Read Full Text: Spinocerebellar ataxia (Unless you have special access, you will need to pay to read this article in its entirety.)
Journal: Nature Reviews Disease Primers
Year Published: 2019
Ranked 50th on our 2016-2021 list of the 100 Most Influential OT Research Articles
I feel a certain weight when reviewing a condition where OT is one of very few management options.
This week’s article on spinocerebellar ataxia (SCA) falls into that category. The authors provide a refresher on the function of the cerebellum, including what can occur when its health is compromised. They also discuss occupational therapy’s role in assessing and helping to manage SCA.
In the absence of treatments to slow or halt spinocerebellar ataxia, an OT’s role is to help patients manage a wide variety of symptoms—as always, with careful attention to each patient’s unique circumstances and values. The article also points you to a fantastic treatment resource that can help you with other forms of ataxia.
Let’s dive in.
Why was this article written?
This article comes to us from the journal “Nature,” and it is part of their “Primer” series, in which they review research on causes and treatment of various diseases.
You’ll definitely need to access the sciencey part of your brain to read this article in full. For a quick overview of the content (and for a baseline for lay people), they did publish this free handout to accompany the article.
What are spinocerebellar ataxias?
If you’re like me, you’re familiar with “ataxias,” but spinocerebellar ataxias (SCAs) may be new to you.
The root of “ataxia” means “absence of order” and thus refers to a syndrome of incoordination.
Basically, ataxias are grouped into two categories: genetic varieties and non-genetic varieties.
Spinocerebellar ataxias fall into the “genetically caused” category, and they are inherited via a dominant gene. This means that parents with SCA have a 50% chance of passing it on to their children.
The clinical hallmarks of SCA are progressive loss of coordination and balance, accompanied by slurred speech. (We’ll go over this in more detail in an upcoming section.)
There are actually 40+ subtypes of SCAs, which are caused by 40 different types of genetic mutations. So, there is a lot of variety in how this disease presents. The types are denoted as:
- SCA1
- SCA2
- SCA3/Machado-Joseph Disease (MJD)
- SCA4
- And so forth…
Onset and prognosis
SCAs typically emerge in the 3rd or 4th decade of life, but it can also manifest in childhood or late-adulthood.
The article cited recent research that estimated that SCA cases were found, on average, in 2.7 out of 100,000 individuals. The mobility and communication skills of individuals with SCA are restricted, which, in turn, impairs their quality of life and often leads to premature death.
What causes SCAs?
SCAs are caused by genetic mutations. If a genetic mutation is passed on, it does have the possibility of becoming even more mutated, thus worsening the impacts from generation to generation.
The article goes in depth regarding the pathophysiology of SCA, meaning the bodily processes that are impacted by the disease.
For occupational therapists, I think it is important to note that the dysfunction is happening at the cellular level, which means the impact will be widespread—as you will see in the clinical features.
Again, cerebellar atrophy is the hallmark of the disease, but other parts of the nervous system are often impacted, which is why in the next section, you will see a long list of non-ataxia symptoms.
Clinical features
As mentioned, the most prominent feature of SCA is ataxia. The ataxia is mostly related to cerebellar dysfunction, but afferernt and vestibular ataxia helps explain the full range of symptoms. Afferent ataxia is caused by dysfunction of sensory feedback during movement and stance. Vestibular ataxia is caused by dysfunction of the vestibular system.
Symptoms related to ataxia include:
- Progressing gait difficulties
- Deterioration of extremities resulting in the loss of fine motor skills
- Difficulty with speech and swallowing
- Oculomotor difficulties:
- Disturbed pursuit eye movements
- Gaze-evoked nystagmus
- Dysmetric saccades
- Double vision
Non-ataxia symptoms include:
- Motor symptoms
- Weakness
- Spasticity
- Amyotrophy
- Movement disorders
- Parkinsonism
- Dystonia
- Chorea
- Oculomotor abnormalities related to brainstem dysfunction
- Slowing of fast saccadic eye movements
- Gaze palsy
- Sensory symptoms
- Autonomic symptoms
- Epilepsy
- Myoclonus
- Cognitive and intellectual dysfunction
- Urinary symptoms
- Sleep disorders
- Restless leg syndrome
- Rapid eye movement sleep behavior disorder
- Excessive daytime sleep
- Insomnia
- Sleep apnea
The manifestation of non-ataxia symptoms varies widely. In exceptional cases, non-ataxia symptoms may even be the predominant manifestation of the disease.
I did want to note that, while the manifestation of cognitive decline varies, it rarely reaches the point of being considered dementia.
Finally, depression does affect 17-26% of SCA patients.
How is SCA diagnosed?
SCA is diagnosed when the following clinical criteria ultimately lead to a positive SCA genotype:
- Progressive ataxia
- No evidence of an acquired cause
- Similar disorder in a previous generation
Assessment
There are several assessments mentioned throughout the article that may help guide your occupational therapy care. They are not specific to OT, but it appears that OTs can administer them:
- 36-Short Form Health Survey (SF-36)
- European Quality of Life - 5 Domains (EQ-5D)
- SCA Functional Index (SCAFI)
- Scale for the Assessment and Rating of Ataxia (SARA)
Management
There is no cure for SCA, and no treatments have been found to alter the disease course. Thus, management is supportive in nature and geared toward managing symptoms.
There are currently no medications approved for routine use with SCA, though a few medications approved for use with other disorders (like ALS) show promise.
Therapy management options
Occupational therapy, physical therapy, and speech therapy are important considerations for these patients.
Three systematic reviews have found that rehab interventions improve function and mobility in SCA patients. This led the authors to recommend that patients with ataxia regularly perform rehabilitation exercises and training. Unfortunately, the accessibility, frequency and type of rehab options varies greatly.
The authors recommend that treatment follow the guidelines set forth by Ataxia UK.
(These guidelines include extensive therapy information, and they are an incredible resource for treating all ataxia patients!)
Medical Guidelines for Ataxia (OT Guidelines included!)
Frequency of therapy
The management of SCA requires periodic neurological follow-ups to evaluate disease progression. With regards to therapy, the authors specifically state that rehab regimens for ataxia and non-ataxia symptoms would be discussed and started, as necessary, at each follow-up visit.
Discussing the big picture
The authors state it is important to discuss prognosis, palliative care, and advance care planning with patients. I’m thinking this was directed at doctors, but I’m going to take the liberty of saying that a palliative care approach is important for therapists, as well.
Outlook for future management
Over the past few decades, our knowledge of SCA has increased tremendously. But, this knowledge sharply contrasts the fact that there’s “almost no progression in the development of therapies for SCAs.” The authors are hopeful that one of the next major steps in treatment of the disease will be discovering more sensitive biomarkers, which can improve how we measure treatment efficacy.
3 Takeaways for OT practitioners
(These are my own takeaways, and were not mentioned directly in the article.)
1.) If an SCA patient appears on your caseload, they are in the right place.
It can be intimidating when a rare diagnosis appears on your caseload, as this means you likely have little to no experience working with it.
But, please keep in mind that your OT care is one of very few management options available to SCA patients. Luckily, the assessments, guidelines, and your own experience in treating similar symptomologies will give you a solid starting point.
2.) Ideally, you have an ongoing relationship with the SCA patients in your community.
As with almost all of your patients with chronic conditions, it is ideal that they see you (or another OT) whenever they have a major functional status change. I was thankful to see the authors explicitly say this in the article.
Personally, I see having trusted healthcare providers to rely upon as particularly important for these patients and their families. Having a rare, poorly understood condition could add to the isolation and challenge of managing a chronic condition.
3.) In the absence of easy answers, ask good questions.
SCA is a complex disease with no easy answers. And, when OTs are called on to step into a palliative care role where patients’ autonomy will slowly erode, I think it’s especially important that we ask good questions early in the course of the disease.
I know I’ve shared these questions before, but here are my favorite questions from the book Being Mortal.
- What is your understanding of the situation and its potential outcomes?
- What are your fears and what are your hopes?
- What are the trade-offs you are willing to make and not willing to make?
- What is the course of action that best serves this understanding?
This week, I was also inspired by a podcast about Alzhehimer’s (another condition where autonomy is slowly taken) to consider using this question:
- How can we help you develop a day that’s safe, social, and engaged?
Here’s the full APA citation for this article:
Klockgether, T., Mariotti, C. & Paulson, H.L. Spinocerebellar ataxia. Nat Rev Dis Primers 5, 24 (2019). Spinocerebellar ataxia | Nature Reviews Disease Primers