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Amr M. N. El-Shehaby, Wael A. Reda, Sameh R. Tawadros and Khaled M. Abdel Karim

Object

The primary concern when performing Gamma Knife surgery for pituitary adenoma is preservation of vision and pituitary function while achieving tumor growth control. Higher prescribed radiation doses are typically correlated with higher incidences of postradiosurgical hormone deficiencies. The goal of the present study was to retrospectively analyze the feasibility of using a lower prescribed radiation dose in the treatment of nonfunctioning pituitary adenomas and the effect of this dose on vision, pituitary function, and tumor growth control.

Methods

The study was conducted in 38 patients with nonfunctioning pituitary adenomas, who were treated between January 2002 and July 2008. Twenty-one patients were available for follow-up (13 men and 8 women). The mean follow-up period was 44 months (range 24–90 months). Nineteen patients had previously undergone surgery. Pituitary dysfunction developed after surgery in 3 patients. One patient had an abnormal pituitary hormone profile before radiosurgery due to an attack of pituitary apoplexy. Visual field defects were present in 12 patients. The prescribed radiation dose was 12 Gy in all patients. The tumor volume ranged from 0.5 to 11.8 cm3 (mean 4.8 cm3). The maximum dose to the visual pathway was kept below 10 Gy. The mean maximum dose delivered to the visual pathway was 7.9 Gy.

Results

The patients were followed up for a period of 24 to 90 months (mean 44 months). The size of the tumor decreased in 11 patients (52%) and remained stable in 9 patients (43%). In 1 patient there was tumor growth outside the previous radiation field (on the contralateral side). Among the 12 patients with visual field defects, 9 (75%) experienced an improvement and the remaining patients' vision remained stable. In only 4 patients was the visual improvement associated with tumor shrinkage. The hormone profile remained normal in all patients except for the 4 patients who had pituitary dysfunction before radiosurgery.

Conclusions

The 12-Gy prescribed dose used in this study seems to be sufficient for producing tumor control while sparing the patient from radiation-induced pituitary dysfunction. In addition, visual improvement was reported in a number of cases. A larger series and longer follow-up are required to confirm these results.

Free access

Amr M. N. El-Shehaby, Wael A. Reda, Khaled M. Abdel Karim, Ahmed M. Nabeel, Reem M. Emad Eldin and Sameh R. Tawadros

OBJECTIVE

The objective of this study was to assess hearing function after Gamma Knife treatment of cerebellopontine angle (CPA) meningiomas and assess factors affecting hearing outcome. Additionally, the authors opted to compare these results with those after Gamma Knife treatment of vestibular schwannomas (VSs), because most of the information on hearing outcome after stereotactic radiosurgery (SRS) comes from reports on VS treatment. Hearing preservation, to the best of the authors’ knowledge, has never been separately addressed in studies involving Gamma Knife radiosurgery (GKRS) for CPA meningiomas.

METHODS

This study included all patients who underwent a single session of GKRS between 2002 and 2014. The patients were divided into two groups. Group A included 66 patients with CPA meningiomas with serviceable hearing and tumor extension into the region centered on the internal auditory meatus. Group B included 144 patients with VSs with serviceable hearing. All patients had serviceable hearing before treatment (Gardner-Robertson [GR] Grades I and II). The median prescription dose was 12 Gy (range 10–12 Gy) in both groups. The median follow-up of groups A and B was 42 months (range 6–149 months) and 49 months (range 6–149 months), respectively.

RESULTS

At the last follow-up, the tumor control rate was 97% and 94% in groups A and B, respectively. Hearing preservation was defined as maintained serviceable hearing according to GR hearing score. The hearing preservation rate was 98% and 66% and the 7-year actuarial serviceable hearing preservation rate was 75% and 56%, respectively, between both groups. In group A, the median maximum cochlear dose in the patients with stable and worsened hearing grade was 6.3 Gy and 5.5 Gy, respectively. In group B, factors affecting hearing preservation were cochlear dose ≤ 7 Gy, follow-up duration, and tumor control. The only determinant of hearing preservation between both groups was tumor type.

CONCLUSIONS

GKRS for CPA meningiomas provides excellent hearing preservation in addition to high tumor control rate. Hearing outcome is better with CPA meningiomas than with VSs. Further long-term prospective studies on determinants of hearing outcome after GKRS for CPA meningiomas should be conducted.

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Yi-Chieh Hung, Cheng-Chia Lee, Huai-che Yang, Nasser Mohammed, Kathryn N. Kearns, Ahmed M. Nabeel, Khaled Abdel Karim, Reem M. Emad Eldin, Amr M. N. El-Shehaby, Wael A. Reda, Sameh R. Tawadros, Roman Liscak, Jana Jezkova, L. Dade Lunsford, Hideyuki Kano, Nathaniel D. Sisterson, Roberto Martínez Álvarez, Nuria E. Martínez Moreno, Douglas Kondziolka, John G. Golfinos, Inga Grills, Andrew Thompson, Hamid Borghei-Razavi, Tanmoy Kumar Maiti, Gene H. Barnett, James McInerney, Brad E. Zacharia, Zhiyuan Xu and Jason P. Sheehan

OBJECTIVE

The most common functioning pituitary adenoma is prolactinoma. Patients with medically refractory or residual/recurrent tumors that are not amenable to resection can be treated with stereotactic radiosurgery (SRS). The aim of this multicenter study was to evaluate the role of SRS for treating prolactinomas.

METHODS

This retrospective study included prolactinomas treated with SRS between 1997 and 2016 at ten institutions. Patients’ clinical and treatment parameters were investigated. Patients were considered to be in endocrine remission when they had a normal level of prolactin (PRL) without requiring dopamine agonist medications. Endocrine control was defined as endocrine remission or a controlled PRL level ≤ 30 ng/ml with dopamine agonist therapy. Other outcomes were evaluated including new-onset hormone deficiency, tumor recurrence, and new neurological complications.

RESULTS

The study cohort comprised 289 patients. The endocrine remission rates were 28%, 41%, and 54% at 3, 5, and 8 years after SRS, respectively. Following SRS, 25% of patients (72/289) had new hormone deficiency. Sixty-three percent of the patients (127/201) with available data attained endocrine control. Three percent of patients (9/269) had a new visual complication after SRS. Five percent of the patients (13/285) were recorded as having tumor progression. A pretreatment PRL level ≤ 270 ng/ml was a predictor of endocrine remission (p = 0.005, adjusted HR 0.487). An increasing margin dose resulted in better endocrine control after SRS (p = 0.033, adjusted OR 1.087).

CONCLUSIONS

In patients with medically refractory prolactinomas or a residual/recurrent prolactinoma, SRS affords remarkable therapeutic effects in endocrine remission, endocrine control, and tumor control. New-onset hypopituitarism is the most common adverse event.