A Study on Ventriculoperitoneal Shunt Infections.

INTRODUCTION : Neurosurgeon Dr. James Drake writes “Perhaps no neurosurgical complication is as distressing as a CSF shunt infection”. The placement and revision of ventriculoperitoneal shunt remains a mainstay in the surgical treatment of hydrocephalus. Ventriculoperitoneal shunting is by far the most popular technique for cerebrospinal fluid (CSF) diversion. It is relatively simple, suitable for patients of all ages with hydrocephalus from any cause like myelomeningocele, aqueductal stenosis, preceding meningitis, preceding subarachnoid haemorrhage, CNS tumour, postopertive adhesion, head trauma, other congenital malformations and other acquired etiology. Ventricular shunts have obviously changed the prognosis for individuals with hydrocephalus, and most attain fairly normal intelligence. In patients who never had a VP shunt inserted before, a shunt can usually be inserted usually in less than an hour. It is important to try to do the procedure as quickly as possible to minimize the risk of infection. AIMS AND OBJECTIVES :  To find out the infection rate associated with ventriculoperitoneal shunts.  To study the association between the underlying conditions that necessitate shunt and the development shunt infection.  To evaluate the risk factors associated with shunt infection.  To isolate and identify the causative pathogens.  To evaluate the usefulness of CSF Gram staining, cell count and biochemical parameters to identify infections at an early stage.  To determine the antimicrobial susceptibility pattern of the isolates so as to use appropriate antibiotics.  To study the therapeutic outcomes. MATERIALS AND METHODS : This is a cross sectional study done involving 428 patients which included 404 patients who underwent primary ventriculoperitoneal shunt insertions during the study period and also 24 old cases of shunt insertion who underwent revision. During the study period 120 cases of malfunction occurred. Place of study: Institute of Microbiology, and Department of Neurosurgery, Madras Medical College. Period of study: MAY 2004 - OCTOBER 2005. Study Group: 120 patients both male and female of age group ranging from 0-60 were chosen. Patients with hydrocephalus of various etiology who had already undergone shunt surgery now presenting with signs and symptoms suggestive of shunt infection such as fever, seizures, headache, disturbed consciousness, vomiting, abdominal signs and other signs of shunt malfunction now undergoing shunt removal or shunt revision without removal of the shunt were studied. Two groups were studied: GROUP 1: This included 96 patients with shunt malfunction for whom shunt insertions were done during the study period. i.e. from 404 cases. GROUP 2: This included 24 patients with shunt malfunction for whom shunt insertions and revisions were already done before the study period. RESULTS : Patients in the age group less than 16 were considered under the paediatric category-248(57.9%). Patients in the age group more than 16 were considered under adult group-180 (42.1%). Space occupying lesions were observed in 50% of adults patients, where as in children congenital malformations were more common. Meningitis was observed as a precipitating factor in both categories. Symptoms such as vomiting, headache, altered consciousness and fever were present in children and adults. Seizures were common in children. 404 patients were treated surgically for hydrocephalus during the study period of which 96 showed signs of shunt malfunction. 2 of them had dual episodes of malfunction. Additional 24 patients who had undergone surgery previously and presented with malfunction were also included in the study. Out of 96 cases, 36 cases were proved culture positive with an infection rate of 8.9%. Two patients had recurrence of infection during the study period. In 24 cases with multiple revisions, the infection rate was 20.8% involving 5 patients. In 24 cases of malfunction, multiple revisions were done before the study period. All cases presented were more than six months duration. About 63.9% infection presented with in one month, 86.1% presented with in 2 months and and 94.4% presented with in 3 months and the remaining presented with in 6 months. No case of infection was present beyond six months during the study period. CONCLUSION : Ventriculoperitoneal shunt infection is a cause of significant morbidity and mortality, causing shunt malfunction and chronic ill health.  The overall infection rate associated with ventriculoperitoneal shunts was 8.9%.  Majority of the infections occurred within one to two months of surgery.  The most frequently isolated organism was Staphylococcus epidermidis.  Young age, cause of hydrocephalus as myelomeningocele, multiple shunt revisions were the main risk factors for shunt infection.  CSF Gram staining and CSF neutrophil count is of immense help in starting empirical antibiotic therapy.  Early identification and with the use of appropriate antibiotics both prophylactically as well as long term along with prompt removal of and replacement of the drainage system will ensure a good outcome.  Surveillance of MRSA and ESBLs are essential to implement strict control measures and antibiotic policies to combat bacterial drug resistance.