Under the Umbrella -- Corticobasal Degeneration
Overview
Corticobasal Degeneration (CBD) is a progressive neurological disorder that presents primarily as a movement disorder, characterized by lack of movement and muscle rigidity. Initial symptoms, which typically begin at or around age 60, may first appear on one side of the body (unilateral), but eventually affect both sides as the disease progresses. A patient with CBD may first present with language disorder, and develop the motor symptoms over time.
Key Clinical Features
Three symptoms associated specifically with CBD (though not all are seen in all patients) are:
* Alien hand syndrome, in which the patient does not recognize his hand as being part of his own body and can't control movement of the hand or arm;
* Apraxia (loss of the ability to make familiar, purposeful movements),and difficulty with spatial orientation, manifested as difficulty using utensils, combing one's hair, or dressing;
* Acalculia, difficulty carrying out simple calculations, such as adding and subtracting.
Motor symptoms of CBD are similar to those found in Parkinson disease, such as:
* Poor coordination
* Akinesia (an absence of movements)
* Rigidity (a resistance to imposed movement)
* Disequilibrium (impaired balance)
* Limb dystonia (abnormal muscle postures)
* Myoclonus (muscular jerks)
* Dysphagia (difficulty swallowing)
Visual-spatial impairments An individual with corticobasal degeneration has difficulty orienting objects in space. This may be seen in an inability to get one's arm through a sleeve when getting dressed.
Language symptoms including hesitant and halting speech (progressive aphasia), are seen in some patients.
Key Pathologic Features
Upon autopsy, the brain tissue of CBD patients is characterized by nerve cell loss, gliosis and atrophy (shrinkage) of the posterior frontal and/or parietal lobes and substantia nigra. Swollen nerve cells that contain neurofilament, and inclusions similar to those seen in Pick's disease, may be observed, as well.
Cause
Scientists have recently determined that these affected cells contain deposits of an abnormal form of the protein tau.
Genetics
The majority of CBD is not hereditary.
Treatment
There is no treatment available to slow the course of Corticobasal degeneration, and the symptoms of the disease are generally resistant to therapy. Drugs used to treat Parkinson disease-type symptoms do not produce any significant or sustained improvement for motor symptoms.
Management and Prognosis
Corticobasal degeneration usually progresses slowly over the course of 6 to 8 years.
Although there is no treatment, therapy does help to manage the symptoms, and perhaps delay their progression. Specifically, occupational and physical therapies provide passive range of motion in affected muscles, and help prevent contractures (paralysis of a muscle in the tense state) in rigid limbs. Speech therapy may help delay the progression of language symptoms.
Death in CBD is generally caused by pneumonia or other complications of severe debility, such as sepsis (an infection throughout the body) or pulmonary embolism (a blood clot that blocks a major blood vessel in the lung).
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Material prepared by Jennifer M. Farmer, MS, CGC, Website Clinical Consultant and Susan L-J Dickinson, MS, CGC, Website Medical and Science Writer.
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