It is well known in children but uncommon in adults.
Diverse predisposing factors have been proposed such as previous abdominal surgeries, multiple VPS revisions, history of necrotizing enterocolitis.
The pseudocyst can either move freely within the peritoneal cavity or adhere to small-bowel loops, the serosal surface of solid organs, the parietal peritoneum, or small-bowel loops. The latter would explain why some bowel loops may become engulfed when the pseudocyst increases in size or why the pseudocyst may be prone to torsion.
Pediatric patients commonly present with symptoms of elevated intracranial pressure and abdominal pain, whereas adults predominantly present with abdominal signs only.
Familiarity with these types of shunt failure is essential for neurologists and pediatricians because they are often the first to evaluate and triage these patients 1) 2).
Ultrasonography proved to be the method of choice in the diagnosis of VPS abdominal complications, especially CSF pseudocyst.
Well defined hypoechoic / anechoic cystic mass with tip of VP shunt within it
Pressure effects on adjacent organs if mass is huge
Multiple septae may form chronically
Debris and internal echoes are seen if the mass is infected
Measurement of attenuation values with CT characterizes the contents as water attenuation and demonstrates the relationships of portions of the shunt catheter with the pseudocyst.
In case of IH signs, a cerebral CT scan can be performed to evaluate the ventricular distension and to check the shunt position 3).
Benign cystic teratoma
Cystic spindle cell tumour
Enteric duplication cyst
It may be difficult to differentiate seroma, urinoma, abscess, lymphocele, and cerebrospinal fluid on the basis of imaging findings alone. Fine-needle aspiration with ultrasound or CT guidance has a high diagnostic yield 4).
Gastroenterological surgeons should be aware of this possible complication, and this complication should be considered during differential diagnosis of an acute abdomen complaint 5)
In case of suspected infection, the VPS is removed and replaced by an external ventricular drain. Antibiotics are started and adjusted to the results of the CSF culture. If there is no direct sign of infection, only the distal catheter is externalized and antibiotics are introduced until infection is treated. Depending on the peritoneal absorption state, the distal catheter is replaced in the abdominal cavity or in the atrium, the pleural space or the gallbladder if there is no suitable place for repositioning. If the peritoneal state allows it, a laparoscopic procedure is recommended to avoid peritoneal adhesion formation increasing the recurrence rate of CSF pseudocyst 7).
An APC is a major long-term complication after ventriculoperitoneal shunt treatment. Although a sterile inflammatory response cannot be excluded completely, our results favor the hypothesis of low-level shunt infection. In both cases, the surgical consequences are the same. An infected APC should be treated as a shunt infection. Uninfected patients can be treated with shunt externalization and replacement of only the peritoneal catheter 8).
In three patients, the cyst was multilocular and of varying size. Fourth one had a unilocular cyst at the lower end of VP shunt. All the four patients had features of varying degree raised intracranial pressure and a two patients had abdominal signs also. All the patients needed open exploration. Cyst fluid was drained and partial to complete excision of the cyst was done along with the repositioning of the shunt in abdominal cavity in three patients and exteriorization of shunt in one patient. Patients were followed for any further complication over a period of 1-year 9).
Four unique cases of abdominal pseudocyst formation. The first patient initially presented with a right upper quadrant pseudocyst. Shunt was externalized and the distal end was revised with placement of catheter on the opposite side. He developed another pseudocyst within 5 months of shunt revision and developed another shunt failure.
The second patient had a history of shunt revisions and a known pseudocyst, presented with small bowel obstruction, and underwent laparotomy for the lysis of adhesions with improvement in his symptoms. After multiple readmissions for the same problem, it was thought that the pseudocyst was causing gastric outlet obstruction and his VP shunt was converted into a ventriculopleural shunt followed by percutaneous drainage of his pseudocyst.
The third patient developed hydrocephalus secondary to cryptococcal meningitis. He developed abdominal pain secondary to an abdominal pseudocyst, which was drained percutaneously with relief of symptoms.
The fourth patient had a history of multiple shunt revisions and a previous percutaneous pseudocyst drainage that recurred with cellulitis and abscess secondary to hardware infection.
Abdominal pseudocysts are a rare but important complication of VP shunt placement. Treatment depends on etiology, patient presentation, and clinical manifestations. Techniques for revision include distal repositioning of peritoneal catheter, revision of catheter into pleural space or right atrium, or removal of the shunt completely 10).
A 14-year-old patient, known to have a VPS as intraventricular hemorrhage treatment, presenting cephalalgia, vomiting, apathy, and an indurate abdominal mass without fever. The first abdominal CSF pseudocyst diagnosis had been established 3 months earlier. Abdominal ultrasounds confirmed a large homogeneous cyst with the shunt tip within the pseudocyst. Cerebral CT revealed an increased ventricular size. An exploratory laparotomy with cyst aspiration, lysis of adhesions, excision of cystic walls, and repositioning of the peritoneal catheter was performed.
No antibiotics were initiated given that the cultures were negative 17).
A case of a 4-month-old girl with shunted hydrocephalus who presented with shunt failure from a suspected abdominal pseudocyst that was found to be a fetal ovarian cyst is reported 18).
A 22-year-old man who was admitted because of diffuse abdominal distention. A VPS was placed 21 years earlier to treat hydrocephalus secondary to spina bifida. Abdominal computed tomography (CT) revealed a homogeneous low-density fluid collection adjacent to the VPS catheter tip, causing stomach obstruction. Thus a peritoneal pseudocyst around VPS was suspected and emergency laparotomy was performed. The large mass was localized in the left upper abdomen between the stomach and mesentery of the transverse colon, exactly at the omental bursa. The cystic mass was opened and 1500 ml of clear fluid was drained; the distal end of the VPS was repositioned outside the mass. Thus, an abdominal cerebrospinal fluid pseudocyst as a complication of VPS was diagnosed 20).
A 13-year-old girl with a VP shunt presented with progressive abdominal distention, pain and vomiting. The shunt was inserted at infancy for congenital hydrocephalus. A shunt infection was treated with externalization of the shunt, antibiotics and subsequent shunt replacement. At the age of four, the shunt was revised for a distal malfunction. Nine years later, abdominal CT and ultrasound demonstrated large multiseptated cysts. The shunt was externalized and 1.8 L of sterile, xanthochromic peritoneal fluid was drained. The cerebrospinal fluid was clear, colorless, acellular and sterile with normal protein and glucose levels. Two days later, the distal portion of the shunt was replaced back into the pleural cavity. Five months later a pleural effusion formed. Thoracentesis was performed and there was no evidence of infection. The shunt was subsequently converted to a ventriculoatrial system. The patient has remained well for over 3.5 years 22).