Lumbar Spine fMRI to Quantify Efficacy of Spinal Cord Stimulation Therapy in Spinal Muscular Atrophy

COEX 

Spinal Muscular Atrophy (SMA) is a genetic disease that causes progressive dysfunction and death of spinal motor neurons, leading to motor deficits ranging from lower limb weakness (type 4) to severe muscle weakness with respiratory failure (type 1). Recent experiments in mice indicate that SMA motor deficits are due to motor neuron death and decreased firing rates in surviving motor neurons due to a maladaptive response to a loss in the excitatory Ia sensory synapses [1]. Epidural spinal cord stimulation (SCS) can selectively activate Ia sensory fibers; thus we hypothesize that targeted stimulation of Ia afferents via epidural SCS would increase inputs to the motor neurons, resulting in increased firing ability and improved leg functions through long-term stimulation effects (Figure 1A) [2-4]. To test the efficacy of our SCS therapy we quantified long term changes in motor neuron functions by performing functional magnetic resonance imaging (fMRI) of the lumbar spinal cord during active and passive mobilization of the knee joint pre- and post- SCS therapy (Figure 1B). Spinal cord fMRI is a rapidly growing field, but the lumbar spine has largely been ignored. Therefore, we leverage recently developed cervical spinal cord fMRI techniques to create a robust lumbar spine acquisition and processing paradigm, which can be applied to any clinical population [5-7].