Primary CNS Hypersomnia

Primary CNS hypersomnia, currently known as idiopathic hypersomnia, is a rare condition characterized by excessive daytime sleepiness. The term "idiopathic" indicates that the cause of the condition is unknown. It is considered a central nervous system disorder in which the sufferer has prolonged episodes of non-REM (rapid eye movement) sleep.

Symptoms

• The primary symptom of idiopathic hypersomnia is excessive sleepiness that is severe enough to interfere with daily life. Sufferers generally sleep long hours at night, sometimes up to 18 hours, but awake unrefreshed and may be irritable or abusive. Napping is common but is also not effective in reducing sleepiness. In extreme cases, patients exhibit confusion, disorientation, poor motor coordination and"sleep drunkenness, a state between sleep and waking.

Onset

• Idiopathic hypersomnia is usually first experienced in adolescence or young adulthood. A small proportion of patients have a family history of the condition and others have had a viral illness such as mononucleosis, hepatitis or viral pneumonia immediately prior to the onset of idiopathic hypersomnia. For most patients, though, there is no family history or viral infection linked to the diagnosis of idiopathic hypersomnia.

Diagnosis

• Because other conditions have symptoms similar to those of idiopathic hypersomnia, diagnosis is by exclusion, meaning that other diseases are ruled out to come to a diagnosis of idiopathic hypersomnia. Doctors need to understand the patient's sleeping patterns and very often an overnight stay at a sleep clinic will be required to confirm the diagnosis. The condition that is most often confused with idiopathic hypersomnia is narcolepsy, but the key differences are that patients with idiopathic hypersomnia do not have cataplexy (sudden loss of muscle tone) or nocturnal sleep disruption.

Prevalence

• It is difficult to estimate the incidence of idiopathic hypersomnia. There are no biological markers and diagnosis is complicated because the same symptoms are also associated other sleep disorders, such as narcolepsy and sleep apnea.

Treatment

• Treatment of idiopathic hypersomnia starts with addressing behaviors and lifestyle issues that may be affecting sleep. Patients are instructed to maintain a regular sleep schedule, avoid too little time in bed at night, and avoid alcohol and medications that may affect sleep. Since these measures are generally not sufficient to address the problem, most sufferers are also prescribed medication to deal with their sleepiness. The most commonly used drug is modafinil (Provigil), a non-addictive stimulant. Ritalin and other drugs that stimulate the central nervous system are also used.

Prognosis

• Idiopathic hypersomnia is a chronic, lifelong condition from which patients do not typically recover. Improvement is also uncommon, and the disease tends to stay in the same form and at the same level of severity over time.