Ataxia represents a neurological disorder that entails the disturbance in coordination of voluntary movement. It attacks various parts of the body and can cause balance and walking problems, speech disorders, and disturbances in fine motor skills. The name "ataxia" is derived from the Greek word "a-taxis," (without order) accurately describing the disorderly, clumsy movements typical of the disease. Ataxia could be due to damage to various parts of the nervous system, most commonly the cerebellum, the part of the brain responsible for motor coordination. The causes of ataxia may range from genetic mutations to injury and infections, even vitamin deficiencies may originate it. Understanding its symptoms and progression is paramount for an accurate diagnosis and proper treatment.

Causes of ataxia

The causes of ataxia can be genetic or acquired.^1,2,3

Genetic mutations

• Spinocerebellar ataxias (SCAs) are autosomal dominant disorders caused by gene mutations, often involving the repetition of DNA sequences
• Friedreich's ataxia is an autosomal recessive disorder caused by mutations in the frataxin gene. The malfunction of the frataxin protein leads to mitochondrial dysfunction

Acquired causes

• Chronic alcohol abuse can give rise to cerebellar degeneration, which can present as ataxia
• Autoimmune diseases, such as multiple sclerosis and coeliac disease, can cause ataxia due to  immune-mediated damage to the central nervous system
• Cancer, such as gynecologic, breast, and Hodgkin lymphoma, can originate from ataxia due to autoantibodies against the nervous system

Understanding ataxia symptoms and their progression

A deteriorated sense of balance and coordination, difficulty walking, or an uncoordinated gait are usually the first symptoms. Disease progression may also include a change in muscle tone, spasticity, rigidity, and alterations in eye movements, such as nystagmus (rapid involuntary eye roving). Hence, the progression of the degeneration in ataxia highlights the need for early diagnosis and immediate symptom management. The rate of progression can be different among the types of ataxias. For example, in the context of SCA, the rate of progression varies widely, depending on the subtype and genetic factors.²

Key symptoms and their impact

Gait abnormalities

Abnormal gait is often the initial characteristic sign of ataxia, manifested as unsteady balance that leads to walking problems. In ataxic patients, the speed and rhythmic characteristic features of a normal gait are greatly compromised, and step length is reduced in size. The variation between subjects is noticeable compared to healthy control subjects, making gait analysis an important diagnostic and explanatory test. Moreover, patients tend to increase the base of walking in a bid to maintain their balance. Thus, a gait alteration demonstrates the body's compensatory ability to maintain balance.⁴

Hand and arm coordination issues

Another common symptom of ataxia is the lack of coordination and clumsiness of the hands and arms. This manifests as difficulty performing tasks that require fine motor skills, such as writing, buttoning clothes, or handling small objects. These symptoms arise because the cerebellum is unable to precisely control the timing and force of muscle contractions, which is a hallmark of its dysfunction.

People with ataxia may notice that their hands shake or that they cannot move their arms smoothly. This incoordination can severely impact daily activities and reduce the quality of life.⁵

Speech disturbances, or dysarthria, are also common in people with ataxia, who experience slurred or slow speech caused by the incoordination of the muscles involved in speaking. Dysarthria can sometimes precede other motor symptoms, making it an early indicator of ataxia.

People with ataxia may find that their speech becomes less clear over time, and they may struggle to control the volume and pitch of their voice. This symptom can be socially isolating, affecting the ability to communicate effectively.² 

Progression of symptoms in ataxia: understanding the journey

Worsening motor coordination

As ataxia progresses, walking becomes more difficult, and the risk of falls increases. People with ataxia are more likely to fall, which can lead to serious injuries. Over time, fine motor skills and dexterity are also lost, making it difficult to perform everyday tasks such as buttoning clothes and writing.⁶

Muscle tone and reflex changes

• Development of muscle spasticity or rigidity: Muscle tone abnormalities are common as ataxia advances. You may develop spasticity (stiff or rigid muscles) or other changes in muscle tone, impacting their movement and comfort
• Reflex changes: They are another hallmark of progressing ataxia. Reflexes may become hyperactive or diminished (weakened), complicating movement and stability

Eye movement abnormalities

• Nystagmus: This condition involves quick, uncontrollable movements of the eyes, disrupting vision and balance
• Difficulty in maintaining a steady gaze: Maintaining a stable gaze can become increasingly difficult, leading to visual disturbances and difficulties with coordination⁵

Speech and swallowing difficulties

• Dysarthria, or slurred speech, often worsens, making communication more difficult for patients
• Dysphagia (swallowing problems) can pose serious health risks, including the potential for food or liquids to enter the lungs, leading to aspiration pneumonia

Symptoms not related to movement

Cognitive impairment

Cognitive functions may decline, leading to problems with memory and performing tasks that require mental effort and coordination. The extent and nature of cognitive impairment can vary widely among different types of ataxia, with some types being more affected than others.⁵

Emotional and psychological changes

Emotional well-being is often impacted, with higher rates of depression and anxiety reported among patients with ataxia. These emotional and psychological changes significantly affect the overall quality of life and the ability to perform daily activities, further complicating disease management.⁵

Disease-specific progression patterns in ataxia

Spinocerebellar ataxia (SCA)

The progression rates of different types of spinocerebellar ataxia (SCA) can vary significantly. This variability makes it essential to consider the specific type of SCA when assessing prognosis and treatment plans. In addition, the progression of SCAs is influenced by several factors, including the mutation involved and the age at which symptoms first appear. Longer DNA repeat expansions in certain genes and an earlier age of onset are associated with faster disease progression.^6,7

Friedreich's ataxia

Friedreich's ataxia usually starts in adolescence, with the average age of onset being around 10-15 years. This early onset often leads to a more severe and rapidly progressing disease course,  marked by increasing muscle weakness, loss of sensory function, and various skeletal deformities such as scoliosis and foot deformities. Over time, these symptoms worsen, significantly impacting mobility and quality of life.¹

Summary

Ataxia is a multifaceted neurological disorder characterized by a lack of coordination in voluntary movements, significantly affecting balance, walking, speech, and fine motor skills. The progression of ataxia is marked by a worsening of motor coordination, changes in muscle tone, eye movement abnormalities, speech and swallowing difficulties, cognitive impairments, and emotional changes. Recognizing and understanding the symptoms and their progression is crucial for timely diagnosis and effective management. The variability in progression among different types of ataxia, such as spinocerebellar ataxia and Friedreich's ataxia, underscores the need for personalized treatment approaches based on specific genetic factors and age of onset.