A myoclonic jerk is a sudden, involuntary jerking movement of part or all of your body’s muscles. “Myo” means muscle, and “clonus” means contraction (although a sudden relaxation of one of your muscles is also called a myoclonus). Myoclonic jerks can occur in normal people at nighttime just before falling asleep. In such cases, you can call them hypnic jerks or hypnagogic jerks. In other words, hypnic jerks are a subset of myoclonus (myoclonic jerks) that only happen before the initiation of sleep, while myoclonus alone can happen at any time of the day or night. An example of a myoclonic jerk you might experience during the day is a hiccup, which is an involuntary spasm of the diaphragm that everyone experiences.
Why do people twitch in their sleep?
Several medical conditions can lead to people twitch in their sleep. In some cases, it can happen if you have a nervous system disorder like epilepsy or if you have some kind of metabolic condition or medication reaction. Because myoclonic jerks look the same regardless of their origin, the doctor must pay attention to your symptoms and should run some tests to see what kind of myoclonus you have. If they exclusively occur just before falling asleep, usually the symptoms alone can identify the condition of hypnagogic or hypnic jerks.
Myoclonic jerks causes a sudden flexion of the upper body muscles. They can also be referred to as spasms or shakes. Lower extremity muscles are less often involved. Characteristics that describe myoclonic jerks are that they are:
- Short in duration
- Have a sudden onset
- Feel like you have been shocked
- Can vary with intensity
- Can be localized or body-wide phenomena
- When during the waking hours, myoclonus can interfere with ambulation, speaking and/or eating.
Ordinary myoclonus refers to things like sleep starts (hypnic jerks), hiccups, anxiety-related spasms, exercise-related spasms, or infant twitching after meals. In some cases, they can be hereditary or completely unexplained in someone who is otherwise healthy and yet has these jerking movements.
Myoclonic Epilepsy can show up as having many myoclonic jerks throughout the day with evidence on the EEG (electroencephalogram) of spikes in electrical activity causing the jerking motion. These muscle jerks might be the only thing an epileptic person exhibits or they can be part of a larger disorder
Can Hypnic Jerks be a sign of Brain Tumor?
Brain tumors are rare (e.g. affecting about 1 in every 500 people in the US ), but myoclonic jerks are experienced by almost everyone. Myoclonic jerks may develop in response to brain tumor. There is also what is known as benign myoclonus and what can be termed as brain tumor jerks. So, the short answer is Yes, hypnic jerks can be a sign of brain tumor but that definitely doesn’t mean you should panic that you might have cancer every time your leg twitches. There have been some cases where myoclonic jerks in a patient were linked with a brain tumor. For example, a man in 2010 discovered he had a brain tumor when experiencing slurred speech and jerking of his tongue. Another patient was diagnosed with a brain tumor after experiencing twitching in their face. Brain tumors have even been linked with chronic hiccups. It’s not surprising that a tumor in the brain can cause symptoms like these. The brain is the control center of the nervous system, and your nervous system is what allows you to move your muscles.
- Should you be worried about myoclonic jerks?
Just because a tumor can cause these jerks doesn’t mean experiencing them is a good sign that you have a tumor. Brain tumors normally cause a range of symptoms at the same time. If you have one, you’ll normally experience headaches, nausea, seizures, and psychological symptoms like confusion or mood swings in addition to movement disturbances .
So a twitching leg on its own is unlikely to be a symptom of a tumor. Still, it is worth keeping track of anything unusual that your body does. If you’re experiencing chronic problems with muscle spasms or unexpected muscle relaxation, go and visit your doctor. Chronic problems with muscle contraction or relaxation can be a sign of other diseases such as Parkinson’s. Any time you experience a persistent issue with movement that is causing you distress, it is worth speaking with your doctor to make sure it’s not a sign of disease.
Harmless hypnic jerks start in your muscles, whereas hypnic jerks caused by a brain tumor start in your brain. Harmless hypnic jerks are sudden, whereas ones caused by your brain carry on. Also, you would not be conscious during a harmful hypnic jerk, because your brain would be experiencing a seizure. Sometimes, very frequent hypnic jerks can be a sign of an underlying disorder. If you suddenly notice an increase in how often you get hypnic jerks, if the jerks are so frequent that they are preventing you from sleeping, or you are experiencing frequent hypnic jerks alongside other problems such as difficulty in movement, speak to your doctor. It may simply be that you have a sleep disorder caused by stress or other life issues.
What causes twitching while sleeping?
A physiological problem can contribute to getting myoclonic jerks, including the following medical disorders:
- Head injury
- Brain infection
- Spinal cord injury
- Chemical/drug poisoning
- Lipid storage disease
- Oxygen deprivation for a prolonged period of time
- Medication interaction
- Metabolic disorder
- Autoimmune disorder
Diagnosis of Myoclonus
After getting your history and general medical examination, the doctor may do an electroencephalogram or EEG, which measures the type of electrical activity going on in the brain. This painless procedure involves putting electrodes on your scalp and looking for telltale spikes of activity meaning that the brain is contributing to the phenomenon of myoclonus. If the EEG is normal, you may have a metabolic condition to account for your symptoms. The doctor may do blood tests to define what is going on and may perform an EMG or electromyogram, which measures the electrical activity in the muscles of various parts of the body. The EMG is done by probing the muscles with small needles; the needles pick up on electrical activity inside the muscles indicating a myoclonic jerk.
An MRI scan of the brain may also help to see if there is a neurobiological reason why you might have these myoclonic jerks. This test generally lasts about 20 minutes and is completely painless. If the myoclonus is caused by something going on with the spinal cord, an MRI would be an appropriate test to evaluate that.
Laboratory tests done in order to identify the cause of metabolic myoclonic jerks include tests for autoimmune diseases, metabolic disorders, diabetes, toxins, drugs, kidney disease, or liver disease.
The treatment of myoclonic jerks depends on their origin. Most of the time, if an underlying disorder is found and treated, the myoclonic jerks disappear. If the myoclonic jerks are not due to an underlying treatable condition, doctors can prescribe medications to lessen their frequency.
Common medications used to treat idiopathic myoclonic jerks include clonazepam (Klonopin), which is a benzodiazepine medication that can block the triggers for myoclonus. It carries the secondary side effects of sleepiness and dizziness during the day.
Seizure medication can also be used to treat myoclonus that has its origins in your brain. Commonly used medications for myoclonus of brain origin include valproic acid (Depakene), levetiracetam, and primidone, which is also called Mysoline. Side effects of these medications also include drowsiness during the day and dizziness. Botox injections can be used if there is just a single muscle or muscle group that is jerking all the time. It blocks the messengers from the brain that are sending signals to contract the muscles.
Surgery is an extreme measure used in the treatment of myoclonic jerks and is reserved for when a brain lesion or brain tumor is the cause of the myoclonus. Myoclonus of the face or ear can be treated surgically. Other patients undergo deep brain stimulation (DBS) to counteract the signals coming from the brain that are triggering the myoclonic jerks.
While myoclonic jerks are not painful or dangerous, they can interfere with the quality of your life and decrease the amount of sleep you get. However, if you are experiencing chronic and/or severe muscular problems, seek medical advice for further diagnosis and treatment, especially if these problems last for a long time and are accompanied with other symptoms such as severe headache, nausea, and/or psychological problems.
Porter, K R et al. 2010. Prevalence estimates for primary brain tumors in the United States by age, gender, behaviour and histology. Neuro-Oncology. 12(6): 520-527.
Myoclonus Fact Sheet | National Institute of Neurological Disorders and Stroke. 2017. Myoclonus Fact Sheet | National Institute of Neurological Disorders and Stroke. [ONLINE] Available at: https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Myoclonus-Fact-Sheet. [Accessed 15 August 2017].
Cuellar, NG et al. 2015. Hypnic Jerks: A Scoping Literature Review. Sleep Med Clin. Sep;10(3):393-401.
Yilmaz, R eta al. 2010. Lingual myoclonus associated with brain tumor: an epileptic origin? Epileptic Disorders. 12(4): 303-5.
Negri, S et al. 1976. Facial myokamia and brain stem tumor. Eur Neurol. 14(2): 108-18.
Chang & Lu. 2012. Hiccup: Mystery, Nature and Treatment. JNM. 18(2): 123-130.
Signs and symptoms of a brain tumor – Understanding – Macmillan Cancer Support . 2017. Signs and symptoms of a brain tumor – Understanding – Macmillan Cancer Support . [ONLINE] Available at: http://www.macmillan.org.uk/information-and-support/brain-tumors/understanding-cancer/signs-and-symptoms-of-a-brain-tumor.html. [Accessed 15 August 2017].
Klawans et al. 1986. Myoclonus and parkinsonism. Clinical Neuropharmacology. 9(2): 202-5.