of the shunt tubing.[45678910] Prevention of shunt migration into the viscera has been recommended by the use of a softer catheter, appropriate redundancy for the abdominal part of the catheter and fixation of shunt system using nonabsorptive suture materials.[567]

Migration of the distal end into the urinary bladder presents with abdominal pain, vomiting, diarrhea and dysuria.[5678910] Although there were symptoms of dysuria and dribbling of urine for short duration, the patient did not show obvious peritoneal signs; suggesting that, penetration of a VP shunt into the urinary bladder can remain asymptomatic for a long period of time, disclosed late and can lead to considerable morbidity. In few cases perforation of the visceral organs by the VP shunt is manifested by septic symptoms due to peritonitis, intra-abdominal abscess, meningitis, encephalitis, and ventriculitis.[5]

In our case time lag between the migration of the shunt into the bladder and the presentation of the patient (dysuria) was long enough to result in vesical calculi formation. While only three cases similar to the present case have been reported in previous literature, but in our case there were two calculi and both were at the site of slit valves at the distal end of the shunt, which was again an extreme rarity.[8910] We propose that vesical calculi formation in our case could be attributed either to precipitation of CSF proteins coming in contact with acidic urine at the slit valves and precipitation of calcium phosphate, calcium carbonate and magnesium phosphate coming in contact with alkaline CSF. Spectroscopic analysis of calculi could not be performed due to its nonavailability in our institute.

Strategies in the management of this extremely rare complication may involve removal of calculi either endoscopically or by open method.[8910] If calculi formation is on the tip of a disused shunt, preferably whole of the assembly may be removed. In case of functional shunt, decision for its removal may be taken if there is urosepsis, positive urine culture or damaged shunt tubing. In our case we reimplanted the shunt because of absence of above mentioned factors and also because of surgeon preference. Finally, an individualized approach is essential for the successful management.

The mortality following VP shunt operations are high, even up to 15%.[2] This implies the importance of careful follow-up and knowledge regarding possible and even rare complications of VP shunt in a patient of hydrocephalus, in order to diagnose and manage possible complications at proper time.

Conclusions

Penetration of a VP shunt into the urinary bladder can remain asymptomatic for a long period of time, disclosed late and can lead to considerable morbidity. Parents of children with implanted VP shunt should be informed about severe and potentially serious complications. Patients should be kept under regular follow-up with meticulous clinical examination so that complications could be unveiled and timely intervened.

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Conflicts of interest

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