To further characterize factors contributing to imbalance and impaired gait in patients with adrenomyeloneuropathy (AMN).

AMN is the most common phenotype of X-linked adrenoleukodystrophy (ALD). AMN primarily affects the corticospinal tract and dorsal columns of the spinal cord. Most patients present with prominent spasticity, ataxia and muscle weakness leading to gait and balance difficulties which can have a profound effect upon quality of life.

We enrolled 33 subjects and 6 controls (14 male, 19 female, mean age of 36) with genetically confirmed AMN. We analyzed balance using the NeuroCom SMART Equitest posturography platform to develop robust clinometric outcomes for capturing disease severity. Balance testing included sensory organization testing (SOT), which measures the amount of sway on a scale from 0 to 100 with 100 being perfect stability, and motor control testing (MCT), which measures latency of autonomic responses. We also obtained data with the 25 Foot Walk test (25FW), Timed Up and Go (TUG), and Six Minute Walk test (6MWT).

Preliminary data showed significant difference in patients versus controls in the SOT and TUG tests. The SOT score was significantly lower in patients with AMN (mean 67.1 sd 11.0) compared to controls (mean 84.2 sd 3.8) (p<0.01). The mean TUG time in seconds for patients was 8.6 sd 3.4 versus 5.6 sd 0.3 for controls (p<0.01). Additionally, although not statistically significant, there were differences in the mean of patients and controls for MCT, 25FW, and 6MWT. 

Balance difficulties are common in patients with AMN. We further characterized imbalance and factors contributing to gait impairment such as sensory ataxia and spasticity, as potential treatment and intervention targets. Results of this study will help us better understand underlying imbalance and help develop more sensitive clinically meaningful measures for future clinical trials.