Hypothalamic Hamartoma

Abstract

Hypothalamic hamartoma (HH) is a rare developmental tumor that has a benign histology and does not progressively enlarge. Pedunculated HH attached to the tuber cinereum may cause precocious puberty, whereas sessile HHs that have intraventricular and intrahypotha-lamic components cause gelastic epilepsy and behavioral disorders. Large HHs with involvement of both mammillary and tuberal regions tend to manifest with neurological and endocrine problems [10, 12, 14]. Gelastic epilepsy is generally resistant to antiepileptic drugs (AED), a ketogenic diet, and vagal nerve stimulation. The epilepsy syndrome that results may be progressive and devastating for the patients and their families. The localization of seizures can be deceptive, with patients previously undergoing temporal lobec-tomy or frontal corticectomy without any effect on the seizures [4, 14, 26]. There is now good evidence that the seizures in these patients emanate from the HH [4]. HHs vary in size considerably, ranging from a few millimeters to several centimeters in diameter (Fig. 34.1). Small HHs are easily missed on brain imaging studies. The larger HHs displace and distort the hypothalamus. It is often feasible to remove or disconnect the lesion from the adjacent hypothalamus in many patients without significant injury to the hypothalamus. The attachment to the mammillary body may be a principal route of spread of the seizures via the mammillo-thalamic tract to the thalamus and from the thalamus to the neocortex [11] (Fig. 34.2). It is probably important to disconnect the HH from the mammillary body and the rest of the hypothalamus to achieve control of the seizures.