Journal of Neuro-Ophthalmology:
Visual Field Improvement After Pituitary Tumor Surgery in Patients With McCune–Albright Syndrome
Ma, Jin MD; Zhao, Chan MD; Wang, Renzhi MD; Feng, Feng MD; Wang, Erqian MD; You, Hui MD; Jiang, Ying MD; Zhang, Meifen MD; Zhong, Yong MD
Departments of Ophthalmology (JM, CZ, EW, MZ, YZ), Neurosurgery (RW), Radiology (FF, HY), and Pathology (YJ), Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Address correspondence to Yong Zhong, MD, Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Shuai Fu Yuan, Dongcheng District, Beijing 100730, China; E-mail: firstname.lastname@example.org
The authors report no financial or conflicts of interest.
J. Ma and C. Zhao contributed equally to this work and both qualify as the first author.
Background: McCune–Albright syndrome (MAS) is a rare, sporadic congenital disorder, in which optic neuropathy may cause devastating visual consequences. Pituitary adenoma with overproduction of growth hormone (GH) is present in approximately two-thirds of MAS patients, and its role in the pathogenesis of MAS-associated optic neuropathy has not been studied.
Methods: Three MAS patients with GH-secreting pituitary adenoma and optic chiasm compression diagnosed between January 2008 and November 2010 were included in this case series. Transsphenoidal pituitary resection was performed in all 3 patients. Neuro-ophthalmologic evaluation was performed at presentation and every 6 months during follow-up.
Results: Of the 3 patients, 2 were female and 1 was male; their ages ranged from 17 to 27 years. Visual acuity ranged from 20/20 to 20/200 before surgery and all had visual field loss. The patients were followed up for 6–18 months with substantial improvement in their visual fields.
Conclusions: GH-secreting pituitary adenoma may contribute to optic nerve damage, at least partially, in MAS patients. Pituitary surgery may be important for visual recovery in some MAS patients in whom there is compression of the optic chiasm.
McCune–Albright syndrome (MAS), characterized by a clinical triad of café-au-lait skin pigmentation, polyostotic fibrous dysplasia (FD), and single or multiple endocrinopathies, is a rare and sporadic congenital disorder first reported by McCune and Albright separately in the 1930s (1,2). Craniofacial involvement of FD may cause acute or chronic vision loss (3,4). Although progressive optic canal narrowing has long been believed to be the leading cause of optic neuropathy in FD/MAS patients (5–7), large case series have failed to document an age-related progression of optic canal narrowing or a causal relationship between optic canal narrowing and optic neuropathy (8,9). Rather, growth hormone (GH) excess has been associated with optic neuropathy and optic nerve stretching from bone expansion postulated to be the mechanism of vision loss (8,9).
Pituitary tumor can be detected in about two-thirds of MAS patients with GH excess (10). In this report, improvement of visual field (VF) was observed after transsphenoidal surgery in 3 MAS patients with GH-secreting pituitary adenoma and optic chiasm compression, providing evidence that pituitary tumor may contribute to vision loss, at least partially, in some MAS patients.
Three newly diagnosed MAS patients with pituitary tumor at Peking Union Medical College Hospital between January 2008 and November 2010 were included. Our study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of Peking Union Medical College Hospital. Informed consent was obtained from each patient before any examination or treatment. Each patient was evaluated by specialists in ophthalmology, endocrinology, neurosurgery, plastic surgery, and otolaryngology and underwent thin-section computed tomography (CT) of the craniofacial structures and magnetic resonance imaging (MRI) of the brain. MAS was diagnosed based on the presence of at least 2 elements of the clinical triad (11). All 3 patients underwent navigation-assisted transsphenoidal tumor resection.
Neuro-ophthalmologic examination included best-corrected visual acuity, color vision (Ishihara pseudoisochromatic plates), pupillary and VF testing, and funduscopy. VFs were performed using the Octopus 101 perimeter (Haag-Streit, Inc, Koeniz, Switzerland) tG2 program with Tendency Oriented Perimetry strategy. Eyes with very poor vision were tested with tG2 program, LVC (central low vision test) program with LVS (low vision Goldmann V) strategy. Color vision was tested with 14 Ishihara color plates in bright diffused light; abnormal color vision was defined as failing to identify 10 or more plates. Neuro-ophthalmologic re-evaluations were performed every 6 months during follow-up.
Ages of patients were 17, 21, and 27 years with 2 females and one male. Visual acuity ranged from 20/20 to 20/200, with some impairment of color vision, and all had optic disc pallor. Preoperative VFs are shown in Figure 1 (top panel).
All 3 patients had typical café-au-lait skin pigmentation, craniofacial polyostotic FD with bilateral optic canal narrowing (Fig. 2), GH excess with acromegaly (patient 1 had concurrent prolactin excess), and pituitary macroadenoma with compression of the optic chiasm (Fig. 3).
All patients underwent transsphenoidal resection, and none had excision or shaving of the osseous lesions or optic canal decompression. Patients 1 and 2 were given intravenous bisphosphonate. Magnetic resonance imaging of the brain in all 3 patients performed 4 to 12 months after the surgery showed successful removal of the pituitary tumor and decompression of the optic chiasm. The patients were followed for 6–18 months after surgery with substantial improvements in VF results (Fig. 1, bottom panel). No improvement was detected in visual acuity, color vision, pupillary testing, or funduscopy. Immunohistochemistry of the surgically removed bone and pituitary tumor confirmed the diagnosis of FD (Fig. 4) and GH-secreting pituitary adenoma (Fig. 5).
Both MAS and isolated FD are sporadic noninherited genetic disorders caused by postzygotic mutations of GNAS1 gene encoding α subunit of stimulatory G protein (12,13). The phenotype from postzygotic single-cell GNAS1 mutation is variable, ranging from a constellation of multisystemic abnormalities to single or multiple FD lesions confined to the skeleton system (14–16). Whether the disease is generalized or localized depends on when the mutation occurs during embryogenesis (12).
Both acute and chronic visual impairment have been well documented in the literature in FD/MAS patients. Michael et al (3) noted that most reported cases of vision loss in FD are because of mass lesions, including cystic FD, mucocele, and aneurysmal bone cyst.
Progressive optic canal narrowing has long been considered a major cause of chronic optic neuropathy in craniofacial FD/MAS patients. This has led to prophylactic optic canal decompression (6,7). However, in a large cross-sectional analysis of a case–control cohort, Lee et al (8) showed that narrowing of the optic canal in craniofacial FD was not associated with visual loss. In this study, the majority of patients did not develop optic neuropathy even with severely narrowed optic canals. In addition, reports (9,10) of both prophylactic and interventional optic canal decompression with long-term follow-up do not demonstrate efficacy of this surgical procedure. Currently, optic canal decompression is only recommended for FD patients with acute or progressive visual impairment (3,9,17).
FD/MAS patients were not screened for pituitary tumor in previous studies. However, in our patients, the results of VF testing and neuroimaging indicated optic chiasm compression, and they all underwent transsphenoidal tumor resection with improvement of VFs. We conclude that chiasmal compression was a contributing factor to visual impairment. In addition, pituitary adenoma also might explain the association of GH excess documented in previous studies of patients with MAS (9,14).
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© 2013 by North American Neuro-Ophthalmology Society