Cranial Settling Causing Intracranial Hemorrhage Through Violation of the Skull Base by Cervical Spine Instrumentation.

Rheumatoid arthritis (RA) is a chronic inflammatory polyarthropathy that affects many synovial joints favoring the hands, knees, and vertebral articulations. Joint laxity manifests as subaxial instability, atlantoaxial instability, and cranial settling (CS). A 70-year-old woman with past medical history of RA, Hashimoto's thyroiditis, osteoporosis, history of C1-2 fusion for instability 15 years prior, with subsequent revision cervicothoracic fusion for degeneration, and trauma 2 years prior presents with new onset headache, nausea, and vomiting of 36-hour duration. Neurologic examination was only notable for mild right dysmetria. Workup revealed acute hemorrhage in the posterior fossa with migration of the right rod implant and screw tulip, as a result of CS. The patient underwent occipital-cervical fusion with removal of the migratory hardware. Intracranial rod migration and hemorrhage secondary to CS is a rare complication that must be brought to the attention of surgeons operating on patients with RA. [ABSTRACT FROM AUTHOR]