Remote brainstem lesion associated with lower cervical spinal dural arteriovenous fistula-venous outflow bottleneck: a case report and literature review.

Spinal dural arteriovenous fistula (SDAVF) is an important cause of venous congestive myelopathy, as timely treatment offers the potential for neurological recovery. However, it is sometimes misdiagnosed when presenting with atypical intracranial or brainstem lesions. Although venous congestion in SDAVFs typically develops adjacent to the shunting site, altered venous outflow dynamics occasionally result in remote parenchymal involvement. We present a case of lower cervical SDAVF manifesting as a remote medullary lesion mimicking area postrema syndrome. Subsequent spinal imaging and digital subtraction angiography revealed a right C6 SDAVF with cranially directed venous drainage. Fusion imaging of three-dimensional rotational angiography and anatomical MRI delineated the venous outflow bottleneck with abrupt focal narrowing at the cerebellomedullary fissure, which likely served as a morphological bottleneck contributing to preferential medullary congestion. The fistula was successfully treated via endovascular embolization, achieving complete angiographic obliteration and clinical recovery. A literature review was also conducted to characterize the clinical features and identify the common diagnostic pitfalls associated with these rare manifestations; however, the precise anatomical mechanisms for remote lesions remain elusive. This case highlights a potential anatomical mechanism wherein focal narrowing in the venous drainage pathway may predispose to atypical lesion localization. Furthermore, therapeutic considerations are discussed, emphasizing a stepwise treatment strategy in which endovascular obliteration is prioritized when the anatomy is favorable and surgical disconnection is reserved for refractory cases.