Patrikios syndrome in two patients with treatable flail-leg weakness

Flail-leg syndrome or lower limb diplegia is a form of motor neuron disease characterized by a slower progression rate. The differential diagnosis with motor neuropathy is important. We present two patients with a previous diagnosis of amyotrophic lateral sclerosis (ALS)-flail-leg syndrome, in whom neurophysiological studies suggested proximal conduction block. Both patients responded to immunomodulatory therapy, which suggested an immunologically mediated, treatable flail-leg syndrome phenotype. We stress the importance of fasciculations in the diagnosis of ALS, and the study of nerve root conduction in the differential diagnosis.