In this study we report three patients with facial-onset sensory and motor neuronopathy (FOSMN), including the first female to be described. A fourth rather atypical case of a pyramidal syndrome with a fast rate of progression is also described. These cases raise the question as to whether upper motor neuron impairment is involved in FOSMN and whether there is a link between this syndrome and amyotrophic lateral sclerosis. The existence of this syndrome suggests that it may be wise to monitor all patients with isolated idiopathic trigeminal sensory neuropathy to ensure that this type of motor neuron disease is not overlooked.