Pathophysiology of Dyt1 dystonia is mediated by spinal cord dysfunction

Dystonia, a neurological disorder defined by abnormal postures and disorganised movements, is considered to be a neural circuit disorder with dysfunction arising within and between multiple brain regions. Given that spinal circuits constitute the final pathway for motor control, we sought to determine their contribution to the movement disorder. Focusing on the most common inherited dystonia, DYT1-TOR1A, we confined a conditional knockout of Tor1a to the spinal cord and dorsal root ganglia (DRG) and found that these mice recapitulated the phenotype of the human condition, developing early onset generalised torsional dystonia. Physiologically, these mice bore the hallmark features of dystonia: spontaneous contractions at rest, excessive sustained contractions during voluntary movements including co-contractions of motor antagonists, and altered sensory-motor reflexes. Furthermore, spinal locomotor circuits were impaired. Together, these data challenge current understanding of dystonia, and lead to broader insights into spinal cord function and movement disorder pathophysiology.