Spinocerebellar Degeneration

Spinocerebellar degeneration is another name for spinocerebellar ataxia (SCA). It describes what happens in these conditions: nerve cells in the cerebellum (the part of the brain that coordinates movement), and in its connections through the brainstem and spinal cord, gradually degenerate and die. "Spinocerebellar ataxia" is not one single diagnosis but a group of more than 40 related inherited conditions.

What are the symptoms?

The main symptom is ataxia, a loss of coordination. It usually starts with unsteady walking and poor balance, and then gradually affects:

• Hand coordination, making tasks such as writing, eating or doing up buttons harder
• Speech, which may become slurred or slow (dysarthria)
• Eye movements, causing jerky or slow eye movements and sometimes double vision
• Swallowing, especially in the later stages

Depending on the type, people may also have muscle stiffness, tremor or other movement problems, nerve problems in the limbs, sleep problems, depression, or changes in thinking and memory.

Symptoms usually begin in adulthood, often between the ages of 30 and 50, although some types can start in childhood or much later in life. Over time, many people need a walking aid and later a wheelchair. Some need help with eating and writing, and some use communication aids as their speech changes.

How does spinocerebellar degeneration develop?

Spinocerebellar ataxias are genetic. They are caused by changes (variants) in specific genes and are usually inherited in an autosomal dominant way. Only one parent needs to pass on the changed gene, and each child of an affected parent has a 50% chance of inheriting it.

In the most common types (SCA1, SCA2, SCA3, SCA6 and SCA7), the change is a "repeat expansion". A short sequence of DNA letters, three letters long (CAG), is repeated many more times than normal. This produces an abnormal form of a protein that gradually damages nerve cells. In general, the longer the repeat, the earlier symptoms start and the faster they progress.

Spinocerebellar degeneration vs other causes of cerebellar degeneration

The cerebellum can also degenerate for reasons that are not inherited. Causes include stroke, long-term heavy alcohol use, multiple sclerosis, certain vitamin deficiencies, an underactive thyroid, some medicines and toxins, and rarely an immune reaction linked to cancer elsewhere in the body. These are known as acquired ataxias. They are not spinocerebellar ataxia, but they can look similar, and some are treatable. This is one reason why careful assessment by a neurologist, including blood tests, a brain scan and genetic testing, is so important.

SCA can also be mistaken for other conditions, such as Parkinson's disease or multiple system atrophy, particularly when there is no known family history.

How is SCA managed?

There is no cure for SCA, and at present no approved treatment that slows the degeneration itself, although several possible treatments are being tested in clinical trials. Treating symptoms does not stop the disease progressing, but it can make a real difference to comfort, safety and independence. Care usually includes:

• Physiotherapy and regular exercise to help balance, strength and mobility
• Speech and language therapy for speech and for safer swallowing
• Occupational therapy, mobility aids and home adaptations
• Medicines for specific symptoms, such as muscle stiffness, tremor, sleep problems or depression
• Genetic counselling for the person and their family

Living with a progressive condition can be hard for the person with SCA and for those around them. Practical and emotional support from family, friends, specialist ataxia services and patient charities helps people stay as active and independent as possible for as long as possible.