The endocrinology of hypothalamic hamartoma surgery for intractable epilepsy

Intractable epilepsy has replaced central precocious puberty (CPP) as the main indication for surgery in patients with hypothalamic hamartoma (HH). However, concern about endocrine complications and the paucity of published endocrine data may dissuade clinicians from recommending HH surgery. We report the preoperative endocrine status and postoperative endocrine findings of patients undergoing HH surgery at our centre. Twenty-nine patients aged 4-23 years (mean 10 years) underwent detailed clinical assessment and biochemical testing of the hypothalamic-pituitary axis before and after transcallosal resection of their HH. The perioperative evaluation included comprehensive evaluation of pubertal status, growth, weight, thyroid and adrenal function, and osmoregulation. Forty-five percent of patients had CPP at presentation and this was not altered by HH surgery. Asymptomatic deficiencies in thyroid hormone, growth hormone and cortisol response were identified in several patients prior to surgery, and biochemical CPP was present in four, clinically prepubertal children. Free thyroxine fell after surgery in the majority, and to clinically significant levels prompting treatment in 5 patients. Low growth hormone was present in 5/8 patients who had had previous HH surgery and in 6/29 following transcallosal surgery at our centre; short stature did not result during the period of follow-up. Hypernatraemia developed in most patients postoperatively with sodium >150 mmol/L seen in 16 (55%) patients; however, this was asymptomatic, not often associated with polyuria, and transient; no patient required ongoing antidiuretic hormone replacement. Appetite stimulation and early postoperative weight gain occurred in 45% patients, but resolved in half. Disturbance of endocrine function may be clinically silent and should be routinely evaluated prior to HH surgery for intractable epilepsy. Following surgery, hypernatraemia, low thyroxine, low growth hormone, and weight gain are the main endocrine problems encountered. Prior, unsuccessful surgery may be a risk factor for endocrinopathy. Except for weight gain in some patients, these postoperative endocrine disturbances appear to be transient, mild or asymptomatic, and easily treated where necessary. Long term follow-up of growth and sexual development in a large series of patients is required.