Yulek Fatma, Demer Joseph L
Department of Ophthalmology, Stein Eye Institute, UCLA, Los Angeles, California.
Department of Ophthalmology, Stein Eye Institute, UCLA, Los Angeles, California; Department of Neurology, Neuroscience Interdepartmental Program, Bioengineering Interdepartmental Program, UCLA, Los Angeles, California.
J AAPOS. 2016 Aug;20(4):343-7. doi: 10.1016/j.jaapos.2016.05.015. Epub 2016 Jul 14.
Progressive strabismus initially considered idiopathic may be caused by isolated schwannomas of motor nerves to extraocular muscles, detectable only on careful imaging. This study reviewed clinical experience of a referral practice in identifying schwannomas on magnetic resonance imaging (MRI).
We reviewed 647 cases imaged for strabismus to identify presumed cranial nerve schwannomas, identified by gadodiamide-enhanced, high-resolution surface coil orbital MRI and thin-section cranial MRI. Clinical features and management were correlated with MRI.
Schwannomas were identified as fusiform intraneural enlargements in 8 cases: 1 affecting the trochlear nerve; 2, the abducens nerve; and 5 the oculomotor nerve. Involved muscles were atrophic. Both abducens schwannomas, 1 superior oblique, and 1 oculomotor schwannoma were subarachnoid; 3 were intraorbital, and bilateral oculomotor lesions of 1 case extended from cavernous sinus to orbit. Associated strabismus progressed for 3-17 years. Abducens schwannoma caused esotropia; trochlear schwannoma caused hypertropia and cyclotropia. Intracranial oculomotor schwannoma caused mydriasis and exotropia. Intraorbital schwannoma caused exotropia with or without hypertropia. Since lesion diameters were 3-9 mm, 6 had been previously missed on routine MRI.
Progressive, acquired strabismus may be caused by isolated cranial nerve schwannomas, representing about 1% of strabismus cases in this study, involving the oculomotor more than abducens nerve. Because most schwannomas are small and deep in the orbit, findings could be readily missed by routine imaging, leading to a possible diagnosis of idiopathic strabismus. Schwannomas should be suspected when extraocular muscles are atrophic, but the causative lesions themselves are identifiable only using targeted, high resolution MRI.
最初被认为是特发性的进行性斜视可能由支配眼外肌的运动神经孤立性神经鞘瘤引起，只有通过仔细的影像学检查才能发现。本研究回顾了一家转诊机构在磁共振成像（MRI）上识别神经鞘瘤的临床经验。
我们回顾了647例因斜视进行成像的病例，以识别假定的颅神经鞘瘤，这些病例通过钆双胺增强、高分辨率表面线圈眼眶MRI和薄层颅脑MRI进行识别。将临床特征和治疗方法与MRI结果进行关联分析。
在8例病例中，神经鞘瘤表现为梭形神经内增粗：1例累及滑车神经；2例累及展神经；5例累及动眼神经。受累肌肉萎缩。2例展神经鞘瘤、1例上斜肌鞘瘤和1例动眼神经鞘瘤位于蛛网膜下腔；3例位于眶内，1例双侧动眼神经病变从海绵窦延伸至眼眶。相关斜视进展3至17年。展神经鞘瘤导致内斜视；滑车神经鞘瘤导致上斜视和旋转斜视。颅内动眼神经鞘瘤导致瞳孔散大和外斜视。眶内神经鞘瘤导致外斜视，可伴有或不伴有上斜视。由于病变直径为3至9毫米，6例在常规MRI检查中此前被漏诊。
进行性后天性斜视可能由孤立的颅神经鞘瘤引起，在本研究中约占斜视病例的1%，累及动眼神经多于展神经。由于大多数神经鞘瘤较小且位于眼眶深部，常规影像学检查很容易漏诊，可能导致特发性斜视的诊断。当眼外肌萎缩时应怀疑神经鞘瘤，但只有使用针对性的高分辨率MRI才能识别致病病变本身。
