My hand shakes

There is a question behind almost every consultation about tremor, and it is almost never said out loud. The person has not come to ask about the tremor: they have come to ask whether they have Parkinson's.

So let us start there. The commonest tremor in the population is not the one that comes with Parkinson's: it is essential tremor, and they are different conditions, with different outlooks and different treatments.

What it actually is

A tremor is a rhythmic, involuntary movement. What matters is not that it exists — everybody shakes a little — but when it appears.

Essential tremor is an action tremor. It appears when the hand is doing something: holding a cup, lifting a spoon to the mouth, pouring from a bottle, signing your name, threading a needle. At rest, with the hand lying on your thigh, it settles or disappears. It usually affects both hands, and often the head as well — a "yes" or "no" movement — or the voice, which comes out shaky. There is frequently a family history: that is why some texts list it as "hereditary tremor". And it has one feature almost no other tremor shares: it improves markedly with a glass of alcohol, something patients tend to discover for themselves.

The tremor of Parkinson's is a rest tremor. It appears precisely when the hand is still and supported, and it tends to lessen when the hand is used. It usually starts on one side only. And it almost never comes alone: it goes with slowness of movement, stiffness, handwriting that shrinks, an arm that stops swinging when walking, shorter steps, a quieter voice, a less expressive face.

That is the practical difference, and you can start to observe it at home: notice whether your hand shakes when it is resting and still, or when you are using it. It is not a diagnosis, but it points a long way.

The numbers worth having

• Essential tremor affects 0.32 per cent of the general population, and the figure rises with age: it reaches 2.87 per cent in people over 80. There are an estimated 25 million people with essential tremor in the world.
• Parkinson's disease affects more than 8.5 million people, according to the World Health Organization, and that number has doubled over the last twenty-five years.
• Most people with essential tremor need no surgical treatment at all: medication is enough, or the tremor is mild enough to live with.

What can be done, and what can be operated on

Medication first. In essential tremor there are drugs that reduce the amplitude of the tremor in a good proportion of patients. In Parkinson's, levodopa and its derivatives remain the mainstay of treatment.

Surgery comes in when medication stops being enough or the side effects become intolerable. And it does not replace medical treatment: it complements it. There are two main routes, and both are worth knowing with their real numbers.

Deep brain stimulation. Fine electrodes are implanted in a specific target in the brain and connected to a generator placed under the skin of the chest, much like a pacemaker. It is reversible and adjustable: it can be tuned, switched off or taken out.

The two landmark randomised trials in Parkinson's give a clear sense of the balance. In the first, with 156 patients, those who received stimulation improved on average by 9.5 points on the quality-of-life scale and 19.6 points on the motor scale compared with medical treatment alone. In the second, with 255 patients, stimulation added 4.6 hours a day of good function without troublesome involuntary movements, against zero hours with the best available medical treatment.

And now the other half, which matters just as much: in that first trial, serious adverse events ran at 13 per cent in the operated group against 4 per cent in the medication group, and they included a fatal brain haemorrhage. It is a procedure with demonstrated benefit and with real risk.

Focused ultrasound. It concentrates beams of ultrasound on a single point in the brain, without opening the skull and without implanting anything. In the landmark randomised trial, with 76 patients with essential tremor compared against a sham procedure, the tremor in the treated hand fell from 18.1 to 9.6 points at three months, while in the sham group it barely changed, and the effect held at one year.

Here too the adverse effects deserve their place: gait disturbance in 36 per cent and numbness or pins and needles in 38 per cent, which at one year persisted in 9 and 14 per cent respectively.

Set side by side, the practical difference is this: focused ultrasound implants nothing and requires no opening, but it leaves more persistent neurological effects and is usually applied to one side only. Deep brain stimulation is adjustable and reversible, but it involves an operation, a device, and the complications that belong to each.

What you will hear that is not true

"If my hand shakes, I have Parkinson's." Essential tremor is far more common in the general population, and it is an action tremor, not a rest tremor. The confusion is so widespread that there is medical literature devoted specifically to telling the two apart.

"Essential tremor is nothing, it is just nerves." It is not a matter of nerves or of anxiety. It is a movement disorder with a neurological basis, and when it is severe it stops people eating in public, writing, working or dressing themselves. Playing it down is a common mistake.

"Focused ultrasound cures Parkinson's." The randomised trial behind it was in essential tremor, not in Parkinson's, and it measured the tremor in one hand, not the disease. In Parkinson's it may have a role, but it is not a cure and it does not halt progression.

"Deep brain stimulation is a desperate last resort." It has two randomised trials with clear benefit. The honest thing is to say both parts: it works, and it carries 13 per cent of serious adverse events.

Stem cells to cure Parkinson's. The United States regulator has issued formal warnings to companies selling cell-derived products for these indications, and published the notice in Spanish as well. If you are offered this, ask to see the published clinical trial.

Supplements and natural treatments for tremor. There are no good-quality studies behind them. And because essential tremor fluctuates — it gets worse with tiredness, coffee, stress and lack of sleep — whatever you happen to be taking when a bad spell passes looks as though it worked.

What will happen at the appointment

You will be asked to do things: hold your arms out, touch your nose with your finger, write a sentence, draw a spiral, pour water from one glass into another. That drawn spiral is worth a great deal, because the line left by essential tremor and the one left by a parkinsonian tremor are different, and it also gives something to compare against later.

Your hand will be watched at rest, supported, while you talk about something else. Slowness of movement, muscle tone, walking and arm swing will all be assessed.

You will be asked about your family, about alcohol, about the medicines you take — several of them cause tremor — and about coffee and smoking.

And if the diagnosis is essential tremor and the tremor is not getting in the way of your life, the likeliest answer is that nothing is needed beyond monitoring. That is a course of action too.

Questions worth writing down before you go

• Is my tremor an action tremor or a rest tremor?
• Is there anything in the examination that suggests Parkinson's besides the tremor?
• Could any medicine I take be causing it or making it worse?
• If we start medication, what improvement is it reasonable to expect, and over what time?
• If surgery is ever considered, am I a candidate for stimulation, for focused ultrasound, or for neither?
• How many of these procedures does this team do a year?

The questions people ask most