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Management of Shunt Infections
CHAPTER 97
Management of Shunt Infections CLAUDIO YAMPOLSKY • PABLO AJLER
Hydrocephalus is one of the most common conditions in neurosurgical practice. Hydrocephalus prevalence in childhood ranges from 0.5 to 1 per 1,000 children.1,2 In the adult population, initial diagnosis is rather uncommon, and incidence is approximately 3.4 per 100,000.3 Since the introduction of cerebrospinal fluid (CSF) shunts in the 1940s,4 morbidity and mortality rates associated with shunt implantation have decreased significantly, from 50% to between 5% and 10%,5 and many shunted patients can lead a normal life. Shunt malfunction and infection, however, are the most common complications in hydrocephalus management, often having serious 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.6 Considering that each procedure costs the American healthcare system $35,000 on average and that infected patients represent an estimated 5% to 15% of shunted patients,1,7-9 the number of cases potentially requiring reoperation could range from 1,393.5 to 4,181 and cost between $48.76 million and $146.34 million annually. These patients require longer hospital stays, multiple diagnostic and treatment procedures, and antibiotic therapy, all of which have an impact on the healthcare system and 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.10 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.11 Shunt malfunction is reportedly around 25% to 35% during the first postimplantation year.12,13 Rates of infection are variable, ranging from 5% to 15% of all implanted shunts.1,7-9 Shunt infection can be ascribed to various factors; reviewing them individually assists in understanding how to minimize the risks of serious complications and implement an 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 rarely been found,11,14 although a recent
review described an association between obstructive hydrocephalus and rate of complications.15 Hydrocephalus following perinatal bleeding has been associated with a higher incidence of infection,16 but we could not establish such an 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.9,17 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 fails to specify whether these were infectious or obstructive.18 Nutritional status is yet another significant factor, as undernourished subjects seem to have a higher rate of infectious complications.19 Infant nutrition may also play an important role, and a lower incidence of infection has been described in breastfed infants.20
Surgical Technique The implantation technique of a ventriculoperitoneal or ventriculoatrial shunt is also extremely important. The absence of an appropriate strategy may turn a procedure normally representing low mortality and morbidity, and presumably requiring a short hospital stay, into a complicated procedure that eventually results in multiple reoperations, longer hospital stays, higher costs for the healthcare system, and potentially serious sequelae for the patient. Shunt implantation is a procedure often performed by neurosurgical trainees who have inadequate experience in the technique; this factor may be critical for the development of postoperative infections.21 Many papers have shown that postoperative infection rates may be reduced by using a meticulous surgical technique.7,11,22 Where possible, the procedure should be carried out in a dedicated neurosurgical operating room and be the first procedure of the day. The paramedic personnel involved in the procedure should be trained in prosthesis manipulation and instructed to maximally restrict circulation into and out of the operating room. Entrance to and exit from the operating room would only be allowed in emergency situations; where possible, the number of
1151
Management of Shunt Infections CLAUDIO YAMPOLSKY • PABLO AJLER
Hydrocephalus is one of the most common conditions in neurosurgical practice. Hydrocephalus prevalence in childhood ranges from 0.5 to 1 per 1,000 children.1,2 In the adult population, initial diagnosis is rather uncommon, and incidence is approximately 3.4 per 100,000.3 Since the introduction of cerebrospinal fluid (CSF) shunts in the 1940s,4 morbidity and mortality rates associated with shunt implantation have decreased significantly, from 50% to between 5% and 10%,5 and many shunted patients can lead a normal life. Shunt malfunction and infection, however, are the most common complications in hydrocephalus management, often having serious 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.6 Considering that each procedure costs the American healthcare system $35,000 on average and that infected patients represent an estimated 5% to 15% of shunted patients,1,7-9 the number of cases potentially requiring reoperation could range from 1,393.5 to 4,181 and cost between $48.76 million and $146.34 million annually. These patients require longer hospital stays, multiple diagnostic and treatment procedures, and antibiotic therapy, all of which have an impact on the healthcare system and 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.10 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.11 Shunt malfunction is reportedly around 25% to 35% during the first postimplantation year.12,13 Rates of infection are variable, ranging from 5% to 15% of all implanted shunts.1,7-9 Shunt infection can be ascribed to various factors; reviewing them individually assists in understanding how to minimize the risks of serious complications and implement an 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 rarely been found,11,14 although a recent
review described an association between obstructive hydrocephalus and rate of complications.15 Hydrocephalus following perinatal bleeding has been associated with a higher incidence of infection,16 but we could not establish such an 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.9,17 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 fails to specify whether these were infectious or obstructive.18 Nutritional status is yet another significant factor, as undernourished subjects seem to have a higher rate of infectious complications.19 Infant nutrition may also play an important role, and a lower incidence of infection has been described in breastfed infants.20
Surgical Technique The implantation technique of a ventriculoperitoneal or ventriculoatrial shunt is also extremely important. The absence of an appropriate strategy may turn a procedure normally representing low mortality and morbidity, and presumably requiring a short hospital stay, into a complicated procedure that eventually results in multiple reoperations, longer hospital stays, higher costs for the healthcare system, and potentially serious sequelae for the patient. Shunt implantation is a procedure often performed by neurosurgical trainees who have inadequate experience in the technique; this factor may be critical for the development of postoperative infections.21 Many papers have shown that postoperative infection rates may be reduced by using a meticulous surgical technique.7,11,22 Where possible, the procedure should be carried out in a dedicated neurosurgical operating room and be the first procedure of the day. The paramedic personnel involved in the procedure should be trained in prosthesis manipulation and instructed to maximally restrict circulation into and out of the operating room. Entrance to and exit from the operating room would only be allowed in emergency situations; where possible, the number of
1151