Shunt is the most common treatment for hydrocephalus, and infection is a very common complication following shunt surgery. Most studies on SI focus on pediatric population. Currently there is only a few studies focusing on SI in adults, and the study samples are limited. Adult hydrocephalus and children hydrocephalus have distinct characteristics. In this study we present one of the largest retrospective investigation on SI specifically in adults.
Both VP shunt and LP shunt are routine surgical options at our center. VP shunt is the most common care for hydrocephalus, LP shunt is another effective shunting procedure in communicating hydrocephalus. There is no consensus on which shunt surgery has lower SI rate, and whether LP shunt can be an alternative to VP shunt remains controversial (6, 15). Our data suggests no significant difference between VP shunt and LP shunt in terms of SI rate.
Hydrocephalus etiology is another factor. We divided these cases into 6 different groups: posttraumatic hydrocephalus, hydrocephalus after spontaneous SAH, hydrocephalus after intracranial hemorrhage (excluding spontaneous SAH), tumor-associated hydrocephalus, idiopathic hydrocephalus, and others. The SI rate for idiopathic hydrocephalus (4.0%,10/252) seems lower than other groups (6.4%,69/1072), but this didn’t show a statistic difference (p = 0.16).
Surgical history of craniotomy or spine surgery is associated with higher rate of SI. 73.4% (58/79) of these SI cases have recent history of craniotomy or spine surgery (less than 2 years). We speculate that this is related to increased levels of protein, blood cells and debris in CSF which makes the CSF suitable for bacteria living. In the meanwhile, we found the craniotomy or spinal surgery underwent more than 2 years ago don’t contribute to a higher risk of SI. Patients who had an craniotomy or spinal surgery performed within two years before shunt, suggest a SI rate of 7.4% (58/789), and this rate is 3.9% (21/535) in rest cases. These two groups show a significant difference (p = 0.015). But these operations performed meanwhile and after shunt surgery didn’t contribute to SI (p = 0.42).
The infection status when shunt surgery is performed is a significant factor of SI rate. In patients with infection of pulmonary, and/or other systems, the SI rate is much higher than patients without infection when shunt surgery is performed. We observe these data and found the SI rate is 4.8% (46/954) in patients without infection when shunt were performed, and 8.9% (33/370) in patients with an infection in their lung or/and other organs. In cases which have infection in two or more system, the SI rate comes to 25%.
Infection is a very common complication following shunt surgery for hydrocephalus. Our study shows most cases of shunt infections are present within 2 months (up to 78.5%) of the shunt surgery, by 1 year 97.5% of shunt infection became clinical manifested. This situation is similar to other reports by different authors. Atiqur Rehman reported 10 cases of SI in 111 VP shunt, and in 70% of the cases clinical symptoms appeared in 2 months post-operation (11). Florian and Fried aim that infections symptomatic rapidly after shunt insertion, 70% of them being diagnosed within the first month (8). We suggest make a more closely follow up in the first 2 months after the shunt operation as an early stage, the infection cases at this stage are usually surgeryl-related, common symptoms include fever, headache, and obstruction, and shunt device removal and antibiotics are often necessary.
There is no persuasive guide to tell us the time point and whether or not to remove the shunt device when the infection is present (14). In our study, 76.3% (29/38) has a good outcome after totally removing catheters, and 78.0% (32/41) has a good outcome of the cases not completely removed shunt devices. However, it was not a random arrangement to remove the shunt device during the treatment of SI cases, often the shunt devices have to be removed when other treatments were not effective. In our study the shunt devices removal rate in these SI cases is as high as 48.1% (38/79).
Gram positive cocci accounted for 50.0% (23/46) of all SI cases in our study, in which 95.7% (22/23) is staphylococcus. These bacteria are parasitic on the skin, which is very easy to be brought into the CSF or adhesive in the shunt device. Based on our experience (9) gram positive cocci have a relatively high morbidity of infection, we usually started out with vancomycin (1.0g twice a day), or linezolid (0.6g twice a day) once SI was diagnosed. This study suggest that shunting infection caused by gram-positive cocci had a good prognosis (cure rate 78.3%), and the cure rate of gram-negative bacilli was only 47.6%. The use of vancomycin may be helpful in the control of gram-positive cocci infection. Compare with our previous data (9), this study shows the proportion of gram-negative bacilli related SI is also high. Further investigation found that 71.4% (15/21) of these cases had lung infection history, whereas only 34.8% (8/23) in gram-positive cocci induced SI cases, and 41.8% (33/79) in all SI cases, but this analysis didn’t show statistical difference. Gram-negative bacilli are mostly conditional pathogenic bacteria, and history of lung infection may contribute to this finding. Because the basic situation of such patients is often poor, this may lead to poor prognosis with a lower cure rate.