Defining and diagnosing involuntary emotional expression disorder.

Uncontrollable episodes of emotional expression occur in a variety of neurological conditions. This emotional disinhibition syndrome is characterized by episodes of crying or laughing that are unrelated to or out of proportion to the eliciting stimulus. This syndrome is common among patients with amyotrophic lateral sclerosis, multiple sclerosis, stroke, and traumatic brain injury and a variety of terms and definitions have been used to describe it. The confusing nomenclature has been a barrier to understanding, diagnosis, and treatment of this disorder. The authors propose a unifying term, involuntary emotional expression disorder (IEED), and provide diagnostic criteria for this disorder.