Bhinder Khurram Khaliq, Shah Mariam, Wahla Madiha Saeed, Khan Nasir, Mehboob Amna, Saghir Sabiyal, Ziad Alishbah
Radiology Department, Shifa International Hospital, Islamabad, Pakistan.
Radiol Case Rep. 2025 May 16;20(8):3832-3835. doi: 10.1016/j.radcr.2025.04.086. eCollection 2025 Aug.
Atlanto-occipital assimilation is extremely rare congenital anomaly, characterized by partial or complete fusion of atlas and occipital bone leading to altered cranio-cervical junction anatomy. In our patient, basilar invagination resulted in acute angulation and narrowing of foramen magnum. Crowding of structures at foramen magnum was seen with tonsillar herniation and compression of brain stem. Edema signal in proximal cervical cord was also seen. Bilateral atlanto-occipital assimilation with increased atlas to dens distance seen suggestive of atlanto-axial instability. Overall findings were suggestive of Chiari I malformation with atlanto-occipital assimilation.
寰枕融合是一种极其罕见的先天性异常，其特征为寰椎与枕骨部分或完全融合，导致颅颈交界区解剖结构改变。在我们的患者中，基底凹陷导致枕大孔急性成角和狭窄。可见枕大孔处结构拥挤，伴有扁桃体疝和脑干受压。颈髓近端也可见水肿信号。双侧寰枕融合，寰椎至齿突距离增加，提示寰枢椎不稳。总体检查结果提示为合并寰枕融合的Chiari I型畸形。
