Objective:

Detailed analysis of the sensory improvements observed in individuals with chronic, cervical spinal cord injury (SCI) following transcutaneous spinal cord stimulation (tSCS) combined with rehabilitation.

Background:

Following SCI, recovery of sensation is often unaddressed despite its critical role in motor task execution and injury prevention. The Up-LIFT trial demonstrated tSCS combined with rehabilitation significantly improved sensation in addition to upper extremity (UE) strength and function. Post-hoc analyses of sensory changes further explore the distributions of these sensory improvements and their functional significance.

Design/Methods:

Sixty participants with chronic, incomplete cervical SCI completed a two-month rehabilitation run-in phase followed by two months of cervical tSCS plus rehabilitation. At baseline and following each month of therapy, sensation was assessed within the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) exam. We detail changes in sensation and stepwise linear regression models assessing the importance of UE sensation in determining functional abilities.

Results:

ISNCSCI UE (C2-T1), trunk (T2-T12), and lower extremity (L1-S4/5) sensory scores significantly improved following tSCS plus rehabilitation (p<0.01) but not following rehabilitation alone (p>0.05). ISNCSCI-UE light touch and pin prick scores significantly improved (p≤0.01), indicating modulation of circuits related to both the lateral spinothalamic and dorsal column medial lemniscus tracts. Notably, 55% of participants with chronic SCI surpassed the ISNCSCI total sensory score minimal clinically important difference established in the acute SCI population. Post-therapy UE sensory scores correlated moderately with functional assessments (Capabilities of Upper Extremity Test (CUE-T) ρ=0.57; GRASSP Prehension Performance ρ=0.51). Stepwise regression models revealed that the addition of ISNCSCI UE sensation with UE motor scores better predicted scores on both functional assessments compared to motor scores alone.

Conclusions:

People with chronic SCI achieved widespread and clinically meaningful improvements in sensation across multiple dermatomes following combined tSCS and rehabilitation. These sensory improvements, together with improved strength, are important contributors to improved function.