Spinocerebellar Degeneration

"Spinocerebellar degeneration" describes what happens in spinocerebellar ataxia (SCA): nerve cells in the cerebellum, the brain's coordination centre, and in its pathways through the brainstem and spinal cord slowly stop working and die. The term is often used interchangeably with SCA, a group of more than 40 inherited conditions.

What it causes

As the cerebellum and its connections lose nerve cells, coordination gradually gets worse. Typical effects are:

• Walking and balance: unsteadiness, a wide-based gait and more falls, usually the first sign
• Hands: clumsiness and difficulty with writing, buttons or using cutlery
• Speech: slurred, slow or uneven speech (dysarthria)
• Eyes: jerky or slowed eye movements, and sometimes double vision
• Swallowing: often affected later, raising the risk of chest infections

Some types also cause stiffness, tremor, nerve damage in the legs, vision loss (SCA7) or changes in thinking. Symptoms usually start in adulthood and progress over many years. See SCA symptoms and how SCA progresses.

How it's inherited

Almost all SCAs are autosomal dominant:

• Only one copy of the changed gene, from one parent, is enough to cause the condition.
• Each child of an affected parent has a 50% chance of inheriting it.
• It doesn't skip generations, although in some families symptoms appear earlier in each generation (anticipation).

This is different from recessive ataxias such as Friedreich's ataxia, where a child has to inherit a changed gene from both parents, the risk for each child of two carriers is 25%, and carriers have no symptoms.

In the most common SCAs, the gene change is a "repeat expansion": a three-letter stretch of DNA (CAG) is repeated too many times, producing a faulty protein that slowly damages nerve cells. Longer repeats usually mean earlier and faster-progressing disease. Read more about SCA and inheritance.

Inherited vs acquired cerebellar degeneration

The cerebellum can also be damaged by things that aren't inherited, including long-term heavy drinking, stroke, multiple sclerosis, vitamin deficiencies, an underactive thyroid, some medicines, gluten ataxia and, rarely, an immune reaction to a cancer elsewhere. These acquired ataxias aren't SCA, but they can look similar, and some can be treated. That's why anyone with unexplained loss of coordination should be assessed by a neurologist, with blood tests, a brain scan and, where appropriate, genetic testing. See cerebellar atrophy for more on the different causes.

Treatment

There's no cure, and no approved treatment yet slows spinocerebellar degeneration, although trials are under way. Physiotherapy, speech and language therapy, occupational therapy, mobility aids, medicines for specific symptoms and genetic counselling all help people stay safe and independent for longer. See treatment options.

This page is for general information and isn't a substitute for advice from your own doctor.