2010 BC Guide in Determining Fitness to Drive

An immediate reduction in daytime sleepiness is often reported with CPAP treatment, althoughstudies indicate that approximately 6 weeks of treatment are required for maximum improvementin symptoms. Estimates of compliance with CPAP treatment vary depending on how they aremeasured. Subjective rates of compliance based on self-report are higher than objectivelydetermined rates. Using objective measures, a 1993 study found that 46% of individuals wereacceptably compliant with their CPAP treatment. The study defined acceptable compliance asthe use of the CPAP machine for at least four hours per night for more than 70% of the observednights.NarcolepsyNarcolepsy is a chronic neurological disorder in which the brain is unable to regulate sleep-wakecycles normally. It is characterized by excessive daytime sleepiness and may also causecataplexy (abrupt loss of muscle tone), hallucinations and sleep paralysis. There is no knowncure. The symptoms of narcolepsy relevant to driving are sleepiness and cataplexy.The excessive daytime sleepiness of narcolepsy comprises both a background feeling ofsleepiness present much of the time and a strong, sometimes irresistible, urge to sleep recurringat intervals through the day. This desire is heightened by conducive or monotonouscircumstances, but naps at inappropriate times, such as during meals, are characteristic. Thenaps associated with narcolepsy usually last from minutes to an hour and occur a few times eachday. Potential secondary symptoms related to sleepiness may include visual blurring, diplopiaand cognitive impairment. Cognitive impairment may include difficulties with attention andmemory.Cataplexy refers to an abrupt loss of skeletal muscle tone. It is estimated that 60 to 90% ofindividuals with narcolepsy experience cataplexy. During a cataplexy attack, which can last upto several minutes and occur several times a day, an individual remains conscious but is unableto move. Generalized attacks can cause an individual to completely collapse, although themuscles of the diaphragm and the eyes remain unaffected. Partial attacks, which affect onlycertain muscle groups, are more common than generalized attacks. Laughter or humorous eventsare a common trigger of cataplexy attacks, although anger, embarrassment, surprise or sexualarousal can also trigger an attack.As there is no cure, treatment for narcolepsy is focussed on the control of sleepiness andcataplexy where present. Medications used for treatment may include: stimulants such as Modafinil (Altertec) tricyclic anti-depressants selective serotonin reuptake inhibitors venlafaxine (Effexor), or reboxetine (Edronax).See Chapter 29, Over-The-Counter and Prescription Drugs, for more information aboutmedications and driving.343