VALIDATION OF DIAGNOSTIC-CRITERIA FOR SOLITARY CEREBRAL CYSTICERCUS GRANULOMA INPATIENTS PRESENTING WITH SEIZURES

Objective - To evaluate a set of clinical and computed tomographic (CT ) criteria (previously described by us) to predict the diagnosis of a solitary cerebral cysticercus granuloma (SCCG) at initial presentation , in patients presenting with seizures. Material and methods - The dia gnostic criteria were applied prospectively to patients presenting wit h seizures and solitary lesion on the CT scan. The clinical diagnostic criteria were as follows: seizures should be the presenting complaint there should be no evidence of persistent raised intracranial pressur e, progressive neurological deficit or an active systemic disease. The CT diagnostic criteria were: evidence of a solitary contrast enhancin g lesion measuring 20 mm or less in its maximal dimension without a sh ift of the midline structures due to the surrounding oedema. A diagnos is of SCCG was made only when all the clinical and CT criteria were fu lfilled. Over a period of 36 months. we managed 401 patients presentin g with seizures and a solitary mass on the CT scan; 215 met the criter ia for the diagnosis of an SCCG. Results - Of the 215 patients initial ly diagnosed to have an SCCG, 197 were ultimately determined to have t hat diagnosis (true positive diagnosis) while 16 were excluded because of lack of follow-up CT assessment. Two of the 215 patients with the initial diagnosis of an SCCG subsequently had histological diagnosis o f a secondary metastasis and a pyogenic abscess (false positive diagno sis). Our set of diagnostic criteria for SCCG had a sensitivity of 99. 5%; specificity of 98.9%; a positive predictive value of 99%; and a ne gative predictive value of 99.5%. The likelihood ratios for the positi ve and negative tests were 92.99 and 0.005 respectively. Conclusions - Our diagnostic criteria help in not only accurately identifying an SC CG but also in differentiating if: from a solitary tuberculoma and oth er brain masses. However, confirmation of the diagnosis of an SCCG is only obtained at follow-up evaluation and therefore careful clinical a nd CT re-evaluation is essential in all patients Initially diagnosed t o have an SCCG.