Neurocognitive outcomes following adult spinal deformity surgery: a prospective study with 12-month follow-up

A common concern is that the stress induced by adult spinal deformity (ASD) surgery may cause a postoperative decrease in cognitive function, especially in the elderly patients with some component of cognitive impairment. On the other hand, it is possible that ASD surgery could stabilize cognitive function by increasing activity and decreasing pain.

Here, we evaluate the effect of ASD surgery on cognitive outcome in a prospective study.

This is a prospective study of patients undergoing ASD surgery at a single institution over a 5-year period.

ASD patients treated with posterior spinal fusion of greater or equal to 7 vertebral segments for adult deformity were included. Only patients with 12 month follow up are included in this study.

The primary outcome variable was performance on the Montreal Cognitive Assessment (MoCA) test of dementia and cognitive impairment, collected prospectively preoperatively and at 12-month follow-up. We also collected outcome metrics including the Oswestry Disability Index (ODI), Scoliosis Research Society questionnaire (SRS-22) with mental health (MH), activity (ACT), pain (P), and self-image (SI) subcomponents. Preoperative and postoperative morphine equivalent dose (MED) of narcotic medication was collected using patient surveys and verified using prescription data.

The primary outcome was assessed using a paired t-test. Further analyses included performing univariate and multivariable analyses comparing patients with improved versus nonimproved MoCA scores across demographic, radiographic, surgical, outcome data, and opioid usage.

We enrolled 55 patients who met inclusion criteria. There was a significant increase in MoCA scores at 12-month follow-up compared to preoperative MoCA scores (p<.001). Overall, 60% of patients exhibited an increase in MoCA scores, and 47.2% met minimally clinically important difference (MCID). More severely cognitively impaired patients tended to improve to a greater degree than less severely impaired patients (p=.003). While there was no clear association between reduction in postoperative opioid use and cognitive improvement, we observed a possible association between postoperative delirium and cognitive decline among patients with baseline cognitive impairment (p=.01).

Our prospective data suggests that ASD surgery is associated with an improvement in cognitive function at one-year follow-up. Further work is required to understand the drivers associated with cognitive improvement and worsening after ASD surgery.