What is Ataxia?

Jul 28

Ataxia is a term that clinically describes a loss of voluntary muscle control in the arms and legs in the absence of muscle weakness, leading to loss of balance and coordination, and potentially gait disturbance (9). Ataxia usually describes symptoms, but it is also a term for a group of hereditary diseases that affect the central nervous system. Although it is commonly due to dysfunction or degeneration in the cerebellum, ataxia may also be a result of dysfunction in other regions of the nervous system, such as the brainstem, cortex, peripheral nerves or spinal cord.

Ataxia can be subdivided into 6 major groups (1):

autosomal dominant spinocerebellar ataxias
autosomal recessive ataxias
congenital ataxias
mitochondrial ataxias
X-linked cerebellar ataxias
acquired ataxias

How Common is Ataxia?

Ataxia is a common finding in neurological practices. It is thought to affect 150,000 people in the US alone, either in acquired or hereditary form (9). Ataxias that are acquired are more common than hereditary ataxia, many of which are quite rare.

Ataxia may affect any age group. Children may be affected by hereditary forms of ataxia or as a symptom following infection, but hereditary ataxias may present at any time from childhood to adulthood. Accidents, injuries, and other external reasons like exposure to toxins such as alcohol or mold may be underlying causes of acquired ataxias, at any point in life.

What are the Early Signs of Ataxia?

While symptoms and time of onset is different with each case, these are the most common symptoms people experience (9):

Loss of balance and coordination occur first. This can present as feeling wobbly or unbalanced while standing or walking and ultimately lead to falling down or being unable to stand.

Loss of coordination of hands, arms and legs, such that doing simple tasks becomes extremely challenging.

Slurred speech occurs as it becomes challenging to coordinate tongue and vocal cord muscles. Swallowing may also become challenging.

Wide-based gait, or walking with the feet wide apart, as a means of creating stability.

Difficulty writing and eating, or doing other fine motor tasks such as buttoning up a shirt or applying makeup.

Slow eye movements.

Acute ataxia, with progression that occurs quickly over 72 hours, is often the consequence of an acquired condition and results in a neurological emergency and hospitalization. It can escalate from feeling unstable while standing to being completely unable to stand up or walk. Acute ataxia commonly presents in children, often presenting post-infection.

Common causes of acute cerebellar ataxia in adults include:

stroke
infectious disease
exposure to toxins
paraneoplastic syndromes
immune-mediated syndromes
vitamin deficiencies
structural disorders
metabolic disease

Genetic ataxias typically result in the slow progression of symptoms and include conditions such as:

Friederich’s ataxia
spinocerebellar ataxia
mitochondrial disease
multiple system atrophy
episodic ataxia (2).

What Causes Ataxia?

The primary region of the brain involved in ataxia is the cerebellum. The cerebellum plays an important role in that it integrates multiple different types of sensory inputs together with motor output predictions in order to create smooth, well-timed movement (10). Ataxia can arise from dysfunction in the cerebellum, or other areas that provide input to the cerebellum, including the brainstem, vestibular system, proprioceptive systems from muscles and joints, or from dysfunction in a combination of these systems.

In hereditary or genetic forms of ataxia, there is usually an underlying reason for degeneration in the cerebellum. In autosomal dominant spinocerebellar ataxias (SCAs), gene mutations occur that result in degeneration and dysfunction of the cerebellum and brainstem (10). As of 2018, there were 44 hereditary SCAs that have been identified and more than 35 SCA-associated genes (11).

While the presentations of the different types of SCAs appear similar, they may be a result of DNA repeat expansions, ion-channel dysfunction, and disorders of signal transduction (10).

Most of these disorders affect the cerebellar cortex and Purkinje cells. Purkinje cells receive excitatory inputs from climbing fibers and parallel fibers traveling from the body and brainstem, and send out inhibitory projections to neurons in the cerebellum and vestibular nuclei, effectively controlling our movements and making them smooth. Without appropriate Purkinje cell output, we see erratic, uncoordinated movements and sometimes tremors.

These are some similarities and differences between three different types of SCAs (11):

SCA1 is pathologically characterized by atrophy (wasting away) and extensive loss of Purkinje cells. These patients present with progressive loss of movement coordination, dysarthria (difficulties speaking), dysphagia (difficulties swallowing), nystagmus and hypotonia (decreased muscle tone). The disease is caused by a repeat expansion within the ataxia 1 protein (ATXN1).

SCA2 is caused by a CAG repeat expansion within the ataxin-2 gene (ATXN2). Patients also see progressive ataxia, unstable gait, and dysarthria, as well as slow saccades. Much of the cerebellar Purkinje cells are lost in this disease process.

SCA3 is also known as Machado-Joseph disease. It is one of the most common inherited ataxias worldwide. It is also a result of a CAG expansion, but on the Atx3 gene. Patients have cerebellar ataxia that affects their gait and limb movements, as well as dysarthria. Other clinical manifestations such as dystonia (abnormal muscle tone putting affecting joints into irregular postures) and ophthalmoplegia (visual problems).

Other reasons ataxia may appear include:

traumatic brain injuries
stroke
brain tumor
congenital abnormalities
infections, exposure to certain drugs or toxins including alcohol
cardiac or respiratory arrests (9) that also affect the cerebellum over time.

Gradual ataxias may be caused by:

vitamin B12 deficiency
vitamin E deficiency
exposure to certain drugs
multiple sclerosis
syphilis or other disorders.

It is important to determine the underlying cause of ataxia, since some of them are quickly reversible.

How is Ataxia Diagnosed?

The cause of ataxia can be difficult to diagnose, as it can be a symptom of another condition or it can be a hereditary ataxia. Usually a thorough medical history, family history and complete neurological and physical examination is performed, as well as some of the following diagnostic procedures (9):

laboratory tests (blood and urine test)

Magnetic resonance imaging (MRI). This type of study uses several large magnets and a computer to create detailed images of entire organs, including the brain (15).

Genetic testing can be performed to identify specific gene mutations or chromosome changes that are responsible for hereditary ataxias.

How is Ataxia Usually Treated?

Treatments for ataxia vary with the causes and symptom presentation. If an ataxia is based on a metabolic condition or vitamin deficiency, treatment will involve supplementation.

For progressive ataxias, treatment usually involves some form of balance therapy and gait retraining to reduce fall risks. It may also involve speech therapy to reduce speech difficulties and swallowing problems. Occupational therapy is also frequently employed, to help you learn new skills to help you perform activities of daily living (23).

People living with ataxia also often receive medication to help manage their muscle pain and stiffness, as well as medications to improve bladder control. Depression is common for people living with ataxia, and medications to help regulate depression are thus commonly prescribed.

How Is the NeuroRescue Program Different?

Your prognosis will vary depending on the cause of your ataxia. Unfortunately, we cannot cure hereditary ataxia or restore tissue that has been lost to a degenerative process. That said, we employ a host of advanced therapies and technologies that can help improve the function of your remaining systems. By doing so, we can often help restore balance, coordination, mobility, speech, eye movements and enhance your quality of life.

If ataxia is due to a stroke, low vitamin levels, or exposure to a toxin, treatment will be aimed at treating those specific conditions, as well as geared toward rehabilitation of the regions of the brain that were affected by the condition.

Much of what happens in ataxia is related to the inability of the cerebellum to integrate multiple different sensory systems and create a motor output that is smooth and accurate. Depending on how far along in the disease process an ataxic patient is, there is often a great deal that can be done to improve smoothness and accuracy movement. We do this by focusing on improving the function and integration of the cerebellar neurons and systems that have not yet been damaged by the disorder.

Your brain makes sense of where you are in the world through inputs from your muscles and joints, inputs from your inner ear, and inputs from your eyes. The eyes are constantly scanning the world to provide the brain with a visual map of the surrounding space. It does this with saccades, which are fast eye movements from target to target. In many cases of cerebellar ataxia, saccade accuracy and speed become compromised. This creates feelings of instability and imbalance, as we cannot take in our dynamic and complex environments quickly enough to respond to them. Patients often become anxious and fearful of movement because they feel unsafe.

In order for you to move through and interact with the world, you first need to know where the world is. This requires that saccades are fast, accurate, stable, and have very quick reaction times. As the cerebellum and brainstem are involved in saccades, all of these functions break down with both acquired and hereditary ataxias (24).

Patients also often develop nystagmus, which is a slow eye movement away from neutral with a quick, corrective saccade back toward neutral, in a directional pattern. This gives the patient the subconscious perception that they are moving, and creates further instability while seated, standing and walking. Research shows that postural ataxia can be secondary to nystagmus (13).

Research also demonstrates that by analyzing the different qualities of saccades, we can differentiate between different types of cerebellar ataxias. We find that by assessing eye movements and vestibular integration, we can discern the functional drivers of cerebellar ataxia and rehabilitate these systems in a very precise manner. We can often improve balance, gait, coordination and postural stability, regardless of whether or not we can directly address the disease process.

Another more complicated eye movement is called an anti-saccade, where a target is presented, and a person needs to inhibit the reflex to look at the target and instead consciously choose to look in the other direction. Anti-saccades are involved in modulating cognitive aspects of motor behavior and executive functions. Research shows that anti-saccades of cerebellar ataxic subjects had prolonged reaction times with larger variability than normal and increased directional error rate. This translates to problems with planning, reasoning, and emotional regulation (12). We find that by rehabilitating these eye movements we can often restore some of the cognitive flexibility and motor control that has been negatively impacted by this disorder.

There are a host of other therapies that we engage in with our ataxic patients. All of these have different functions and allow us to rehabilitate specific capacities. These range from vestibular rehabilitation to improve balance, gait, and cognition (13), to visual optokinetic stimulation to improve motor control and postural stability (14, 15). They include a number of different types of electrical stimulation to improve cognition, eye movements, balance, gait, tremor, cognition, blood pressure regulation, and even swallowing (17, 18, 21, 22). They even include therapies such as transcranial magnetic stimulation to improve motor function, emotional regulation and balance (19), and virtual reality exercises to improve the ability to function in the world and decrease fall risk (20).

No two ataxia presentations are alike, and the same holds true for the NeuroRescue program. A cookie-cutter approach will be doomed to fail in a condition as complicated as ataxia. All of our therapy protocols are tailored to the unique needs of the individual.

How Does the NeuroRescue Program Work?

We begin with a detailed history and neurological exam to assess the overall function of all systems that could be involved in your ataxia. Additionally, we perform tests that can help determine which type of ataxia a patient is presenting. We use state of the art technology to assess eye movements, balance and stability, vitals in multiple positions and video head-impulse testing (VHIT) to assess vestibulo-ocular reflexes (3,6). Research demonstrates that VHIT can accurately differentiate between cerebellar ataxias and other disorders affecting the vestibular and visual systems.

Treatment protocols are designed to determine the pathways most affected by the disease process or dysfunction and activate sensory systems that directly feed into those areas. By activating these systems with sensory stimuli, we can recalibrate the motor loops and make movement more controlled, in order to reduce fall risks and improve general function and independence. Repetition of activation throughout a NeuroRescue program is the best way to ensure neuroplastic changes occur in these fragile systems (7).

We design your unique NeuroRescue Program to be among the most comprehensive diagnostic and therapeutic protocols available today. We create individual NeuroRescue Programs based on a comprehensive analysis of every relevant neurological system and pathway, using gold-standard, cutting edge neurodiagnostic technologies and examination procedures and state-of-the-art therapies.

We begin with your Discovery Day, wherein we perform a comprehensive history of not only your condition, but your life on a timeline. This allows us to dive deeply into your case and see all of the factors that led to where you are now. It helps us uncover hidden problems and associated conditions that may be making it difficult for you to move your recovery forward.

In the case of ataxia, this requires a deep dive into your family history, the onset of your symptoms and their progression.

Our examination allows us to identify the areas and pathways of your brain that have been impacted by the disease or degenerative processes. We begin by precisely quantifying the function of your visual, vestibular, and proprioceptive systems through computerized analysis of your eye movements, your inner ear reflexes, and your balance in a host of different sensory conditions.

We employ technologies including Videooculography and Saccadometry to measure several classes of eye movements. We use Video Head Impulse Testing to measure the function of your inner ear, and Computerized Dynamic Posturography to assess your balance in different sensory conditions.

We use NeuroSensoriMotor Integration testing to evaluate hand-eye coordination and cognition, and Virtualis testing to assess dynamic eye tracking and perception of vertical in a virtual reality environment.

We combine all of this with a comprehensive physical and neurological examination of your sensory, motor, autonomic, and cognitive systems. We review any relevant laboratory testing, radiological imaging, and prior neurodiagnostic testing, and integrate that information with our findings.

We use this information to identify which parts of your brain are working properly, which systems are struggling, and the precise point at which your systems fatigue.

We can then design a NeuroRescue Program that is unique and specific to your brain, and yours alone. Your NeuroRescue Program works to rejuvenate and reintegrate the damaged neurons and pathways in your brain. It works to improve energy, endurance, and functional capacity within your fragile systems.

We use our technologies and procedures to not only see what we need to address, but also when it is time to stop and let you rest. We address your impaired neurological function from multiple angles of therapy, and provide metabolic support to improve neurological recovery.

While we cannot bring back neurons that have been lost to your ataxia, your NeuroRescue Program allows us to take the pathways that remain and maximize their efficiency and endurance. And by focusing on the integration of systems, we can do more than just get pathways working better, we can get them working together again. This gives us our best opportunity to help you limit your ataxia and return to living a healthy, vibrant, and fulfilling life.

Your Next Best Step:

Living with ataxia can be challenging, but there is hope for functional recovery. Many of the symptoms can be managed, stability can be improved, independence can be regained, and quality of life can be restored.

To see if the NeuroRescue Program is right for you, contact one of our patient care coordinators to schedule your Discovery Day.

And remember, it’s never too late to start getting better.