Kakizaki Hirohiko, Zako Masahiro, Iwaki Masayoshi, Mito Hidenori, Katori Nobutada
Department of Oculoplastic and Orbital Surgery, Seirei Hamamatsu General Hospital, Hamamatsu, Japan.
Jpn J Ophthalmol. 2005 May-Jun;49(3):246-52. doi: 10.1007/s10384-004-0184-6.
Incarceration of the inferior oblique muscle (IO) branch of the oculomotor nerve may occur in cases of orbital floor trapdoor fracture.
Two orbital floor trapdoor fracture cases, with lesions located just outside of the inferior rectus muscle but without its incarceration, were examined pre- and postoperatively for visual acuity, intraocular details, the nine diagnostic ocular positions of gaze, binocular single vision field with the Hess chart, and by computed tomography (CT). One case was also examined by magnetic resonance imaging (MRI; T1-weighted images). A forced duction test was conducted intraoperatively.
Each case presented good visual acuity and neither globe showed any injury. Motility disturbance of the IO was shown in each case by binocular single vision field testing and the Hess chart. The possibility of the incarceration of the IO branch of the oculomotor nerve, which runs from the incarcerated lesion to the superior belly of the IO, in an orbital floor trapdoor fracture was shown on CT and MRI. Intraoperative forced duction testing revealed a restriction due to the incarceration of the connective tissue septa.
As inferred from the CT and MRI analyses conducted in this study, IO palsy may be one of the causes of ocular motility disturbance of the IO in an orbital floor trapdoor fracture, in addition to the ocular motility disturbance due to the connective tissue septa.
动眼神经下斜肌（IO）分支嵌顿可发生于眶底活板门骨折病例中。
两例眶底活板门骨折病例，病变位于下直肌外侧但未发生嵌顿，术前及术后检查了视力、眼内情况、九个诊断性注视眼位、用Hess屏检查双眼单视野，并进行了计算机断层扫描（CT）。其中一例还进行了磁共振成像（MRI；T1加权图像）检查。术中进行了强制牵拉试验。
每例患者视力良好，眼球均未显示任何损伤。通过双眼单视野测试和Hess屏检查，每例均显示IO运动障碍。CT和MRI显示了动眼神经IO分支从嵌顿病变至IO上半肌腹走行过程中在眶底活板门骨折中发生嵌顿的可能性。术中强制牵拉试验显示因结缔组织间隔嵌顿导致受限。
根据本研究进行的CT和MRI分析推断，除结缔组织间隔导致的眼球运动障碍外，IO麻痹可能是眶底活板门骨折中IO眼球运动障碍的原因之一。
