INTRODUCTION

Ascites is defined as a pathologic accumulation of liquid inside of the peritoneal cavity. It is usually a consequence of decompensated cirrhosis (80%), right-sided heart failure, malignancy, tuberculosis, renal disease, and pancreatic disease.1 Assessment of the serum ascites albumin gradient (SAAG) can help differentiate the etiology of ascites.2 Cerebrospinal fluid (CSF) ascites is an extremely rare cause of ascites in adults who can present with a high SAAG.3 We present a case of a patient with confirmed CSF ascites, and high SAAG, who developed symptoms almost 40 years after placement of her VP shunt treated with acetazolamide.

CASE REPORT

A 38-year-old woman presented to the emergency department for new-onset, left-sided abdominal pain for the past 1 week. Her medical history was significant for neonatal meningitis, complicated by hydrocephalus, and treated by placement of a bilateral VP shunt during her first year of age. Her VP shunt was revised 20 years ago. On arrival, her vital signs were stable. She had no risk factors for liver disease. Review of systems was positive for abdominal pain. Physical examination demonstrated a soft, nondistended abdomen, with mild tenderness to palpation, and a VP shunt incision site without erythema. An abdominal computed tomography scan demonstrated a large volume of simple intra-abdominal ascites and a known VP shunt (Figure 1). Her serum laboratory test results on admission demonstrated a normal complete blood cell count, complete metabolic profile, and liver function tests. A VP shunt series demonstrated an intact VP catheter, without kinking or discontinuity along its course. She underwent 2 ultrasound-guided large-volume paracentesis (LVP), which revealed a total of 4.7 L of yellow-tinged peritoneal fluid, 525 White Blood Cell (WBC)/μL, polymorphonuclear neutrophils < 250, <1,000/μL of Red Blood Cell (RBC), 0.9 g/dL of albumin (serum albumin of 3.2 g/dL and SAAG of 2.3 g/dL), and a total protein of 1.3 g/dL. Her abdominal pain resolved after drainage of fluid. She was discharged to follow-up as an outpatient.

Figure 1.:

Computed tomography scan with Intravenous (IV) contrast showing two different cuts. (A) A large volume of simple fluid intra-abdominal ascites, with a ventriculoperitoneal shunt terminating within the right upper quadrant. (B) A liver that demonstrates uniform contrast enhancement and homogeneous parenchymal attenuation.

She was seen at the emergency department shortly after being discharged because of similar abdominal symptoms as before. She underwent another paracentesis and was started on furosemide 20 mg and spironolactone 50 mg daily. She underwent a transjugular liver biopsy (TJLB) with a hepatic venous pressure gradient of 5 mm Hg. Her liver biopsy was normal. Her imaging did not demonstrate any obvious intra-abdominal malignancy. In addition, her fluid studies were inconsistent with a biliary or pancreatic source. Her diuretics were increased to furosemide 40 mg and spironolactone 100 mg daily to help control her symptoms, and she was discharged.

The patient kept having symptomatic reaccumulation of her abdominal fluid every 2–4 weeks, requiring LVP every 1–2 months, despite uptitration of her diuretics. She underwent exploratory laparotomy and was found to have a large pseudocyst encircling her VP shunt catheter. The cyst was removed, and the intraperitoneal portion of her VP shunt was replaced. In addition, the shunt was redirected to a different area of the abdomen to maximize reabsorption of CSF. Her postoperative course was uncomplicated, with adequate wound healing.

After the surgery, the patient remained asymptomatic for about 7 months before reaccumulation of fluid requiring LVPs once again. By this point, the patient had undergone 8 LVPs with about 24 L of fluid drained in 2 years. Fluid from her LVP tested positive for β2-transferrin. Placement of a ventriculoatrial (VA) shunt was discussed but deferred by the patient, and she was instead started on acetazolamide 500 mg twice a day. Three months later, a repeat abdominal ultrasound demonstrated minimal abdominal fluid. The patient has been free of her abdominal symptoms and has not needed an LVP for more than a year.

DISCUSSION

CSF ascites is a rare complication with an incidence of 1.3% in children.4 To this date, there are around 50 CSF ascites cases reported, of which only 5 cases are in adults.3,5–8 Its pathophysiology remains a controversial topic, and proposed theories include (i) increased production of CSF surpassing the absorption capacity of the peritoneum, (ii) impaired peritoneal absorption because of high protein quantity in the CSF, and (iii) chronic peritoneal inflammation.5,9 The formation of pseudocysts has also been reported as a cause of CSF ascites.10 VP to VA shunt conversion has been successful as treatment.5–8 Placement of a Denver shunt has also shown good results.9

Our case is notable for many reasons: The patient's symptoms presented almost 38 years after the placement of her VP shunt, representing the largest interval reported as of yet. We could theorize her CSF ascites was multifactorial, given the presence of a pseudocyst around her VP shunt, and her response to acetazolamide, indicating CSF overproduction as a culprit. She initially presented with a high SAAG, requiring a TJLB to rule out portal hypertension as the cause of her ascites. This is consistent with previous cases of CSF ascites.9 The cause of high SAAG in CSF ascites cases could be due to the intrinsically low albumin content of the CSF, as well as the lack of albumin production in the central nervous system.11 Her β2-transferrin test, a biomarker with 99%–100% specificity for CSF, was initially positive, all but confirming that her accumulated abdominal fluid was CSF.12

Finally, this is the only reported case of CSF ascites treated successfully with acetazolamide. Data regarding the use of acetazolamide in patients with VP shunts are very scarce, although there is evidence of decreased CSF production in ventilated pediatric patients with VP shunts.13

In conclusion, CSF ascites can have various etiologies, as well as present from weeks to many years after VP shunt placement. Analysis of peritoneal fluid can present as a sterile fluid, with an SAAG >1 g/dL. Additional studies, such as cultures, brain imaging, and TJLB, should be considered to rule out other etiologies. Our case opens up discussions about the viability of medical therapy with acetazolamide in patients who are not candidates for a VA shunt.

DISCLOSURES

Author contributions: DR Lora: wrote manuscript, acquisition, and analysis of data and is the article guarantor; Z. Post: acquisition and analysis of data; JE Mitchell: acquisition and analysis of data; all authors have read and approved the manuscript for submission.

Financial disclosure: None to report.

Previous presentation: Poster presentation at the American College of Gastroenterology 2023 Annual Scientific Meeting; October 24, 2023; Vancouver, Canada.

Informed consent could not be obtained for this case report. All identifying information has been removed.

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