Corticobasal degeneration

This is a rare brain disease that starts almost without warning and nearly always on one side: first a hand stops obeying, and a year or two later the trouble spreads to the rest of the body, to speech, memory and swallowing. Early on it is usually mistaken for something else — Parkinson's disease, the after-effects of a stroke, a trapped nerve in the neck, or simply age. It appears most often between the ages of fifty and seventy. Nothing available today halts it, and it is more honest to say so at the outset. That does not mean there is nothing to be done: almost every individual problem it causes can be eased, and the complications that ultimately shape the course are largely preventable, provided you know about them in advance rather than discovering them as they happen.

How it begins

One limb usually gives way first, most often an arm. Strength is preserved, and for months the person cannot explain what exactly is wrong. From the outside it looks like clumsiness with no cause:

• a button will not fasten, a key will not turn, a coin cannot be fished out of a pocket, although the hand has lost no power;
• it feels stiff, the fingers are hard to straighten, and the hand gradually settles into an awkward fixed position;
• a tremor appears, along with short sudden jerks of the muscles, mostly when the arm is held out or busy with something;
• the skin tells touch apart less well: without looking, it is hard to recognise what is lying in the palm;
• the hand starts acting on its own — lifting, grabbing objects, getting in the way of the other hand. The person knows it is their hand but does not feel in charge of it.

That last one is called an alien limb, and it is one of the few features that point a doctor straight to this diagnosis. In some people everything starts in a leg instead: walking becomes unsteady, the foot catches on the floor, and falls begin. The other side of the body may stay well for years, and it is exactly this stubborn one-sidedness that separates the disease from most of the conditions it resembles.

How the picture changes over time

The pace differs from person to person and cannot be predicted. The direction is consistent: over the years the other side joins in, and everything else is added to the movement problem.

• Speech becomes slow, slurred and effortful. Separately from that, language itself may go: the word will not come, reading and writing get tangled, while the thought behind them is intact.
• Memory for recent events suffers, while old facts and personal history are recalled well — a fairly telling combination.
• Anything that needs a plan and several steps ahead becomes hard: sums, bills, an unfamiliar route, circumstances that change unexpectedly.
• Orientation in space breaks down: the eyes are slow to find an object, furniture corners get knocked into, a hand misses the door handle.
• Personality shifts. More often than sharpness there is a fading: interest and initiative drain away. Less often the opposite happens, with irritability, anxiety and restlessness.

In the late stage the stiffness keeps building, movement is lost in one or more limbs, and walking without help becomes impossible. Uncontrolled closing of the eyelids and difficulty opening the eyes appear, speech may become hard for others to follow, and swallowing stops being safe. It is that last problem that most often decides the outcome.

What happens in the brain, and why there is no single test

A protein called tau builds up inside nerve cells. Everyone has it in a healthy brain, where it is broken down in good time; here it clumps together and the cells slowly die. Two levels are hit at once: the cortex, the brain's surface, which handles language, planning and orientation, and the deep nuclei, which govern smoothness of movement. Hence the combination that is otherwise hard to explain — a locked-up hand and a lost word at the same time. There is a hereditary contribution, but a very weak one: the risk to children and siblings is barely different from anyone else's.

No single blood test or scan confirms the diagnosis. The doctor assembles it from the whole picture, and the tau build-up itself cannot be proven during life — which is why the term written down is often corticobasal syndrome rather than degeneration. This is not a softer way of putting it: behind an identical clinical picture some people turn out to have a different disease altogether, and the reverse happens too. The practical consequence is a single one: the diagnosis is refined over time, and that is normal.

A neurologist takes this on. Tests serve less to confirm than to rule out other causes, including the treatable ones: a stroke, a tumour, blood collected under the coverings of the brain after an old knock, excess fluid in the brain's chambers, vitamin B12 deficiency, a thyroid disorder. An MRI scan is usual, and studies of brain metabolism and dopamine are sometimes added. Another approach is a short trial of the drug that works well in Parkinson's disease: if it brings no clear improvement, that tips the balance. Neuropsychological testing is also done — a set of tasks covering memory, attention, language, arithmetic and visual perception, which incidentally shows where the person needs help at home.

What genuinely helps

Help is assembled from parts, and it works best when the professionals talk to each other rather than each working in isolation. The team usually includes a neurologist, a physiotherapist, a speech and language therapist, an occupational therapist and, where needed, a dietitian and a social worker.

• Medicines. There is nothing for the disease itself, but there is for what it causes: muscle stiffness and painful spasms, jerking movements, pain, broken sleep, low mood and anxiety, bladder trouble. Where memory is badly affected, the drugs used in Alzheimer's disease are sometimes tried. If one muscle group stays clenched, botulinum toxin injections open up a hand that would otherwise injure its own palm. One rule runs through all of it: sensitivity to side effects is heightened here, so doses start low and rise slowly.
• Movement. Regular exercise does not slow the disease, but it preserves the range of the joints, posture and balance. Work on falls matters just as much: the later a broken hip arrives, the better everything else goes. It is worth checking bone strength and vitamin D at the same time.
• Daily life. An occupational therapist adapts the home and chooses the equipment: rails beside the bath, a shower seat, cutlery with thick handles, a walking frame and later a wheelchair. It is the least impressive part of the work and the one that keeps independence going longest.
• Speech and communication. A speech and language therapist teaches ways of making the voice clearer and, when speech is no longer enough, ways of getting by without it: boards, apps, simple devices. They are best learned before they are urgently needed.
• Supportive care. Easing pain and distressing symptoms and having somewhere to talk about what frightens you is not something reserved for the end: it fits at any point and alongside everything else.

Swallowing, the weakest point

The muscles of the throat weaken like the rest, and food or liquid starts slipping into the airway. Often this happens silently, without coughing, and what gets noticed is the pneumonia that follows. Warning signs are coughing or a wet, bubbly voice after a swallow, food held in the cheek for a long time, choking on drinks, giving up meals that used to be favourites, unexplained weight loss and repeated chest infections.

These signs call for an assessment by a speech and language therapist who works with swallowing. Simple measures help: eating sitting upright and unhurried, swallowing each mouthful twice, not talking while eating, staying upright for half an hour afterwards, changing the texture of food and thickening drinks. Separately, and without exaggeration, mouth care matters: the fewer bacteria in the mouth, the less harm a mouthful that goes the wrong way can do. When swallowing stops being safe, tube feeding is discussed; it has both advantages and drawbacks, it does not suit everyone, and it is far better decided calmly and in advance than at night in a hospital.

When to get help immediately

Call the emergency number (112 in Europe) if any of the following appears:

• fever, fast breathing, breathlessness or chest pain, especially after episodes of choking: this may be food that has reached the lung;
• an episode of choking, or being unable to speak or cough while eating;
• a fall with a blow to the head, particularly in someone taking blood-thinning medicines; deterioration after such a knock is not always immediate and can come a day later or more;
• sudden weakness or numbness of an arm and a leg, a drooping face, speech lost out of nowhere: this is the picture of a stroke, which arrives in minutes rather than months;
• confusion, drowsiness or agitation that has come on over a day or two: a urine infection, dehydration or a drug side effect look like this, and all of them are reversible;
• the person has stopped drinking and is passing small amounts of dark urine;
• severe pain and inability to stand on a leg after a fall.

What is worth agreeing on early

The disease moves slowly, and that gives something most serious diagnoses do not: time to choose for yourself. While speech and judgement are intact, it is worth talking calmly with family and with the doctor about where the person wants to be cared for, whether they accept tube feeding if swallowing fails, and what they agree to if the heart stops. Those decisions are written down and shared with the people who will be there; it is also sensible to appoint someone who can speak on your behalf. None of it is compulsory and nobody has the right to rush you. But once that conversation has happened, the family is not left afterwards guessing and blaming itself for someone else's choice.

It is worth being plain about life expectancy too, because everyone asks. On average around six to eight years pass from the first signs, and the end usually comes from pneumonia rather than from the disease itself. But the spread is enormous, an average says little about an individual, and good care, attention to swallowing and prevention of falls genuinely shift those figures.

Online consultation

A remote appointment is a good place to work through what a face-to-face visit rarely has room for. If there is no diagnosis yet, the doctor will listen to how and where it all began and advise which investigations make sense and which specialist to see: with rare diseases, getting as far as a neurologist often takes longer than the diagnosis itself. If the diagnosis is already made, an online consultation can cover what to do about stiffness and jerking, review the medicines list for anything unnecessary or poorly combined, plan safety at home, food and swallowing, and discuss support for whoever is doing the caring: their exhaustion is part of the same illness and deserves attention too. The emergency signs listed above are not assessed remotely — those mean calling for an ambulance straight away.

This material is for information only and does not replace medical advice.