Transient ventriculoperitoneal shunt malfunction in a pediatric patient: An illustrative case

BACKGROUND

Hydrocephalus affects both pediatric and adult populations, with an estimated prevalence in the general populations of between 1.0% and 1.5%.[16] While hydrocephalus is a relatively common and life-threatening condition, transient hydrocephalus is rare, and only a few case reports are available in the current literature.

There are, to the best of our knowledge, 15 available case reports describing transient hydrocephalus in pediatric patients. Of these, only four represent patients with ventriculoperitoneal shunt (VPS) dysfunctions; other suspected etiologies include subarachnoid hemorrhage and intraventricular clots,[7,13] carbon monoxide poisoning,[17] head trauma,[18] lead poisoning,[19] suspension of adrenocorticotropic hormone (ACTH) therapy,[9] central nervous system infections, meningitis, on/off dysfunction of the VPS, and one of unknown etiology.[4,19,23] While transient VPS dysfunction is a relatively well-recognized cause of transient symptoms in patients harboring VPS, there is a relative paucity of well-documented cases in the literature.

In this report, we provide radiographic evidence on computed tomography (CT) and magnetic resonance imaging (MRI) of spontaneously resolving hydrocephalus secondary to suspected VPS dysfunction in a 4-year-old boy.

CASE DESCRIPTION

A 4-year-old boy presented to the Emergency room with recurrent episodes of vomiting. He had a prior history of embolized Vein of Galen malformation (treated at the age of 3 months) complicated by intraventricular hemorrhage and hydrocephalus which was treated with a VPS (age of 3 months). Over a 6-month period, he was hospitalized on four separate occasions for transient episodes of intractable vomiting, lasting on average <1 day. On his third hospitalization, a brain MRI [Figure 1a] and CT head showed ventriculomegaly (compared to baseline), and a decision was made to proceed with a surgical shunt revision [Figure 1b]. A brain MRI was planned for the morning of the surgery to assess the feasibility of endoscopic third ventriculostomy (ETV) for the treatment of hydrocephalus. On the morning of the scheduled surgery, he had symptomatically improved; his surgery was cancelled after MRI demonstrated spontaneous reduction of ventricle size [Figure 1c]. He was followed clinically and discharged after a few days of observation. He had one more transient episode of vomiting before being hospitalized 2 weeks later where imaging demonstrated ventriculomegaly [Figure 1d], and he was treated surgically through ETV. During ETV, it was noted that there was partial obstruction of the VPS catheter by the choroid plexus. On his past follow-up 24 months later, he was clinically well with no recurrence.

Close

Figure 1:: (a) Baseline noncontrast axial T2 magnetic resonance imaging (MRI) demonstrating baseline ventricle size. (b) Noncontrast axial computed tomography (CT) in a 4-year-old boy with known ventriculoperitoneal shunt demonstrating acute hydrocephalus and increased ventricle size when compared with his baseline. (c) Repeat MRI on the morning of the scheduled OR demonstrating spontaneous resolution of hydrocephalus coinciding with symptomatic improvement. (d) Noncontrast axial CT performed a few weeks later demonstrating acute hydrocephalus.

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DISCUSSION

Transient hydrocephalus has been described in pediatric patients with several proposed mechanisms, including intraventricular hemorrhage, suspension of ACTH therapy, carbon monoxide suspension, as well as other unknown etiologies.[6,9,10] A summary of known case reports discussing transient hydrocephalus is shown in [Table 1].

Table 1:: Case reports of transient hydrocephalus in pediatric patients.

This case report is unique in that the 4-year-old boy already had a VP shunt in place. The transient hydrocephalus was most likely due to transient shunt dysfunction. The on-off shunt failure, as mentioned by Cengiz et al.,[3] can present as slit-ventricle syndrome, which includes the triad of intermittent headache, smaller than normal ventricles on imaging, and slow refilling of the shunt pumping device. The phenomenon is explained by the proximal catheter initially being in an adequate position, but potentially malfunctioning as the child grows. It is thought that the shunt proximal tip eventually migrates to the border of the ventricle; here, the fenestrated portion of the catheter can be very easily obstructed by tissue, such as brain parenchyma and/or choroid plexus.[5,11,20] As the ventricle’s size increases because of CSF fluid accumulation, it may allow the end of the catheter to move back in the right place and drain cerebrospinal fluid (CSF) adequately, explaining the transient symptoms.

It is also possible that the catheter could transiently have been obstructed by blood cells or a heap of proteins in the CSF. One review analyzed patients after VP shunt insertion (15-year follow-up); here, 84% of patients required a revision, with catheter occlusion being the primary reason for VPS revision.[21] Tissue debris could also obstruct the proximal catheter and cause shunt migration. These clots could be transiently dissolved, which may explain the transient symptoms. Mild viral or bacterial infections before the obstruction could also explain this phenomenon by affecting the efficiency of the drainage.[8] There are case reports where abdominal issues, such as bladder infections, transiently cause VPS dysfunction.[22] Another possible etiology is chronic constipation, in which elevated intraperitoneal pressure causes VPS dysfunction due to the elimination of the pressure gradient through the shunt tubing,[16] although it is difficult to determine whether the constipation was a consequence of or the trigger for hydrocephalus.[14] The appropriate management of constipation, including disimpaction, may relieve distal shunt malfunction and help reestablish CSF circulation.[12] In these situations, surgical exploration of the shunt can be avoided.[15]

CONCLUSION

Although transient hydrocephalus due to VPS dysfunction in children is rare, it should be suspected in certain patients with a VPS shunt presenting with transient or improving symptoms.

Treatment may range from conservative medical management to surgical intervention and shunt revision. Thorough workup and careful monitoring of patient status are important to guide surgical decision-making in patients suffering from suspected transient VPS malfunction.