Management of Shunt Infections

Introduction

Hydrocephalus is currently one of the most common conditions in neurosurgical practice. Hydrocephalus prevalence in childhood ranges from 0.5 to 1 per 1000 children. ^, In the adult population, the initial diagnosis is rather uncommon and incidence is approximately 3.4 per 100,000.

Since the introduction of cerebrospinal fluid (CSF) shunts in the 1940s, morbidity and mortality rates associated with shunt implantation have decreased significantly, from 50% down to 5% to 10%, and many shunted patients can lead a completely normal life. However, shunt malfunction and infection are the most common complications in hydrocephalus management, often having severe sequelae. Furthermore, shunt complications represent a significant cost to healthcare systems and a serious problem. According to recent reports, approximately 27,800 shunt implantation or revision procedures were performed in the United States in 2000 alone. Considering that each procedure costs USD 35,000 on average to the American healthcare system and that infected patients represent an estimated 5% to 15%, ^{, , ,} the number of cases potentially requiring reoperation could range from 1393.5 to 4181 annually and cost between USD 48,755,000 and USD 146,335,000. These patients require longer hospital stays, multiple diagnostic and treatment procedures, and antibiotic therapy, all of which have an impact on the healthcare system, which could be averted with the right preventative measures. Moreover, the aforementioned complications are associated with high morbidity and mortality rates and the subsequent sequelae affecting patients for life.

Several studies have tried to establish why these patients develop infections, and, in some cases, the use of strict surgical techniques has reduced the incidence of infections nearly to zero.

Shunt malfunction is reportedly approximately 25% to 35% during the first postimplantation year. ^, Rates of infection are very variable, ranging from 5% to 15% of all implanted shunts. ^{, , ,} Shunt infection can be ascribed to various factors; reviewing them individually assists in understanding how to minimize the risks of serious complications and implement appropriate treatment.

Etiology of Hydrocephalus

The etiology of hydrocephalus as a risk factor for the development of infections has not been clearly shown. An association between the causal agent and a higher risk for shunt infection has been rarely found, ^, although a recent review has described an association between obstructive hydrocephalus and the rate of complications.

Hydrocephalus following perinatal bleeding has been associated with a higher incidence of infection, but we could not establish such association in our series of 964 operated patients.

Patient Age and Nutritional Status

Many reports stress the importance of age as a risk factor for infectious complications in patients who have a CSF shunt. ^, The risk of complications is mainly present in infants and elders. A multicenter study analyzing shunt complications, in general, found that younger children were at a higher risk of complications and malfunction; however, the study failed to specify whether these were of an infectious or obstructive nature.

Nutritional status is yet another significant factor because undernourished subjects seem to have a higher rate of infectious complications.

Infant nutrition may also play an important role, and a lower incidence of infection has been described in breastfed infants.