Diagnosing narcolepsy is a challenge. Sometimes symptoms may point to another sleep disorders. Detecting this sleep disorder at the earliest avoids future problems. This article details different tools used for diagnosing narcolepsy.
When to take a test for narcolepsy?
First, I want to apologize for delaying this article. A lot I have invested in learning how the web works.
It’s true, diagnosing Narcolepsy requires few medical tests. However, some symptoms help in primarily diagnosing narcolepsy disorder. Often doctors perform the physical examination. They also record medical histories. Then the combination of both helps in diagnosing narcolepsy.
One or two major symptoms can not conclude the final diagnosis. Below questions determine whether the person would be tested for narcolepsy.
1. Do you get the sudden urge to sleep? Does this happen despite having enough sleep at night?
2. Did you sleep while performing daily activities? Activities like eating, speaking or even working?
3. How long you remain alerted after having enough sleep? Is duration of alertness is minimized?
Positive answers to above questions usually point to narcolepsy. Narcolepsy is not a common disorder. Around 25-28% of narcolepsy individuals have finalized the diagnosis by means of below tests. Practitioners often struggle while diagnosing narcolepsy. And sometimes its due to the duration of symptoms expression. It may take 5-7 years from the onset to conclude this sleeping disability.
Age group and Narcolepsy
Although uncommon, this sleep disorder may start at any age. Typical onset is found in between 10 to 30 years of life. However, there of few examples where the onset of narcolepsy was reported after 35 years. In rare cases, this sleep disorder was detected even after the 5th decade.
Certainly, there are many myths about this sleeping disability. Because of misinformation, many fear for their prolonged sleepiness. However, sleep disorders like chronic insomnia maybe the reason. In fact, diagnosing narcolepsy is the complex thing. Hence it must be done by the qualified physician.
As such, there is no correlation between narcolepsy symptoms severity and age of onset. Narcolepsy cases identified in age group 40-50 are due to other neurological illnesses. For example sleeping disability due to Parkinson’s disease, multiple sclerosis or trauma could be referred as secondary narcolepsy. In addition, sleeping pattern alters in elderly individuals. Hence comparatively diagnosing narcolepsy in elderly patients is the complex task.
In addition, sleeping pattern alters in elderly individuals. Hence comparatively diagnosing narcolepsy in elderly patients is the complex task.
To emphasize, diagnosing narcolepsy requires expert supervision and judgment.
Another key point to remember. Diagnosing narcolepsy is difficult when cataplexy is mild or absent. Moreover, cataplexy may occur in an isolation.
International Classification of Sleep Disorders
Let’s see what International Classification of Sleep Disorders stands for. As per ICSD, primary hypersomnia syndromes maybe due to narcolepsy. Also idiopathic hypersomnia or recurrent hypersomnias maybe the reasons.
ICSD defines narcolepsy as excessive sleepiness. It defines narcolepsy typically associated with cataplexy and other REM-sleep phenomena. For example sleep phenomena like sleep paralysis and hypnagogic hallucinations.
The ICSD established baseline categorical standards for diagnosis of narcolepsy. It has 2 sets of well-defined criteria. Let we discuss the second one.
1] Complaint of excessive sleepiness or sudden muscle weakness
2] Associated features that include:
- sleep paralysis
- disrupted major sleep episode
- hypnagogic hallucinations automatic behaviors.
3] Polysomnography with one or more of the following:
- sleep latency less than 10 minutes
- REM sleep latency less than 20 minutes
- an MSLT with a mean sleep latency less than 5 minutes
- two or more sleep-onset REM periods (SOREMPs)
4] No medical or mental disorder accounts for the symptoms
Important tests used for diagnosing narcolepsy
Let we discuss 3 important tests used for diagnosing narcolepsy.
Epworth Sleepiness Scale
This scale is used for measuring daytime sleepiness. The short questionnaire administered to assess sleep problems. The patient rates the probability of falling asleep during daily activities. The scores are added to obtain a single number. The resultant value used for diagnosing narcolepsy.
- The number 0-9 indicates normal value.
- The range 10-24 indicates abnormal value. This range requires expert opinion for the conclusion.
- The scores between 11-15 indicate the possibility of mild sleep apnea.
- And the scores above 16 indicate severe sleep apnea or narcolepsy.
The scale includes certain questions directing to a specific sleep disorder. This scale provided the useful tool for diagnosing narcolepsy.
Additionally, the scale defines sleep quality. It compares sensitivity and specificity of other similar measurements of sleep quality.
Be comfortable while answering these questions. Describe your sleep patterns correctly. Your accurate responses will help in diagnosing narcolepsy.
The questionnaire for detecting narcolepsy
The questionnaire provides daily life situations. One has to score his likelihood of dozing. The below-mentioned scale is applied while diagnosing narcolepsy.
0: would never doze or sleep
1: slight chance of dozing or sleeping
2: moderate chance of dozing or sleeping
3: high chance of dozing or sleeping
Routine life activities are scaled. The patient is encouraged to do these activities if he hadn’t done them in the past. The patient has to weigh these activities as per above scale. Few activities are mentioned below.
1: Sitting and reading
2: Watching TV
3: Sitting inactive in public space
4: Being passenger in a car for an hour
5: Lying down in the afternoon
6: Sitting and talking to someone
7: Sitting quietly after lunch
8: Stopping for few minutes in traffic
Scores used for diagnosing narcolepsy
0-10: Normal range
11-14: Mild sleepiness
15-17: Moderate sleepiness
This is the multi-parametric test. The test is intended to diagnosing narcolepsy and similar sleep disorders. It is abbreviated as PSG. The study records bio-physiological changes that occur during sleep. This test is usually performed during the night. However, in the case of shift workers, it can be carried away during the daytime.
This is the non-invasive and painless test for diagnosing narcolepsy.
The PSG includes EEG study for the brain. It also includes EOG test for measuring eye movements. Muscle activities (EMG) and heart rhythm (ECG) are also recorded. Along with diagnosing narcolepsy, this test rules out other sleep disorders also.
The person appears in the sleep lab in the early evening. It usually takes 1-2 hours to wired him up. Multiple channel data being recorded after he falls asleep. Such sleep labs are set in hospitals. However, some medical offices or even hotels provide such facility. The sleep physician attends and monitors the test. The patient can be discharged in the early morning. Second by second the data is recorded.
Nowadays one can conduct the test in his home. This adds to the patient comfort value.
The scorer reviews test data. The resultant information details the sleep onset, sleep efficiency and sleep stages.
The study also records breathing irregularities, cardiac rhythm abnormalities, leg movements, body positions while sleeping and oxygen saturation.
Only the sleep physician can interpret the data accurately. Ideally, medical history details and other relevant details help in diagnosing narcolepsy.
Multiple Sleep Latency Test
This sleep test is abbreviated as MSLT. While diagnosing narcolepsy like sleep disorders, this test measures sleep latency. Sleep latency means the time elapsed from start of the daytime nap to the first sign of sleep. The test follows one important principle.
More sleepy the person is, he will fast fall asleep. This test is used extensively for diagnosing narcolepsy. Additionally, this test differentiates tiredness from true sleepiness. In fact, this test determines how the person falls asleep in favorable conditions. It measures the variations and their consistency. It also measures REM sleep pattern. Hence diagnosing narcolepsy or other disorders becomes easier.
Usually, this test carried out during the daytime. The test completes within 8 hours. Approximately 4 to 5 nap data recorded. The patient takes nap for 20 minutes. He repeats nap after 2 hours. The test also records EEG, patient’s muscle activities, and eye movements.
MSLT Procedure for diagnosing narcolepsy and other sleep disorders
Avoid stimulants like tea, coffee or chocolates
Formal sleep study a night before
Urine test to rule out substances that may interfere sleeping patterns.
- First, technician attaches the electrodes to the patient’s head
- Then technician attaches the electrodes to patient’s eyes
- The technician then attaches electrodes to patient’s chin
- The technician wires patient chest for ECG
- Patient can perform simple tasks when asked
- The patient takes nap for 20 minutes
- Electrodes attached to head record patient’s brain activity, electrodes attached to eyes record eye movements. The chin electrodes record muscle activities.The chest electrodes record the cardiac rhythm.
- After 20 minutes patient makes awake. The patient repeats nap after 2 hours. Total 4-5 naps recorded.
- The patient completes the post-test questionnaire.
- The electrode sensors record the data while the patient was awake and in sleep. Transmit data determines the REM sleep.
- The sleep specialist reviews the results while diagnosing narcolepsy or other sleep disorders.
Diagnosing Narcolepsy with Cataplexy
Evaluation of narcolepsy symptoms should be proper. Otherwise, it remains unnoticed for years.
We often overlook sleepiness in this busy life. Diagnosing narcolepsy at the earliest is the real challenge. So far we have discussed the tools and techniques used while diagnosing narcolepsy. However, the patients having narcolepsy with cataplexy require different questionnaire. It is termed as Ullanlinna Narcolepsy Scale (UNS).
The 11-item scale (range 0-44) assesses the two main features of the narcoleptic syndrome, the abnormal sleeping tendency, and cataplexy.
The scores also differentiate patients with narcolepsy syndrome and patients with sleep apnea, multiple sclerosis, and epilepsy.
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Ok. I guess enough I have detailed for diagnosing narcolepsy. Although uncommon, it is important to detect this sleep disorder at the earliest.