Unilateral vs. Bilateral Lower Extremity Motor Deficit Following Complex Adult Spinal Deformity Surgery: Is there a Difference in Recovery Up to 2 Year F/U?

BACKGROUND CONTEXT: Scoli-RISK-1 is a multicenter prospective cohort designed to study neurologic outcomes following complex adult spinal deformity (ASD). The effect of unilateral versus bilateral postoperative motor deficits on the likelihood of long term recovery has not been previously studied in this population.

PURPOSE: Evaluate if bilateral postoperative neurologic deficits have a worse recovery than unilateral deficits.

STUDY DESIGN: Secondary analysis of a prospective, multicenter, international cohort study.

METHODS: In a cohort of 272 patients neurologic decline was defined as deterioration of the American Spinal Injury Association Lower Extremity Motor Scores (LEMS) following surgery. Patients with lower extremity neurologic decline were grouped into unilateral and bilateral cohorts. Differences in demographics, surgical variables, and patient outcome measures between the two cohorts were analyzed.

RESULTS: 265 patients had LEMS completed at discharge. Unilateral decline was seen in 32 patients (12%), while 29 (11%) had bilateral symptoms. At 2 years, there was no significant difference in either median LEMS (unilateral 50.0, interquartile range [IQR]: 47.5 to 50.0; bilateral 50.0, IQR: 48.0 to 50.0, p=0.939) or change in LEMS from baseline (unilateral 0.0, IQR: -1.0 to 0.0; bilateral 0.0, IQR: -1.0 to 0.0, p=0.920). In both groups, approximately two-thirds of patients saw recovery to at least their preoperative baseline by two years postoperatively (unilateral n=15, 63%; bilateral n=14, 67%). The mean Scoliosis Research Society-22R (SRS-22R) score at 2 years was 3.7 0.6 versus 3.2 0.6 (p=0.009) for unilateral and bilateral, respectively.

CONCLUSION: The prognosis for neurologic recovery of new motor deficits following complex adult spinal deformity is similar with both unilateral and bilateral weakness. Despite similar rates of neurologic recovery, patient reported outcomes for those with bilateral motor decline measured by SRS-22R are worse at 2 years after surgery.