The effects of a low-carbohydrate, ketogenic diet (LCKD) on sleepiness and other narcolepsy symptoms were studied. Nine patients with narcolepsy were asked to adhere to the Atkins' diet plan, and their symptoms were assessed using the Narcolepsy Symptom Status Questionnaire (NSSQ). The NSSQ-Total score decreased by 18% from 161.9 to 133.5 (p = 0.0019) over 8 weeks. Patients with narcolepsy experienced modest improvements in daytime sleepiness on an LCKD.

BACKGROUND:Narcolepsy is a rare neurological sleep disorder especially in children who are younger than 10 years. In the beginning of 2010, an exceptionally large number of Finnish children suffered from an abrupt onset of excessive daytime sleepiness (EDS) and cataplexy. Therefore, we carried out a systematic analysis of the incidence of narcolepsy in Finland between the years 2002-2010.

METHODS:All Finnish hospitals and sleep clinics were contacted to find out the incidence of narcolepsy in 2010. The national hospital discharge register from 2002 to 2009 was used as a reference.

FINDINGS:Altogether 335 cases (all ages) of narcolepsy were diagnosed in Finland during 2002-2009 giving an annual incidence of 0.79 per 100,000 inhabitants (95% confidence interval 0.62-0.96). The average annual incidence among subjects under 17 years of age was 0.31 (0.12-0.51) per 100,000 inhabitants. In 2010, 54 children under age 17 were diagnosed with narcolepsy (5.3/100,000; 17-fold increase). Among adults≥20 years of age the incidence rate in 2010 was 0.87/100,000, which equals that in 2002-2009. Thirty-four of the 54 children were HLA-typed, and they were all positive for narcolepsy risk allele DQB1*0602/DRB1*15. 50/54 children had received Pandemrix vaccination 0 to 242 days (median 42) before onset. All 50 had EDS with abnormal multiple sleep latency test (sleep latency<8 min and≥2 sleep onset REM periods). The symptoms started abruptly. Forty-seven (94%) had cataplexy, which started at the same time or soon after the onset of EDS. Psychiatric symptoms were common. Otherwise the clinical picture was similar to that described in childhood narcolepsy.

INTERPRETATION:A sudden increase in the incidence of abrupt childhood narcolepsy was observed in Finland in 2010. We consider it likely that Pandemrix vaccination contributed, perhaps together with other environmental factors, to this increase in genetically susceptible children.

BACKGROUND:Associations between influenza infection and sleep disorders are poorly studied. We investigated if pandemic influenza infection or vaccination with Pandemrix in 2009/2010 was associated with narcolepsy or hypersomnia in children and young adults.

METHODS:We followed the Norwegian population under age 30 from January 2008 through December 2012 by linking national health registry data. Narcolepsy diagnoses were validated using hospital records. Risks of narcolepsy or hypersomnia were estimated as adjusted hazard ratios (HRs) in Cox regression models with influenza infection and vaccination as time-dependent exposures.

RESULTS:Among the 1,638,526 persons under age 30 in Norway in 2009, 3.6% received a physician diagnosis of influenza during the pandemic, while 41.9% were vaccinated against pandemic influenza. Between October 1st 2009 and December 31st 2012, 72 persons had onset of narcolepsy and 305 were diagnosed with hypersomnia. The risk of a sleep disorder was associated with infection during the first six months, adjusted HR 3.31 with 95% confidence interval [CI], 1.01-10.79 for narcolepsy and adjusted HR 3.13 (95% CI, 1.12-8.76) for hypersomnia. The risk of narcolepsy was strongly associated with vaccination during the first six months adjusted HR 17.21 (95% CI, 6.28-47.14), while the adjusted HR for hypersomnia was 1.54 (95% CI, 0.81-2.93).

CONCLUSIONS:The study confirms an increased HR of narcolepsy following pandemic vaccination. Slightly increased HRs of narcolepsy and hypersomnia are also seen after influenza infection. However, the role of infection should be viewed with caution due to underreporting of influenza.

Narcolepsy type 1 (NT1) is a chronic sleep disorder, characterized by excessive daytime sleepiness, cataplexy and fragmented nocturnal sleep. It is caused by a hypocretin deficiency due to a significant reduction of the neurons producing it. In the last years, it has been postulated that an autoimmune mechanism would be responsible for the destruction of these neurons in those genetically predisposed patients. The increased incidence of narcolepsy after the pandemic H1N1 influenza vaccination campaign in 2009-2010 is known. We present below the case of an adult patient who, 10 days after receiving H1N1 vaccination, suffers a traffic accident after falling asleep. Subsequent studies revealed hyperthyroidism due to Graves disease. In spite of the treatment, the patient persisted with daily and disabling daytime sleepiness, sleep attacks and episodes of generalized muscle atony with preservation of consciousness. A nocturnal polysomnography and multiple sleep latency test (MSLT) were performed with a diagnosis of NT1. The particularity of this case is the presentation of 2 autoimmune diseases triggered by an H1N1 vaccine without adjuvant, so far there is only evidence of NT1 associated with vaccines with adjuvant and viral infection. The association of both entities has made us reflect on the autoimmune mechanism, reinforcing the theory of its role in the onset of the disease.

STUDY OBJECTIVES:An increased risk of narcolepsy has been observed in children following ASO3-adjuvanted pandemic A/H1N1 2009 (Pandemrix) vaccine. We investigated whether this risk extends to adults in England.

METHODS:Six adult sleep centers in England were visited between November 2012 and February 2014 and vaccination/clinical histories obtained from general practitioners. Suspected narcolepsy cases aged older than 17 y were selected. The risk of narcolepsy following Pandemrix was calculated using cases diagnosed by the time of the center visits and those with a diagnosis by November 30, 2011 after which there was increased awareness of the risk in children. The odds of vaccination in cases and in matched population data were compared using a case-coverage design.

RESULTS:Of 1,446 possible cases identified, most had onset before 2009 or were clearly not narcolepsy. Of the 60 remaining cases, 20 were excluded after expert review, leaving 40 cases with narcolepsy; 5 had received Pandemrix between 3 and 18 mo before onset. All the vaccinated cases had cataplexy, two received a diagnosis by November 2011 and two were aged 40 y or older. The odds ratio for vaccination in cases compared to the population was 4.24 (95% confidence interval 1.45-12.38) using all cases and 9.06 (1.90-43.17) using cases with a diagnosis by November 2011, giving an attributable risk of 0.59 cases per 100,000 doses.

CONCLUSIONS:We found a significantly increased risk of narcolepsy in adults following Pandemrix vaccination in England. The risk was lower than that seen in children using a similar study design.