Etiology and management of single small CT lesions in patients with seizures: understanding a controversy

Taenia solium cysticercosis

Cysticercosis, the infection of the larval tissue stage of the pork tapeworm, Taenia solium, is endemic to most developing countries and increasingly is seen in industrialized countries because of immigration. Human infection is a major cause of acquired epilepsy, and porcine infection causes important economic losses to farm workers. Clinical manifestations vary because of the variable number, size, and location of the cysts and the immune response of the host. Diagnosis is based on imaging techniques (CT and MR imaging) and serology (immunoblot). Current research efforts are centered on control and eradication of the taeniasis cysticercosis complex in endemic areas.

Neurocysticercosis and epilepsy in developing countries

Neurocysticercosis is a disease of poverty and underdevelopment. Little is known about the natural history of the infection in humans, but some of the mechanisms whereby the parasite remains silent and evades the host immune response are understood. Symptomatic neurocysticercosis usually results from host inflammatory response after parasite death, and the clinical manifestations can be diverse. There is no evidence that cysticidal treatment does more good than harm in addition to conventional antiepileptic treatment. Population control measures involving immunisation or mass treatment have not shown long term effectiveness.Epilepsy, similarly to neurocysticercosis, is a largely unrecognised but increasing burden on the welfare and economies of developing countries. The technology of drug treatment and psychosocial rehabilitation is well known but requires widespread and effective dissemination at low cost. There is little epidemiological data on risk factors for epilepsy in developing countries on which to base prevention strategies. The public health prioritisation of chronic disorders such as epilepsy remains a challenge for policy and practice in developing countries. For both neurocysticercosis and epilepsy, there is a dilemma about whether limited public resources would better be spent on general economic development, which would be expected to have a broad impact on the health and welfare of communities, or on specific programmes to help individual affected people with neurocysticercosis and epilepsy. Either approach requires detailed economic evaluation.

Single-enhancing CT lesions in Indian patients with seizures: a review

Single enhancing CT lesions are the commonest radiological abnormality in Indian patients with new-onset partial seizures. In few patients the lesions may be 'tuberculoma' (especially in presence of evidence of tuberculosis elsewhere). However, histopathological studies have proved that neurocysticercosis is the most frequent cause for these lesions. Acute inflammation in and around the cerebral lesions of cysticercosis manifests as acute seizure disorder. These cysticercal granulomas represent 'colloidal' and 'nodular-granular' stages of Escobar's pathological classification of natural evolution of a parenchymal cysticercus cyst. In 8-12 weeks time majority of these lesions spontaneously disappear, few may calcify. As albendazole therapy is of controversial value, these patients, possibly, need to be treated only with antiepileptic drugs. Associated seizure disorder is also benign in nature and remit in majority within 6-8 months, recurrences are usually infrequent. Antiepileptic drug may be withdrawn once follow-up CT scan shows resolution of the lesion. If seizures recur after resolution of the lesion, CT lesion persists or CT lesion calcified, a long-term (2-3 years) antiepileptic therapy may be required. The single enhancing CT lesions which persist despite anticysticercal or antituberculous therapy may need histopathological evaluation to establish the correct diagnosis.

Focal seizures with single small ring-enhancing lesion

An 8-year-old girl presented with simple partial seizures. The differential diagnosis and evaluation point out the fact that in most of the world, conditions considered rare in the United States are important diagnostic considerations.

Acute symptomatic seizures - incidence and etiological spectrum: a hospital-based study from South India

We analysed the incidence and etiological spectrum of acute symptomatic seizures in 2531 patients with seizure disorder, both in-patients and out-patients, seen in a university hospital in South India. Seizure(s) occurred in close temporal association with an acute systemic, metabolic, or toxic insult or in association with an acute central nervous system (CNS) insult in 22.5% of patients. Of the 572 patients, 8% could be grouped under the International League Against Epilepsy (ILAE) category 4.1 and 92% under category 1.2. The seizure type was generalized in all the patients included in category 4.1 and 78% of patients grouped in category 2.1 had simple or complex partial seizure(s) with or without secondary generalization. Sixteen (3%) patients developed status epilepticus during the acute phase of illness and 7% of patients had only single seizure. Infections of the central nervous system (CNS) and single CT enhancing lesions (SCTEL) together accounted for 77% of the provoking factors in patients grouped under category 2.1. These two etiological factors together accounted for 95% of etiologies in patients aged under 16 years. SCTEL and neurocysticercosis together accounted for 67% of the provoking factors. In 14% of patients cerebrovascular diseases were the etiological factors and 60% of the patients were aged over 40 years. In patients with cerebrovascular diseases, aged under 40 years, cortical sinovenous thrombosis accounted for 37%. SCTEL was the provoking factor in 61% of patients with isolated seizure. Infections of CNS and SCTEL together accounted for 62.5% of etiological factors for status epilepticus. This study illustrates that the etiological spectrum of acute symptomatic seizures in this part of the world is different from that described from developed countries and CNS infections account for a significant number of cases.

Family studies and human leukocyte antigen class II typing in Indian probands with seizures in association with single small enhancing computed tomography lesions

PURPOSE

To define the clinical features of the syndrome of seizures associated with single, small, enhancing computed tomography (CT) lesions (SSELs) in 235 Indian probands and seizure types among their family members. Human leukocyte antigen (HLA) class II genomic typing in randomly selected 41 probands was done to identify the role of hereditary factors in this syndrome.

METHODS

The seizure types among 235 probands, their clinical outcome, and seizures in their family members were studied. Family data were collected on relatives of 212 additional probands with neurologic diseases other than epilepsy. HLA class II antigens were studied by using polymerase chain reaction (PCR) amplified DNA and sequence-specific oligonucleotide probe (PCR-SSOP) hybridization.

RESULTS

The seizures in 86% were partial with or without generalization; 77% had fewer than five seizures before the first CT scan. Evanescent focal neurologic deficits after seizures were noted in 40%. Most patients (97%) were treated with a single antiepileptic drug (AED). Significant resolution of the CT scan lesion was noted within 6 months in 125 (53%) of 235 cases. Two thirds of patients had no seizures while taking a single AED, and an additional 18% had no seizures even after their AEDs were discontinued. Epilepsy among relatives of Indian probands having seizures in association with SSELs was more common as compared with relatives of probands with other neurologic diseases. A family history of seizures was noted in 21% probands, the ratio of affected first- to second-degree relatives was 4.3:1, and 60% of affected sibs had syndromic concordance with probands. There was a positive association of HLA-DRB1*13 (Pc = 0.036) with this syndrome.

CONCLUSIONS

The syndrome of seizures in association with SSELs seems to be a benign localization-related epileptic syndrome. Our results of HLA studies point to an inherited susceptibility to an infective agent, which in most cases is of cysticercal etiology.

Cysticercosis and epilepsy: a critical review

Neurocysticercosis (NC) remains a major public health problem in developing and some developed countries. Currently, the best procedures for diagnosing NC are neuroimaging studies. Immunoserologic assays, such as enzyme-linked immunoelectrotransfer blot assay (EITB) or enzyme-linked immunosorbent assay (ELISA), detect antibodies against Taenia solium, or cysticercus. Consequently, they are useful in identifying a population at risk of contact with the parasite but do not necessarily indicate a systemic active infection. Most seropositive individuals are asymptomatic. No data from prospective studies concern the proportion of these individuals that will develop seizures or other neurologic symptoms. There is a discrepancy between the results of serologic assays and neuroimaging studies: >50% of those individuals with NC diagnosed by computed tomography (CT) scan test EITB negative. Pathophysiologic classification of NC into active, transitional, and inactive forms permits a good correlation between clinical manifestations and neuroimaging procedures and facilitates medical and surgical management and research. The most frequent clinical manifestations of NC are seizures. We assume that NC is the main cause of symptomatic epilepsy in developing countries; however, no case-control or cohort studies demonstrate this association. Most patients with NC with seizures have a good prognosis; nevertheless, further studies analyzing factors related to recurrence of seizures and possibilities of discontinuation of antiepileptic medications (AEDs) are needed. Regarding treatment of NC with antihelminthic drugs, no controlled clinical trials exist that establish specific indications, definitive doses, and duration of treatment. The most effective approach to taeniasis/cysticercosis infection is prevention. This should be a primary public health focus for developing countries. We critically review the available information regarding the epidemiology and diagnosis of human cysticercosis, the physiopathology and imaging correlation of the parasite in the central nervous system (CNS) of the host, the relation between seizures or epilepsy and NC, and the issues surrounding the treatment and prognosis of NC, including the use of antihelminthic therapy.

Prognosis of epilepsy associated with single CT enhancing lesion: a long term follow up study

This is a retrospective analysis to study the long term prognosis of epilepsy associated with single CT enhancing lesion (SCTEL). Follow up CT scan showed resolution of the lesion in all of the 102 patients. Seizures did not recur in 64 (63%) patients after starting antiepileptic drugs. Twenty eight (27.5%) patients had recurrence of seizures for a median period of 2 months before remission was achieved. In the remaining ten (10%) patients seizures remitted only after albendazole therapy and the median period of seizure recurrence was 8 months. Sixteen (42%) of the 38 patients who had recurrence of seizures had type B CT lesion (ring lesion with central enhancing area, probably scolex) (P<0.02 (95% CI 3.2-40.3)). Patients with type B CT lesion had more numbers of seizures and also longer intervals between first and last seizure. Antiepileptic drugs were withdrawn in all the 102 patients. The mean period of follow up was 45 months (range 19-101). Only one patient had a relapse and his follow up CT showed gliotic scar at the site of the previous lesion. We conclude that epilepsy associated with SCTEL is a benign form of epilepsy and seizures recur as long as the lesion persists. Antiepileptic drugs can safely be withdrawn once the follow up CT shows resolution of the lesion.

Albendazole therapy in children with focal seizures and single small enhancing computerized tomographic lesions: a randomized, placebo-controlled, double blind trial

BACKGROUND

Single small enhancing computerized tomographic (CT) lesions (SSECTLs) are common in children with focal seizures. These are considered to represent solitary cysticercus granulomas. Controversy exists regarding their treatment.

OBJECTIVE

To evaluate the efficacy of albendazole in cases of focal seizures with SSECTLs.

DESIGN

Randomized, placebo-controlled, double blind trial.

SETTING

Pediatric service of Nehru Hospital, PGIMER, an urban tertiary care teaching hospital.

SUBJECTS

63 children between 2 and 12 years of age with focal seizures for <3 months and SSECTLs.

INTERVENTION

All children were randomly assigned to receive either albendazole (15 mg/kg/ day) or placebo for 28 days. CT scan was done at 1 and 3 months after beginning treatment. Codes opened after 6 months of inclusion in the study showed that 31 had received albendazole and 32 had received placebo. All children were followed up for at least 15 months.

RESULTS

Disappearance of lesions on CT scan was noted in 41% of albendazole vs. 16.2% of placebo patients after 1 month of follow-up (P < 0.05) and 64.5% of albendazole- vs. 37.5% of placebo-treated patients after 3 months of follow-up (P < 0.05). During the first 4 weeks of therapy seizure recurrence was seen in 9.7% of albendazole vs. 3.2% of placebo-treated children (odds ratio, 3.32; 95% confidence interval, 0.33 to 33.8). After 4 weeks seizure recurrence was seen in 31.3% of placebo-treated children vs. 12.9% of albendazole-treated children (odds ratio, 3.07; 95% confidence interval, 1.18 to 11.15).

CONCLUSIONS

Albendazole therapy results in significantly faster and increased resolution of solitary cysticercus lesions (SSECTLs) and appears to reduce the risk of late seizure recurrences.

Etiological spectrum of symptomatic localization related epilepsies: a study from South India

Putative etiology was studied in 991 patients with symptomatic localization-related epilepsies seen in a university hospital in South India. They formed 39% of patients with various types of epilepsies and epileptic syndromes seen during the study period. Seizure occurred in close temporal association with an acute central nervous system (CNS) insult in 53% of patients. Infections of CNS including single CT enhancing lesion (SCTEL) accounted for 77% of patients with acute symptomatic epilepsy. Cerebrovascular diseases were the risk factors in 48% of patients with remote symptomatic epilepsy. Neurocysticercosis, SCTEL and small single cerebral calcific CT lesion (SSCCCTL) together accounted for 40% of etiological factors and neurotuberculosis for 10%. Infections of the central nervous system and SCTEL together were the putative risk factors in 52% of patients aged < or =40 years. Cerebrovascular diseases were the etiological factors in 64% of patients aged >40 years. Neurological handicaps from birth manifested by mental retardation and/or cerebral palsy was the feature in 21% of children. The type of seizure was either simple partial or complex partial with or without secondary generalization in 76% of patients. The remaining patients presented with either generalized tonic clonic seizures or unlocalized seizures. Localization to a single site of seizure origin proposed by the International League Against Epilepsy (ILAE) was possible in only 67.5% of patients. The most readily identifiable was motor cortex. In patients with unlocalized or generalized seizures the type of pathology was diffuse in 17% of patients and in 48.5% of patients, the lesion was located in the frontal brontoparietal lobe.

The syndromic classification of the International League Against Epilepsy: a hospital-based study from South India

PURPOSE

To determine the distribution of various epilepsies and epileptic syndromes in the epileptic population treated in a university hospital in a developing country.

METHODS

Data concerning 2,531 patients with epilepsy seen between January 1989 and June 1994 were analyzed using the International League Against Epilepsy (ILAE) classification.

RESULTS

Of 2,531 cases, 48% fell into ILAE categories 1.3, 3.2, or 4.1 (cryptogenic, without unequivocal generalized or focal seizures; or situation-related seizures, respectively). Localization-related epilepsies (LREs) and epileptic syndromes (1.1, 1.2, 1.3) were found in 1,591 (62.9%) patients; of these patients, symptomatic localization-related epilepsies totaled 62.7%. and idiopathic localization-related epilepsies accounted for only 0.7%. Juvenile myoclonic epilepsy was the most common type of idiopathic generalized epilepsy (IGE), comprising 4.9% of the total study population and 7.7% of patients registered in the epilepsy clinic. A combination of childhood and juvenile absence epilepsies were found in only 0.4% of the total study population. Single computed tomography (CT) enhancing lesion (SCTEL) and focal cerebral calcification (FCC) accounted for 22% of the etiologic factors for localization-related epilepsies. Neurologic deficits were found in 9.5% of patients with SCTEL; none were found with FCC. None of the patients with these lesions had any history of antecedent events that suggested CNS involvement. In patients with localization-related epilepsies with unremarkable clinical data, the proportion of CT scans showing SCTELs was 39 (95% confidence interval [CI], 0.35-0.43) and 0.18 (95% CI, 15-0.21) for FCCs. The proportion for both lesions together was 0.57 (95% CI, 0.53-0.61). Seizures did not recur once the lesion resolved in patients with SCTELs. In patients with FCCs, seizure remission was 71.5% (95% CI, 53.7-85.4) at 3 years.

CONCLUSIONS

This study illustrates the rarity in one patient population of some of the syndromes and categories described in the ILAE classification. Childhood and juvenile absence epilepsies together formed a small proportion. SCTEL and FCC were important etiologic factors for localization related epilepsies. The epilepsy associated with SCTEL was a form of benign epilepsy; epilepsy associated with FCC had remission rates similar to other remote symptomatic epilepsies. Without neuroimaging evidence, these 2 lesions would have been missed and the patients might have been grouped under cryptogenic localization related epilepsy. For this reason, we emphasize the need for neuroimaging in patients with localization related epilepsies with unremarkable clinical findings, before classification into the cryptogenic category. In the absence of neuroimaging, such patients should be classified as "probably cryptogenic."

Neurocysticercosos in South-Central America and the Indian subcontinent. A comparative evaluation

Neurocysticercosis is an important public health problem in South-Central American and South Asia. A review of the differences in epidemiological and clinical attributes of cysticercosis and taeniasis in South Central America and India, respectively, is undertaken in the present communication. Intestinal taeniasis is hyperendemic in several American countries. In comparison, the prevalence of Taenia solium infestation is lower in India. The clinical manifestations in several American neurocysticercosis series comprise epilepsy, intracranial hypertension and meningeal-racemose cysticercosis, in roughly equal proportions. An overwhelming majority of the Indian subjects present with seizures. The commonest pathological substrate of the disorder in Indian patients is the solitary parenchymal degenerating cyst. The reasons for the predominance of solitary forms in India, and of multilesional forms in South Central America are discussed. The magnitude of Taenia solium infestation and the frequency of pork consumption in a given population appear to influence the quantum of cyst load in affected individuals.

Validation of diagnostic criteria for solitary cerebral cysticercus granuloma in patients 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 diagnostic criteria were applied prospectively to patients presenting with 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 pressure, progressive neurological deficit or an active systemic disease. The CT diagnostic criteria were: evidence of a solitary contrast enhancing lesion measuring 20 mm or less in its maximal dimension without a shift of the midline structures due to the surrounding oedema. A diagnosis of SCCG was made only when all the clinical and CT criteria were fulfilled. Over a period of 36 months, we managed 401 patients presenting with seizures and a solitary mass on the CT scan; 215 met the criteria for the diagnosis of an SCCG.

RESULTS

Of the 215 patients initially diagnosed to have an SCCG, 197 were ultimately determined to have that 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 of a secondary metastasis and a pyogenic abscess (false positive diagnosis). 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 negative predictive value of 99.5%. The likelihood ratios for the positive and negative tests were 92.99 and 0.005 respectively.

CONCLUSIONS

Our diagnostic criteria help in not only accurately identifying an SCCG but also in differentiating it from a solitary tuberculoma and other brain masses. However, confirmation of the diagnosis of an SCCG is only obtained at follow-up evaluation and therefore careful clinical and CT re-evaluation is essential in all patients initially diagnosed to have an SCCG.

CT in simple partial seizures in children: a clinical and computed tomography study

INTRODUCTION

Therapeutic relevance of computed tomography (CT) in children with simple partial seizures (SPS) is reported to be remarkably low (1-2%). There are not studies, however, from the developing countries where neuroinfections are among important causes of seizures. The present study from India is aimed at evaluating the significance of CT in the management of SPS in children and to determine the difference in clinical features of children with and without focal brain lesions in CT.

PATIENTS AND METHODS

CT scans of all patients aged 15 years of younger with SPS, seen over a period of 15 months, were reviewed. The clinical features of the patients with focal lesions in the CT were compared with those of children without focal abnormalities.

RESULTS

Focal structural lesions were present in 117 (59.09%) of 198 children. These included: solitary contrast enhancing CT lesion-16.16%, focal calcification-12.12%, cysticerosis-10.10%, focal atrophy-9.59%, tuberculoma-6.56% and infarction-6.06%. Neuroinfections or their sequelae were responsible for seizures in 89 children (44.94%). There were no statistically significant differences in clinical features of patients with and without focal lesions in CT.

CONCLUSIONS

CT study in children with SPS in developing countries has significant therapeutic relevance. It is not possible to clinically differentiate children with focal lesions from those without focal lesions in CT.

Occurrence of epilepsies in family members of Indian probands with different epileptic syndromes

PURPOSE

Large numbers of families with many members having seizures have been used to understand the role of hereditary factors in the pathogenesis of human epileptic syndromes. We aimed to establish a genetic database to form a hypothesis on the possible genetic contributions in different epileptic syndromes.

METHODS

The occurrence and patterns of different epilepsies and epileptic syndromes in 1,219 Indian probands and their relatives were studied. The concordance of epilepsies between probands and relatives was also analyzed.

RESULTS

Of probands, 231 (19% of 1219) had first- or second-degree relatives affected with seizures. Incidence of family history in probands with generalized epilepsies (GES) and syndrome of single, small, enhancing lesions (SSEL) was comparable and significantly higher than that in probands with localization-related epilepsies (LRES). The ratio of affected first- to second-degree relatives was close to 4:1. Generalized epilepsies were the commonest type of epileptic syndromes seen among all relatives. The proportion of sibs and second-degree relatives with epileptic syndromes similar to probands was significantly greater in the GES group as compared with the concordant relatives of probands with LRES and SSEL.

CONCLUSIONS

A significant percentage of first- and second-degree relatives of probands with all types of epileptic syndromes have seizures. The risk of relatives being affected varied as a function of the relation with the proband. Concordance of epileptic syndromes between probands and relatives was related to the epileptic syndromes in probands. The syndrome of SSEL is probably a benign epileptic syndrome seen in Indians genetically predisposed to seizures. Hereditary factors may play an almost equal role in the predisposition of relatives to epilepsy in families of probands with different epileptic syndromes.

Proposal of diagnostic criteria for human cysticercosis and neurocysticercosis

Taenia solium cysticercosis is a major public health problem in several areas of the world. While the disease has a recognized etiologic agent, its definitive histological diagnosis is not possible in most cases because this parasite tends to lodge in cerebral tissues where routine biopsy is not feasible. Therefore, the diagnosis of human cysticercosis (and neurocysticercosis) should rest on the proper interpretation of the patients' symptoms together with data provided by radiological studies and immunologic tests for the detection of anticysticercal antibodies. Unfortunately, the pleomorphism of this parasitic disease creates confusion when non-specific clinical, radiological, or immunologic criteria alone are used to detect cases among populations or to diagnose hospitalized patients with neurological manifestations. We propose a chart of diagnostic criteria for human cysticercosis that objectively permit clinicians and health care workers to evaluate clinical, radiological, immunologic, and epidemiologic data of patients. The chart uses four degrees of criteria: absolute, major, minor, and epidemiologic, that were selected on the basis of their individual diagnostic strength. Interpretation of such criteria will result in three categories of diagnostic certainty: definitive, probable and possible, according to the likelihood that cysticercosis is present in a given person.

Comparative study of CT and MRI in patients with seizures and a solitary cerebral cysticercus granuloma

We hypothesized that when contrast-enhanced CT reveals a solitary cerebral cysticercus granuloma, MRI would not usually provide additional information that might assist in management. We retrospectively compared visualisation of solitary cysticercus granulomas on contrast-enhanced CT and MRI in 16 patients presenting with seizures; gadolinium (Gd) enhancement was used in 6 patients. The granuloma was delineated well on both CT and MRI in 15 patients; in one patient, in whom CT was performed with 10-mm slices, it was seen only on contrast-enhanced MRI, CT and unenhanced MRI revealing only the surrounding oedema. On CT the granuloma was seen best on thin (2-5 mm) contrast-enhanced sections (in 10 patients). On MRI, Gd-enhanced images showed the granuloma best, as a ring-enhancing lesion, in all 6 patients. In the other 10 patients, the granuloma was seen only on T2-weighted images in 8 and on both T1- and T2-weighted images in 2. On T2-weighted images a characteristic low-signal ring with a high-signal centre was seen in 12 patients. Sensitivity of the imaging techniques was: contrast-enhanced CT (5 and 10 mm slices) 93.8% (15/16); thin (2-5 mm) section contrast-enhanced CT 100% (6/6); unenhanced MRI 93.8% (15/16). MRI did not reveal additional granulomas or cysts in any patient. In patients strongly suspected to be harbouring this lesion, when 10-mm contrast-enhanced CT reveals only oedema, thin (2-5 mm) slice CT is a cost-effective alternative to MRI.

Clinicoradiological and pathological correlations in patients with solitary cysticercus granuloma and epilepsy: focus on presence of the parasite and oedema formation

A study of the clinical, radiological, and pathological correlations in 43 patients with solitary cysticercus granuloma and epilepsy focused on factors that might help in predicting the presence of the parasite in the granuloma and those that might influence the formation of oedema around the granuloma. The duration of symptoms (< six months and > or = six months) and CT morphology of the granuloma (ring and disc, type A; nodular lesion, type B) were studied as factors that could possibly predict the presence of the parasite in the granuloma. The influence of sex of the patient and the presence of a neutrophilic response in the granuloma on the intensity of oedema around the lesion as seen on CT was also studied. The pathological features were studied in the excised granulomas. The intact or degenerated form of the cysticercus was evident in 22 of 43 specimens. Neither the duration of seizures (P = 0.17) nor the type of lesion on CT (P = 0.16) was predictive of the presence of the parasite in the granuloma. The sex of the patient (P = 0.51) and the neutrophilic response in the specimen (P = 0.73) did not correlate with the degree of oedema on CT indicating that neither of these host factors was a major determinant of oedema production. The findings point to the varied and unpredictable natural history of solitary cysticercus granulomas and the complex nature of host-parasite interactions in individual patients. The inability to predict the presence of the parasite in the granuloma on the basis of the clinical or radiological features precludes a selection of patients with such lesions for cysticidal drug treatment.

Oral cysticercosis

Although cysticercosis is a common disease in developing countries, oral lesions produced by this parasitic infestation are rare. In this report we document a case of oral cysticercosis in a 7-year-old girl who sought treatment for an asymptomatic nodule of the left buccal mucosa that had been clinically diagnosed as a mucocele.

Predictive value of computed tomography-based diagnosis of intracranial tuberculomas

The need to obtain histological diagnoses of intracranial tuberculomas, before initiating therapy, is not universally accepted, because some clinicians believe that an image-based diagnosis is fairly accurate in patients from endemic regions. To evaluate the sensitivity, specificity, and predictive value of computed tomography (CT)-based diagnosis of an intracranial tuberculoma, we prospectively compared the preoperative imaging diagnoses with histological diagnoses in 105 consecutive patients with intracranial masses. CT differential diagnoses (first or second) of tuberculomas were considered in 21 patients. Seven of them were histologically confirmed to have tuberculomas (true-positive results); 14 had other diseases (false-positive results). The 14 false-positive cases included 6 cases of astrocytomas, 5 of metastases, and 3 with miscellaneous diagnoses. All tuberculomas were correctly diagnosed on the CT scans (5 by both surgeons and 2 by one surgeon). During the study period, we encountered 11 patients who were referred by other clinicians with diagnoses of tuberculomas on the basis of their CT scans. We concurred with their CT diagnoses in 5 of them, but only 1 patient had a histologically verified tuberculoma. Astrocytomas (4 patients), metastases (3 patients), and solitary cysticercus granulomas (3 patients) were the causes of misdiagnosis in this group of patients. Although the sensitivity of CT in the diagnosis of intracranial tuberculomas is 100%, and its specificity is 85.7%, the positive predictive value is only 33% (confidence limits, 24-42%). The negative predictive value is 100%. The low positive predictive value for a diagnosis of intracranial tuberculoma on CT alone indicates the need for a confirming histological diagnosis.

[Neurologic and laboratory findings in a population of an endemic area for taeniasis-cysticercosis, Lagamar, MG, Brazil (1992-1993)]

A clinic-epidemiological enquiry was conducted on in an endemic area for teniasis-cysticercosis. From the whole population 1080 (32.2%) individuals were examined. We found 198 (18.3%) individuals referring teniasis-bearing in the past, and 103 (9.5%) affirming to have had convulsions, either in the past or present. From the last group, 39 (37.8%) indicated that the crisis had begun in adulthood. From the group of patients presenting convulsions, 62 (62%) had laboratory tests performed. Computed tomography showed intracranial calcifications in 21 (33.8%) patients, variable in number and location, suggesting neurocysticercosis and no evidence of disease activity. Electroencephalograms showed abnormal waves in 21 (33.8%) patients and cerebrospinal fluid analyses were altered in 27 (43.5%) cases, having detected eosinophils only in 3 (4.8%) patients. Spinal fluid tests for cysticercosis through enzyme linked immunosorbent assay (ELISA) or indirect immunofluorescence were taken in only 26 (41.9%) patients, obtaining positive results in 6 (23%) samples. Varying upward shifts of protein levels were found in spinal fluid analysis. Assuming that all epidemiologic risk factors for teniasis-cysticercosis in the studied region and its correlation with the laboratory alterations described in convulsing crisis, a prevalence of 1.9% for neurocysticercosis was found.

Enlarging solitary cysticercus granulomas

Solitary cysticercus granulomas that produce seizures usually measure less than 20 mm in diameter and diminish in size spontaneously. Unlike live cysticercus cysts, they have not been known to increase in size. In a prospective follow-up study of 93 consecutive patients with epilepsy and small solitary lesions (< 20 mm in diameter) enhancing on computerized tomography (CT), 91 were found to have solitary cysticercus granuloma; of these, seven (7.7%) were diagnosed as having an enlarging cysticercus granuloma. Enlarging lesions were defined as those that, on follow-up CT, had increased by more than 50% of their original size but were still less than 20 mm in diameter (Group 1, three patients) or those that had increased to more than 20 mm (Group 2, four patients). Excision biopsy is recommended for Group 2 solitary lesions, regardless of the clinical progression, to eliminate the possibility of other pathologies. However, a trial of albendazole therapy with early CT re-evaluation (within 4 to 6 weeks) may be warranted in those with Group 1 lesions and in selected patients with Group 2 lesions. It is important to recognize the entity of enlarging solitary cysticercus granuloma to avoid mistaking it for a tuberculoma and treating the patient with empiric antituberculous therapy.

Differentiating solitary small cysticercus granulomas and tuberculomas in patients with epilepsy. Clinical and computerized tomographic criteria

It is commonly believed that differentiating solitary small cysticercus granulomas and small tuberculomas in patients with seizures is difficult without resorting to an excision biopsy. The aim of this study was to formulate clinical and computerized tomography (CT) criteria to distinguish these two entities in patients with epilepsy. Toward this end, clinical and CT data from six consecutive patients with histologically proven small solitary tuberculomas and 25 consecutive patients with histologically proven solitary cysticercus granulomas were compared. Evidence of raised intracranial tension and a progressive focal neurological deficit was seen only in patients with tuberculomas (two of six cases). All tuberculomas were greater than 20 mm in size and five of the six were irregular in outline. Only tuberculomas were associated with a midline shift on CT (four of six cases). All cysticercus granulomas were less than 20 mm in size and 24 (96%) of the 25 were regular in outline, conforming to one of two characteristic patterns. No cysticercus granuloma was associated with a midline shift. Based on the above clinical findings (evidence of raised intracranial tension and a progressive neurological deficit) and CT criteria (size, shape, and association with a midline shift), it is possible to separate these two entities in a majority of patients with seizures and with a single small lesion on CT.