Adult-onset tethered cord syndrome with a retained medullary cord due to adhesive arachnoiditis

Background: Adult-onset tethered cord syndrome (ATCS) is occasionally reported, but older adult onset is very rare. We treated a patient who was asymptomatic until older adulthood and then developed subacute exacerbation of neurological symptoms. Case description: A 76-year-old woman presented with bilateral leg pain, numbness, and weakness plus low back pain and dysuria for 1 month. Imaging showed a retained medullary cord with a syrinx and an enhanced mass lesion. She was diagnosed with symptomatic ATCS and underwent surgery. Intraoperative findings were an intramedullary syrinx and inflammatory granulation due to adhesive arachnoiditis. Conclusion: We experienced a very rare case in which an older adult developed ATCS. Caution is required because idiopathic adhesive arachnoiditis can exacerbate the neurological symptoms.