Division of Neuroradiology, Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University, Kocamustafapasa-Istanbul, Turkey.
Neurosurgery. 2013 May;72(5):E863-7; discussion E867. doi: 10.1227/NEU.0b013e318285ba68.
Anatomic variations of the superior sagittal sinus (SSS) and falx cerebri (FC) are uncommon in that agenesis of these structures is extremely rare. We report an extremely rare anatomic variation, total agenesis of the SSS and FC, and briefly discuss it from the anatomical, embryological, radiological, and clinical perspectives.
A 49-year-old woman presented with long-standing headache, gait disturbance, and nausea. Imaging studies showed a bilateral subdural hematoma crossing the midline, dilated venous structures, and perineural cysts, but SSS and FC. Following right-sided hemiparesis and consciousness disturbances, the subdural hematoma was evacuated from a left-sided parietal burr hole because of thick hematoma in this side. After the surgical evacuation, the hemiparesis and consciousness disturbances were regressed; however, she still had severe headache. On account of ongoing headaches and related imaging findings, it was thought that she had possible spontaneous intracranial hypotension. She was treated with autologous epidural blood patch and recovered well.
Agenesis of the SSS and FC are extremely rare variations. Agenesis of the SSS results in development of alternative venous pathways and may lead to misdiagnosis as dural arteriovenous fistulas. Agenesis of FC may cause diagnostic confusion, because subdural pathologies such as hematomas can cross the midline in rare occasions.
上矢状窦（SSS）和大脑镰（FC）的解剖变异并不常见，因为这些结构的发育不全极为罕见。我们报告了一种极其罕见的解剖变异，即 SSS 和 FC 的完全发育不全，并从解剖学、胚胎学、影像学和临床角度简要讨论了这种变异。
一名 49 岁女性因长期头痛、步态不稳和恶心就诊。影像学研究显示双侧额顶叶中线处硬膜下血肿，扩张的静脉结构和神经周围囊肿，但未发现 SSS 和 FC。在出现右侧偏瘫和意识障碍后，由于对侧血肿较厚，从左侧顶骨钻孔进行硬膜下血肿清除术。手术清除血肿后，偏瘫和意识障碍得到缓解；然而，她仍有严重头痛。鉴于持续的头痛和相关影像学表现，考虑到可能存在自发性颅内低血压。她接受了自体硬膜外血贴治疗，恢复良好。
SSS 和 FC 的发育不全是非常罕见的变异。SSS 的发育不全导致了替代静脉通路的发育，可能导致误诊为硬脑膜动静脉瘘。FC 的发育不全可能导致诊断混淆，因为在罕见情况下，血肿等硬膜下病变可能会穿过中线。
