Long-term outcome of optic nerve encasement and optic nerve decompression in patients with fibrous dysplasia: Risk factors for blindness and safety of observation

Department of Oral and Maxillofacial Surgery, University of California, San Francisco, San Francisco, California, United States
Neurosurgery (Impact Factor: 3.62). 12/2006; 59(5):1011-7; discussion 1017-8. DOI: 10.1227/01.NEU.0000254440.02736.E3
Source: PubMed


Fibrous dysplasia (FD) of bone may occur solely as a skeletal condition or it may occur in association with extraskeletal manifestations, including growth hormone (GH) excess. Uncertainty exists as to the management of FD involving the optic nerves. In an effort to clarify management, the authors studied a large population of patients.
One hundred four patients underwent an evaluation that included review of records, endocrine testing, cranial computed tomography, and neuro-ophthalmological examination.
Ninety-one of 104 patients had craniofacial FD; complete records were available for 87 patients (174 nerves). Seventeen percent of the optic nerves were less than 50% encased, 22% were 50 to 99% encased, and 61% were 100% encased. Twelve percent of the nerves that were 100% encased showed evidence of optic neuropathy, but 88% did not. The group with optic neuropathy was not older than the group without. Patients with GH excess were significantly more likely to have nerves that were 100% encased (relative risk, 4.1; 95% confidence interval, 1.5-11.1; P = 0.0017) and to have optic neuropathy (relative risk, 3.8; 95% confidence interval, 2.0-7.1; P = 0.0019). Six prophylactic optic nerve decompressions were performed; in five patients, vision was stable after surgery, and one patient was blind after surgery. Thirteen interventional optic nerve decompression procedures were performed; six of the 13 patients showed some improvement and seven of the 13 showed no improvement or worsened vision.
The vast majority of optic nerves encased with FD do not exhibit symptoms of optic neuropathy and seem to be stable over time. GH excess is associated with increased risk of nerve encasement and optic neuropathy. Patients with craniofacial FD should be screened for GH excess, and optic nerve decompression should be performed only when there is objective evidence of progressive optic neuropathy.

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    • "In the cases of other lesions such as an aneurysmal bone cyst or mucocele, vision loss can be much more rapid. A study by Cutler et al [33] demonstrated that 12% of patients with relatively severe craniofacial PFD had evidence of optic neuropathy, that patients with GH excess had a higher relative risk for complete encasement of the optic nerve (4.1 fold), and had a higher relative risk for optic neuropathy (3.8 fold) compared to patients without GH excess. Preliminary findings by Glover et al demonstrated that patients with an early diagnosis and treatment of GH excess had no optic neuropathy (0 of 14 patients that were diagnosed and treated by age 18) while 4 of 7 patients diagnosed and treated for growth hormone excess after age 18 had optic neuropathy [80]. "
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    ABSTRACT: Fibrous dysplasia (FD) is a non-malignant condition caused by post-zygotic, activating mutations of the GNAS gene that results in inhibition of the differentiation and proliferation of bone-forming stromal cells and leads to the replacement of normal bone and marrow by fibrous tissue and woven bone. The phenotype is variable and may be isolated to a single skeletal site or multiple sites and sometimes is associated with extraskeletal manifestations in the skin and/or endocrine organs (McCune-Albright syndrome). The clinical behavior and progression of FD may also vary, thereby making the management of this condition difficult with few established clinical guidelines. This paper provides a clinically-focused comprehensive description of craniofacial FD, its natural progression, the components of the diagnostic evaluation and the multi-disciplinary management, and considerations for future research.
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    • "GH and prolactin excess are common (21%), and the signs and symptoms can be very subtle. Since GH excess can worsen craniofacial bone disease [5,40,41], it is important to make the diagnosis and treat. All patients should have an oral glucose tolerance test (OGTT) to look for non-suppressible GH at least once. "
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    ABSTRACT: McCune-Albright syndrome (MAS) is characterized by the clinical triad of polyostotic fibrous dysplasia, cafe-au-lait pigmented skin lesions, and multiple endocrinopathies. The molecular basis of MAS is a mutation in G(s)alpha that results in constitutive activation of adenylyl cyclase in affected tissues. This mutation occurs during early embryogenesis, and therefore patients with MAS are mosaic. The identification of activating mutations of Gsa in liver, heart, and gastrointestinal tract of patients with MAS suggests a broader spectrum of clinical disease than previously appreciated
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