1219 Diagnosing Narcolepsy by MSLT Without Taking in the Full Picture

Abstract Introduction Narcolepsy is typically diagnosed by symptoms and an abnormal multiple sleep latency test (MSLT). However, many factors can affect the results of the MSLT, leading to an overdiagnosis of narcolepsy. Report of case(s) A 37-year-old female was referred with prior diagnoses of narcolepsy, depression, post-traumatic stress disorder, polysubstance abuse, obstructive sleep apnea (OSA), and hypertension. The patient obtained the diagnosis of narcolepsy by polysomnography/MSLT through another facility and was prescribed amphetamine/dextroamphetamine. The overnight polysomnogram demonstrated: total sleep time 285 minutes, rapid-eye movement (REM) latency 223 minutes, overall apnea-hypopnea index (AHI) 6/h, and REM AHI 45/h. The next day MSLT demonstrated a mean sleep latency of 7 minutes and 2 sleep-onset REM periods on the second and fourth naps. A urine drug screen (UDS) was not obtained. She reported 4-6 hours of sleep/day at the time of her MSLT. She denied cataplexy, sleep paralysis, or sleep-related hallucinations. Conclusion This case is one of many seen at our tertiary referral center of patients presenting with a diagnosis of narcolepsy by MSLT, but the MSLT was performed in invalid conditions. Many medications, substances, insufficient sleep, inappropriate timing of testing, untreated OSA, and other medical conditions all have the potential to lead to an abnormal MSLT that would appear consistent with narcolepsy, but often these factors are not considered. Insufficient sleep at home or on the preceding polysomnogram can lead to an abnormal MSLT. Though our patient had a history of polysubstance abuse, a UDS was not obtained. The American Academy of Sleep Medicine enjoins a polysomnogram for a duration of a 7-hour minimum (with 6 hours of sleep) prior to conducting an MSLT. Our patient only slept for 4.75 hours in the overnight polysomnogram. Her polysomnogram also showed OSA. A combination of these factors likely contributed to the patient’s daytime sleepiness. Her insufficient sleep, OSA, and use of sedating medications/substances should have been addressed first before performing an MSLT. We strongly encourage providers to ensure the MSLT is done in valid conditions to prevent the misdiagnosis of narcolepsy and initiation of unnecessary treatment. Support (if any)