Dr Melanie: Tics, tremors and twitches

involuntary movements can be worrying, or simply annoying. Here’s what you need to know…

Our bodies have more than 600 named skeletal muscles. These contract individually or in teams to help our bodies move in all directions, perform acts of great strength or fine precision, and signal our emotions.

These voluntary movements are controlled by the motor cortex in the brain, which works out what we need to do and sends signals down to junction boxes in the spinal cord. These spread out along motor nerves to our muscles, where they turn into chemical signals, and trigger contractions that bend or straighten our joints. Our brains constantly monitor and adjust our muscle activity, so we often notice a fine tremor, especially after an adrenaline surge.

Our muscles are also coordinated by other brain areas that help us to balance, adapt our movements to our environment and carry out repetitive, learnt or exploratory movements. But when things go wrong, our muscles may ignore instructions, or even do their own thing.

Tics and twitches

Tics are involuntary repetitive movements that can occur almost anywhere – blinking, coughing, fingerdrumming or even shouting out. They’re often triggered by fatigue, stress or excitement and may feel irresistible. In extreme cases (Tourette’s syndrome) they may include swearing. They can be irritating or disabling and embarrassing; if necessary, psychological treatments (distraction, learning to override the urge) or medication can help.

Repetitive twitches affecting facial muscles, hands or other single muscles are also common, and often occur randomly for a while before disappearing again. Benign fasciculation syndrome can cause painful leg cramps and visible spasm, often at night, but it isn’t progressive. Occasionally twitches, cramps or muscle weakness are caused by chemical abnormalities in the blood, sometimes linked to medication such as water pills.

Dystonia

This is a condition affecting the brain and nervous system, but which rarely affects thinking, reasoning and memory processes. It can, however, cause abnormal, persistent or repetitive spasms and contractions in a single muscle or group of muscles.

Dystonia can be genetic or part of other neurological conditions including cerebral palsy, Parkinson’s disease, Huntington’s disease (a genetic condition), multiple sclerosis, strokes or brain tumours. It can also be triggered by infection or injury, toxins including carbon monoxide, and medication used for epilepsy or mental-health problems. Writer’s cramp is a minor form of the condition; rarer causes include nerve trapping in the spine and motor neurone disease.

Dystonia may be focal (affecting one muscle only), affect one side of the body, or target disconnected areas, leading to unusual or uncomfortable postures. It may be possible to relieve

symptoms with muscle relaxant drugs, physiotherapy, Botox injections or surgery.

Tremor (shaking)

An overactive thyroid, low blood sugar and caffeine, smoking and alcohol withdrawal can all provoke shaking. It can also be a side-effect of medication used for asthma, epilepsy, heart conditions, dental injections and cancer treatment. Benign essential tremor often runs in families and gets worse as we get older.

You’ll notice a fine shaking, when carrying teacups for example, and your voice may be shaky too; it can be treated with beta-blocker drugs. Tremor can also be a sign of Parkinson’s disease, when it’s linked to muscle rigidity (stiffness) and slow movement.