P5. Diagnosis and management of hypersomnia in bilateral thalamic lesions

Abstract

Introduction The rare bilateral thalamic lesions (BTL) are usually accompanied by hypersomnia and apathy. The temporal course and prognosis of hypersomnia in BTL is still unclear. No specific treatment is available for this condition. Methods Case-report of a 44-year-old Caucasian male with MRI-confirmed bilateral paramedian thalamic lesions due to streptococcus pneumoniae meningo-encephalitis and sleep–wake behavior documented with repeated actigraphy over a period of 1.5 years. Results During the acute phase (1st month) the actigraphic pattern showed an irregular sleep/wake cycle with prolonged phases of assumed inactivity during the daytime ( Fig. 1 A). In the (sub-) chronic phase (3rd month) a regular hypersomnic pattern ( Fig. 1 B) with average assumed 24-h sleep time of 14 h, with 5.6 of them occurring during the daytime. Administration of 100 mg and 50 mg of modafinil (single morning dose) led to a prominent circadian rhythm disruption ( Fig. 1 C and E). Although the average 24-h-sleep time decreased to 9.5–10.4 h, mean daytime sleep length exceeded the nocturnal one. Withdrawal of modafinil resulted in a complete re-establishment of the previous hypersomnic pattern ( Fig. 1 D). A further attempt with an even lower dose of modafinil (25 mg/day) reduced the average 24-h sleep time to 10.9 h, daytime sleep to 3.5 h and nocturnal sleep to 7.4 h, without disrupting the circadian sleep/wake pattern ( Fig. 1 F). Clinical follow up after 2 months confirmed good efficacy of this low dose of modafinil. Conclusions To our knowledge, this is the first long-term actigraphic documentation of sleep–wake behavior and response to modafinil in BTL. Treatment with modafinil was associated with the emergence of dose-dependend circadian disruption, recommending the use of very low dosages in treating hypersomnia in BTL.