Altered sensory-motor plasticity in amyotrophic lateral sclerosis and complex regional pain type I syndrome: a shared mechanism?

Besides the prominent motor syndrome, some patients affected by amyotrophic lateral sclerosis (ALS) complain of many non-motor symptoms during the disease course, in particular chronic pain that significantly reduces the patients' quality of life. Complex regional pain syndrome (CRPS) is a rare painful condition, rarely described in ALS patients. We present the clinical case of a patient affected by spinal-onset ALS, who developed a type I CRPS (CRPS-I) at the upper limbs. To the best of our knowledge, only five cases of ALS-CRPS-I have been reported and they share some peculiar features: ALS spinal-onset with classic phenotype, rapid deterioration of quality of life, and a poor prognosis. Different mechanisms have been supposed in the pathogenesis of both CRPS and ALS, resulting in distinctive clinical presentations. Altered plasticity of brain sensory and motor areas might represent a common feature that seems to influence negatively ALS progression and prognosis.