Progressive superficial siderosis from Chronic CSF leak as a long-term complication of cervical anterior corpectomy: A case report and review of the literature.

Background: Superficial siderosis of the central nervous system (SSCNS) is a rare progressive neurological disorder resulting from chronic subarachnoid hemorrhage and subsequent subpial hemosiderin deposition. A prolonged cerebrospinal fluid (CSF) leak is a known cause of SSCNS. We present a novel case where progressive SSCNS resulted from a chronic CSF leak related to an anterior cervical corpectomy. Case Description: A 73-year-old man presented with gait ataxia and progressive hearing loss. Thirteen years before, he had undergone a combined anterior-posterior cervical decompression for symptomatic ossification of the posterior longitudinal ligament (OPLL). The presenting MR imaging showed extensive superficial siderosis and focal spinal cord herniation at the site of a ventral dural defect at the corpectomy site. A CT myelogram showed extensive CSF leakage into the corpectomy surgical site and a communicating pseudomeningocele in the anterior neck. Conclusion: This is the first reported case of progressive SSCNS as a long-term complication of an anterior cervical corpectomy for OPLL. Clinicians should be aware of SSCNS secondary to a chronic CSF leak in patients with a prior corpectomy.

Multiple stages of evolutionary change in anthrax toxin receptor expression in humans.

The advent of animal husbandry and hunting increased human exposure to zoonotic pathogens. To understand how a zoonotic disease may have influenced human evolution, we study changes in human expression of anthrax toxin receptor 2 (ANTXR2), which encodes a cell surface protein necessary for Bacillus anthracis virulence toxins to cause anthrax disease. In immune cells, ANTXR2 is 8-fold down-regulated in all available human samples compared to non-human primates, indicating regulatory changes early in the evolution of modern humans. We also observe multiple genetic signatures consistent with recent positive selection driving a European-specific decrease in ANTXR2 expression in multiple tissues affected by anthrax toxins. Our observations fit a model in which humans adapted to anthrax disease following early ecological changes associated with hunting and scavenging, as well as a second period of adaptation after the rise of modern agriculture.