ABSTRACT
The authors reported a case and its diagnostic process of post-traumatic narcolepsy which had developed after a head trauma. The 51-years-old patient showed frequent generalized paralytic attack, which was aggravated during stressful situation, diet time, and in front of hospital staffs. During the paralytic attack, consciousness was alert, and he never collapsed to hurt. All laboratory findings including serum potassium level were within normal limit, and also brain imaging studies and electroencephalography revealed no specific abnormal findings. Our clinical impression was a conversion disorder or a malingering at first, but after the detailed history taking and the careful observation, daytime sleep attack and some sleep problems were revealed. Thus nocturnal polysomnography and multiple sleep latency test(MSLT) were performed, and then the authors could diagnose as "narcolepsy". HLA-DR2 typing was negative. After imipramine trial, the frequency and the intensity of attack was dramatically reduced. The authors concluded that narcolepsy should be considered in the differential diagnosis of sleepiness or transient loss of muscle tone after traumatic brain injury.