Volume 32 Number 4

Introduction

Ventriculoperitoneal (VP) shunts, commonly used to treat hydrocephalus, are typically made from silicone due to their flexibility and biocompatibility. However, hypersensitivity reactions to silicone, though rare, can lead to significant clinical complications such as skin breakdown, chronic inflammation, and allergic responses.^1,2 These reactions are usually mediated by delayed-type hypersensitivity mechanisms involving cell-mediated immune responses.

In cases where silicone hypersensitivity occurs, repeated surgical revisions are often necessary, with traditional management involving replacing silicone components with alternative materials such as polyurethane. While polyurethane has been used successfully in some cases, it is not without its limitations, including an increased risk of infections and mechanical failures.³ Moreover, the availability of polyurethane in some regions is limited, particularly in developing countries.

Polytetrafluoroethylene (PTFE), commonly known as Teflon, is recognised for its biocompatibility and inert nature, making it a potential alternative in cases of silicone hypersensitivity. PTFE has been evaluated as a material for cerebrospinal fluid shunting, though its porosity sometimes allows tissue ingrowth, which can complicate its use.⁴

We report a case in which a novel approach of using Teflon (PTFE) sheets to cover the silicone valve surface successfully prevented a hypersensitivity reaction.

Case report

A 22-year-old male with a history of multiple shunt surgeries and wound revisions after craniopharyngioma surgery (Figure 1) was admitted to our clinic for wound dehiscence after 1.5 years of no wound-related issues after previous surgery.

 

Figure 1. Timeline for the patient marking all the previous surgeries

 

The patient was awake on the presentation, with a Glasgow Coma Scale of 15 and a normal neurological examination. Upon inspection of the wound, the shunt valve could be visualised; the surrounding skin was markedly erythematous, and loose propylene sutures could be seen from the recent attempts at primary closure (Figure 2). He had a body temperature of 36.7 with no history of fever. The patient had a C-reactive protein level of 0.08 mg/dL, a procalcitonin level of 0.03 µg/L, and a white blood cell count (WBC) of 7.75 10^3/µL.

 

Figure 2. A) Over the course of the three months to his admission, the patient’s shunt site first had (A) erythema,  then (B) the epidermis eroded, leaving a thin red dermis layer. Then, (C) the skin completely opened up, revealing the fascia lata graft from previous surgeries, and propylene sutures from an attempt for reconstruction can be seen.

 

With the patient’s previous history of three failed flap surgeries and his young age, an alternative diagnosis of late hypersensitivity reaction to silicone was considered. The patient was operated on, and the shunt valve and cranial entry point were wrapped in Teflon/Polytetrafluoroethylene  (PTFE) felt sheets (Venaporta Ltd, Ankara, Türkiye). Then, the wound was approximated using 2–0 propylene sutures. The patient was put on a treatment regimen of methylprednisolone for two weeks that was planned to be tapered off, and the patient was discharged after three days in the inpatient unit.

After one month, the wound healed completely (Figure 2), and the patient is revision-free at ten years post-surgery (Figure 3). The PTFE sheet covering the shunt can be seen in the postoperative MRI (Figure 4).

 

Figure 3. 10-year follow-up photo of the patient.

 

Figure 4. Preoperative (A) and postoperative (B) T2 sequence MRI demonstrating the PTFE layer over the shunt valve (red arrow)

 

Discussion

Hypersensitivity reactions to silicone are rare but significant clinical challenges, especially in patients requiring long-term implantable devices such as ventriculoperitoneal (VP) shunts. Silicone is widely used due to its flexibility and biocompatibility, yet it occasionally induces adverse immune responses. These reactions are typically mediated by delayed-type hypersensitivity mechanisms characterised by cellular immune responses and chronic inflammation.^3,5–7

In our case, the patient exhibited multiple episodes of wound dehiscence and inflammation, raising suspicion of a hypersensitivity reaction to the silicone VP shunt. The clinical presentation, including recurrent wound breakdowns and erythematous reactions, aligns with documented cases where silicone implants have led to similar complications. Such responses often involve the formation of granulomas and chronic inflammatory tissue.^3-6

Traditional approaches to managing silicone hypersensitivity include replacing the silicone with alternative materials like polyurethane. However, these alternatives are not without complications. For instance, polyurethane shunts have been associated with their own issues, such as infections and mechanical failures.⁶ Moreover, the availability of polyurethane shunts can be limited, as they are not readily accessible in every country and often rely on a single supplier, restricting options. Therefore, exploring new materials or protective strategies is crucial for improving patient outcomes.

In this study, we used Teflon (PTFE) sheets to cover the silicone valve of the VP shunt. Teflon, known for its excellent biocompatibility and inert properties, provided an effective barrier between the silicone and the patient’s immune system. This approach successfully resolved the hypersensitivity reaction, as evidenced by the complete healing of the wound and the absence of further complications over a 10-year follow-up period. This innovative method highlights the potential of Teflon as a protective covering for silicone implants, offering a promising solution for patients with similar hypersensitivity issues.

Conclusions

The case presented demonstrates the successful resolution of a hypersensitivity reaction to a silicone VP shunt using Teflon (PTFE) sheets. This novel approach may offer a promising alternative for managing silicone hypersensitivity, particularly in cases where other alternatives, such as polyurethane, are not available. However, further studies are needed to evaluate the effectiveness and safety of this intervention in a broader patient population.

Acknowledgements

None.

Conflict of interest

The authors declare no conflicts of interest.

Ethics statement

An ethics statement is not applicable.

Funding

The authors received no funding for this study.

Author(s)

Hüseyin Biçeroğlu¹, Bilal Bahadır Akbulut*¹, Tuncer Turhan¹, Taşkın Yurtseven^1
1Department of Neurosurgery, Ege University, Izmir, Türkiye
*Corresponding author email b.bahadirakbulut@gmail.com

References

1. Hamzah Z, Muly, CVR. Silicone hypersensitivity necessitating removal of ventriculoperitoneal shunt in schizencephaly patient complicated with hydrocephalus: A case report. Indonesian Journal of Neurosurgery. 2021;4(3):129-131. doi: 10.15562/ijn.v4i3.207
2. Lanlokun MA, Guerriero E, Friedlander RM, Fajt ML. A case series of hypersensitivity reactions to ventriculoperitoneal shunt material. J Clin Neurosci. 2021;91:84–87.
3. Jimenez DF, Keating R, Goodrich JT. Silicone allergy in ventriculoperitoneal shunts. Childs Nerv Syst. 1994;10(1):59–63.
4. Gower DJ, Watson D, Harper D. e-PTFE ventricular shunt catheters. Neurosurgery. 1992 Dec;31(6):1132–1134.
5. Dargan D, McGoldrick C, Khan K. Type IV hypersensitivity to a textured silicone breast implant. J Plast Reconstr Aesthet Surg. 2012 Jul;65(7):969–972.
6. Bosker HM, Terra JB, Stenekes MM. Breast implant causes allergic contact dermatitis or foreign body reaction? Case Reports Plast Surg Hand Surg. 2020 Sep 3;7(1):108–111.
7. Narini PP, Semple JL, Hay JB. Repeated exposure to silicone gel can induce delayed hypersensitivity. Plast Reconstr Surg. 1995;96(2):371–380.