Two cases of germ cell tumors (GCTs) of the basal ganglia are presented and 40 previously reported cases are reviewed. The incidence of GCTs of the basal ganglia and thalamus was estimated as less than 14% of all intracranial GCTs. All patients except for two (95%) were male, aged 7-19 years. The clinical course was usually slow. The major symptoms were hemiparesis, mental deterioration such as dementia or character change, precocious puberty, diabetes insipidus, oculomotor palsy, speech disturbance, and hemianopsia. Signs of intracranial hypertension did not occur until the late stages of the disease. The plain CT finding was characterized by an irregularly defined, slightly high-density area frequently accompanied by central low-density areas without significant mass effect. The tumors showed mild to moderate and nonhomogeneous contrast enhancement. An ipsilateral cerebral hemiatrophy was often found. MR images demonstrated the corresponding findings. GCTs of the basal ganglia had a high possibility of containing components other than germinoma such as choriocarcinoma, endodermal sinus tumor, and embryonal carcinoma. Thus, tumor markers in the serum, CSF, or cyst fluid were frequently positive. With recent refinement of microsurgical techniques as well as immunohistochemical study and measurements of tumor markers of serum, CSF, and cyst fluid, major resections of tumor, accurate pretreatment histologic diagnosis, and early determination of the specific types of this tumor appear to be readily possible. This is essential for effective treatment of patients not only with radiosensitive germinoma, but also those with radioinsensitive nongerminoma variants and a combination of them located in this region.

The authors present a case in which a large high-flow arteriovenous malformation was totally excised. The success of the operation was in part attributed to the prevention of hyperperfusion breakthrough phenomena by the use of Selverstone clamps on the cervical carotid artery. Monitoring of cortical blood flow during surgery was found to be helpful.

Thirty-two cases of pineal cyst diagnosed by magnetic resonance imaging (MRI) were reviewed and are described. The pineal cyst was demonstrated to be an area with slightly less intensity than the surrounding tissue and with slightly greater intensity than the CSF on T1-weighted images. On the T2-weighted images this lesion was identified as a high-intensity area with smooth margins and was homogeneous in nature. In three cases presenting with headache, compression of the vein of Galen was identified, and compression of the quadrigeminal plate was demonstrated in five cases. No patients presented with both pineal and quadrigeminal lesions. Of the cases, 63% were not detected by CT scanning alone. There were two cases in which the cyst ruptured and collapsed spontaneously during follow-up. It is emphasized that the presence of this lesion, which was more frequent than previously expected, should be kept in mind when diagnosing pineal tumors and should not be misdiagnosed. Surgery should not be undertaken unless the lesion produces symptoms due to the compression of the quadrigeminal plate, aqueduct, or the vein of Galen.