title: Role of pituitary radiosurgery for the management of intractable pain and potential future applications.
abstract: BACKGROUND
  Two or three decades ago, cancer pain was treated by surgical/chemical hypophysectomy. In one report, the control of central pain (thalamic pain syndrome) was also approached with chemical hypophysectomy. Although in most of the patients these treatments resulted in a decrease in severe pain, concomitantly severe adverse effects (panhypopituitarism, diabetes insipidus and visual dysfunction) occurred in most patients. This historical evidence prompted us to perform Gamma Knife surgery (GKS) for this kind of intractable severe pain using a high irradiation dose to the pituitary stalk/gland. In the majority of patients, marked pain relief was achieved, surprisingly without any of the complications mentioned above.
  
  
  METHODS
  A prospective multicenter study was conducted to evaluate the efficacy and safety in patients treated in Prague, Hong Kong and Tokyo. Indications of this treatment were: (1) failure of other effective treatment approaches prior to GKS, (2) good general patient condition (Karnofsky performance status >40%), (3) response to morphine for pain control (cancer pain), and (4) no previous radiotherapy of brain metastases (GKS/conventional radiotherapy). Eight patients with severe cancer pain due to bone metastasis and 12 patients with post-stroke thalamic pain syndrome were treated with GKS. The target was the border between the pituitary stalk and gland. Maximum dose was 160 Gy for cancer pain and 140 Gy for central pain. Follow-up included 6 patients (>1 month) with cancer pain and 8 patients (> 6 months) with thalamic pain syndrome.
  
  
  RESULTS
  All patients (6/6) with cancer pain experienced significant pain reduction, and 87.5% (7/8) of the patients with thalamic pain had initially significant pain reduction. In some patients, pain reduction was delayed for several hours. Pain relief was noted within 7 days (median 2 days). No recurrence was observed in the patients with cancer pain. However, in 71.4% (5/7) of the patients with thalamic pain syndrome, disease recurred during the 6-month follow-up. Up to now, other complications have not been observed.
  
  
  CONCLUSIONS
  Our clinical study protocol is only preliminary. Further clinical results on the management of thalamic pain are required to develop this treatment protocol. However, efficacy and safety have been shown in all our cases. In our opinion, this treatment has a potential to control severe pain, and GKS will play an important role in the management of intractable pain.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, Japan. GKRmoto@aol.com
authors.forename: Motohiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Takaomi
authors.initials: T
authors.lastname: Taira
authors.forename: Mikhail
authors.initials: M
authors.lastname: Chernov
authors.forename: Masahiro
authors.initials: M
authors.lastname: Izawa
authors.forename: Roman
authors.initials: R
authors.lastname: Liscak
authors.forename: Chung Ping
authors.initials: CP
authors.lastname: Yu
authors.forename: Robert T K
authors.initials: RT
authors.lastname: Ho
authors.forename: Yoko
authors.initials: Y
authors.lastname: Katayama
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kouyama
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Tomokatsu
authors.initials: T
authors.lastname: Hori
authors.forename: Kintomo
authors.initials: K
authors.lastname: Takakura
mesh_terms: D001859:Bone Neoplasms / Q000150:complications / Q000556:secondary; D001943:Breast Neoplasms / Q000473:pathology; D005260:Female; D006801:Humans; D007016:Hypophysectomy; D008297:Male; D010146:Pain / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D010902:Pituitary Gland / Q000378:metabolism / Q000601:surgery*; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology; D016634:Radiosurgery; D013788:Thalamus / Q000503:physiopathology; D016896:Treatment Outcome; D001615:beta-Endorphin / Q000378:metabolism
chemical_list: D001615:beta-Endorphin