Facial twitching: when is it harmless, and when is it hemifacial spasm?

A twitch is an involuntary contraction of a muscle or a group of muscle fibres. Cleveland Clinic divides twitches around the eye and face into four types. The commonest is myokymia: small, slow, regular flickers, especially in the lower eyelid; it usually lasts a short time. A fasciculation feels like a brief, quick jump in the lid or around the eye and passes quickly. In blepharospasm, the eyelids contract strongly enough to force the person to blink or close their eye; it can affect one eye or both at once. Hemifacial spasm, on the other hand, involves the muscles on only one side of the face, usually starts in the eyelid and over time spreads to the whole of that side.

The triggers of harmless twitching mostly come from everyday life. Cleveland Clinic lists stress and anxiety, lack of sleep, stimulants such as caffeine and nicotine, side effects of medicines, going suddenly from darkness into bright light, eye strain and excessive physical tiredness among the commonest causes; it writes that often several of these play a part together, and that the commonest types of twitching are harmless and pass on their own. If the twitching has become more frequent after you started a new medicine, it is recommended that you tell your doctor.

There is a simple distinction you can make at home: watch the twitching for a week and answer these questions. Is it only in the eyelid, or do the cheek and the corner of the mouth contract along with it? Is it on one side, or in both eyes at once? Has your partner seen contractions in your face while you sleep? Does it ease on days when you cut down on caffeine and sleep well? Twitching only in the lid, which comes and goes and changes with the triggers, fits myokymia. Twitching that spreads to the cheek and mouth, is one-sided and continues in sleep fits hemifacial spasm. Strong contractions that force the eye shut and stay around the eye, on the other hand, suggest blepharospasm. A one-minute phone video makes it much easier for the doctor to tell them apart.

The cause of hemifacial spasm is mostly mechanical. MSD Manuals defines this picture as one-sided, painless, simultaneous contraction of the facial muscles caused by repeated involuntary signals from the facial nerve, and writes that it is usually caused by a blood vessel pressing on the facial nerve with a pulsing beat. The contractions mostly start in the eyelid, then spread to the cheek and mouth; at first they come now and then, but over time they can become almost constant. Cleveland Clinic adds that the condition usually starts between the ages of 40 and 60, is uncommon, and is twice as common in women as in men.

Cleveland Clinic also lists some details particular to hemifacial spasm: the eye closing involuntarily, the eyebrow lifting involuntarily, the mouth being pulled to one side, a clicking sound in the ear, and the contractions continuing during sleep. Stress, tiredness, eating and anxiety can make the symptoms worse. The spasms do not cause pain; in this respect they differ from trigeminal neuralgia, which causes pain in the face like an electric shock. MSD states that the two conditions share a similar mechanism of pressure from a blood vessel, which is why some medicines and surgery are used in both.

Less often, the twitching is the result of another disease. Cleveland Clinic lists among the causes of secondary hemifacial spasm injuries near the facial nerve, Bell's palsy, damage to the brainstem such as multiple sclerosis or stroke, structural problems such as an aneurysm in the blood vessels of the brain, infection of the middle ear and of the bone behind the ear, and tumours of the salivary gland in front of the ear. That is why, with hemifacial spasm, an MRI scan is requested both to show the vessel causing the pressure and to rule out these causes. MSD writes that focal epileptic seizures, blepharospasm and tics can also look similar and should be borne in mind when making the distinction.

Involuntary movements seen after Bell's palsy are a separate picture. MSD writes that recovering facial nerve fibres can head for the wrong muscles, and that as a result involuntary linked movements (synkinesis), such as the corner of the mouth moving when you blink, or the eye watering when you eat, can appear. People may describe this as twitching. If you have had facial palsy in the past, be sure to tell your doctor.

The side that concerns the dentist is the jaw muscles. Hemimasticatory spasm is a rare condition linked not to the facial nerve but to the nerve that works the chewing muscles: it causes sudden contractions or twitches in the jaw-closing muscles on one side. In a review bringing together 117 cases from 57 publications, the muscle most often involved was the masseter, the main chewing muscle (97.4%), followed by the temple muscle (47.9%); in some of the cases there was also hardening of the skin or loss of tissue on one half of the face. A review by the same author states that most patients with movement disorders of this kind first go to a dentist or oral surgeon, and that they may be diagnosed with teeth clenching or a jaw joint disorder. With one-sided jaw contractions that come in attacks and continue during sleep, this possibility should come to mind.

Neither list is for making a diagnosis; they are for deciding whether to see a doctor and how quickly. The pictures in the first list mostly pass on their own; if any item from the second list applies, see a doctor.

The sequence deliberately starts with the most dangerous possibility, then moves down to the commonest and harmless causes, and finally to a doctor's assessment.

1. 1

   Check for urgent signs

   If, together with the twitching, one side of your face has suddenly dropped, or there is arm weakness, a speech problem, a change in consciousness or the contraction spreading to an arm or leg, call 112. Sudden loss of vision or blurring in one or both eyes can also be a sign of a stroke; call 112 and do not drive yourself. The same route applies even if the symptoms pass quickly.

2. 2

   Cut down on the triggers

   For a week or two, cut down on caffeine and nicotine, get your sleep pattern back in order and take regular breaks at the screen. Cleveland Clinic writes that myokymia usually passes when these contributing factors are put right.

3. 3

   Observation and video

   Note where the twitching starts, where it spreads to, how often it happens and whether it continues during sleep. Take a short video with your phone during a contraction; there may be no twitching at the moment of the examination.

4. 4

   Examination by a doctor

   If the twitching is continuing, spreading or worrying you, see your GP (family doctor) or a neurologist. Cleveland Clinic writes that with hemifacial spasm the doctor carries out a physical and neurological examination and, where needed, requests electromyography (EMG), which measures the electrical activity of the muscles, to make the distinction.

5. 5

   MRI scan

   With hemifacial spasm, an MRI scan of the brain is done both to show the vessel pressing on the facial nerve and to rule out secondary causes such as a tumour, multiple sclerosis or a vascular abnormality. MSD writes that the vessel causing the pressure is often seen on MRI, but that the diagnosis is ultimately made by examination.

6. 6

   Botulinum toxin

   MSD writes that the most effective treatment for hemifacial spasm is a botulinum toxin injection into the contracting muscles. Cleveland Clinic states that the effect starts 3–6 days after the injection and usually lasts 3–4 months, which is why the injection is repeated regularly. A Cochrane review found no randomised trials comparing it with placebo; observational data, however, show a strong improvement in symptoms and a favourable safety profile.

7. 7

   Medicines and surgery

   In people who do not want injections or do not respond to them, anti-seizure medicines, muscle relaxants and some other medicines are tried; Cleveland Clinic writes that these do not work for everyone and can cause drowsiness and tiredness with long-term use. The permanent solution is microvascular decompression surgery, in which the vessel pressing on the nerve is separated from it; it is recommended in severe cases and when injections have not worked.

These are pictures that cause involuntary movement in the face and can be confused with twitching. Examination, video and, if needed, imaging and electromyography make the distinction.

The following are the wrong decisions commonly seen with this picture, and what they cost.

The course is very different depending on the type. The sequence below summarises the usual expectations, from harmless eyelid twitching to the treatment of hemifacial spasm.

1. Harmless eyelid twitching

   Cleveland Clinic writes that myokymia flickers mostly last seconds or minutes, that most cases pass without treatment within days or weeks, and recommends seeing an eye doctor or a GP for twitching that has not passed in a few weeks or is disrupting daily life.

2. Hemifacial spasm, untreated

   Cleveland Clinic writes that the spasms tend to get worse over time and involve more muscles of the face, and that in some people they can become almost constant.

3. The first week after botulinum toxin

   The effect starts in 3–6 days. Cleveland Clinic lists eye irritation, a drooping eyelid and temporary facial weakness among the possible side effects.

4. 3–4 months

   The effect wears off and the injection is repeated. The dose and the injection sites can be adjusted according to the response.

5. After surgery

   Cleveland Clinic writes that successful microvascular decompression ends the condition, but that it carries risks such as temporary or permanent facial palsy, hearing loss and leakage of cerebrospinal fluid.

We do not give figures here, because the scope varies a great deal with the type of twitching. Harmless eyelid twitching mostly needs no treatment at all. With hemifacial spasm, the items that determine the scope:

Imaging and tests

An MRI scan of the brain and, where needed, electromyography.

Type of treatment

Botulinum toxin is a treatment repeated at regular intervals; medication needs to be continuous; surgery, on the other hand, is a one-off procedure but needs a hospital stay.

Number of muscles involved

The more muscles of the face the spasm involves, the more injection points and the higher the dose.

The underlying cause

With secondary hemifacial spasm, the treatment of the tumour, ear disease or brainstem disease itself is added to the scope.