Original ArticleA Retrospective Analysis of Vision-Impairing Tumors Among 467 Patients with Neurofibromatosis Type 2
Introduction
Neurofibromatosis type 2 (NF2) is a rare, autosomal dominantly inherited tumor predisposition syndrome caused by inactivating mutations of the NF2 tumor suppressor gene on chromosome 22q12.1 NF2 is characterized by the presence of bilateral vestibular schwannomas, which occur in 90%–95% of patients.2 Other nervous system tumors mainly include meningiomas, schwannomas of other cranial nerves and spinal nerve roots, and ependymomas. However, neurofibromas are rarely found in patients with NF2.3
Most patients with NF2 develop bilateral progressive hearing loss. Almost 90% of patients have their hearing ability impaired before the age of 45 years.4 Researchers have attempted various methods to preserve their patients' hearing ability. Some molecule-targeted agents, such as bevacizumab and lapatinib, have succeeded in prolonging the preservation of hearing in some patients.5, 6 However, the outcome of bilateral deafness cannot be avoided in most cases. The treatment effects of hearing restoration options, such as the cochlear implant and auditory brainstem implant, remain unsatisfactory.7 Therefore, vision becomes increasingly important in patients with NF2 for communication as the disease progresses and hearing decreases.
In patients with NF2, various ocular manifestations have been identified, such as juvenile cataracts, epiretinal membranes, combined pigment epithelial detachments and retinal hamartomas, and optic disc gliomas.8 Most of these complications do not significantly impair the vision. In some patients with NF2, tumors can damage the anterior visual pathway, causing serious visual loss, sometimes even bilaterally.9, 10, 11 These tumors can cause disastrous hearing loss in patients with NF2 if left untreated. It is essential to know the clinical features and prognosis of these tumors adjacent to the anterior visual pathway. Only a few case reports and small-series studies have been reported. Here, we present a detailed analysis of these potentially vision-impairing tumors in a large series of patients with NF2.
Section snippets
Methods
Between May 2006 and May 2016, 467 patients with NF2 presented at the Department of Neurosurgery, Beijing Tian Tan Hospital. All the patients underwent enhanced cranial magnetic resonance imaging examinations and fulfilled the Manchester criteria12 for the diagnosis of NF2. Their cranial magnetic resonance images were carefully reviewed to find tumors adjacent to the anterior visual pathway, mainly including the optic nerve and chiasma. The tumors were categorized into the following 3 groups:
General Characteristics
Among the total of the 467 patients with NF2, 235 (50.3%) were male, and 232 (49.7%) were female. The age at diagnosis ranged from 1 to 70 years, with a mean age of 30.6 years (standard deviation [SD] ± 13.5 years; Figure 1A). Seventy-three patients with NF2 (15.6%) had tumors adjacent to the anterior visual pathway. The mean age at diagnosis in the 73 patients was similar to that in the other 394 patients (28.8 ± 12.1 years vs. 31.0 ± 13.8 years; t test, P = 0.195; Figure 1B). These 73
Discussion
Vision is undoubtedly important for patients with NF2 with hearing loss. However, many factors can threaten the patient's precious visual ability, such as various ocular manifestations, increased intracranial pressure, corneal opacification secondary to cranial nerve damage, and tumors adjacent to the anterior visual pathway. Tumors adjacent to the anterior visual pathway can originate from the intraorbital tissues, clinoid process, TS, suprasellar cistern, sphenoid ridge, cavernous sinus, and
Conclusions
Tumors adjacent to the anterior visual pathway were not common in patients with NF2. An evident male prevalence could be observed. These tumors could cause progressive visual loss if left untreated, causing disastrous hearing loss in patients with NF2. Early surgical intervention seems to be the primary treatment strategy, except for cases of ONSM. Seriously impaired visual ability is difficult to reverse. If patients adopt the wait and see approach, regular visual examination seems to be
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Conflict of interest statement: This study was supported by the National Science Foundation of China (grant no. 81372715), the Natural Science Foundation of Beijing (grant no. 7162057), the High Level Developing Program of Health and Technical Personnel of the Beijing Health System (grant no. 2014-2-008), and the National Natural Science Funds for Distinguished Young Scholars (grant no. 81502390).