The symptoms of IEED may appear similar to symptoms of other conditions. As a result, IEED is often misdiagnosed as depression, bipolar disorder, generalized anxiety disorder, personality disorder, and, occasionally, epilepsy.^{Arciniegas DB, Lauterbach EC, Anderson KE, et al} 

Two standard rating scales are available to evaluate patients with IEED.
The Center for Neurologic Study-Lability Scale (CNS-LS), a short (seven item), self-administered scale used to screen patients for symptoms of lability, has been shown to be effective in evaluating patients with MS and ALS.^{Smith RA, Berg JE, Pope LE, Callahan JD, Wynn D, Thisted RA; Moore SR, Gresham LS, Bromberg MB, et al}  The CNS-LS provides a quantitative measure of severity of IEED episodes, incorporating subscales measuring labile laughter and labile tearfulness. It shows high consistency and reliability, and successfully predicts neurologists' diagnoses of IEED. A CNS-LS (PDF) score of 13 or higher is suggestive of IEED.

The Pathological Laughter and Crying Scale (PLACS), a qualitative scale that measures the severity of IEED, has shown high reliability and has been used to effectively rate IEED in patients with various neurologic conditions. ^{Robinson RG, Parikh RM, Lipsey JR, Starkstein SE, Price TR; Tateno A, Jorge RE, Robinson RG} The Pathological Laughing and Crying Scale (PLACS) is an interviewer-rated scale comprising eighteen questions. It quantifies aspects of laughter and crying, including the relation of the episodes to external events, duration, degree of voluntary control, inappropriateness in relation to emotions, and the degree of resulting distress. This scale can also be used to diagnose IEED. A PLACS (PDF) score of 13 or higher is suggestive of IEED.