Corticobasal degeneration (CBD) is a rare neurological disease in which some portions of the brain deteriorate or degenerate. It involves the cerebral cortex and the basal ganglia. It is known by the characteristics like disorders in movement and cognitive dysfunction.
CBD generally occurs in patients who are about 45-70 years of age. The duration of the disease is about 5-10 years.
Corticobasal Degeneration Causes
The exact cause of CBD is not known. Studies of the brain tissues have shown certain changes in the brain cell. These changes are involved with a brain protein called tau. An autopsy of the brain tissue shows nerve cell loss, gliosis and atrophy or shrinkage of the deeper layers in the posterior frontal and or parietal lobes and the substantia nigra. Swollen or ballooned nerve cells containing tau and phosphorylated neurofilament epitopes. Affected CBD cells contain abnormal forms of this protein tau, as found by scientists. Tau is present in all neurons and plays an important role in the structure and function of neurons. The abnormally phosphorylated tau is the biochemical change that keeps it from functioning properly.
Corticobasal Degeneration Symptoms
In this condition, there is severe damage in the cortex (the outer layer of the brain) – mostly in the fronto-parietal regions found near the center-top of the head. Other deeper brain locations also experience an impact which includes the basal ganglia and hence the name is given to this disease.
Picture 1 – Corticobasal Degeneration
The symptoms of this syndrome can be divided into the following categories:
The motor symptoms of CBD, same as those found in Parkinson’s disease, include:
- Tremor sensation
- Slowness or absence of movements or lack of spontaneous movements
- Limb dystonia or abnormal posture of the extremities
- Acalculia, or trouble in carrying out simple calculations such as adding or subtracting.
- Alien hand syndrome, in which a patient does not understand the actions of his hand and cannot regulate the movement of the hand or arm.
- Visual Spatial Impairment or difficulty in orienting objects in space.
- Apraxia, an inability to make familiar purposeful movements that get demonstrated as trouble in using familiar objects or doing familiar things.
Language symptoms, such as hesitant and halting speech, are also observed. The other difficulties include trouble in finding the right words to express and also naming problems.
Corticobasal Degeneration Diagnosis
It is difficult to detect the disease in its early stage since CBD is quite similar to neurodegenerative diseases. Diagnosis is conducted with the help of some comprehensive neurological exam which is combined with laboratory evaluations.
CT or MRI scans can also be used as they provide images of asymmetric atrophy of the fronto-parietal regions of the cortex.
The imaging methods that are mostly utilized when studying or diagnosing CBD, involve:
- Magnetic resonance imaging (MRI)
- Fluorodopa positron emission tomography (FDOPA PET)
- Single-photon emission computed tomography (SPECT)
MRI images are helpful in showing atrophied portions inside the brain. These help in identifying different parts of the brain that have experienced a negative impact due to the complications associated with CBD. The images also show atrophy in the corpus callosum. Functional MRI has been used to study the activation patterns in various portions of the brain.
SPECT conducts perfusion analysis of the parts of the brain. The evaluation comprises of monitoring blood release into varied locations in tissue or organ regions. Tissue can be characterized as experiencing different types of blood flow:
SPECT usually reveals hypoperfusion inside both the posterior regions of the frontal and parietal lobes. Additional studies show the presence of abnormalities in perfusion in the thalamus, basal ganglia and pontocerebellar locations of the brain.
FDOPA PET scanning is a method for identifying CBD. It focuses on analyzing the efficiency of neurons in the striatum which utilize the neurotransmitter dopamine. This method also helps to distinguish between CBD and Parkinson’s disease.
Other clinical tests or procedures that detect the presence of dopamine inside the brain have shown similar results. Β-CIT acts as an indicator for presynaptic dopaminergic neurons. IBZM, on the other hand, is a tracer which reveals affinity for the postsynaptic neuron of the same type. AN EEG (Electroencephalogram) is another method which, with time, shows changes in the brain function which are consistent with neuro-degeneration.
Corticobasal Degeneration Treatment
There are no specific drugs or therapies to cure this disease as the exact cause of the CBD is not known. Medications are provided to cure the symptoms.
There are some medications that help treat CBD directly. These involve:
Memantine is designed to treat Alzheimer’s disease. It also helps reduce abnormal brain activity, which helps slow the progression of abnormal brain activity which improves mental and physical functions. However, one should always discuss with the doctor. The side effects of Memantine are drowsiness, shortness of breath, headaches, dizziness and constipation.
It is generally used for curing Parkinson’s disease. This medication may provide a short term improvement in muscle stiffness and rigidity as it is less effective on people with CBD. Levodopa works by maximizing the levels of a brain chemical called dopamine which transfers messages from the brain which regulate and supervise the body’s movements. The common side effects of Levodopa are nausea and indigestion. If used for a long time, it may produce side effects like:
- Involuntary physical movements, such as jerking as well as mood changes
It is used to treat muscle stiffness and rigidity. It works by blocking out the nerve signals that cause muscle stiffness. The side effects of Baclofen include:
- Increased need to urinate
The side effects pass away once the body gets habituated to them.
It is used for treating symptoms of muscle spasm. The side effects of this medication include:
- Loss of co-ordination
- Light headedness
- Muscle weakness
Alcohol intake must be reduced during this time as it only aggravates the symptoms and also magnifies the impact of alcohol.
It is a therapy that is used to treat the symptoms of Dementia. It also includes participating in activities and exercises that are designed to improve memory, problem solving skills and language ability of patients. It usually consists of two 45-minute sessions a week. This therapy is provided by a trained expert.
Speech & Language Therapy
This therapy helps improvise the speech and swallowing difficulties. It also teaches patients varied techniques to make the most of the speech function by training the voice and making it clear. Patients need some technological support to communicate with other people when CBD progresses. A wide range of communication technologies are available these days.
It helps in making use of remaining mobility by using exercise. Regular exercise helps strengthen the muscles, improve the posture of the body and prevent stiffening of the joints.
In this process, therapists advise patients on how to cope with problems while carrying out daily activities and how to prevent trips and falls. An occupational therapist is also able to identify places in the home that might cause accidents or falls, such as poor lighting, loosely kept rugs, crowed corridors and walk ways.
Treatment of Dysphagia
Dysphagia or trouble and difficulty in swallowing food and water should be treated or it will result problems of constipation. The treatment involves exercises to help stimulate the nerves which are used to trigger your swallowing reflex and strengthen the muscles which are used during swallowing. A lot of physical techniques are there to make swallowing easier.
Picture 2 – Corticobasal Degeneration Image
If the symptoms of dysphagia get severe it will require more additional treatment. A dietician may make some changes in the diet such as adding more food and liquids that are easier to swallow while making sure that the patient receives a balanced diet.
Corticobasal Degeneration progresses slowly over the years. Death in CBD is usually caused by pneumonia and other complications such as sepsis or pulmonary embolism which means clotting of blood that blocks out a vital blood vessel in the lung.