Intraventricular Tumors

Lateral ventricle tumors, while varying in pathology, all arise from cells located within or around the ventricular walls. About half of lateral ventricular tumors consist of low-grade gliomas with choroid plexus papillomas and meningiomas, accounting for about 35%. Subependymal giant cell astrocytoma (SEGA) is a variant of astrocytomas and is found in patients with tuberous sclerosis. These are generally asymptomatic lesions, but can obstruct CSF flow. Choroid plexus tumors are most commonly seen in children, although they can occur in adults. Histology is the most important prognostic factor with choroid plexus papillomas having a much better prognosis than choroid plexus carcinomas. The remainder is made up of neurocytomas, congenital tumors, ependymomas, and metastasis. Neurocytomas are rare tumors, commonly found near the septum pellucidum near the foramen of Monro. They are very slow growing and histologically low grade.

Not all intraventricular lesions represent neoplasm. The colloid cyst is a benign remnant of the embryonic paraphysis and often seen in the intraventricular foramen of Monro, producing obstructive hydrocephalus. Some neurosurgeons approach the cyst through a cortical incision into the hydrocephalic right lateral ventricle or through the corpus callosum. Both approaches are satisfactory, although there is risk of neurologic damage.

Clinical Manifestations. The most common sign and symptom with intraventricular tumors is hydrocephalus. The onset is usually insidious because the majority of the tumors are slow growing. Lesions occurring in the pineal region and third ventricle can cause Parinaud syndrome secondary to compression of the quadrigeminal plate.

Diagnostic Studies. MRI allows for easy visualization of the tumor. Subependymomas and neurocytomas often present as a heterogenous cystic lesion. SEGAs are found near the foramen of Monro and are characterized by calcifications and intense enhancement in the context of other stigmata associated with tuberous sclerosis. Choroid plexus tumors are heavily lobulated and appear as a vascular tumors centered on the choroid. As stated earlier, a complete diagnostic evaluation for ependymoma includes imaging of the entire neuroaxis and examination of the CSF.

Treatment. Treatment varies, depending on the histology. Surgery is the mainstay of treatment for ependymomas, with a total or near-total resection a favorable prognostic factor. Resection of infratentorial ependymomas is technically more challenging than that of their supratentorial counterpart and associated with higher surgical morbidity. Nonetheless, attempt at gross total resection is crucial for management of ependymomas. Historically, adjuvant radiation treatment has been used based on results from retrospective studies showing that patients who received postoperative radiation had a better prognosis than those patients who only had surgery. The role of chemotherapy remains unclear, although it has been used in young children in an attempt to deter radiation. Subependymomas and neurocytomas have excellent prognosis with surgical resection without a need for adjunct therapy. Those choroid plexus tumors that can be completely excised have improved prognosis compared with those treated with subtotal resection. Radiotherapy has been associated with significantly better survival in choroid plexus carcinomas. Unfortunately, the rarity of these tumors results in limited information regarding their natural history and the optimal treatment.

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