Corticobasal syndrome

Corticobasal Syndrome (CBS) is a rare, progressive neurodegenerative disorder characterized by a combination of motor and cognitive symptoms. It is often considered under the umbrella of Parkinson's Plus Syndromes, which are disorders that present with Parkinsonism but with additional features that distinguish them from classic Parkinson's Disease. CBS is particularly noted for its asymmetrical presentation and a variety of symptoms that can include motor dysfunction, cognitive impairment, and language difficulties.

Symptoms and Signs

The hallmark of CBS is the combination of corticobasal degeneration (CBD) symptoms with other neurological signs. Patients may exhibit:

• Motor Symptoms: These include rigidity, akinesia (lack of movement), and dystonia (muscle contractions causing abnormal postures). One of the most distinctive features is the "alien limb phenomenon," where a limb acts seemingly on its own accord.
• Cognitive Symptoms: Executive functions are often impaired, along with difficulties in spatial orientation and apraxia (difficulty in performing tasks or movements when asked, despite having the desire and the physical ability to perform them).
• Language Impairment: Progressive nonfluent aphasia is common, characterized by slow, effortful speech and difficulty in constructing sentences.
• Sensory Deficits: Some patients may experience an inability to recognize objects by touch (astereognosis) or by sight (visual agnosia).

Causes and Pathophysiology

The exact cause of CBS is unknown, but it is associated with the accumulation of an abnormal form of the protein tau in the brain, leading to cell death in specific areas, including the cortex and basal ganglia. This accumulation is similar to that seen in other neurodegenerative diseases, such as Alzheimer's Disease and Frontotemporal Dementia.

Diagnosis

Diagnosing CBS can be challenging due to its overlap with other neurodegenerative disorders. It is primarily a clinical diagnosis based on history and physical examination. Imaging studies, such as MRI, may show atrophy in specific brain regions, and PET scans can reveal reduced brain metabolism in affected areas. However, a definitive diagnosis can only be made through a post-mortem examination.

Treatment and Management

There is currently no cure for CBS, and treatment is focused on managing symptoms. This may include:

• Pharmacological Treatments: Medications such as levodopa may offer limited relief for parkinsonian symptoms, but their effectiveness is often minimal.
• Physical and Occupational Therapy: These therapies can help manage motor symptoms and improve quality of life.
• Speech Therapy: To address language and speech difficulties.

Prognosis

CBS is a progressive disorder, and the symptoms typically worsen over time. The rate of progression can vary widely among individuals. Life expectancy following diagnosis can range from a few years to over a decade, with complications such as pneumonia being a common cause of death.

See Also

• Parkinson's Disease
• Frontotemporal Dementia
• Progressive Supranuclear Palsy
• Alzheimer's Disease