Micro-abscesses and presumptive inflammatory nodules of the brain

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.

Diagnostic and staged stereotactic aspiration of multiple bihemispheric pyogenic brain abscesses

BACKGROUND

Empiric antibiotic therapy for multiple brain abscesses is not advised, as biopsy to rule out other causes and material for cultures can be obtained with minimal morbidity using computed tomography (CT)-guided stereotaxy.

METHODS

We report a good outcome following treatment of this 60-year-old nonimmunocompromised patient with six pyogenic cerebral abscesses. CT-guided stereotactic aspiration of two abscesses were done on the first occasion and appropriate antibiotics were administered. Serial CT scans were done and the abscesses that recollected or enlarged were again aspirated.

RESULTS

Group A beta hemolytic streptococci were grown from the pus. Two abscesses recollected and one enlarged during antibiotic therapy. These were aspirated on the second and third occasions, 1 week and 2 weeks after the first procedure. The abscess less than 3 cm resolved with antibiotics alone. Intravenous crystalline penicillin, chloroamphenicol, and metronidazole were given for 2 weeks followed by oral ampicillin and cotrimoxazole for 10 weeks. There was no morbidity related to the multiple procedures and the patient had a good outcome at the end of 16 weeks.

CONCLUSIONS

CT-guided stereotactic aspiration of multiple brain abscesses is known to have a low morbidity and mortality. We highlight the additional option of multiple, staged aspirations for those abscesses not readily responding to antibiotic therapy.

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.

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.

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

Single, small (less than 1 cm) enhancing lesions are frequent findings on CT scans of Indian patients with seizures. These lesions have also been reported in patients from other parts of the world. They often resolve spontaneously and their etiology has been disputed for over a decade. Initially diagnosed in Indian patients as tuberculomas, a number of other etiologies have been suggested. More recently, based on biopsy data, we have shown that a majority of these lesions are caused by cysticercosis. This review traces the development of the controversy and reports the current understanding of their etiology. A logical approach to their management is also discussed.

Single small enhancing CT lesions in Indian patients with epilepsy: clinical, radiological and pathological considerations

Thirty consecutive Indian patients with focal or generalised seizures and single, small (less than 10 mm), enhancing lesions on CT scans (SSECTL) were studied. Five patients (Group A) were treated with anticonvulsants alone and did not have a biopsy. In ten patients (Group B) a CT guided stereotaxic biopsy of the lesion was carried out and in the remainder (15-Group C) and excision biopsy of the lesion was carried out following CT guided stereotaxic localisation. In all patients in Group B the lesion were reported as "chronic nonspecific inflammation". In seven of 15 patients in Group C the lesions showed a cysticercus with a granuloma and in a further five the pathology was that of a "parasitic granuloma" but the parasite could not be identified. Biopsy did not reveal a tuberculoma or neoplasm in any of the patients. The lesions studied are the same as "disappearing" CT lesions reported in Indian patients, as in 12 of 15 patients in Groups A and B, who could be followed up for more than three months, the lesions had spontaneously disappeared or left calcific residues. It is concluded that in Indian epileptic patients with SSECTL cysticercosis is the commonest aetiology. A treatment protocol for these patients is suggested on the basis of the findings.

The value of different methods of treatment of brain abscess in the CT era

67 cases of brain abscess were analyzed retrospectively. As 2 comatose patients died on admission before any treatment was started, the results are based on 65 treated patients. Different methods of treatment included: total removal in 36 patients, drainage in 14, aspiration in 6 and conservative treatment in 9. Management mortality was 18.5% and was almost not dependent on the method of treatment (except aspiration) being lowest in the drainage group. The mortality was significantly higher in patients with serious impairment of consciousness on admission. Follow-up examination after 1 to 11 years was performed in 47 out of 53 discharged patients and revealed in 25 of them (53%) full recovery. 10 additional cases (21%) are independent. The best early and long term results were obtained in patients by drainage and medical treatment. Chronic epilepsy developed in 34% of patients with supratentorial lesions. The risk of epilepsy was lowest in the group of patients treated by drainage. The authors present the opinion that removal of brain abscess is necessary only in exceptional cases.

Stereotaxic surgery in the treatment of multiple brain abscesses

Controversy exists regarding the optimal treatment for patients with multiple brain abscesses. These lesions are often small and located deep in the brain and close to vital structures, making surgery difficult. With this in mind the authors review their experience in treating multiple abscesses using computerized tomography (CT)-guided stereotaxic aspiration. From 1983 to 1985, 15 patients were treated for multiple brain abscesses, of whom eight underwent stereotaxic aspiration. There were a total of 28 abscesses in these eight patients: 11 abscesses were aspirated and two excised using CT-guided techniques. Most were cortical in location, although there were 12 in the deep white matter, one in the thalamus, and two in the caudate nucleus. All patients received a total of 6 weeks of antibiotic therapy. Follow-up CT showed resolution of the abscesses in all patients. Currently, four are neurologically normal, one has a mild hemiparesis, one has a well-controlled seizure disorder, and one requires supportive care. A single death occurred 5 weeks postoperatively of unrelated causes. Location, size, and age of an abscess all have bearing upon the response to management and outcome of the patient. Stereotaxic surgery is a procedure with minimal morbidity and mortality. Stereotaxic aspiration should be considered in patients with small, multiple, or deep-seated abscesses, in those who are poor operative candidates, and in those who have failed prior therapy.

Treatment by aspiration of brain abscesses

Sixteen patients, with a total of 18 abscesses, were treated by aspiration and systemic antibiotic therapy, to which antiepileptic prophylaxis and corticosteroids were added. Diagnosis of the abscesses and monitoring of their evolution relied principally upon computed tomography; this technique was also used per-operatively when aspirating small abscesses. Bacteriological examinations were positive in all our cases and a polymicrobial flora was found in half of these. One or, eventually, two aspirations within the same week were sufficient, in most cases, to promote healing. Nevertheless, in three patients, the abscesses, however sterilized, did not show any volume reduction, probably because of adhesions to the dura mater, of a large part of the abscess surface area. One patient died from concomitant cardiac disease and one patient remained seriously disabled. Epilepsy was observed as a sequela, in six patients. This study emphasizes the role of neuroradiological and bacteriological examinations, whilst surgery may be restricted, in most cases, to a simple aspiration.

Treatment of deep brain abscesses by stereotactic implantation of an intracavitary device for evacuation and local application of antibiotics

Complete recovery from deep brain abscesses was achieved in four patients treated by a specialized stereotactic method. In one patient the lesion was in the right thalamus, in two patients within the brain stem and in one case in the right rolandic cortex. The technique consists in the stereotactic implantation of a chronic intracavitary catheter connected to a subcutaneous reservoir to allow postoperative multiple evacuations and local antibiotic irrigations. Serial CT scan examinations guided the timing of intracavitary treatment and the removal of the catheter. No recurrence developed. The diagnostic and therapeutic advantages of this stereotactic technique are emphasized.

Long term sequelae of hemispheric abscesses as a function of the treatment

The authors compared the clinical, electroencephalographic and CT evolution of 31 cases of brain hemispheric abscesses. The vital prognosis was largely improved by the introduction of the CT scan, as compared with previous series. The functional evolution was better in the group of patients receiving high dosage (15 cases) antibiotics and/or puncture (4 cases) in the case of a large lesion, than in patients whose abscesses were removed (12 cases). The CT scan confirmed this difference, with frequent atrophy after excision.