From the Guidelines
Corticobasal degeneration (CBD) is a rare, progressive neurodegenerative disorder that affects movement and cognitive function, and its management focuses on symptomatic treatment with medications and therapies to improve quality of life. According to the study by 1, CBD is a tauopathy characterized by abnormal accumulation of tau protein in brain cells, particularly in the cerebral cortex and basal ganglia, leading to cell death and brain atrophy. The clinical presentation of CBD typically begins around age 60-70 and is characterized by:
- Asymmetric rigidity
- Apraxia (difficulty with purposeful movements)
- Alien limb phenomenon (involuntary movements of a limb)
- Cortical sensory loss
- Myoclonus
- Cognitive impairment
The study by 1 highlights the importance of imaging in the evaluation of patients presenting with Parkinsonian symptoms, including CBD. Management of CBD focuses on symptomatic treatment, including:
- Medications like levodopa (starting at 100mg three times daily, potentially increasing to 800-1000mg daily) for parkinsonian symptoms, though response is typically poor
- Clonazepam (0.5-2mg daily) for myoclonus
- Botulinum toxin injections for dystonia
- Antidepressants such as SSRIs (e.g., sertraline 50-200mg daily) for depression
- Physical, occupational, and speech therapy to maintain function and address swallowing difficulties
As the disease progresses, patients will need increasing assistance with daily activities and eventually full-time care. The average survival from symptom onset is about 7-10 years, with death usually resulting from complications like pneumonia or other infections, as reported in the study by 1.
From the Research
Clinical Characteristics of Corticobasilar Degeneration
- Corticobasilar degeneration (CBD) is a neurodegenerative disorder characterized by a combination of cortical and basal ganglia signs 2.
- The most distinctive clinical feature is its unilateral or markedly asymmetric presentation, with rare exceptions, only Parkinson's disease presents with such asymmetry 2.
- Common presenting cortical features include apraxia, aphasia, parietal lobe sensory signs, frontal dementia, or myoclonus 2.
- Basal ganglia signs include rigidity, akinesia, limb dystonia, and postural instability 2.
Diagnosis and Differential Diagnosis
- The diagnosis of CBD is often challenging due to the rarity of the full complement of findings at presentation, and the substantial overlap with other parkinsonian and dementing illnesses 2.
- The differential diagnosis includes Parkinson's disease, progressive supranuclear palsy, frontotemporal dementia, primary progressive aphasia, and Alzheimer's disease 2.
- The clinical diagnosis is not confirmed pathologically in up to half of cases, so the term corticobasal syndrome is often preferred during life, reserving the term corticobasal degeneration for pathologically verified cases 2.
Treatment and Management
- Treatment of CBD is primarily supportive, and most patients die within 10 years of onset 2.
- Parkinsonian signs may improve to a modest degree with levodopa, clonazepam can suppress myoclonus, and botulinum toxin can relieve dystonia 2.
- Early speech therapy, physical therapy, and occupational therapy, as well as assist devices such as a rolling walker may improve functioning and reduce complications such as aspiration pneumonia and falls 2.
- A multidisciplinary therapeutic approach employing low-frequency repetitive transcranial magnetic stimulation (rTMS) has shown improvement in UPDRS and quality of life in patients with corticobasal syndrome 3.
Pathology and Biomarkers
- CBD is a rare neurodegenerative disease characterized by the predominance of pathological 4 repeat tau deposition in various cell types and anatomical regions 4.
- Developments of MRI-based and nuclear medicine imaging modalities have increased pathophysiological insights of CBS and may improve diagnostic accuracy 5.
- Cerebrospinal fluid and plasma levels of neurofilament light chain can distinguish CBS from Parkinson's disease but not from other atypical forms of Parkinsonism 5.
- Biofluid markers reflecting the distinct tau and/or astrocyte disease of CBD are needed, and examining biosamples along with clinical parameters from longitudinally followed patients with autopsy-confirmed CBD diagnosis shall hopefully delineate improved biomarkers 5.