Shunt for Hydrocephalus Causing Cerebral Spinal Fluid Ascites and Pleural Effusion

AUTHORS:

Daniel Lohner, DO; James J. Burns, MD, MPH
University of Florida School of Medicine, Pensacola, Florida

CASE REPORT | PUBLISHED SPRING 2025 | Volume 45, Issue 2

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Abstract

Complications of ventriculoperitoneal shunts, used to treat hydrocephalus, usually involve mechanical obstruction or infection. This case describes a new onset of sterile cerebrospinal fluid ascites in a 14-year-old female patient three years after shunt revision. The patient presented with rapidly increasing abdominal distension, without associated fever, requiring paracentesis of 4 liters of ascites fluid. Diagnostic findings were negative for infection, and the serum to ascites albumin gradient, calculated by subtracting the ascitic fluid albumin value from the serum albumin value, was elevated at 2.4 g/dL. The presence of a gradient ≥ 1.1 g/dL is most commonly associated with liver disease with portal hypertension. However, an extensive workup for liver disease, hypothyroidism, heart disease, or infection was found to be negative. Beta-2 transferrin, a marker for the presence of cerebrospinal fluid, was positive on the ascites fluid. Because of the rapid reaccumulating ascites, at a rate of 4-6 liters every two weeks, the patient had the ventriculoperitoneal shunt distal terminus transferred to the pleural space. This resulted in the complete resolution of the ascites. However, 6 months after the placement of the catheter in the pleural space, the patient presented with a massive pleural effusion, requiring emergency chest tube placement. Plans are being made for the placement of a ventriculoatrial shunt. Cerebrospinal fluid ascites and pleural effusion are rare complications in the treatment of hydrocephalus and should be considered in patients with shunt placement.

Introduction

A ventriculoperitoneal (VP) shunt is a standard hydrocephalus treatment characterized by cerebrospinal fluid (CSF) accumulation in the brain. Due to the ability of the peritoneum to absorb liquid, the VP shunt is the most commonly used shunting procedure.1 While it is generally successful in managing the condition, VP shunting is not without complications. These complications are generally broadly categorized into mechanical or infective complications. Mechanical complications include obstruction, disconnection, or migration of the shunt. Infective complications include abscess formation, skin necrosis, and ventriculitis.1

A rare but significant complication that can occur post-VP shunting is the development of CSF ascites. As of 2019, approximately 50 cases of sterile CSF ascites have been reported in English literature.2 Hepatic, renal, or cardiac disorders most commonly cause ascites in children. The serum-ascites albumin gradient (SAAG) is used to classify ascites as portal hypertensive (SAAG > 1.1 g/dl) and non–portal hypertensive (SAAG < 1.1 g/dl).3 A 2019 case report cites four known cases of CSF ascites with an elevated
SAAG (> 1.1 g/dl). The patients described in these reports were six, seven, 26, and 28 years old.2 VP shunt-related ascites does not have a well-understood mechanism. Furthermore, the causes of VP shunt-related ascites may differ between age groups.4

Primary Objective

This case report aims to illustrate a rare complication of VP and ventriculopleural shunts, including CSF ascites and pleural effusion, respectively, and present a description of evaluation and management.

Subject Presentation

A 14-year-old female patient with a history of tuberculous meningoencephalitis at one year of age had complications, including hydrocephalus, spastic quadriplegic cerebral palsy, profound intellectual and gross motor disabilities, and epilepsy, requiring a vagal nerve stimulator and anticonvulsant medications. The patient was G-tube dependent and had associated hypothyroidism that is closely followed with regular testing, partial ACTH deficiency, intermittent diabetes insipidus, and syndrome of inappropriate ADH. She required a VP shunt, using a Codman® Hakim® Precision Fixed Pressure Valve at age 14 months, with revision using a Medtronic Delta Valve Small Performance Level 1.0® at eleven years of age, due to candida peritonitis. No further revisions were needed. For these multiple conditions, she is managed with numerous medications, including baclofen, clobazam, levetiracetam, valproic acid, oxcarbazepine, levothyroxine, albuterol, fluticasone, singular, famotidine, ferrous sulfate, vitamin D, sodium chloride, and calcium carbonate.

She presented to the Emergency Department with a chief complaint of increased agitation and a recent onset of a distended abdomen. Vital signs were stable, and the physical exam was only significant for a grossly distended abdomen (abdominal circumference of 88 cm) and general agitation. Abdominal X-ray showed ascites. This subsequently increased over the ensuing weeks, requiring paracentesis, which yielded 4 liters of clear fluid with 2 WBCs/HPF, 1 RBC/HPF, albumin of 0.8 g/dL, total protein of 1.1 g/dL, amylase of 34 U/L, lipase < 4 U/L, pH of 6.5, LDH of 46 U/L. Serum albumin at the time of paracentesis was 3.2 g/dL; total protein was 8.5 g/dL. Cytology was negative for cellular atypia. Bacterial and gram stains, acid-fast bacterial cultures, and fungi cultures were negative. Blood culture was also negative. The post-paracentesis abdominal circumference was 65 cm.

Liver enzymes were mildly elevated, with ALT ranging from 13-131 U/L and AST from 16-107 U/L. The remainder of the comprehensive metabolic panel showed normal creatinine, BUN, bilirubin, and calcium. Sodium levels varied from 129-145 mEq/L. Magnesium and phosphorus were normal.

The serum to ascites albumin gradient (SAAG), calculated by subtracting the ascitic fluid albumin value from the serum albumin value, was 2.4. The presence of a gradient ≥ 1.1 g/dL (≥11 g/L) predicts the presence of portal hypertension with 97 percent accuracy.5 A gradient < 1.1 g/dL (<11 g/L) indicates that the patient does not have portal hypertension.5

The SAAG will also be elevated in cardiac failure, liver metastases, and myxedema.3

To address the elevated liver enzymes and the elevated SAAG, further testing, including PT/PTT, alpha-1 antitrypsin, hepatitis serologies, ANA, AMA, ASMA, LKM, GGT, TTG, ceruloplasmin, iron, iron-binding capacity, CPK, amylase, and lipase, was conducted; these were all normal. Thyroid function testing was noted to be normal on multiple occasions.

QuantiFERON®-TB Gold test was positive, but further workup with serial gastric aspirates and paracentesis fluid for acid-fast bacteria was negative. The Gold test positivity was attributed to the prior history of TB meningitis.

Imaging included a normal cardiac echo, normal shunt series, stable MRI of the brain showing a stable VP shunt position, stability of the size of the anterior horns of the lateral ventricles, with some decrease in size compared to previous studies, small stable lacunar infarcts in bilateral basal ganglia and right internal capsule, and a normal CT abdomen except for ascites. Abdominal ultrasound with elastography ruled out chronic liver disease.

Serial paracentesis was required every 2 weeks, and 4-6 liters of fluid were obtained each time while the investigation was being completed. Beta-2 transferrin, a marker for CSF, was suggested to be obtained on the paracentesis fluid to measure the presence of CSF. It was found to be positive.

After this comprehensive laboratory and radiological testing, consultation with Gastroenterology, Neurosurgery, and Infectious Disease, with no hepatic or other cause for ascites found, and a positive beta-2 transferrin test, the presumptive diagnosis of CSF ascites was made. The patient underwent transfer of the VP shunt distal terminus to the pleural space. Since then, there have been no further recurrences of ascites, with the abdominal girth remaining non-distended.

Unfortunately, approximately six months after the shunt was placed into the pleural space, the patient presented to the Emergency Department with sudden decompensation due to massive pleural effusion requiring chest tube placement. Analysis of this fluid was unremarkable for infection. The placement of a ventriculoatrial (VA) shunt resulted in resolution, and the patient is now stable without reaccumulating ascites or pleural effusion.

Discussion

This case underscores the complexities involved in diagnosing and managing VP shunt-related ascites, particularly in pediatric patients with multiple comorbidities. The elevated SAAG (> 1.1 g/dL) in this patient initially suggested a portal hypertensive etiology, which is typically associated with hepatic causes. However, comprehensive testing ruled out traditional hepatic, renal, and cardiac causes of ascites.

In the literature, CSF ascites have been reported to be successfully treated by the replacement of the VP shunt with a VA shunt.4,6-8 One case report described pleural effusion when a ventriculopleural shunt was used to manage VP shunt-associated ascites.9 This case also eventually required VA shunt placement. Finally, another case report describes using a peritoneovenous shunt (Denver Shunt) rather than VA to manage the ascites.2

In retrospect, a question arose whether the extensive work-up may have been avoided with the positive results of the beta-2 transferrin test indicating that the ascites fluid was CSF. Beta-2 transferrin is a desialated (carbohydrate-free) isoform of the transferrin protein, which is found only in CSF, perilymph of the cochlea, and the aqueous and vitreous humor of the eye. Beta-2 transferrin is produced by neuraminidase activity within the nervous system. The assay requires only a 0.5 ml fluid specimen for the electrophoresis assay, costs around $450, and takes 3 hours to complete. It has been widely used as a marker for suspected CSF leakage in CSF rhinorrhea and otorrhea. A systemic review on CSF rhinorrhea found the use of beta-2 transferrin assay had a sensitivity ranging from 87% to 100% and specificity ranging from 71% to 100%.10

The use of beta-2-transferrin to assess suspected CSF ascites or pleural effusion has not been validated with systematic research. Instead, it has been advocated in case reports11, or perhaps as a confirmatory test after appropriate workup.12 False negatives have been reported. One article published in Pediatrics in Review describes a 20-year-old subsequently found to have CSF ascites with a negative beta-2 transferrin.13 Another case reported by Patel and coworkers describes false negative results on 2 out of 5 pleural fluid samples from the same patient with proven CSF pleural effusion.14 Because the data on beta-2 transferrin utility is based on case reports, no sensitivity/specificity data are available. Furthermore, unlike in the assessment of CSF rhinitis, where no CSF fluid is expected, in the setting of patients experiencing suspected VP shunt-related CSF ascites, where it might be expected there be CSF present from the shunt, the utility of this test may be less definitive in determining the cause of ascites. Therefore, a complete evaluation for multiple causes of ascites was needed in this case.

Unexplained remains why there was a three-year delay in the development of ascites from the time of placement of the VP shunt and a six-month delay in the development of the sudden pleural effusion after placement of the ventriculopleural shunt, which in both cases progressed rapidly, once underway.

In summary, with CSF-associated ascites from VP-shunts, the SAAG gradient can be elevated, and this doesn’t always signify portal hypertension. Additionally, measuring beta-2 transferrin can help determine the cause of ascites to be shunt-related CSF, considering the possibility of false negative results. Still, research on the reliability of this test remains to be conducted. Furthermore, pleural effusion can be a serious complication of ventriculopleural shunts.

References

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