Narcolepsy is a medical condition where there is inability of the brain to regulate waking and sleeping cycles normally. A person suffering from narcolepsy is likely to have an overwhelming urge to fall asleep. While in some cases, a person may fall asleep for a few seconds or few minutes, others may remain asleep for much longer. Such episodes of daytime sleepiness can be dangerous and disabling. Narcolepsy can result in excessive daytime sleepiness or sudden sleep attacks. In many cases, narcolepsy remains undiagnosed.
Major symptoms of narcolepsy include REM sleep disturbance, cataplexy, hallucinations and sleep paralysis. Cataplexy indicates sudden loss of muscle control leading to weakness. This can occur during the initial attacks of narcolepsy. Such episodes are not to be confused with seizures. While some patients notice weakness in some muscles such as eyelids, others may suffer a loss of tone in all voluntary muscles. Hallucinations are another symptom of narcolepsy. The patient is likely to experience delusions that can often be frightening. Sleep paralysis refers to a temporary inability to move while suffering a sleeping attack during narcolepsy. The patient might notice this while falling asleep or waking up.
Diagnostic tests such as overnight polysomnography or Multiple Sleep Latency Test (MSLT) are used. Polysomnogram involves placement of electrodes on your scalp before falling asleep. This test measures the movement of the eyes and muscles and monitors the electrical activity of the brain. MSLT is a test to check how long it takes you to fall asleep. This throws light on the sleep patterns of the patient and helps in understanding and measuring sleep latency. Medications for narcolepsy can help reduce signs and symptoms. These medicines may interfere with other health conditions such as hypertension and diabetes. Antidepressants can reduce symptoms of cataplexy and sleep paralysis.
Cataplexy is muscle weakness accompanied by typically triggered emotions such as laughing, crying or terror. These emotions are exhibited in full conscious awareness. The term cataplexy is derived from Greek 'Kata' meaning down, and 'plexis' meaning stroke. Cataplexy affects about 70% of those with narcolepsy. It is caused by autoimmune destruction of the neurotransmitter hypocretin which regulates arousal and wakefulness. Cataplexy without Narcolepsy (neurological disorder with symptoms of excessive daytime sleepiness, uncontrollable sleep and cataplexy) is rare and the cause is unknown.
Cataplexy manifests itself as muscular weakness. It can range from slackening of facial muscle to complete muscle paralysis with postural collapse. Severe attacks may result in inability to stand or move. Attacks are often brief and last from few seconds to about 30 minutes. This typically involves dropping the jaw, neck weakness and buckling of knees. The cataplectic attack is slow and progressive, so much so, the patient is usually able to avoid injury as they notice the feeling before the attack begins. As they are fully conscious during attacks, even extreme ones, they are aware of what is happening around them. Speech is slurred and vision may be impaired, it could be double vision or inability to focus, but hearing and awareness remain normal.
The hypothalamus region in the brain regulates basic functions of hormone release, emotions and sleep. During cataplexy, the neurochemical hypocretin is significantly reduced. Hypocretin is a primary chemical in regulating sleep as well as states of arousal and its deficiency can lead to decreased levels of histamine and epinephrine, chemicals that promote wakefulness, arousal and alertness.
Since cataplexy attacks are self-limiting, they resolve without the need for medical intervention. For instance, if the person is reclining comfortably, he/she may transition into sleepiness, hypnagogic hallucinations or a sleep onset period.
Cataplexy worsens with fatigue, and is different from narcoleptic sleep attacks. It is usually triggered by strong emotional reactions such as laughter, surprise, awe, embarrassment or by sudden physical effort, when a person is caught off guard. Such attacks could also occur spontaneously without any identifiable emotional trigger.
Cataplexy - Causes
Most have cataplexy with narcolepsy. Cataplexy is the most dramatic symptom of narcolepsy. And most cataplectic attacks are brought on by strong or extreme emotional feelings such as anger, stress, anxiety, depression and joy. Laughter and other positive emotions are the most common triggers of cataplexy. While the cause of cataplexy without narcolepsy is unknown, secondary cataplexy is linked to reduced levels of the chemical hypocretin, a neurotransmitter in the brain.
Secondary cataplexy is also associated with specific lesions located primarily in the lateral and posterior hypothalamus. Other conditions causing cataplexy include ischemic events, multiple sclerosis, head injury, Paraneoplastic syndromes and infections such as encephalitis. Cataplexy may occur transiently or permanently due to lesions of the hypothalamus caused by surgery especially in difficult tumor resections.
Recent ongoing research has found a clear association of Narcolepsy with an allele of the HLA gene family which provides instructions for the making a group of related proteins known as the Human Leukocyte Antigen (HLA) complex. This allele strongly increases the susceptibility for cataplexy. But 41% of patients without the explicit symptoms of cataplexy are carriers.
Diagnosis of cataplexy is usually made by symptoms presentation. Excessive daytime sleepiness, sleep onset paralysis, hallucinations are some symptoms strongly evidencing cataplexy. A multiple sleep latency test is often conducted in order to quantify daytime sleepiness.
There is no cure for cataplexy but is treated with medications to manage symptoms. There are no behavioral treatments. Those with narcolepsy often try to avoid thoughts and situations that they know are likely to evoke strong emotions as they know that these emotions are likely to trigger cataplectic attacks. Regardless of whether a person has narcolepsy or not, the doctor prescribes a selective serotonin and norepinephrine re uptake inhibitor to alleviate symptoms of cataplexy. Sodium oxybate is another effective drug for cataplexy.
However taking Xyrem and other sleep medications which are narcotic pain relievers or alcohol can lead to difficulty in breathing, coma and even can be fatal. In case of high blood pressure, diabetes, or other health problems, it is recommended to take medications only after consultations with the doctor.
Cataplexy is not a life threatening condition, unless engaging in potentially dangerous activities while experiencing an attack such as operating heavy machinery or driving motor vehicle. Sleep disturbances and sexual dysfunction can be caused by narcolepsy of which cataplexy is a primary symptom. As cataplexy is sudden, brief loss of voluntary muscle tone can be triggered by strong emotions such as laughter.
Cataplexy can occur during the waking hours and attacks can sometimes be rarely visible such as drooping of eyelids or severe total body collapse. As cataplexy is a neurological problem, chances are it can be misdiagnosed as a seizure disorder. As there is no cure for cataplexy, it has to be managed with medications and modifications of potential triggers.
EEG or Electroencephalography is a diagnostic test that measures the brain's electrical activity. This non-invasive test is used to detect any abnormality in the brain's electrical impulses. Nearly 16 - 25 electrodes are placed over different areas of your head and they record electrical activity. A study of the pattern of these electrical activities of the brain help in detecting any abnormality. Electroencephalography helps in detecting causes of seizures, epilepsy or degenerative diseases.
It helps in evaluating head injury, tumor or infections. But an EEG cannot help diagnose mental illness. Sleep disorders such as narcolepsy can be evaluated with the help of EEG. An EEG helps confirm brain death in comatose patients. Brain tumors, encephalitis, meningitis, Parkinson's disease or cerebral infarct can be detected with EEG test.
The patient will need to lie down with eyes closed during the EEG test. Sometimes the doctor may ask the patient to breathe deeply or look at bright flickering lights. Sometimes the patient may also be asked to go to sleep. The patient must not consume caffeine, tea, cola or chocolate for about 8 hours prior to the EEG test. The hair must be free of oils, creams or sprays. Medications such as tranquilizers, muscle relaxants and anti-epilepsy medicines might need to be discontinued for a short period.
Bibliography / Reference
Collection of Pages - Last revised Date: March 18, 2019