From the Guidelines
Corticobasal degeneration (CBD) is a rare, progressive neurodegenerative disorder characterized by asymmetric rigidity, limb apraxia, alien limb phenomenon, and cortical sensory loss, typically beginning around age 60-70, as described in the most recent study 1.
Key Features of Corticobasal Degeneration
- Asymmetric limb clumsiness
- Unilateral limb rigidity and dystonia, including the "alien limb phenomenon"
- Postural imbalance
- Cortical features, including apraxia, cortical dementia, cortical sensory deficits, and impaired language production
Pathophysiology
The condition results from abnormal accumulation of tau protein in brain cells, particularly in the cerebral cortex and basal ganglia, leading to cell death, as noted in 1.
Treatment and Management
There is currently no cure for CBD, and treatment focuses on symptom management.
- Levodopa may be tried for parkinsonian symptoms but typically provides minimal benefit at doses of 300-1000 mg daily.
- Clonazepam (0.5-2 mg daily) or botulinum toxin injections can help manage dystonia and myoclonus.
- Antidepressants like SSRIs (e.g., sertraline 50-200 mg daily) may be needed for depression.
- Physical, occupational, and speech therapy are essential components of management.
- Assistive devices should be considered as the disease progresses.
Prognosis
Unfortunately, CBD typically progresses over 6-8 years, eventually causing significant disability, as mentioned in 1. Regular follow-up with a neurologist is important to adjust symptom management as the disease evolves.
Diagnostic Considerations
Correctly diagnosing a Parkinsonian syndrome, including CBD, on clinical features alone can be challenging, and imaging remains an essential diagnostic tool, as highlighted in 1. The diagnostic criteria for CBD and other neurodegenerative diseases are outlined in 1.
From the Research
Definition and Characteristics of Corticobasal Degeneration (CBD)
- Corticobasal degeneration (CBD) is a neurodegenerative disease with substantial overlap of clinical features with other neurodegenerative diseases, including Parkinson's disease (PD) 2.
- CBD is characterized by neuronal loss, astrogliosis, and deposition of filamentous tau inclusions in neurons and glial cells in cerebral cortical areas, basal ganglia, brainstem, and cerebellar nuclei 3.
- The clinical diagnostic accuracy of CBD is the lowest among common neurodegenerative diseases, and its antemortem diagnosis is challenging, especially when comorbid with another brain disease 2, 4.
Clinical Presentation and Symptoms
- The classic clinical presentation of CBD is corticobasal syndrome, which typically presents as an asymmetric parkinsonism with a variable combination of ideomotor apraxia, rigidity, myoclonus, and dystonia, often associated with the presence of an alien limb phenomenon 4.
- Dystonia, often accompanied by painful rigidity and fixed contractures, is one of the most disabling features of CBD, and asymmetric limb dystonia, particularly affecting one arm, is a common manifestation of CBD 5.
- Other clinical manifestations of CBD include a behavioural variant of frontotemporal dementia syndrome, speech disorders, Richardson’s syndrome, and, rarely, posterior cortical syndrome 3.
Diagnosis and Treatment
- The diagnosis of CBD requires autopsy confirmation, and a new set of diagnostic criteria has been developed, but specific biomarkers confirming CBD as the underlying pathology responsible for clinical manifestations are still lacking 4, 3.
- Treatment of CBD is symptomatic, and options include levodopa/carbidopa for parkinsonism, botulinum toxin injections for limb dystonia, clonazepam and levetiracetam for myoclonus, and physical therapy for motor treatment 6.
- General supportive care, including assessing for sores related to dystonia or immobility, monitoring dysphagia, and identifying needs for support services, is also important in the management of CBD 6.