Dear Sir,
In the letter “Reproducibility of Diagnostic Criteria for Ventricular Neurocysticercosis,”1 the authors manifest their unhappiness with the results of the systematic review we conducted to assess reliability of the revised Del Brutto’s set of diagnostic criteria for ventricular neurocysticercosis (NCC), mainly concerning specificity.2
Specificity is the ability of a test to appropriately detect as negative a condition that does not exist in a given patient. According to the revised Del Brutto’s set of diagnostic criteria for NCC,3 only four of the 41 reviewed patients with other ventricular infections would be erroneously diagnosed as definitive NCC.2 These four false-positive diagnoses resulted from the presence of two major neuroimaging findings (ventricular cystic lesion plus additional parenchymal lesions) together with clinical/exposure criteria.3 None of the 41 cases had any absolute criteria for NCC, nor any confirmative neuroimaging criteria, and as such no other definitive diagnoses of NCC would be made using our criteria. This means that for this set we found a specificity of 90.2% (95% confidence interval [CI]: 75.9–96.8%), as detailed in our systematic review.2 We don’t understand how specificity was calculated as 31.7% or 55% by Fleury et al. Perhaps they included “probable” cases as positively diagnosed.
According to the modified set of criteria for NCC used to determine the specificity for our set, a definitive diagnosis of extraparenchymal NCC is established in patients presenting with subarachnoid or intraventricular cysts without scolex, associated with at least two of the following: 1) hydrocephalus, 2) inflammatory cerebrospinal fluid (CSF), 3) positive CSF immunological tests (enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunotransfer blot (EITB), and 4) presence of single or multiple calcifications or parenchymal vesicular or degenerating cysts.4 The poor specificity of this categorization is obvious because any patient with an intraventricular cyst associated with hydrocephalus and an inflammatory CSF would be characterized as definitive NCC. Both hydrocephalus and inflammatory abnormalities in the CSF are unspecific, and many patients with other infections requiring different management might be misdiagnosed as NCC.5 Indeed, 25 of the 41 cases with proven non-cysticercotic ventricular lesions that we analyzed in our systematic review had either ventricular cystic or granulomatous lesions (with a cystic component) without scolex associated with hydrocephalus and inflammatory CSF or with concomitant parenchymal lesions.4 These 25 false-positive cases thus lower the specificity to 39% (95% CI: 24.6–55.5%). It is difficult to understand how specificity, as calculated by Fleury et al, was 78.1% or 82.5% in spite of the categorization of these 25 cases. Again, one possibility is that their case review was not blind, and perhaps they did not categorize lesions with cystic contents as cysts. Relevant information on the 25 false-positive cases is summarized in Table 1.
Cases with non-cysticercotic–related ventricular cystic lesions or granulomas, where the diagnosis is definitive cysticercosis based on the modified set of diagnostic criteria proposed by Carpio et al.4
| Reference | Ventricular cystic lesion or granuloma* | Other imaging findings | Hydrocephalus | CSF analysis | Definitive diagnosis |
|---|---|---|---|---|---|
| Acta Neurochir 2004;146:1151 | Yes | – | Yes | Inflammatory | Tuberculoma |
| AJNR 1996;17:110 | Yes | – | Yes | Inflammatory | Cryptococcosis |
| AJNR 2002;23:273 | Yes | Parenchymal cyst no scolex | Yes | Inflammatory | Cryptococcosis |
| BMJ Case Rep 2014;bcr2014-203837 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Br J Radiol 2010;83-e14 | Yes | – | Yes | Inflammatory | Cryptococcosis |
| Case Rep Clin Med 2013;2:81 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Case Rep Neurol 2015;7:156 | Yes | – | Yes | Inflammatory | Pyogenic abscess |
| Clin Infect Dis 1993;16:435 | Yes | – | Yes | Inflammatory | Pyogenic abscess |
| Indian J Pathol Microbiol 2008;51:553 | Yes | Parenchymal cyst no scolex | – | Inflammatory | Cryptococcosis |
| Indian J Tuberc 2014;61:166 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Indian Pediatr 2011;48:161 | Yes | – | Yes | Inflammatory | Tuberculoma |
| J Comput Assist Tomogr 1993;17:547 (case 1) | Yes | – | Yes | Inflammatory | Cryptococcosis |
| J Comput Assist Tomogr 1993;17:547 (case 2) | Yes | – | Yes | Inflammatory | Cryptococcosis |
| J Craniofacial Surg 2010;21:1291 | Yes | – | Yes | Inflammatory | Aspergillosis |
| J Neuroradiol 2008;35:63 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Mayo Clin Proc 1999;74:803 | Yes | – | Yes | Inflammatory | Histoplasmosis |
| Med Mycol Case Rep 2015;10:18 | Yes | – | Yes | Inflammatory | Rhizopus abscess |
| Neurol India 1999;47:327 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Neurol India 2014;62:73 | Yes | Parenchymal cyst no scolex | Yes | – | Tuberculoma |
| Neurol Med Chir (Tokyo) 2002;42:501 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Neuropathology 2014;34:210 | Yes | – | Yes | Inflammatory | Cryptococcosis |
| Neuroradiology 1993;35:149 | Yes | Parenchymal cyst no scolex | Yes | – | Hydatid disease |
| Neuroradiology 2003;45:908 | Yes | – | Yes | Inflammatory | Pyogenic abscess |
| Pediatr Neurosurg 2017;52:93 | Yes | – | Yes | Inflammatory | Tuberculoma |
| Surg Neurol 2007;67:647 | Yes | – | Yes | Inflammatory | Cryptococcosis |
Granuloma with cystic component.
REFERENCES
- 1.↑
Fleury A, Carpio A, Romo ML, San-Juan D, Sander JW, 2017. Reproducibility of diagnostic criteria for ventricular neurocysticercosis. Am J Trop Med Hyg 97: 1952.
- 2.↑
Bustos JA, Garcia HH, Del Brutto OH, 2017. Reliability of diagnostic criteria for neurocysticercosis for patients with ventricular cystic lesions or granulomas: a systematic review. Am J Trop Med Hyg 97: 653–657.
- 3.↑
Del Brutto OH, Nash TE, White AC Jr, Rajsherkhar V, Wilkins PP, Sing G, Vasquez CM, Salgado P, Gilman RH, Garcia HH, 2017. Revised diagnostic criteria for neurocysticercosis. J Neurol Sci 372: 202–210.
- 4.↑
Carpio A et al. 2016. New diagnostic criteria for neurocysticercosis: reliability and validity. Ann Neurol 80: 434–442.
- 5.↑
Gilman RH, 2016. Diagnostic criteria for neurocysticercosis – a difficult update. Nat Rev Neurol 12: 560–561.