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Health condition · Clinically reviewed

Corticobasal degeneration, a rare 4R tauopathy with an asymmetric signature.

One arm, stiff and apraxic. A limb that moves on its own. Poor response to levodopa. This is what CBD and corticobasal syndrome look like, and how UK specialists reach the diagnosis.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against MDS diagnostic criteria, PSP Association UK, NICE and peer-reviewed neurology sources.

  • 03

    Current for 2026

    Reflects modern tauopathy science including 4R tau imaging, MDS 2013 CBS criteria and current trial landscape.

Key facts

CBD at a glance.

The essentials, in plain English. What CBD is, how it differs from CBS, who it affects, and where UK specialist care sits.

  • What it is

    A rare neurodegenerative 4R tauopathy causing asymmetric parkinsonism plus cortical signs. Part of the atypical parkinsonism and FTD spectrum.

  • CBD vs CBS

    CBD is the pathology (tau). CBS is the clinical syndrome, which can be caused by CBD, Alzheimer, PSP or FTLD-TDP pathology.

  • How common

    Estimated prevalence around 5 per 100,000. Peak onset in the 60s and 70s. Slight female predominance.

  • Prognosis

    Progressive over years. Median survival is around 6 to 8 years from symptom onset, with wide individual variation.

  • Classic hallmark

    Asymmetric limb rigidity and apraxia, alien limb phenomenon, myoclonus and poor levodopa response.

  • Care model

    MDT movement disorders care with specialist tauopathy input, allied health and palliative planning throughout.

Why this guide matters

A rare tauopathy that hides in plain sight.

CBD is often mistaken for Parkinson disease early on. The three points below explain why recognition matters, and what changes when the diagnosis is right.

  • It is not Parkinson disease

    Asymmetric onset, prominent cortical signs and poor levodopa response set CBD apart. Getting the diagnosis right reshapes expectations, medications and support.

  • It sits on a tauopathy spectrum

    CBD shares 4R tau pathology with progressive supranuclear palsy and overlaps clinically with frontotemporal dementia. That informs both prognosis and access to trials.

  • MDT care changes the journey

    Specialist neurology, allied health and palliative planning together do more for quality of life than any single medication.

How the diagnosis is made

From first signs to a specialist plan.

The steps a UK neurologist will normally follow when CBD or CBS is suspected, in order, so you know what to expect and why.

  1. 01

    Assessing

    Focused clinical history

    Asymmetric onset, gradual progression, poor response to levodopa, cognitive change and any family history of parkinsonism or dementia.

  2. 02

    Assessing

    Neurological examination

    Asymmetric rigidity and akinesia, dystonia, myoclonus, cortical sensory loss, apraxia, alien limb and eye movement review.

  3. 03

    Assessing

    Cognitive assessment

    MoCA and ACE-III at minimum, with formal neuropsychology to map executive, language and praxis deficits.

  4. 04

    Confirming

    MRI brain

    Looks for asymmetric perirolandic and frontoparietal atrophy, usually contralateral to the more affected limb.

  5. 05

    Confirming

    Functional and molecular imaging

    FDG-PET shows asymmetric hypometabolism, DAT-SPECT shows reduced dopamine transporter uptake, tau-PET can show 4R tau binding.

  6. 06

    Confirming

    CSF biomarkers

    Amyloid beta, total tau and phospho-tau help rule out Alzheimer pathology, which is a common cause of CBS and often co-exists.

  7. 07

    Preparing

    Specialist MDT referral

    Movement disorders and cognitive neurology, with access to a UK tauopathy centre such as Queen Square, King’s, Newcastle, Sheffield, Manchester or Cardiff.

Typical timeline: specialist workup unfolds over weeks, with imaging and biomarker results shaping the plan.

Symptoms

What CBD actually looks like.

A distinctive mix of asymmetric parkinsonism and cortical signs. Presentation is heterogeneous, and features accumulate over years rather than months.

  • Asymmetric onset

    Symptoms start in one limb, typically an arm, and stay markedly one-sided for years before the other side is involved.

  • Rigidity, akinesia and dystonia

    Extrapyramidal features with a fixed abnormal posture of the affected limb and a poor response to levodopa.

  • Apraxia

    Ideomotor, limb-kinetic and orobuccal apraxia. Inability to perform learned movements despite normal strength and sensation.

  • Alien limb phenomenon

    The affected limb moves without conscious control, sometimes grasping or levitating. Classical for CBD and rare in other disorders.

  • Cortical sensory loss

    Astereognosis and agraphaesthesia. Objects and numbers traced on the palm are no longer recognised.

  • Myoclonus

    Sudden jerks of the affected limb, often stimulus-sensitive and triggered by touch or movement.

  • Cognitive and language change

    Executive dysfunction, apraxia of speech, non-fluent aphasia and behavioural features overlapping with frontotemporal dementia.

  • Falls, gaze palsy and dysphagia

    Later features include gait apraxia and falls, supranuclear gaze palsy overlapping with PSP, and progressive swallowing difficulty.

Treatment

How CBD is managed in the UK.

There is no cure yet. Care is symptomatic and supportive, delivered by an MDT, with growing access to tau-targeted trials at national centres.

  • Levodopa trial

    Worth a structured trial at adequate dose. Response is usually limited, which itself helps confirm the diagnosis.

  • Botulinum toxin

    For focal limb dystonia, painful spasticity and orobuccal dystonia. See our botulinum toxin for neurological indications guide.

  • Myoclonus treatment

    Clonazepam or sodium valproate can dampen stimulus-sensitive jerks. Start low and titrate to tolerance.

  • Trihexyphenidyl and baclofen

    Anticholinergic and antispasticity agents used cautiously for dystonia and spasticity, balanced against cognitive side effects.

  • Speech and swallow therapy

    SLT input for dysarthria and communication aids, plus formal swallow assessment. PEG feeding considered if dysphagia becomes unsafe.

  • Physiotherapy and OT

    Falls prevention, gait aids, orthotics, adaptive equipment and home modification to keep people safe and independent for longer.

  • Neuropsychology and mood care

    Cognitive rehabilitation, plus active treatment of depression, anxiety and sleep disorder, which are common and treatable.

  • Specialist trials and planning

    Access to tau-targeted therapies, antisense oligonucleotide and immunotherapy trials at national centres, alongside advance care planning and palliative input.

What this guide is based on

The sources behind every claim on this page.

Movement disorders society criteria, UK charity guidance and specialist tauopathy programmes, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your neurologist knows your history and examination and can tell you which parts apply to you. If in doubt, get seen.

  • Armstrong MJ et al. Criteria for the diagnosis of corticobasal degeneration. Neurology (MDS 2013).

  • PSP Association UK. Guidance and support for people living with CBD and PSP.

  • NICE NG71. Parkinson’s disease in adults (relevant for differential and symptom control).

  • Queen Square Brain Bank and UK tauopathy research programmes.

Red flags

When to seek urgent review.

CBD is chronic, but some events need same-day or specialist attention. These are the situations that should not wait for the next clinic letter.

  • Rapid cognitive decline

    Fast progression over weeks or months is unusual and prompts review for alternative diagnoses including prion disease and autoimmune encephalitis.

  • Unsafe swallow

    Choking, recurrent chest infections or weight loss require urgent SLT reassessment and consideration of feeding options.

  • Recurrent falls with injury

    Head injury, fractures or subdural risk. Needs urgent physiotherapy, environment review and medication rationalisation.

  • New severe pain or fixed dystonia

    Painful contracture affecting hand or arm function deserves early botulinum toxin and orthotics referral.

  • Suicidal thoughts or severe depression

    Common and under-treated in tauopathies. Urgent GP and mental health assessment, with active pharmacological and psychological care.

  • Aspiration pneumonia

    Fever, cough, breathlessness after a meal. Treat as a medical emergency and reassess swallow and goals of care.

  • Sudden loss of communication

    Rapid worsening of speech or comprehension warrants review to exclude stroke or seizure superimposed on the tauopathy.

  • Carer burnout

    A red flag in its own right. Respite, carer assessment and social work involvement protect both patient and family.

  • Loss of capacity for key decisions

    Trigger for early advance care planning, lasting power of attorney and clear documentation of wishes.

Living with it

A progressive illness, with real things that help.

Four practical priorities that make the biggest difference day to day, from team assembly to advance care planning.

A quiet reminder

Early planning is kindness, not surrender.

Setting up the team, the home, the voice and the future while capacity is strong protects choice for the years ahead.

  1. 01 Team

    Build the MDT early

    Movement disorders neurologist, SLT, physio, OT, neuropsychology and palliative care. Getting the team in place early smooths every transition.

  2. 02 Home

    Adapt the environment

    Grab rails, raised toilet seats, wet rooms, chair raisers and clear walking routes reduce falls and preserve independence.

  3. 03 Voice

    Plan for communication

    Speech deteriorates. Introduce writing boards, tablets and AAC devices early, while typing and pointing are still reliable.

  4. 04 Future

    Plan advance care and legacy

    Lasting power of attorney, advance care plan, hospice contact and, if wished, brain donation to a UK research brain bank.

Frequently asked

Everything we get asked about CBD.

Quick answers on diagnosis, treatment, prognosis and where to get UK specialist help.

  • What is corticobasal degeneration?

    Corticobasal degeneration is a rare progressive neurodegenerative disease driven by abnormal 4R tau protein. It is one of the atypical parkinsonism syndromes and sits on a spectrum with progressive supranuclear palsy and frontotemporal dementia. Prevalence is roughly 5 per 100,000, with onset usually in the 60s or 70s.

  • What is the difference between CBD and CBS?

    CBD is a pathological diagnosis defined by tau protein changes in the brain. Corticobasal syndrome, or CBS, is the clinical picture of asymmetric parkinsonism with cortical signs. CBS can be caused by CBD, but also by Alzheimer disease, progressive supranuclear palsy or FTLD-TDP pathology. That is why we use the term CBS during life and confirm CBD only on brain examination.

  • What is the alien limb phenomenon?

    It is a striking symptom in which the affected limb moves without conscious intention. The hand may grasp objects, levitate, or interfere with what the other hand is doing. It is classical for CBD and rarely seen in Parkinson disease or other tauopathies.

  • Does levodopa work in CBD?

    Response to levodopa is usually poor or absent, which is one of the features that distinguishes CBD from Parkinson disease. A properly conducted trial at adequate dose is still worthwhile, because a minority of people gain some benefit and a clearly negative response supports the diagnosis.

  • How is CBD investigated?

    Diagnosis is clinical, supported by MRI showing asymmetric perirolandic and frontoparietal atrophy, FDG-PET showing asymmetric hypometabolism, DAT-SPECT showing reduced dopamine transporter uptake, and CSF biomarkers to rule out Alzheimer pathology. Tau-PET is increasingly used in specialist centres. Neuropsychology maps the cognitive and language profile.

  • What is the outlook and where should care happen?

    CBD is progressive with a median survival of around 6 to 8 years from onset. Care is best delivered by a specialist MDT with links to a UK tauopathy centre such as Queen Square, King’s, Newcastle, Sheffield, Manchester or Cardiff. The PSP Association UK is an excellent source of information, peer support and access to research.

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