Ataxia is the name given to involuntary discoordination of muscles of our body. Ataxia interferes with coordinated motor function. Thus, ataxia affects speech, ambulation and fine motor coordination of our body. In this article, we will discuss about one such form of ataxia called Spinocerebellar Ataxia, which is caused as a result of genetic mutation.1
What Is Spinocerebellar Ataxia?
When people talk about Spinocerebellar Ataxia (SCA), they actually refer to a collection of neurodegenerative disorders, which cause progressive clumsiness. The medical research has identified more than 30 different types of Spinocerebellar Ataxias, each one of them being caused by a different genetic mutation. The continuous ongoing research of this terrible disease has indicated there are several other genetic mutations, which are as yet unknown. Thus genetic mutation has caused various types Spinocerebellar Ataxia. Even though there are numerous variations of Spinocerebellar Ataxia, this disorder is rare. But among the diseases caused by genetic mutation, Spinocerebellar Ataxia is one of the most common genetic disease.
Causes of Spinocerebellar Ataxia
Spinocerebellar Ataxia (SCA) is caused by genetic mutation. The genetic mutation resulting in Spinocerebellar Ataxia is also known as "expansion mutations". Expansion mutation results in repeated formation of several nucleotides of chromosome.2 The nucleotide formation repeats periodically in patients suffering with Spinocerebellar ataxia unlike in healthy individual.
Spinocerebellar Ataxia is generally an inherited disease condition. It is autosomal dominant disease, which means that if one parent has this condition then there is more than 50% chance that their child will have it as well.
Symptoms of Spinocerebellar Ataxia
In Spinocerebellar Ataxia (SCA), there will be slowly progressive discoordination of gait along with poor coordination of hands, speech, and eye control. Frequent hand motions causes intentional tremor in affected individuals. More frequently, there is atrophy of the cerebellum. Different ataxias affect different regions of the cerebellum. Spinocerebellar Ataxia causes unsteady motion due to discoordination of muscles.
The list of symptoms and signs of Spinocerebellar Ataxia are as follows-
- Unsteady Walk- Patient is unable to sustain normal walk because of loss of balance and coordination. Walk is uncoordinated because of uncoordinated muscle contraction involving different group of muscles.
- Poor Co-ordination- The function of upper and lower extremity muscles are affected because of lack of normal coordination. Patient is unable to comb hair or use hand for fine movements like eating or opening door with key. Similarly coordination of lower extremity is also affected resulting in unsteady walk.
- Speech Abnormality- The uncoordinated muscle contraction of tongue and pharynx muscles causes abnormal speech and sound of words.
- Nystagmus- The uncoordinated contraction of external eye muscles causes nystagmus.
- Food Regurgitation in Mouth- Swallowing of the food is uncoordinated and patient is unable to swallow food into esophagus. Food content remains in the mouth and pharynx.
Diagnosis for Spinocerebellar Ataxia
The Investigations Conducted For Spinocerebellar Ataxia Are
- MRI scan: This may reveal atrophy of cerebellum and brainstem.
- EEG: This may reveal salient features of epilepsy.
- EMG: This may reveal continuous motor unit activity.
- Genetic testing is also carried out and if positive it will show a defect in chromosome resulting abnormal metabolism.
Treatment for Spinocerebellar Ataxia
At present, there is no cure for Spinocerebellar Ataxia (SCA), which is termed as a progressive disease that is irreversible. Not all forms of Spinocerebellar Ataxia cause severe disability but generally treatments are geared towards control of symptoms and not the disease. Individuals with hereditary form of Spinocerebellar Ataxia experience other symptoms apart from ataxia and so medications and/or therapies are given for those symptoms.
Use of Cane or Walker in Spinocerebellar Ataxia -
- Use of Cane or Walker for Ambulation- Patient is encouraged to use cane or walker to ambulate if patient has a tendency to fall.
Physical Therapy For Spinocerebellar Ataxia
- Patient is advised join physical therapy treatment periodically to train some of the uncoordinating muscles.
Muscle Relaxants For Treating Spinocerebellar Ataxia -
- Severe prolonged muscle contraction causes spastic condition and pain. Patient is often treated with muscle relaxants like Baclofen to prevent spastic contraction or relax the muscles, which is contracting and causing pain.
Speech Therapy For Patients Suffering From Spinocerebellar Ataxia
- Patient suffering with speech deformity is treated by speech therapist to improve use of muscles so as to sound the words in correct phonic.
Occupational Therapy For Spinocerebellar Ataxia
- Patient is referred to occupational therapy so that patient can learn to modify some of the motor function.
Life Expectancy In Spinocerebellar Ataxia
The research study published suggests life expectancy is between 19 to 25 years.3
1. Spinocerebellar ataxia type 11 (SCA11) is an uncommon cause of dominant ataxia among French and German kindreds.
Bauer P1, Stevanin G, Beetz C, Synofzik M, Schmitz-Hübsch T, Wüllner U, Berthier E, Ollagnon-Roman E, Riess O, Forlani S, Mundwiller E, Durr A, Schöls L, Brice A. Arch Dis Child. 2006
J Neurol Neurosurg Psychiatry. 2010 Nov;81(11):1229-32. doi: 10.1136/jnnp.2009.202150. Epub 2010 Jul 28.
2. A new dominant spinocerebellar ataxia linked to chromosome 19q13.4-qter.
Brkanac Z1, Bylenok L, Fernandez M, Matsushita M, Lipe H, Wolff J, Nochlin D, Raskind WH, Bird TD.
Arch Neurol. 2002 Aug;59(8):1291-5.
3. Survival probability in ataxia telangiectasia.
Crawford TO1, Skolasky RL, Fernandez R, Rosquist KJ, Lederman HM.
Arch Dis Child. 2006 Jul;91(7):610-1.