18 cases of benign intradural spinal cyst (9 arachnoidal, 2 neuroepithelial, 7 endodermal) are reported and compared with 94 cases (67 arachnoidal, 7 neuroepithelial, 20 endodermal) obtained from the literature. Arachnoidal intradural cysts (AIC) have no sex preference, occur at around the fourth-fifth decades of life and have characteristic intermittent root symptoms. They prefer the thoracic level and the posterior position. (Myelography images the cystic cavity (diverticular form). Surgical removal is usually easy. Neuroepithelial intradural cysts (NIC) are rare, have a 2:1 predilection for females and occur after the fourth decade. They have a serious clinical course similar to intramedullary or extramedullary tumours. They prefer the conus-cauda and the anterolateral positions. They often give rise to manometric block and to albuminocytological dissociation. There may be substantial adhesions to the cord and roots and the intramedullary variety presents no clear plane of cleavage. Endodermal intradural cysts (EIC) have a 2:1 predilection for males and prefer the second and third decades. They may have an intermittent or serious course with signs of root and cord impairment. They prefer the cervical segment (in the anterior position) and the conus-cauda (in the posterior position). As a rule they present manometric block and albuminocytological dissociation. Their frequent tough adhesions to the roots and cord demand special care during their removal.

A series of 7 cases of PCA aneurysm treated between 1978 and 1992 were analytically reviewed together with 79 cases culled from the literature. In comparison to those localized elsewhere, PCA aneurysms are more frequently large, more frequently present with tumour-like symptoms and appear at an earlier age. Surgical outcome was evaluated in relation to clinical onset, site and size of the aneurysm, the surgical procedures adopted for excluding it and pre-operative clinical grading appeared to influence outcome. The fact that site, size and surgical technique do not significantly influence prognosis is probably due to the rich collateral flow present in the areas fed by the posterior cerebral artery. The authors conclude that, clinically speaking, PCA aneurysms should be considered as a separate group.

We report the long-term outcome of surgery for cerebral hydatid cyst in 12 children. In only one child, who had been operated on for cardiac hydatidosis a year earlier, was the brain cyst known to be secondary. Of the 12 children. 10 had a single cyst and 2 had multiple cysts. Five single cysts were removed intact by “hydatid birth,” two cysts—one single and one multiple—were removed after puncture and aspiration of the cyst fluid, and the other five—four single and one multiple—were accidentally ruptured in the course of the operation. One patient died of infection of the residual space. 2 died of intracranial recurrence of the parasite (7 and 22 months later, respectively), and one. the child with secondary cerebral echinococcosis, died 6 years later of systemic echinococcosis. Eight patients who had a mean follow-up of 28 years are still living and enjoy very good health, both general and neurological. This long-term follow-up with such good results confirms the usually primary character of cerebral hydatid disease, at least in children. The combination of patent ductus arteriosus and ingestion of unboiled animals' milk might well explain how primarv cerebral hvdatid disease develops in children.

Cerebral meningiomas are rare tumors in children that represent 1.4% of CNS tumors and 1.5% of intracranial meningiomas. We have analyzed 197 cases of cerebral meningiomas under 16: 178 cases were taken from the available literature and 19 from our series. When comparing pediatric meningiomas with those of adults, we noted some differences. Before the age of 16 there is a slight preference for males; the intraventricular variety is more frequent; cystic meningiomas and the absence of dural attachment are more frequent findings; the neuroradiological diagnosis is more difficult.

The clinical findings and the results of surgical treatment in 16 patients with spinal dermoid or epidermoid tumors are reported. In 9 patients the tumor capsule adhered so tightly to the nervous tissue that part of it was left in situ. In a follow-up study ranging from 5 to 30 years with a mean of 14.2 years only 1 patient had a recurrence of the tumor and 10 patients resumed a normal working life.

Of the 62 patients with intramedullary spinal cord ependymoma treated surgically at our Neurosurgery Division between January 1951 and December 1990 45 had a follow-up of at least 3 years and the longest 30 years. The 28 conus-cauda equina-filum ependymomas operated during the same period are not considered in this study. An analysis of our cases and of the larger published series shows that favourable prognostic factors, apart of course from total tumour removal, which is now usually possible, are a site below the high cervical segments and a mild pre-operative symptom pattern. Patient age at diagnosis, tumour size and "low dose" (< 40 Gy) radiotherapy seem to have no influence on the prognosis. Aggressive surgical removal is the treatment of choice and also for long-term recurrence.

Intramedullary glioblastomas are uncommon tumors. They occur chiefly in the cervicothoracic segments, have a slight tendency to occur in the early decades of life, and have a short clinical history before diagnosis. We report seven cases and discuss the salient features of these tumors, particularly the pathological features and treatment, in light of the relevant literature.

Twenty-two cases of unusual intracranial meningioma associated with a cyst are reported and 144 published cases reviewed. The complex mechanisms leading to the formation of the cyst within the meningioma are analyzed on the basis of the surgical and histopathological evidence. The neuroradiological features (Computed Tomography and Angiography) which supply a correct preoperative diagnosis are discussed. It is clear from the literature how difficult preoperative diagnosis is, being possible only in 38% of cases with CT scanning and in 13% with angiography. It is necessary to remove not only the solid portion of the meningioma but also the cyst wall in order to prevent a recurrence. This is technically difficult for the type II intratumoural variety of Nauta's classification.