Corticobasal Degeneration

February 7, 2017

Corticobasal degeneration (CBD) is a rare and gradually progressive neurodegenerative disorder where brain cells become damaged over time and certain sections of the brain start to shrink. It is a form of atypical parkinsonism (a parkinsonism-plus syndrome), which means that it shares some features with Parkinson’s disease such as stiffness (rigidity), tremor, slowness of movement (bradykinesia) and instability.  Several regions of the brain degenerate in CBD. The cortex, or outer layer of the brain, is severely affected, especially the fronto-parietal regions, located near the center-top of the head. Other, deeper brain regions are also affected, including parts of the basal ganglia, hence the name corticobasal degeneration.

The disease, also known as corticobasal ganglionic degeneration, leads to the loss of brain tissue in the cortex, or outer layer of the brain, especially the area in the upper, front section of the brain. The brain tissue of patients with CBD show cell changes that also appear in patients with two other disorders — frontotemporal dementia and progressive supranuclear palsy. These changes involve a brain protein called tau and may provide researchers with some initial clues regarding the causes of corticobasal degeneration. Currently, there are no known causes, such as toxins or infections.

As the cortex is responsible for higher level cognitive functioning like thinking and understanding, and the basal ganglia helps people to perform smooth movements, CBD may affect both the physical and cognitive functioning of people with the disease.

CBD is rare, affecting an estimated 2000-3000 people in United States, of whom only 500-750 are diagnosed. It usually progresses slowly over the course of 6 to 8 years. Death is generally caused by pneumonia or other complications of severe debility such as sepsis or pulmonary embolism.


CBD occurs when brain cells in certain parts of the brain are damaged as a result of a build-up of a protein called tau. The surface of the brain (cortex) is affected, as well as a deep part of the brain called the basal ganglia. Tau occurs naturally in the brain and is usually broken down before it reaches high levels. In people with CBD, it isn’t broken down properly and forms harmful clumps in brain cells.

CBD has been linked to changes in certain genes, but these genetic links are weak and the risk to other family members is very low.

However, corticobasal degeneration does not run in families, meaning that environmental factors such as exposure to certain infections or toxins may play a role. All in all, it is not known why some people develop corticobasal degeneration while others don’t.

Risk Factors

  • Race – No racial predilection is known.
  • Sex – In several studies, CBDG was reported to be more common in women.
  • Age – Typically, CBGD presents between the ages of 50 and 80 years.


Symptoms of CBD usually begin after age 60. The initial symptoms of CBD are often stiffness, shakiness, jerkiness, slowness, and clumsiness, in either the upper or lower extremities. Other initial symptoms may include dysphasia (difficulty with speech generation), dysarthria (difficulty with articulation), difficulty controlling the muscles of the face and mouth, or walking and balance difficulties. Symptoms usually begin on one side of the body, and spread gradually to the other. Some patients (probably more than commonly recognized in the past) may have memory or behavioral problems as the earliest or presenting symptoms.

Symptoms begin, on average, when an individual is in the early 60’s, but may start as early as in the 40’s. These include:

  • Stiffness, shakiness, jerkiness, slowness, and clumsiness in either the upper or lower extremities
  • Difficulty with speech generation (dysphasia)
  • Difficulty with articulation (aphasia)
  • Difficulty controlling the muscles of the face and mouth (dysarthria)
  • Walking and balance difficulty
  • Asymmetric onset of symptoms (occuring on one side of the body first then gradually moving to the other side)
  • Memory or behavior problems

Symptoms of advanced CBD include –

  • Parkinsonism (rigidity, slow movements, postural instability)
  • Tremor
  • Myoclonus (sudden, brief jerky movements)
  • Dystonia, including blepharospasm
  • Speech difficulty
  • Mild-to-moderate cognitive impairment (memory loss, difficulty planning or executing unrehearsed movements, dementia)
  • Sensory loss
  • “Alien hand/limb” phenomenon (difficulty controlling the movements of a limb, which seems to undertake movements on its own, sometimes combined with a feeling that the limb is not one’s own)

Corticobasal degeneration usually progresses slowly over the course of 6–8 years. Movement symptoms tend to progress slowly from one side of the body to the other or from leg to arm on the same side of the body.


  • Physical therapy – Physical therapy aims to help an individual regain strength, flexibility, coordination, and balance of movement through exercise and practice. Physical therapy also supports adaptation to changing ability levels, such as teaching a person how to get around using a wheelchair.
  • Occupational therapy – Occupational therapy focuses on supporting and adapting an individual’s ability to complete “activities of daily living” (ADLs), such as dressing, feeding, bathing, grooming, toileting, doing chores, and completing errands.
  • Speech-language and swallow therapy – A speech-language therapist is a professional who works with both communication disorders and swallowing impairment (dysphagia). Speech-language and swallowing therapy focus on supporting speech, language, cognitive-linguistic, communicative, reading, writing, and swallowing abilities, and providing adaptive strategies as needed.
  • Parkinson’s medications – Medications typically used for Parkinson’s disease, such as levodopa, may help to relieve some of the physical symptoms of corticobasal degeneration in some people.
  • Alzheimer’s medications – Medications aimed at relieving some of the symptoms of Alzheimer’s disease, such as memantine, may help some individuals see improvement in cognitive or physical symptoms.
  • Muscle relaxants / seizure medications – Stiffness and spasms may be partly relieved in some people with the use of muscle relaxants, such as baclofen, or seizure medications, such as clonazepam.
  • Antidepressants – Individuals who experience depression or anxiety may benefit from antidepressant medications.

Alternative Treatment


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