Distinct from the CNS candidiasis related to hematogenously disseminated candidiasis, neurosurgery-related CNS candidiasis follows surgical interventions that involve placement of plastic devices into the brain. Most infections are due to ventriculo-peritoneal (VP) shunt placement. Only a few cases have followed simple craniotomies or lumbar punctures [438, 816].
Fungal meningitis in patients with VP shunts in place occurs relatively infrequently. Incidence rates of between 1% and 17% have been reported [436, 2017]. The highest rates were seen in infants less than 1 year old .
Neurosurgery-related CNS candidiasis may be increasing in relevance as a nosocomial infection. One center has recently reported Candida spp. as the fourth leading pathogen causing meningitis in neurosurgical patients . A practice that may explain an increase in the incidence of neurosurgery-related CNS candidiasis is the use of prophylactic antibiotics for patients with ventricular catheter for monitoring and CSF drainage . However, through 1998 only 26 adult patients affected by this condition had been reported in the English-language literature .
Risk Factors associated with Neurosurgery-related CNS Candidiasis
VP shunt placement or replacement is the most prominent association. A few cases have been seen following craniotomy or placement of lumbar drains [438, 816, 1644]. Not surprisingly, abdominal infections in patients with VP shunts in place and previous bacterial meningitis have also been linked to this problem [816, 1644].
Neurosurgery-related CNS Candidiasis and Candida spp.
In the largest (N = 26) and newest series of neurosurgery-related cases in adults, C. albicans was responsible for less than 50% of cases, while C. parapsilosis was isolated in 25% of cases. C. tropicalis was the least frequent species . In the largest series in the pediatric population, C. albicans was responsible for 5 of 8 (63%) cases. C. parapsilosis, C. tropicalis and C. glabrata caused one case each .
In adults, a clinical picture quite similar to the one of bacterial meningitis has been described [816, 2017]. The most frequent findings are fever, nuchal rigidity, altered mental status, confusion, headache, nausea and vomiting, disorientation, focal neurologic signs, and seizure activity. In children with VP shunt infections, a more subtle picture is described . Characteristic findings in this age group include lack of nuchal rigidity and fever in only 1/3 of cases. More common are signs of shunt obstruction (progressive head enlargment is frequently found) and nonspecific symptoms such as poor appetite, poor activity, and vomiting.
Specific Diagnostic Strategies
Growth of Candida spp. from CSF is of course a critical element in making this diagnosis. Analysis of the CSF is often suggestive of only a mild inflammatory response, with increased cells and protein, but relatively normal glucose being typical:
|Author, Year, Reference||Geers, 1999 ||Chiou, 1994 |
|WBC* (cells/mm3)||445 (2-7,899)||194 (2-660)|
|Protein (mg/dl)||113 (14-440)||347 (32-1,032)|
|Glucose(mg/dl)||67 (22-150)||38 (11-50)|
* WBC: White blood count
Occasionally a single sample of CSF drawn from a catheter will grow Candida spp. and not be related to actual infection. Geer et. al identified eleven such patients . Only two of these patients received antifungal therapy, but the whole group did well. These authors compared clinical characteristics and laboratory findings of these patients with a similar number of patients that also had Candida spp. isolated from the CSF but who were considered to be truly infected. Based on this comparison, the authors found that the presence of one or a combination of the following findings was indicative of such insignificant recovery of Candida from the CSF:
- Negative results when the sample was subsequently cultured from a CSF specimen obtained by lumbar puncture
- Negative results after culturing a second CSF sample obtained by aspiration from the same device
- Absence of clinical manifestations such as meningismus, focal neurological signs and/or altered mental status
As with most device-related Candida infections, treatment of neurosurgery-related CNS candidiasis usually requires both antifungal therapy and removal of the infected device.
Comparative data do not exist. However, numerous clinical reports have stated that catheter removal was a crucial step in achieving cure of such infections [494, 816, 1644, 2371]. Based on this, experts coincide in recommending that in cases of VP shunt-related candidal meningitis:
- Remove the device
- Use externalized drainage during initial therapy
- Initiate antifungal therapy
- Place a new shunt once therapy is well underway and clinical response is apparent
The princples of treatment of invasive candidiasis-related CNS candidiasis apply to neurosurgery-related candidiasis. If device removal is not possible, permanent suppressive therapy might be required.