The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. The cases of 40 pediatric patients with arachnoid cysts treated between 1978 and 1989 are reported. Five children with mild symptoms and small cysts that remained stable on follow-up studies have not required surgical intervention. Of 15 patients with cysts initially treated by fenestration, 10 (67%) showed no clinical or radiographic improvement postoperatively and have undergone cyst-peritoneal (eight patients) or ventriculoperitoneal (VP) shunting (one patient), or revision of a VP shunt placed for hydrocephalus before cyst fenestration (one patient). Two other patients with existing VP shunts required no further procedures. Thus, only three (20%) of 15 patients initially treated by fenestration remain shunt-independent after a median follow-up period of 8 years. The 20 other patients were initially treated by cysts shunting and all improved postoperatively; shunt revision has been necessary in six (30%) of these 20 patients because of cysts recurrence. Cyst location influenced the success of shunt treatment; none of the seven middle cranial fossa cysts treated by shunting have required revision, but results with cysts in other locations were less favorable. In all locations, though, shunting was more successful than fenestration. It is concluded that cyst-peritoneal or cyst-VP shunting is the procedure of choice for arachnoid cysts in most locations, including those in the middle cranial fossa.

To explore the potential usefulness of imaging studies in the diagnosis of focal central nervous system (CNS) lesions associated with acquired immunodeficiency syndrome (AIDS), the authors retrospectively examined the radiographic studies of 149 AIDS patients who presented with signs and symptoms of the three most common focal CNS lesions. Of these patients, 74 (50%) had Toxoplasma abscesses, 45 (30%) had primary CNS lymphoma, and 30 patients (20%) had progressive multifocal leukoencephalopathy (PML). Magnetic resonance (MR) imaging was more sensitive than computerized tomography (CT) in detecting lesions, especially in cases of PML. Whereas CT was unable to distinguish mass lesions caused by toxoplasmosis from those caused by lymphoma, 71% of the solitary lesions seen on MR images were lymphomas. These results indicate that empirical treatment for toxoplasmosis, the most common initial treatment for AIDS patients with neurological symptoms stemming from mass lesions, is not likely to be successful for patients with solitary lesions on MR images. Rather, early biopsy is advisable. If the presence of lymphoma is confirmed, the rapid initiation of treatment can allow prolonged high-quality survival.

The lower overall obliteration rate reported in this series is most likely due to the larger mean AVM volumes treated at UCSF as well as conservative dose-volume prescriptions delivered to children. Significantly higher obliteration rates were observed when a marginal radiation dose of at least 18 Gy was delivered. The permanent complication rate is low and should encourage those treating children to use doses similar to those used in adults.

Since the advent of magnetic resonance (MR) imaging, angiographically occult or ‘cryptic’ vascular malformations (CVMs) have been detected with increasing frequency in the pediatric population. The natural history of these lesions is uncertain and treatment remains controversial. We retrospectively reviewed the presentation, radiology, treatment and outcome of 37 pediatric patients with CVMs seen at our institution between 1982 and 1992. MR imaging was diagnostic in all patients studied. Angiography was negative in 20 of 21 patients studied, while 1 teenage girl was found to have a venous malformation. Total surgical excision was the treatment goal in all patients presenting with symptomatic CVMs. There has been no surgical mortality. Perioperative complications occurred in one third of the patients but quickly resolved in most cases. Only 2 patients with multiple CVMs, including brainstem lesions, who presented with progressive neurologic deficits were clearly worse following surgery. Six of seven patients with radiation-induced CVMs have remained asymptomatic with close radiographic follow-up, while 1 patient with a hemorrhage has required surgical evacuation. We conclude that CVMs occur more commonly in the pediatric population than previously assumed. Patients presenting with seizures or hemorrhage should undergo craniotomy with the goal of complete excision. Radiation therapy plays no role in the treatment of these lesions and may actually result in their formation. Careful clinical and radiological follow-up is critical to assess the completeness of surgical removal and to evaluate progression of lesions in patients with multiple or radiation-induced CVMs treated conservatively.