History

Fact Explanation
Extreme daytime sleepiness. (EDS) [1] Irresistible sleepiness and sleep attacks of brief duration (about 15 minutes). [2] Occurring almost daily during a period of at least six months plus a clear clinical history of cataplexy is needed for clinical diagnosis.[3]
Cataplexy [1] Temporary episodes of sudden loss of muscle tone while awake or when experiencing emotions. [4]
Sleep paralysis [1] Transient inability to voluntarily move or speak during sleep. Specially during the transition between sleep and wakefulness. [3]
Hypnagogig hallucinations [1] Abnormal visual or auditory perceptions which are experienced while falling asleep. [3] Narcolepsy is characterized by the classic tetrad of symptoms. Which are, EDS, cataplexy, sleep paralysis and hypnagogig hallucinations. [5]
Secondary emotional and social difficulties [6] Due to the symptoms of their disorder people experience embarrassment, feelings of loss of self-worth and academic decline in adolescents. They also avoid social situations that would precipitate cataplexy or draw attention to the degree of somnolence. [6]
References
  1. NISHINO S, RIEHL J, HONG J, KWAN M, REID M, MIGNOT E. Is narcolepsy a REM sleep disorder? Analysis of sleep abnormalities in narcoleptic Dobermans. Neurosci Res [online] 2000 Dec, 38(4):437-46 [viewed 17 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/11164570
  2. MANFREDI RL, BRENNAN RW, CADIEUX RJ. Disorders of excessive sleepiness: narcolepsy and hypersomnia. Semin Neurol [online] 1987 Sep, 7(3):250-8 [viewed 17 May 2014] Available from: doi:10.1055/s-2008-1041425
  3. NISHINO S. Clinical and Neurobiological Aspects of Narcolepsy Sleep Med [online] 2007 Jun, 8(4):373-399 [viewed 17 May 2014] Available from: doi:10.1016/j.sleep.2007.03.008
  4. VASSALLI A, DELLEPIANE JM, EMMENEGGER Y, JIMENEZ S, VANDI S, PLAZZI G, FRANKEN P, TAFTI M. Electroencephalogram paroxysmal θ characterizes cataplexy in mice and children. Brain [online] 2013 May, 136(Pt 5):1592-608 [viewed 17 May 2014] Available from: doi:10.1093/brain/awt069
  5. AKINTOMIDE GS, RICKARDS H. Narcolepsy: a review Neuropsychiatr Dis Treat [online] 2011:507-518 [viewed 18 May 2014] Available from: doi:10.2147/NDT.S23624
  6. BROUGHTON WA, BROUGHTON RJ. Psychosocial impact of narcolepsy. Sleep [online] 1994 Dec, 17(8 Suppl):S45-9 [viewed 17 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/7701199

Examination

Fact Explanation
Thorough and complete neurological examination. In order to exclude structural neurological abnormalities which can mimic narcolepsy. Except for atonia and areflexia in patients having active cataplexy, neurological examination should be normal. [1]
Cardiovascular examination. Look for arrhythmias, aortic stenosis which can cause drop attacks. [2]
References
  1. AKINTOMIDE GS, RICKARDS H. Narcolepsy: a review Neuropsychiatr Dis Treat [online] 2011:507-518 [viewed 18 May 2014] Available from: doi:10.2147/NDT.S23624
  2. EGEL RT, LEE A, BUMP T, JAVOIS A. Isolated Cataplexy in the Differential Diagnosis of Drop Attacks: A Case of Successful Clinical Diagnosis and Treatment Case Rep Neurol Med [online] 2012:757586 [viewed 18 May 2014] Available from: doi:10.1155/2012/757586

Differential Diagnoses

Fact Explanation
Sleep apnea syndrome Sleepiness due to disturbed nocturnal sleep usually associated with excessive snoring and intermittent upper airway obstruction. [1]
Idiopathic hypersomnia Inability to wake up completely until several hours after getting up and prolonged nocturnal sleep but without clinical or electrophysiologic features of REM sleep disturbance as in narcolepsy. [2] Presence of cataplexy is single out narcolepsy from the other forms of hypersomnia. [4]
hypersomnia associated with depression Depressive disorder is diagnosed in the presence of sad mood and/or anhedonia and four out of nine other symptoms,one of which is insomnia or hypersomnia. [3]
Syncopes, drop attacks, atonic attacks or attacks of a histrionic nature When cataplexy is more predominant narcolepsy can be misdiagnosed as such. [4]
Epilepsy Cataplexy can mimic certain forms of epilepsy. For example - atonic seizures. Nocturnal seizures can cause sleep disturbance, causing day time somnolence.[4]
References
  1. DEMPSEY JA, VEASEY SC, MORGAN BJ, O'DONNELL CP. Pathophysiology of Sleep Apnea Physiol Rev [online] 2010 Jan, 90(1):47-112 [viewed 17 May 2014] Available from: doi:10.1152/physrev.00043.2008
  2. ANDERSON KN, PILSWORTH S, SHARPLES LD, SMITH IE, SHNEERSON JM. Idiopathic Hypersomnia: A Study of 77 Cases Sleep [online] 2007 Oct 1, 30(10):1274-1281 [viewed 17 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2266276
  3. DAUVILLIERS Y, LOPEZ R, OHAYON M, BAYARD S. Hypersomnia and depressive symptoms: methodological and clinical aspects BMC Med [online] :78 [viewed 17 May 2014] Available from: doi:10.1186/1741-7015-11-78
  4. NISHINO S. Clinical and Neurobiological Aspects of Narcolepsy Sleep Med [online] 2007 Jun, 8(4):373-399 [viewed 17 May 2014] Available from: doi:10.1016/j.sleep.2007.03.008

Investigations - for Diagnosis

Fact Explanation
12-lead electrocardiography and echocardiography. To exclude cardiac causes giving rise to drop attacks. Example: Aortic stenosis. [1]
Brain Imaging and EEG. When drop attacks caused by seizure episodes needed to be excluded.[1]
Polysomnogram- multiple sleep latency test (MSLT). To diagnose according to diagnostic criteria. Average sleep latency < 8 minute or presence of two sleep-onset REM periods (SOREMPs) during the multiple sleep latency test (MSLT) are considered positive polygraphic abnormalities in the diagnosis. [2]
Nocturnal polysomnogram. To exclude other possible causes like periodic leg movements and obstructive sleep apnea. [2]
HLA type diagnostic markers. Most patients are HLA DQB1*0602 positive. Which predispose patients to the disorder. Presence of markers is supportive of the diagnosis. [3]
CSF hypocretin-1 measurement. Low CSF hypocretin levels (< 110 pg/ml, one-third of mean control value) are included in the diagnostic criteria of narcolepsy. ( in the second revision of ICSD) [2]
References
  1. EGEL RT, LEE A, BUMP T, JAVOIS A. Isolated Cataplexy in the Differential Diagnosis of Drop Attacks: A Case of Successful Clinical Diagnosis and Treatment Case Rep Neurol Med [online] 2012:757586 [viewed 18 May 2014] Available from: doi:10.1155/2012/757586
  2. NISHINO S. Clinical and Neurobiological Aspects of Narcolepsy Sleep Med [online] 2007 Jun, 8(4):373-399 [viewed 17 May 2014] Available from: doi:10.1016/j.sleep.2007.03.008
  3. DAUVILLIERS Y, ARNULF I, MIGNOT E. Narcolepsy with cataplexy. Lancet [online] 2007 Feb 10, 369(9560):499-511 [viewed 17 May 2014] Available from: doi:10.1016/S0140-6736(07)60237-2

Investigations - Followup

Fact Explanation
Polysomnographic test- maintenance of wakefulness test (MWT) Is to assess the effect of treatment with psycho stimulants. [1]
References
  1. NISHINO S. Clinical and Neurobiological Aspects of Narcolepsy Sleep Med [online] 2007 Jun, 8(4):373-399 [viewed 17 May 2014] Available from: doi:10.1016/j.sleep.2007.03.008

Management - General Measures

Fact Explanation
Explanation of the diagnosis and nature of disorder having recurrences and necessity of life long treatments. Reassurance of the patient and prevention of accidents.[1]
Patient education on avoiding dangerous activities such as driving or operating machinery, and possible dangerous situations like occurrence of a drop attack while climbing stairs, swimming , and suggest suitable precautions. Example- having a companion while going on heights, having a life preserver when swimming. Prevents accidents. [2]
Avoid alcohol and heavy meals. Disturbs the sleep- wake cycle and can give rise to alcohol-dependent sleep disorder. [3]
References
  1. MITLER MM, HAJDUKOVIC R, ERMAN M, KOZIOL JA. Narcolepsy J Clin Neurophysiol [online] 1990 Jan, 7(1):93-118 [viewed 19 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2254143
  2. DE MELLO MT, NARCISO FV, TUFIK S, PAIVA T, SPENCE DW, BAHAMMAM AS, VERSTER JC, PANDI-PERUMAL SR. Sleep Disorders as a Cause of Motor Vehicle Collisions Int J Prev Med [online] 2013 Mar, 4(3):246-257 [viewed 17 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3634162
  3. ABAD VC, GUILLEMINAULT C. Diagnosis and treatment of sleep disorders: a brief review for clinicians Dialogues Clin Neurosci [online] 2003 Dec, 5(4):371-388 [viewed 18 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181779

Management - Specific Treatments

Fact Explanation
Regular/planned day time napping. Relieves drowsiness for one or two hours. [1]
Maintaining regular sleep- wake patterns. relieves daytime drowsiness. [1] The combination of planned daytime naps and maintaining regular nocturnal sleep times produce significant reduction in severity of daytime sleepiness in treated narcoleptics. [2]
Medical Therapy 1) CNS stimulants - Amphetamine, Methamphetamine, Dextroamphetamine, Methylphenidate - considered main treatment for sleepiness associated with narcolepsy. 2) Non-amphetamine wakefulness promoting medication - Modafinil and Armodafinil. 3) Sodium Oxybate - Is a rapidly acting sedative. Improves cataplexy and reduces daytime somnolence. 4) Tricyclic antidepressants and fluoxetine - effective in the treatment of cataplexy. [2]
References
  1. NISHINO S. Clinical and Neurobiological Aspects of Narcolepsy Sleep Med [online] 2007 Jun, 8(4):373-399 [viewed 17 May 2014] Available from: doi:10.1016/j.sleep.2007.03.008
  2. WISE MS, ARAND DL, AUGER RR, BROOKS SN, WATSON NF. Treatment of Narcolepsy and other Hypersomnias of Central Origin: An American Academy of Sleep Medicine Review Sleep [online] 2007 Dec 1, 30(12):1712-1727 [viewed 17 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2276130