What mimics narcolepsy?

Demons in the Sleep Center: Narcolepsy Mimicking Other Sleep Disorders

Citation:
Hu K, Salas RME. Demons in the sleep center: narcolepsy mimicking other sleep disorders [published online September 23, 2019]. Consultant360.

Narcolepsy is a chronic neurological disorder that affects how the brain controls sleep patterns. It is characterized by excessive daytime sleepiness and uncontrollable episodes of sleep that greatly disrupt a daily routine. Other symptoms include cataplexy, which is the muscle weakness of rapid-eye movement (REM) sleep triggered by strong emotions while awake, vivid hallucinations, and sleep paralysis. 1

Early descriptions of narcolepsy appeared in German case reports during the late 1800s, describing a unique condition that featured both episodes of sleepiness and muscle weakness triggered by excitement. 2 Narcolepsy was later recognized as a clinical disorder and named by the French physician Gélineau, after the landmark diagnosis of a wine merchant suffering from daytime drowsiness and sleep attacks. 2 However, Gélineau proposed a fairly open-ended definition that did not differentiate the cataplexic symptoms from those associated with somnolence.

In the early 1900s, Löwenfeld was the first to use the term cataplexy in describing muscle paralysis caused by strong emotions. 3 The confusion surrounding narcolepsy-cataplexy continued into the 1900s, as further research revealed the association between REM sleep and narcolepsy, leading to the creation of the multiple sleep latency test (MSLT) as a diagnostic tool for narcolepsy. 2 The MSLT is used to measure how quickly patients fall asleep in quiet daytime situations.

The pathophysiological causes of narcolepsy lie in the hormone orexin (also known as hypocretin). The neuropeptide regulates sleep/wake states and appetite. Type 1 narcolepsy features low levels of orexin, excessive daytime sleepiness, and cataplexy. Type 2 narcolepsy is associated with normal levels of orexin and features less-severe symptoms without cataplexy. 1

Due to the variability in its symptoms and similarity to other sleep disorders, narcolepsy can be misdiagnosed. Currently, the disorder affects nearly 1 in 2000 people in the United States and 3 million people worldwide, but it is estimated that narcolepsy is properly diagnosed in only 25% of the individuals who have it. Symptoms typically begin to appear during childhood and adolescence, but people can live with narcolepsy for years before receiving a definitive diagnosis. 4

This report describes an interesting case in which a patient presented with symptoms mimicking those of other sleep disorders but in whom narcolepsy was ultimately diagnosed and confirmed with the results of an MSLT study.

CASE REPORT

A 35-year-old man presented to the clinic with chief concerns of excessive daytime sleepiness and profound tiredness. He works as a physical trainer and had a strong, healthy build with no medical issues. He lives with his wife and 3 children, one of whom is a newborn, and he reported that he often takes care of the children and house due to his spouse’s work schedule. In addition to his domestic duties, he reported having a busy work life, needing to get up very early every day to train clients. He was currently at his highest weight for his lifetime.

On review of symptoms, he reported having gastroesophageal reflux disease, snoring, and memory and concentration difficulty. He also said that his brother has apnea and that both of his parents snore. On physical examination, his body mass index was 31.5 kg/m 2 , his modified Mallampati score in the passive view was class IV, with only the hard palate visible. He had a thick, short neck. The rest of the examination findings, including the heart and lungs, were normal.

Based on his clinical presentation, especially his symptoms of somnolence and tiredness, his snoring, his comorbidities, and his family history, the patient completed an overnight sleep study to evaluate for obstructive sleep apnea. The study did not demonstrate any significant sleep apnea.

Due to the concern for night-to-night variability in sleep apnea and persistent hypersomnia despite modification of his sleep-wake schedule, another overnight test was conducted to check for apnea once more and then was followed with an MSLT study. The MSLT was ordered to look for a central hypersomnia such as narcolepsy or idiopathic hypersomnia. The patient described previous episodes that were consistent with cataplexy, and he reported that he felt unrefreshed after waking up in the morning but felt better with naps.

The MSLT results clearly pointed to a diagnosis of narcolepsy. The patient had a mean sleep latency of 1.9 minutes and a median sleep latency of 1.5 minutes (Figure 1). He experienced cataplexy during the testing period and fell into REM sleep for 3 out of the 5 naps (Figure 2).

Figure 1. MSLT statistics showing sleep latency. N1 refers to the first stage of sleep, N2 refers to the second stage of sleep, and SSS Pre refers to the patient’s score on the Stanford Sleepiness Scale before taking the MSLT.

Figure 2. MSLT hypnogram, featuring the 3 of 5 naps with REM sleep. N1, N2, and N3 refer to stage 1, 2, and 3 of NREM sleep, respectively. REM sleep is indicated by the red line, and MT refers to movement time.

These results and the diagnosis of narcolepsy were communicated to the patient during his next follow-up visit in the clinic. During this follow-up, he appeared distraught and agitated over his diagnosis. He reported that during his naps, he was unable to move due to sleep paralysis combined with hallucinations of a “demon” sitting on him. While excessive daytime sleepiness and sleep paralysis could be indicative of other sleep disorders, these vivid hypnopompic hallucinations, which appeared for the first time during the MSLT, further corroborated a diagnosis of narcolepsy.

In summary, although the man presented with symptoms of severe daytime sleepiness and tiredness characteristic of many different sleep disorders, he ultimately received a diagnosis of narcolepsy.

1. National Institutes of Health, National Institute of Neurological Disorders and Stroke. Narcolepsy fact sheet. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Narcolepsy-Fact-Sheet. NIH publication No. 17-1637. Updated August 13, 2019. Accessed September 23, 2019.
2. Mignot E. A hundred years of narcolepsy research. Arch Ital Biol. 2001;139(3):207-220.
3. Todman D. Narcolepsy: a historical review. Internet J Neurol. 2007;9(2). https://print.ispub.com/api/0/ispub-article/7361. Accessed September 23, 2019.
4. Narcolepsy Network. Narcolepsy fast facts. https://narcolepsynetwork.org/about-narcolepsy/narcolepsy-fast-facts/. Revised June 2015. Accessed September 23, 2019.

How Narcolepsy Is Diagnosed

Mark Gurarie is a freelance writer, editor, and adjunct lecturer of writing composition at George Washington University.

Published on February 23, 2021

Nicholas R. Metrus, MD, is board-certified in neurology and neuro-oncology. He currently works at the Glasser Brain Tumor Center with Atlantic Health System in Summit, New Jersey.

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Next in Narcolepsy Guide

Narcolepsy is a chronic neurological condition that disrupts the sleep-wake cycle. It’s most often associated with extreme daytime sleepiness, though it can also lead to other symptoms, including cataplexy, a sudden loss of muscle control due to a strong emotional response.

While home exams and online tools can help with a diagnosis, and a physical examination will rule out other neurological disorders, narcolepsy is confirmed only after an evaluation at a specialized sleep clinic.

There, two tests, the polysomnogram (PSG), which measures physiological activity while you sleep, and the multiple sleep latency test (MSLT), which tracks daytime sleepiness, can confirm the presence of narcolepsy.

In light of recent advances in the understanding of narcolepsy, other evaluations are emerging as potentially helpful for diagnosis, These include genetic testing and an assessment of levels of hypocretin (a neurotransmitter associated with regulating sleep and wake cycles).

Self-Checks/At-Home Testing

For most patients, the first steps in a narcolepsy diagnosis involve observation and at-home assessment, often in consultation with a healthcare provider. While the following steps alone won’t confirm the presence of the condition, they’ll help to start the process:

• Keeping a sleep journal over a one-to-two-week period is often recommended if narcolepsy is suspected. You’ll be asked to track the duration and quality of sleep overnight, as well as any daytime sleep attacks. Not only is this a good record for your healthcare provider to have, but it’ll also give you a sense of the scope and scale of your case.
• Epworth Sleepiness Scale is a self-assessment available online that measures daytime sleepiness often associated with narcolepsy. This simple questionnaire, available from the Division of Sleep Medicine at Harvard Medical School, can’t provide a definitive diagnosis, but it can help determine if you should seek out a sleep specialist.
• Ullanlinna Narcolepsy Scale is another questionnaire that can help determine the possibility of narcolepsy with cataplexy, which is the most common type. However, it’s important to note that some people with narcolepsy—those with what’s called “type 2 narcolepsy”—don’t experience that symptom.

Physical Examination

Initial evaluation for this condition involves a thorough assessment of medical history. Your healthcare provider will ask you about your sleep habits and evaluate for cataplexy, daytime hallucinations, and other symptoms. They may also perform neurological tests to make sure other issues aren’t causing the problems.

Labs and Tests

Since the exact causes of narcolepsy are still unknown, clinical diagnosis is a multistep procedure that involves ruling out other causes of sleep disorders. Here’s a quick breakdown of typical approaches.

Polysomnogram

In a polysomnogram examination, which is also known as a “sleep study,” your muscular movements, breathing, eye movements, and brain activity are recorded overnight while you sleep. Basically, this test evaluates the quality of the sleep you’re getting to rule out other disorders as the cause of the problems.

Multiple Sleep Latency Test

The day after PSG testing, the MSLT is applied; this is the most definitive and important test in narcolepsy diagnosis. Basically, you’ll be asked to take five short naps in a day, each separated by two hours. Those who consistently fall asleep within eight minutes are considered to have excessive daytime sleepiness.

People with narcolepsy experience a quicker than normal onset of rapid eye movement (REM) sleep—the stage that causes dreaming. Achieving this state within 15 minutes of falling asleep in at least two of the five naps, as well as during the PSG, is a sign of this condition.

Hypocretin 1 Level Measurement

A more recently established diagnostic tool involves measuring levels of the neurotransmitter hypocretin 1. A small sample of cerebrospinal fluid is taken using a lumbar puncture (also known as a “spinal tap”) and clinically tested. A smaller than normal amount of hypocretin 1, which regulates sleep and wake cycles, is a sign of narcolepsy with cataplexy.  

Genetic Testing

While not conclusive, the presence of a certain genetic marker, HLA-DQB1*06:02, is closely linked to narcolepsy. This is a derivation of a gene that regulates sleep and wake cycles. Genetic testing helps healthcare providers diagnose cases in which symptoms are atypical.

Differential Diagnosis

As noted, the key to narcolepsy diagnosis often involves differentiating it from other disorders. Quite a few conditions are similar, including the following.

Idiopathic Hypersomnia

Idiopathic hypersomnia is a rare chronic or acute condition in which episodes of extreme sleepiness arise due to no known cause. It differs from narcolepsy in that sufferers don’t feel refreshed after taking naps, and they don’t experience uncontrollable sleep attacks.

Also, cataplexy is not associated with this condition. In some cases, those with idiopathic hypersomnia require 10 or more hours of sleep at night to feel rested.

Sleep Apnea

Sleep apnea is a common disorder characterized by breathing difficulties and interruptions while asleep. Sleep apnea leads to interruptions during sleep, loud snoring, daytime drowsiness, irritability, and problems concentrating, among other symptoms.

Associated with obstructions in the body’s airways, this condition, if untreated, can lead to high blood pressure, irregular heartbeat, diabetes, stroke, and heart failure, among other issues.

Kleine-Levin Syndrome

Those with this rare disorder experience hypersomnolence, a need to sleep up to 20 hours a day, and compulsive hyperphagia, which is an excessive need to eat, as well as other behavioral issues.

When awake, those with this condition experience confusion, irritability, apathy, and lethargy (lack of energy). Other symptoms of this condition mimic narcolepsy, as Kleine-Levin syndrome can also cause hallucinations.

Other Conditions

Some other conditions can also mimic narcolepsy, including brain tumors, head trauma, psychosis, and arteriosclerosis (hardening of the arteries) in the brain. These conditions can lead to a similar kind of excessive daytime sleepiness experienced by people with narcolepsy.  

A Word From Verywell

Unlike many other diseases or conditions, narcolepsy can be challenging to diagnose; its exact causes are still unknown, and its symptoms and severity can vary a great deal.

However, as healthcare providers and researchers learn more about it, there’s no doubt that approaches to taking it on, including detecting the condition, are only getting better. With the right medical help, this often challenging condition can certainly be overcome.

Essential to that, however, is a proactive approach to getting the care you need. If you or a loved one suspects narcolepsy, don’t hesitate to call your practitioner and get on the path toward better days ahead.

3 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

1. National Organization of Rare Disorders. Narcolepsy.
2. National Institute of Neurological Disorders and Stroke. Narcolepsy fact sheet. National Institutes of Health.
3. Division of Sleep Medicine Harvard University. Self-evaluation: narcolepsy.

By Mark Gurarie
Mark Gurarie is a freelance writer, editor, and adjunct lecturer of writing composition at George Washington University.

Narcolepsy Differential Diagnoses

Idiopathic hypersomnia is similar in presentation to narcolepsy, but patients with this condition have no sleep-onset rapid eye movement (REM) period, and naps are unrefreshing. [47] In addition, idiopathic hypersomnia is not associated with cataplexy. Idiopathic hypersomnia can be difficult to distinguish from narcolepsy, though the advent of the modern sleep laboratory has aided in diagnosing these challenging cases.

Differentiation of these 2 disorders can provide valuable insight for therapy. Although amphetamines are used for treatment of both idiopathic hypersomnia and narcolepsy, the excessive daytime sleepiness (EDS) in patients with idiopathic hypersomnia is often resistant to stimulant treatments. In addition, sodium oxybate, which is very costly, is not approved for use in idiopathic hypersomnia.

In addition to the conditions listed in the differential diagnosis, other problems to be considered include the following:

Prader-Willi syndrome
Kasabach-Merritt syndrome
Syndrome of autosomal dominant cerebellar ataxia, deafness, and narcolepsy [48]
Delayed sleep-phase syndrome
Autism
Depression
Diencephalic lesions
Drug abuse
Insufficient sleep syndrome
Kleine-Levin syndrome [49]
Medication effect
Norrie disease [50]
Poor sleep hygiene
Posttraumatic narcolepsy [51]
Increased intracranial pressure
Conversion disorder, factitious disorder, and malingering

Differential Diagnoses

• Absence Seizures
• Benign Childhood Epilepsy
• Brainstem Gliomas
• Complex Partial Seizures
• Frontal Lobe Epilepsy
• Periodic Limb Movement Disorder
• REM Sleep Behavior Disorder
• Shuddering Attacks
• Syncope
• Transient Global Amnesia

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