Bacterial brain abscesses occur in approximately 1500 to 2500 patients each year in the United States. Multiple abscesses have been noted in 10 to 50% of these patients. The goal of this study was to better define the roles of surgery and medical management in patients harboring multiple brain abscesses and to develop an algorithmic approach to the treatment of these complex patients. Between 1976 and 1992, 16 patients with multiple brain abscesses were treated by a single physician (M.L.R.). The ages of the patients ranged from 1.5 to 73 years (median, 47 yr). In all patients, a diagnosis of multiple abscesses was made by computed tomography (15 patients) or magnetic resonance imaging (1 patient) brain scans. The number of abscesses per patient ranged from 2 to 30, and the abscesses were located in all regions of the brain. Thirteen received a combination of antibiotics and surgical drainage, and three received antibiotics only. Surgery was performed on abscesses larger than 2.5 cm or on those situated in critical areas of the brain or causing significant mass effect. Excision and open aspiration via craniotomy and stereotactic aspiration were analyzed on the basis of the location of the lesion and infecting organism. Any abscess that enlarged after 2 weeks of antibiotics or that failed to shrink after 3 to 4 weeks of antibiotics was again aspirated or excised. Forty-three surgical procedures were performed in 13 patients, and 8 (62%) of the patients operated on required more than one surgical procedure. No significant morbidity was observed in any of the surgical procedures. Antibiotics were administered intravenously for an average of 6 to 8 weeks and were adjusted according to organism type and sensitivity to antibiotics. One patient (6%) died, and the remaining 15 patients had resolution of all abscesses and good neurological recovery within 6 months. On the basis of these results, we propose a combined surgical and medical approach to the treatment of patients with multiple brain abscesses. We recommend the aggressive surgical drainage of all abscesses larger than 2.5 cm in diameter, combined with 6 to 8 weeks of intravenous antibiotics. Biweekly computed tomography or magnetic resonance imaging is necessary to closely monitor patients for evidence of abscess growth or failure to resolve despite antibiotics, prompting another operation. The application of this combined approach should yield cure rates of more than 90% in patients with multiple brain abscesses, a result similar to that expected when treating patients with solitary lesions.

Little is known about the risk of developing multicentric disease in patients with juvenile pilocytic astrocytoma (JPA), and even less about its prognosis. Only five cases have been reported. Between 1986 and 1992, the authors treated 90 patients with either primary or recurrent JPA, 11 of whom developed multicentric spread. Ten patients had primary tumors in the hypothalamic region, eight were under 4 years of age at initial diagnosis, all had initially undergone a subtotal resection or biopsy, and 10 received postoperative multiagent chemotherapy or irradiation for residual disease. Multicentric spread was discovered immediately to 108 months after initial diagnosis; nine patients were asymptomatic at the time. Most patients received chemotherapy for the multicentric disease, which was found throughout the craniospinal axis. During 21 to 148 months of follow-up monitoring, seven patients had stabilization or regression of multicentric disease and four died. Patients with hypothalamic region tumors were 23 times more likely to develop multicentric spread than were those with primary tumors located elsewhere (p < 0.001). Based on this review, it is concluded that multicentric spread of JPA occurs more frequently than was previously recognized. In patients with subtotally resected JPA and several years of follow-up review via magnetic resonance imaging, the incidence of recurrence in a site different from the original was 12%. Patients with subtotally resected JPA in the hypothalamic region should be considered to be at high risk for developing multicentric spread. Chemotherapy appears useful in stabilizing multicentric disease. Earlier detection and intervention may result in longer disease-free survival in patients with multicentric spread of JPA.

The successful management of nocardial brain abscess remains problematic. The authors report 11 cases of nocardial brain abscess treated between 1971 and 1993 and review 120 cases reported since 1950. The clinical findings included focal deficits in 55 patients (42%), nonfocal findings in 36 (27%), and seizures in 39 (30%). Extraneural nocardiae were present in 66% of the cases; pulmonary (38%) and cutaneous/subcutaneous (20%) locations were the most frequent. The abscesses were single in 54% of the patients, multiple in 38%, and of unknown number in 8%. Forty-four of 131 patients (34%) were immunocompromised; since 1975, 18 of 40 immunocompromised patients (45%) were transplant recipients and six (15%) had human immunodeficiency virus. The mortality rate was 24% after initial craniotomy and excision (11/45), 50% after aspiration/drainage (17/34), and 30% after nonoperative therapy (7/23); 29 cases (22%) were diagnosed at autopsy. The mortality rate was 33% in patients with single abscesses and 66% in those with multiple abscesses (P < 0.0003). There was no difference in the mortality rates of immunocompromised and nonimmunocompromised patients treated before computed tomography (CT) was available; since the advent of CT, however, the mortality rate has been significantly higher in immunocompromised patients (55% vs. 20%, P < 0.05). Although the mortality rate for nocardial brain abscesses has dropped almost 50% since the advent of CT, it has remained virtually unchanged in immunocompromised patients and is three times higher than that of other bacterial brain abscesses (30% vs. 10%). The authors recommend image-directed stereotactic aspiration for diagnosis; however, craniotomy and total excision are necessary in most cases, because nocardial abscesses are usually multiloculated. Patients with minimal neurological deficits or small abscesses may be treated initially with antibiotics alone. Sulfonamides, alone or in combination with trimethoprim, are most effective and should be continued for at least 1 year. Minocycline, imipenem, or aminoglycoside in combination with a third-generation cephalosporin may be used with reasonably good success as second-line agents in cases of allergy or nonresponsiveness to sulfa agents.

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The authors report the cases of three patients with epidermoid cysts which insinuated themselves into the brain stem. In all three patients, the tumor occupied the pons, although in one it was predominantly located in the medulla. The cyst contents and nonadherent tumor capsule were removed in all three patients, but no attempt was made to remove tumor densely adherent to the brain stem. One patient's cyst was removed in one operation, but maximal resection in the other two required two operations. After surgery, sixth nerve function completely returned in one patient; another patient had a stable pontine gaze palsy but developed new facial weakness; and the third patient had stable cranial nerve deficits with a diminished hemiparesis. The last patient developed a pseudomeningocele and communicating hydrocephalus, and required a lumboperitoneal shunt. In all three patients, computerized tomography scans demonstrated hypodense tumors not enhanced by contrast material. Magnetic resonance imaging was performed on two patients; in both, the tumors showed increased signal intensity relative to brain on T1-weighted images and decreased signal intensity relative to brain on T2-weighted studies. Magnetic resonance imaging, the most accurate modality for localizing these lesions and determining their extent, was also invaluable for postoperative monitoring and follow-up evaluation. Safe and adequate resection includes decompression of cyst contents and removal of nonadherent portions of the cyst capsule. Cyst wall adherent to the brain stem, however, should not be removed.

The authors report the case of a metastatic juvenile pilocytic astrocytoma of the hypothalamic region in a 10-year-old boy. Eight years after craniotomy and radiation therapy, the tumor spread via cerebrospinal fluid pathways to the left cerebellar tonsil and the lumbosacral region. Histological evaluation of both the original hypothalamic and the new lumbosacral masses showed features of a slow-growing juvenile pilocytic astrocytoma with no evidence of malignant transformation. The clinical implications and possible mechanisms of metastatic spread are discussed.

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The histopathological changes associated with ultrasonic heating of normal cat brain have been correlated with thermal distributions. Ultrasound energy was applied for 50 min at different intensities to generate tissue temperatures from 42 to 48 degrees C. Animals were sacrificed at various intervals from 1 to 56 days. The organization and resolution of thermal damage was characterized by three stages of histopathological changes within the nervous tissue. The acute stage (Days 1-3) was defined by (1) extensive coagulation necrosis, (2) pyknosis of neuronal elements in the gray matter, (3) edema and vacuolation in the white matter, and (4) polymorphonuclear leukocytes. The subacute stage (Days 3-21) was characterized by (1) the appearance of lipid-laden macrophages, (2) liquefaction of the necrotic regions, (3) fibroblastic proliferation, and (4) vascular proliferation with some perivascular inflammatory infiltration (lymphocytes). Lastly, the chronic stage (Days 21-56) was defined by (1) fibrosis (reticulin and collagen formation) and (2) gliosis (reactive astrocytic proliferation) occurring around the fluid-filled necrotic center. Analysis of these data has also included a study of the lesion size versus the dose (temperature for 50 min) of heating. The results demonstrate a significant linear dose-response correlation. The results of this study indicate that the histological appearance and time course of repair of thermal injury in the normal brain tissue are analogous to acute brain necrosis resulting from cerebral infarction, except the thermal damage does not result in significant hemorrhage.