Introduction

Neonatal hydrocephalus is an extremely common condition managed by paediatric neurosurgeons. To date, the ventriculoperitoneal shunt (VPS) is the most established method of cerebrospinal fluid (CSF) diversion for lifesaving measures [1]. Nonetheless, the VPS remains imperfect, and implant-related morbidities are still prevalent worldwide [1, 2]. One such example is the migration of the distal end of the VPS catheter into the scrotum—a rare complication that has been infrequently described in the literature at the time of this writing [3, 4]. At the time of this writing, there is a paucity of literature describing the spontaneous regression of a migrated VPS catheter from the scrotum back into the peritoneal cavity. We present a case of a child who initially presented with scrotal migration of his VPS catheter and subsequently had spontaneous regression of the catheter back into his peritoneum. Given the infrequency of this phenomenon, this unique case is discussed in corroboration with current literature and management strategies.

Historical background

In 1983, Croffort and Balsam reported the first case series of 4 children presenting with migration of the distal VPS tip through the patent process vaginalis (PV) [5]. Of note, this is the period in neurosurgery whereby VPS is replacing ventriculoatrial shunt as the procedure of choice owing to its comparatively lower complication and revision rates for CSF diversion in children [5]. Although significant progress has been made in implant biomaterials and perioperative sterility practices, shunt complications are still major public health challenges [1, 6, 7]. In children, scrotal migration of the distal end of the VPS catheter is a rare complication that has been limited to case reports and small series in the literature [3,4,5, 8, 9]. Management usually involves prompt removal of the distal catheter from the scrotal sac to avoid serious sequelae such as scrotal oedema, acute scrotum, scrotal perforation, incarcerated hernia, shunt extrusion, and CSF leak from scrotum [3, 10,11,12]. To identify articles pertinent to our topic of interest, a systematic search of publications in the English language according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines is performed [13]. Patients aged 18 years old and above are excluded from the review, as we are primarily interested in the condition’s incidence in children.

Diagnosis and management

The PV is a blind-ended evagination of the abdominal wall that develops during fetal life and typically undergoes obliteration in early life [10]. Persistence of PV is associated with a spectrum of pathologies, including congenital indirect inguinal hernias, communicating hydroceles, funicular and encysted hydroceles, canal of Nuck cysts, and acquired undescended testis [10]. A patent PV is reported to be more prevalent in premature infants [14]. Broadly speaking, asymptomatic scrotal swelling in young males is not uncommon, and the physiological obliteration of a male PPV is typically completed by 2 years old [10]. However, patent PVs have been reported to be present in up to 40% of males between 2 and 16 years old [10]. Most of the time, scrotal swelling in young children is likely secondary to a hydrocoele caused by a collection of fluid within a patent PV. Regardless, the discovery of an onset of scrotal swelling warrants early medical evaluation for diagnosis to guide the next step of treatment.

Separately, several theories exist with regard to the mechanism of scrotal migration in VPS. The most accepted theory is that VPS implantation results in an increase in intra-abdominal pressure, resulting in the prolonged patency of the PV [3]. In addition, the smaller size of a young child’s peritoneal cavity compared to adults has been postulated to be a risk factor for VPS migration into a patent PV. For a male patient with a VPS in situ, the presence of a patent PV predisposes him to the herniation of a distal VPS catheter into the scrotum, especially within the first year of insertion. One of the salient concerns is that the skin sac (also known as the dartos fascia) overlying the scrotum is thin [3, 15] and hence, it has the theoretical risk of perforation if there is pressure from prolonged implant contact, excess CSF accumulation, or both. Under such circumstances, concurrent surgical repositioning of the VPS and obliteration of the patent PV are recommended to prevent further complications and malfunctioning of the shunt [3, 10].

Prognosis and outcomes

Overall, the incidence of scrotal shunt migration in the paediatric age group remains uncommon, with varying estimates up to approximately 3.7% [3, 11, 16, 17]. Our literature review combines selected cases from a recent systematic review by Hauser et al. and subsequent case reports to date [3, 8, 11, 18] (Table 1). At this juncture, we want to highlight that there are limitations to our literature review as the patient numbers are modest and, therefore, our findings are, at best, descriptive. Based on our results, there are 49 reported cases (including our patient) of scrotal migration of shunt catheters in patients less than 18 years old. We included a case report of a 2-month-old infant whereby this complication developed very early post-operatively and spontaneously resolved [18]. Pertinent differences between this case and ours include the age (2 months old versus 24 months old) and the time interval between VPS insertion and scrotal migration of its catheter (5 days versus 18 months). This is significant as the patent PV is theoretically obliterated by 2 years old [10]—thereby reducing the risks of this particular VPS complication. Of interest, the incidence of right-sided scrotal migration of VPS catheters is also higher (76.9%). Despite its potentially worrisome sequelae, scrotal shunt migration has a good prognosis when timely surgical intervention is initiated. Recommendations are for hernia repair in addition to repositioning the migrated shunt catheter [3]. Figure 1 is a pictorial representation of our literature review.

Table 1 Summary of findings from the literature review
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Fig. 1
figure 1

A Pie chart illustrating breakdown of total number of published cases based on patients aged less than 2 years old versus those who are older. Based on the literature review, the main risk factor for scrotal migration of VPS catheter is the presence of a patent PV. Overall, management of these patients are similar—which is removal of the catheter from the scrotal sac and PPV closure. B Pie chart illustrating that majority of cases reports that the right scrotum is more frequent in cases of VPS catheter migration

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Exemplary case description

A 2-year-old male with a background of prematurity, non-immune foetal hydrops, and congenital hydrocephalus had a VPS insertion at 6 weeks old. He was otherwise progressing well with regard to his developmental milestones. During an outpatient review for VPS surveillance, his parents mentioned that the patient had asymptomatic, bilateral scrotal swelling. A referral to the paediatric surgery team was initiated. A follow-up groin ultrasound confirmed the diagnosis of bilateral hydroceles. There was no sonographic evidence of hernia incarceration, vascular anomaly, or other suspicious masses. A decision was made for an interval herniotomy when the child was older. However, the patient presented with increased painless, swelling of his right scrotum, especially noticeable when he was crying. There were no symptoms of VPS malfunction. Clinical examination noted a palpable, coiled tubular structure within his right scrotum. An abdominal X-ray reported loops of shunt tubing within the right scrotum, likely herniating through the right inguinal canal. Overall, the impression was that of scrotal migration of the patient’s distal VPS catheter likely through a patent PV (Fig. 2). In view of this finding, the patient was counselled for early surgical intervention to re-place the shunt tubing back into the peritoneal cavity and definitive closure of bilateral PPVs. Owing to an ongoing viral illness, the surgery was listed at 2 weeks from the time of diagnosis. During his elective admission, repeat X-rays were ordered by the neurosurgical team to re-assess the position of the tip of the distal shunt catheter. These demonstrated that no segment of the shunt catheter was visualised in the right scrotum (Fig. 2). Put together, it was likely that the previously migrated catheter in the scrotum had spontaneously been reduced back into the peritoneal cavity. The patient went on to have bilateral herniotomies. Intraoperative findings confirmed both hernia sacs were empty and that the right sac had intussuscepted into the adjacent hydrocele sac. He was discharged home uneventfully on the same day after his surgery (Fig. 3).

Fig. 2
figure 2

Antero-posterior X-ray of the patient’s abdomen in supine position. The distal VPS appears intact. Of note, loops of tubing are seen in the right scrotum, likely herniating through the right inguinal canal (white arrow). No gas is evident in the right scrotum to suggest herniated bowel loops

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Fig. 3
figure 3

A Repeat antero-posterior X-ray of patient’s abdomen in supine position performed just prior to planned surgery. The VPS is intact and no segment of the catheter is seen herniating into the scrotum (white arrow). B Lateral X-ray shows that the tip of the VPS catheter is projected over the left abdomen within the peritoneal cavity (white arrow). No pneumoperioneum is radiologically evident

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In the case of our patient, we postulate that the spontaneous regression of the shunt loop from his scrotum back into his peritoneum was likely from a combination of increased intra-abdominal pressure from his preoperative viral upper respiratory tract symptoms causing increased abdominal pressures. Furthermore, this phenomenon illustrated in our patient concurs with the theory that VPS catheter movement within the peritoneum is congruent with increased abdominal pressures. Nevertheless, we are cognizant that our hypothesis requires validation in a real-time setting to be proven. We were fortunate that the child did not have any visceral complications. At the same time, we acknowledge the value of updated imaging to re-evaluate the patient.

Conclusions

We therein report a case of a previously migrated shunt catheter in the scrotum that spontaneously regressed back into the peritoneal cavity more than 1 year after the VPS was inserted. This case contributes to the limited body of literature on this unique complication. Our findings reiterate the need for consistent long-term shunt surveillance in growing children.