Corticobasal Degeneration
Corticobasal degeneration is a rare brain disease that causes areas of the brain to shrink and nerve cells to die over time, leading to increasing difficulty with movement, speech, memory, and swallowing.
Table of contents
- What is corticobasal degeneration?
- Other names for this condition
- Parts of the brain affected
- Symptoms and how they progress
- When symptoms typically begin
- What causes this condition
- How doctors diagnose the condition
- Treatment and management
- What to expect over time
- Support and resources
What is corticobasal degeneration?
Corticobasal degeneration is a rare brain condition that damages and destroys brain cells over time. The disease causes areas of the brain to shrink, and nerve cells break down and die. This ongoing process affects your ability to move, speak, remember, and swallow.[1][2]
The condition is progressive, which means symptoms slowly get worse over time. As the disease affects more of your brain, you may find it difficult to safely maintain your independence.[2]
Corticobasal degeneration is very rare. There are only about 2,000 to 3,000 people diagnosed with this condition in the United States. These numbers are likely underestimates because some people have not yet been accurately diagnosed.[8]
Other names for this condition
corticobasal syndrome, cortical basal ganglionic degeneration
Healthcare professionals often use the term corticobasal syndrome rather than corticobasal degeneration. This is because the clinical diagnosis given during life is increasingly called corticobasal syndrome, while the term corticobasal degeneration is reserved for cases confirmed through autopsy after death.[8]
Parts of the brain affected
- cerebral cortex
- basal ganglia
The word “corticobasal” refers to the two main parts of your brain that the disease affects. The cerebral cortex is the outer layer of nerve tissue that helps with memory, learning, voluntary movements, and your senses. The basal ganglia is a group of nerve cells deep within the brain that is important for learning and motor functions.[2]
“Degeneration” means deterioration or loss of function. In this case, it refers to the loss of function of these two parts of your brain.[2]
The condition primarily affects the cerebral cortex and the basal ganglia, but may affect other areas of your brain as it progresses.[5][2]
Symptoms and how they progress
The symptoms of corticobasal degeneration are very variable, and many people only have a few of them. The condition usually affects one side of your body much more than the other, at least at first.[3][4]
Common symptoms include trouble with movement on one or both sides of the body, which gets worse over time. You may experience poor coordination, trouble with balance, and stiffness. Your hands or feet may form postures that you cannot control, such as a clenched fist.[1]
Many people experience muscle jerks, spasms, twitches, or tremors. You might have difficulty with fine motor skills like buttoning a shirt or using a fork. Some people feel like they have lost control of one limb, or that a hand has a mind of its own. This is sometimes called alien hand syndrome.[2][4]
The condition can affect your ability to perform common movements or gestures. This difficulty carrying out learned purposeful movements is called apraxia.[2]
You may also experience changes in speech and language. Speech may become slow, effortful, and halting. Some people have trouble finding the right words. This language difficulty is called aphasia.[1][2]
Other symptoms can include trouble swallowing, changes in eye movements, loss of feeling in an area of your body, and slowed movements. Some people experience a decline in mental functioning, which is called dementia. You might also notice mood and behavior changes, such as attention problems, impulsiveness, irritability, or apathy.[1][2]
The condition affects everyone differently, and it often happens in stages. You might first notice symptoms targeting one limb, like an arm, or only one side of your body. Then, it progresses to your other arm and legs. You may feel clumsy when walking, and then not feel safe walking without support. You might stumble over a few words in a conversation, and then not be able to make coherent sentences over time.[2]
Symptoms worsen gradually as the disease affects more of your brain.[2] Eventually, people with the disease lose the ability to walk.[1]
When symptoms typically begin
The disease typically starts between ages 50 and 70. Most cases develop in adults aged between 50 and 70, with the average age of onset being 64.[2][3][4]
Symptoms may start as early as age 40, but no reported cases happen before age 40.[2]
What causes this condition
The cause of corticobasal degeneration is unknown. The disease results from the deterioration and death of brain cells and tissue. The breakdown usually starts in your cerebral cortex and basal ganglia.[2]
Researchers believe that a protein called tau plays a central role in corticobasal degeneration. Tau is a protein found naturally in brain cells. In healthy people, tau occurs naturally in the brain and is important for normal nerve cell function. However, in people with this condition, tau abnormally clumps together. These clumps, called neurofibrillary tangles, cause your brain cells to degenerate or die. This buildup of abnormal tau protein appears to damage nerve cells and other brain cells in certain areas, leading to problems with movement, speech, and memory.[1][2][4]
The exact reason why tau tangles happen is not well understood. Many people with corticobasal degeneration have a genetic change on chromosome 17 called the H1 haplotype. This gene change may increase the production of tau, causing the protein to clump together. However, researchers know that this gene is not the only factor that could cause corticobasal degeneration.[2]
The disease is not hereditary, and it has not been linked to any environmental exposures. The risk to other family members is very low.[3][4]
How doctors diagnose the condition
There is no single test for corticobasal degeneration. At this time, there is no specific test to diagnose the condition.[3][8]
The diagnosis is based on your medical history and neurological examination. Your doctor will gather information about your neurological symptoms, when they started, and how they impact your daily life. The diagnosis is based on the pattern of your symptoms.[3][4][8]
Because symptoms can be similar to other diseases such as Parkinson’s disease, progressive supranuclear palsy, Alzheimer’s disease, or stroke, it can be difficult to diagnose, especially in the early stages. Your doctor will try to rule out other conditions that can cause similar symptoms.[1][3][4]
You may need to have a brain scan to look for other possible causes of your symptoms. Scans like magnetic resonance imaging (MRI) or computed tomography (CT) are often useful. Imaging may rule out other diseases that may mimic corticobasal degeneration. Imaging may also find specific patterns of brain shrinkage. Sometimes, positron emission tomography (PET) scans can identify brain changes related to corticobasal degeneration.[4][12]
You may also have tests of your memory, concentration, and ability to understand language.[3] There are no blood tests for the diagnosis. However, your healthcare professional may test your blood or cerebrospinal fluid for certain proteins to determine whether Alzheimer’s disease is the cause of your symptoms.[12]
You will usually see a neurologist, who is a specialist in conditions that affect the brain and nerves.[3]
Sometimes the diagnosis is only made by autopsy. Even with careful examination during life, diagnosis can be difficult. A definitive diagnosis can only be made upon examination of brain tissue after death.[4]
Treatment and management
There is currently no cure for corticobasal degeneration and no treatment to slow it down. There is no effective treatment to stop the disease from getting gradually worse.[3][10][4]
Treatment is symptomatic, meaning it focuses on managing your symptoms and improving your quality of life. Care is best provided by a team of health and social care professionals working together. This is known as a multidisciplinary team.[3][10]
Members of your care team may include a neurologist, physiotherapist, speech and language therapist, occupational therapist, social worker, and specialist neurology nurse. A care plan will be drawn up with your team to outline the treatments you need and the support to make your life easier.[3][10]
Medications
There are currently no medicines that treat corticobasal degeneration specifically. However, depending on your symptoms, there are medicines that may help with muscle stiffness or contractions, jerky movements, memory and related mental abilities, irritability or depression, sleep problems, bladder problems, and pain.[10][18]
If Alzheimer’s disease is the underlying cause of your symptoms, medicines used to treat Alzheimer’s disease may be available, such as donepezil or memantine. These are called cholinesterase inhibitors, and they increase the level of a brain chemical called acetylcholine, which is important for attention and memory. Common side effects include nausea, diarrhea, and dizziness.[10][14]
Medications such as levodopa, which is used to treat Parkinson’s disease, can be given to address motor symptoms, but symptom response is uncommon and limited. This is in contrast to Parkinson’s disease, where motor symptoms typically respond well to levodopa.[14]
Medications can also be prescribed to address mood and anxiety symptoms. Antidepressants can be given to treat depression, anxiety, or irritability. Low doses of antipsychotic medications may be considered to help address delusional thinking or aggression.[14]
In general, people with corticobasal degeneration are sensitive to medicine side effects. Doses may start low and be increased gradually.[10][18]
Therapy and rehabilitation
Physical therapy can help you remain safely mobile. Regular exercise can help strengthen your muscles, improve your posture, and prevent stiffening of your joints. A physiotherapist can also teach you breathing exercises to use when you eat, to reduce your risk of developing pneumonia caused by food particles falling into your lungs.[10][18]
Occupational therapy can give you advice about the best ways to increase your safety and prevent trips and falls during your day-to-day activities. An occupational therapist can help provide strategies and techniques to compensate for the cognitive and motor changes. They can also arrange access to mobility equipment such as walking frames and wheelchairs, as well as equipment to help with everyday activities like washing, dressing, eating, and using the bathroom safely.[10][14][18]
Speech and language therapy can help assess and treat speech and swallowing problems. A therapist can teach techniques to help make your voice as clear as possible and can advise you about suitable communication aids or devices that you may need as the disease progresses. They can also improve language and communication, and advise you about different swallowing techniques.[10][14][18]
Diet and nutrition
A dietitian can advise you about making changes to your diet, such as including food and liquids that are easier to swallow, while ensuring that you eat a balanced diet. Working together with a speech therapist, they may suggest altering the consistency of your food to make swallowing easier.[10][18]
Feeding tubes may be recommended for severe swallowing problems, where the risk of malnutrition, weight loss, fatigue, and dehydration is increased. You should discuss the pros and cons of feeding tubes with your family and care team. The decision about whether and when to consider a feeding tube depends on the individual and should be discussed with a specialist.[10][18]
Supportive care
Palliative care aims to relieve pain and other distressing symptoms while providing psychological, social, and spiritual support. It can be offered at any stage of the disease, alongside other treatments. Palliative care can be received in a hospice, at home or in a residential home, or on a day patient basis.[10][18]
What to expect over time
Corticobasal degeneration gets worse over 6 to 8 years. The average life expectancy for someone with this condition is around 6 to 8 years from when their symptoms start. However, this is only an average and the disease is very variable. People with the condition can sometimes live longer.[1][3][5]
The disease has high morbidity and poor prognosis. It may shorten your life expectancy and lead to life-threatening complications. Difficulty swallowing can cause choking, or inhaling food or liquid into the airways. This can lead to pneumonia, which can be life-threatening.[3]
Many people find it helpful to plan ahead with their doctors to make decisions about what to do in later stages of the illness.[3]
Support and resources
Good care and assistance can help someone with corticobasal degeneration be more independent and enjoy a better quality of life. Support is available to help you and your family cope with the condition.[3]
Support groups can help you learn strategies from other caregivers and learn more about the condition. Organizations such as CurePSP and the Association for Frontotemporal Degeneration offer support groups and additional resources for living with corticobasal syndrome.[8][14]
You may want to consider participating in clinical research to help researchers learn more about the disease and perhaps find better ways to safely detect, treat, or prevent it. All types of volunteers are needed, and participating in a clinical trial can contribute to advancing care for people with this condition.[5]
