Editing Hypersomnia (section)

==== Primary hypersomnia mimics ====

There are also several genetic disorders that may be associated with primary/central hypersomnia. These include the following: [[Prader-Willi syndrome]]; [[Norrie disease]]; [[Niemann–Pick disease, type C]]; and [[myotonic dystrophy]].  However, hypersomnia in these syndromes may also be associated with other secondary causes, so it is important to complete a full evaluation. Myotonic dystrophy is often associated with SOREMPs ([[Sleep onset|sleep onset REM periods]], such as occur in narcolepsy).<ref name="Dauvilliers" />

There are many [[neurological disorders]] that may mimic the primary hypersomnias, narcolepsy and idiopathic hypersomnia: [[brain tumors]]; [[Stroke|stroke-provoking lesions]]; [[clinophilia]]; and dysfunction in the [[thalamus]], [[hypothalamus]], or [[brainstem]].  Also, neurodegenerative conditions such as [[Alzheimer's disease]], [[Parkinson's disease]], or [[multiple system atrophy]] are frequently associated with primary hypersomnia. However, in these cases, one must still rule out other secondary causes.<ref name="Dauvilliers" />

Early [[hydrocephalus]] can also cause severe excessive daytime sleepiness.<ref name="ref-3">{{Cite web | title = International classification of sleep disorders, revised: Diagnostic and coding manual | url = http://www.esst.org/adds/ICSD.pdf | publisher = American Academy of Sleep Medicine | year = 2001 | access-date = 25 January 2013 | url-status = dead | archive-url = https://web.archive.org/web/20110726034931/http://www.esst.org/adds/ICSD.pdf | archive-date = 26 July 2011 }}</ref> Additionally, [[head trauma]] can be associated with a primary/central hypersomnia, and symptoms similar to those of idiopathic hypersomnia can be seen within 6–18 months following the trauma. However, the associated symptoms of headaches, memory loss, and lack of concentration may be more frequent in head trauma than in idiopathic hypersomnia. "The possibility of secondary narcolepsy following head injury in previously asymptomatic individuals has also been reported."<ref name="Dauvilliers" />