The palmomental reflex predicts earlier corticobulbar involvement in ALS

Objective: The palmomental reflex (PMR) is a primitive reflex, which may appear when cortical inhibitory pathways are disrupted by disease. In this study, we examined whether the PMR is associated with corticobulbar involvement in people with ALS (PALS). Methods: PMR was routinely tested for each patient attending the ALS clinic. Three hundred and eighteen consecutive PALS were included, of whom 271 were PMR positive (PMR+). Clinical evaluation defined the presence of upper motor neuron (UMN) and lower motor neuron (LMN) signs in the bulbar, cervical and lumbosacral segments. Results: The PMR + group had a higher rate of both UMN and LMN bulbar involvement (BI) as well as more UMN upper-limb involvement and UMN involvement of any type, the strongest association being between PMR + and UMN BI. In patients without BI at presentation, UMN BI developed roughly 15 months early in the PMR + group compared to the PMR– group. Conclusion: We found that the PMR is strongly associated with UMN signs within the bulbar region and to a lesser extent with upper-limb UMN involvement. We propose the PMR be considered a harbinger of corticobulbar involvement in PALS.