Corticobasal degeneration

Corticobasal degeneration (CBD) is a rare brain disease that can cause a collection of symptoms known as corticobasal syndrome (CBS). CBS symptoms include trouble with thinking, speaking, movement on one side of the body, poor coordination and stiffness.

Corticobasal degeneration happens when a protein called tau builds up in the brain. This buildup causes nerve cells to die and areas of the brain to shrink. While CBD is a common cause of CBS, these symptoms can be due to other conditions such as Alzheimer's disease or progressive supranuclear palsy.

Corticobasal degeneration affects the area of the brain that processes information and brain structures that control movement. People with this disease have trouble with movement on one or both sides of the body. Trouble with movement gets worse over time.

Symptoms also may include poor coordination, stiffness, trouble thinking and trouble with speech or language.

The only way to confirm CBD as the cause of CBS is to examine brain tissue after death, but exams and tests can help diagnose the condition during life.

There is no cure for CBD yet, but medicines and therapies can help to manage symptoms.

Symptoms caused by CBD can affect thinking, language, behavior and movement. Changes in thinking or behavior may appear before changes in movement. When these symptoms show up, they may be diagnosed as corticobasal syndrome (CBS). More tests may be needed to know if CBD is the root cause of CBS.

Mental processing symptoms may include:

• Trouble with decision-making, planning or problem-solving. These also are known as executive function skills.
• Memory changes.
• Difficulty with visual and spatial awareness.
• Not being able to do a learned task. This is known as apraxia.
• Speech changes, such as slow and halting speech. This is known as aphasia.

Behavioral symptoms may include:

• Depression, withdrawing or feeling like nothing matters.
• Feeling irritable or agitated on a regular basis.
• Acting out, also known as compulsivity.
• Fixations on certain behaviors, such as putting objects in the mouth.
• Marked increase in sexual desire.
• Laughing for no reason.

Movement symptoms may include:

• Trouble moving on one or both sides of the body, which gets worse over time.
• Trouble with balance or coordination.
• Stiffness.
• Postures of the hands or feet that can't be controlled. For example, the hand may form a clenched fist.
• Muscle jerks, or limbs that seem to move on their own.
• Trouble swallowing.
• Changes in eye movements.

Symptoms tend to get worse over time. Eventually, people with the disease lose the ability to walk. A wheelchair or other aids may be needed as movement declines. CBD can cause serious complications that often lead to death. Life expectancy with confirmed CBD can range from 2 to 12 years. But it tends to last between 6 to 8 years on average.

Corticobasal degeneration is due to a buildup of a protein called tau in brain cells. The buildup of tau may lead to the breakdown of the cells. This breakdown can lead to signs and symptoms of corticobasal syndrome.

Most people with CBS have CBD, but other causes are common. These include Alzheimer's disease, progressive supranuclear palsy, Pick's disease and Creutzfeldt-Jakob disease.

While risk factors for CBD aren't clearly understood, family genes may play a role. Differences in certain genes may raise the risk of CBD. These genes include MAPT and MOBP.

MAPT helps the body make tau. MOBP supports processes that create the protective covering of the nerves, called myelin. More research is needed to fully understand the connection between these gene changes and CBD.

Lifestyle choices or environmental factors do not seem to play a role in getting or preventing CBD.

People with corticobasal degeneration may develop serious complications. This is because CBD affects the body's functions that control breathing, swallowing and movement. Complications often lead to death.

Complications include:

• Pneumonia.
• Choking.
• Blood clots in the lungs.
• Sepsis, which is a dangerous response to an infection.

Diagnosing corticobasal degeneration can be hard. The collection of symptoms that it causes is called corticobasal syndrome (CBS). CBS can result from corticobasal degeneration or from other conditions, including progressive supranuclear palsy, Alzheimer’s disease, Pick’s disease or Creutzfeldt-Jakob disease.

The only way to confirm that corticobasal degeneration is the cause of corticobasal syndrome is by examining brain tissue after death. During life, the diagnosis is based on symptoms, imaging tests and expert evaluation to rule out other conditions.

During exams, care team members will discuss your symptoms and test the function of your nervous system. They may look at how you move, swallow, speak, solve problems or make decisions.

Other tests can offer other clues but may not confirm the difference between CBD and similar conditions. More research is needed to improve testing options. Current testing options may include:

MRI and CT scans

MRI and CT scans can show shrinking in the brain. Also, they can help rule out other conditions such as stroke. Sometimes, these tests are performed every few months to look for changes in the brain.

Positron emission tomography (PET) scans

PET scans can show brain changes related to CBD. During PET scans, a safe, radioactive tracer is used. This tracer travels to the more active parts of your brain, making them "light up" on the scan. Areas that are less active will be dimmer. A special kind of PET scan, called an FDG PET scan, uses radioactive sugar as a tracer. Because the brain uses a lot of sugar when active, the contrast shows more clearly between high and low activity in the brain.

This lower activity in the brain is called hypometabolism. When hypometabolism is uneven between the two sides of the brain, it's called asymmetrical hypometabolism. If the scan shows asymmetrical hypometabolism in certain lobes of the brain, it can be a strong sign of corticobasal degeneration, especially if it affects lobes at the front and sides of the brain. These are called the frontal and parietal lobes. But asymmetrical hypometabolism of the frontal and parietal lobes can be caused by other conditions as well.

Another type of PET scan, called a tau PET, can show clumps of protein in the brain that may cause CBD.

Blood and fluid tests

Your healthcare professional may test your blood or cerebrospinal fluid (CSF). These tests cannot confirm or rule out CBD. Nor can they confirm the difference between CBD and certain diseases such as Parkinson's disease. But they can confirm or rule out Alzheimer's disease. Also, they can show factors that may lead to CBD. These factors include a buildup of tau proteins or protein molecules that don’t stay in their correct shape. Protein molecules that lose shape and fold differently are called amyloid proteins. Amyloid proteins can become clumped together, forming amyloid plaques that cause damage.

Currently, there are no treatments that help slow the progression of corticobasal degeneration. But there may be options to help you manage your symptoms. If your symptoms are due to Alzheimer's disease, new medicines may be available.

Treatments to help you manage your symptoms may include:

Medicines

Medicines cannot cure CBD and may offer only limited relief from symptoms. Still, the following medicines may be prescribed for the mild relief they may give.

• Parkinson's medicines. Because CBS can be caused by different conditions including CBD and Parkinson's disease, medicines used to treat Parkinson's may be prescribed. A common choice is levodopa. A special combination medicine, called carbidopa-levodopa may be prescribed when CBD might be a possible cause. This medicine is meant to help relieve stiffness and other movement symptoms. Also, levodopa may be used to rule out Parkinson's. If there is no response to levodopa, it is likely that Parkinson's is not the cause of CBS.
• Antiseizure medicines. Medicines such as gabapentin may be used to relieve muscle shakes and jerks.
• Muscle relaxants. Medicines such as baclofen may help ease stiffness.
• Botox. Injections of botulinum toxin may help relieve spasm and pain.
• Mental processing medicines. Medicines called cholinesterase inhibitors may help with memory or other mental processing symptoms. Examples of cholinesterase inhibitors include donepezil and rivastigmine. These medicines also are used in the treatment of dementia.

Supportive therapies

• Physical therapy. A physical therapist can help with range of motion, balance and coordination.
• Occupational therapy. An occupational therapist can help with doing routine tasks such as dressing or eating.
• Speech therapy. A speech therapist can help with communication and swallowing.
• Mental health support. Depression is a common symptom of CBD. Noticing and treating depression early is important.
• Walking devices. Devices such as wheelchairs should be used to prevent falls.
• Nutritional support. A dietitian can help create a balanced diet and reduce the risk of choking.
• Magnetic therapy. Although more research is needed, transcranial magnetic stimulation (TMS) shows promise in treating mental health and nervous system conditions. In this treatment, a large magnet is placed near the head. It delivers quick, gentle, magnetic pulses. These pulses pass through the skull and help balance activity in different areas of the brain.

You may start by seeing your healthcare professional. Or your healthcare professional may refer you to a specialist, such as a neurologist, right away.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance. For example, you might ask if you need to fast before a specific test. Make a list of:

• Your symptoms. Include any that seem unrelated to the reason for your appointment.
• Key personal information. This includes major stresses, recent life changes and family medical history.
• All medicines, vitamins or other supplements you take. Include the doses.
• Questions to ask. This can help you make the most of your time at the appointment.

Take a family member or friend along to help you remember the information you're given.

For corticobasal degeneration, some basic questions to ask include:

• What's likely causing my symptoms?
• Other than the most likely cause, what are other possible causes for my symptoms?
• What tests do I need?
• Is my condition likely temporary or chronic?
• What's the best course of action?
• What are the alternatives to the primary approach you're suggesting?
• I have these other health conditions. How can I best manage them together?
• Are there limits I need to follow?
• Should I see a specialist?
• Are there brochures or other printed materials I can have? What websites do you recommend?

Don't hesitate to ask other questions you may have.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, such as:

• When did your symptoms begin?
• Have your symptoms been continuous or occasional?
• How bad are your symptoms?
• What, if anything, seems to make your symptoms better?
• What, if anything, seems to make your symptoms worse?