Cystic thalamic gliomas.

Primary tumours of the thalamus are rare and present several diagnostic and therapeutic problems. Cystic thalamic lesions tend to be low grade astrocytomas and have only been reported in children. Signs and symptoms can be divided into those due to intracranial hypertension and those due to loss of function of thalamic nuclei and surrounding structures. Histologic diagnosis can be established by CT-guided needle biopsy and therapy begun by evacuation of the cyst contents. The prognosis remains uncertain.