Surgical Approach to Posterior Third Ventricular Lesions – An Initial Experience

Background: Posterior third ventricular lesions are uncommon deep seated, heterogeneous mass lesions. They constitute pineal gland tumors, epidermoid, choroid plexus papillomas, meningioma, metastases and vascular lesions. Surgical excision of these lesions pose a major challenge due to the complex anatomy of this region. Objective: The objective of this paper is to ascertain the management strategy of posterior third ventricular lesions with emphasis on surgical management. The advantages and disadvantages of the two main approaches and their indications are compared and discussed. Patients and Methods: Ten patients with posterior third ventricular region tumors were operated by the authors with age ranging from 21 to 36 years. All patients with obstructive hydrocephalus underwent a ventriculoperitoneal shunt and in one patient an endoscopic third ventriculostomy was performed. During the shunt CSF was obtained for tumor markers. Tumor excision was done through the infratentorial supracerebellar approach in five cases while the infraoccipital transtentorial approach was adopted in two patients. A combined two stage approach was adopted in two cases. In one patient an endoscopic biopsy was carried out after an endoscopic third ventriculostomy which revealed a germinoma. Results: Gross total excision of the tumor was performed in 07 (70%) patients. A subtotal excision was performed in 02 (20%) and an endoscopic biopsy in 01 (10%) patient. Two of the operated patients developed transient parinaud’s syndrome which resolved in the subsequent follow up and transient ataxia was observed in two of the patients. One patient developed venous hemorrhage of the occipital lobe but had no worsening of her visual deficit as the patient was already blind preoperatively. We encountered two deaths in our series - one due to postoperative hematoma and the other due to refractory brain edema. The most common tumor encountered in our study was pinealoblastoma (04) followed by meningioma (02), germinoma (02), epidermoid (01) and pilocytic astrocytoma (01). Conclusion: Despite advances in surgical techniques, surgical excision of these lesions remains challenging owing to the proximity of deep cerebral veins and dorsal midbrain structures. The surgical approach depends on the size and extent of the lesion and the vascular anatomy of the region. The learning curve in this is steep and the surgeon s experience plays an important role in the overall morbidity and mortality.