Case Study - Myotonic Dystrophy Type 1

Original Editor -Michael Miglietta, Queen's University Neuromotor Function Project - Physiopedia (physio-pedia.com)

Top Contributors - Sarah Medeiros, Sienna De Caro, Kaylyn Turcotte

Clinical Hypothesis

Diagnosis :

Myotonic dystrophy is medically diagnosed through genetic testing. However, the physical therapy diagnosis for Mr. J would be, “patient presents with impaired motor function of the distal upper and lower extremities bilaterally, dropped head, impaired balance, apical breathing pattern, and requires moderate assistance for completion of ADLs”

Problem list:  

1. Muscle atrophy in distal upper and lower extremities due to disuse  

2. Muscle weakness in distal upper and lower extremities due to disuse  

3. Decrease upper extremity coordination due to underlying neurological impairment

4. Drop foot gait pattern throughout swing phase due to dorsiflexor weakness bilaterally  

5. Apical breathing pattern due to weakened diaphragm  

6. Dropped head presentation due to weak neck extensors  

7. Impaired balance due to coordination impairment and muscular weakness

8. Increased fatigability due to sedentary lifestyle

Intervention

Patient centered goals:  

As Mr. J previous indicated his goals of physical therapy were to, “be able to walk more and to complete more daily activities.”  

When taking these goals as outlined by Mr. J, the following long-term goals were created:  

1. Prior to discharge from physical therapy, the patient will be able to achieve a 2-point increase in their score regarding mobility on the Assessment of Life Habits as compared to their initial assessment  
2. Prior to discharge from physical therapy, the patient will be able to achieve a 0.8m/s gait speed on their 10m walk test
3. Prior to discharge from physical therapy, the patient will be able to dress themselves with minimal assistance (no more than 3 points of contact) from the physical therapist  

Once these long-term goals were identified and agreed upon by Mr. J, the following short-term goals were created to meet the long-term goals above:  

1. After two weeks, the patient will be able to complete 3 rounds of successive thumb to finger tapping with minimal error (no more than 3 misses within each round).
2. After two weeks, the patient will be able to demonstrate an increase in neck extension MMT from a 3- to a 4- when assessed for a single activation.  
3. After two weeks, the patient will be able to demonstrate an increase in diaphragmatic excursion by 3 cm
4. After three weeks, the patient will demonstrate an increase in finger flexion strength by increasing hand dynameter strength by 5 kilograms.  
5. After three weeks, the patient will improve ankle dorsiflexion MMT from a 2- to a 3 when assessed for a single activation.
6. After three weeks, the patient will be able to demonstrate an increase in their 30 second sit-to-stand result by 3 repetitions with the use of a chair’s armrest    
7. After four weeks, the patient will demonstrate an increase in their Berg Balance Scale from 43/56 points to 48/56 points  

It is critical to remember that during goal setting, the patient is heavily involved in this process and must have their voice always heard.

It is important to remember that DM1 is a progressive neuromuscular disorder. This means that although it is possible for patients who have no experience with physical therapy to show improvements over short periods of time, over a long term (several years), a patient's conditions will worsen naturally. For example, in one study, it was found that over nine years 30.3-43.5% of individuals with DM1 presented with loss of muscle strength as compared to individuals without DM1 (Gagnon et al. 2019). Therefore, it is the responsibility of physical therapist to help attenuate the consequences of such a progressive disorder.  

Interventions provided to Mr. J were considered in tandem with Mr. J to ensure that he was an active participant in this process. The following interventions were provided:  

Diaphragmatic breathing- to improve diaphragmatic breathing, patient facilitated tactile cued deep breathing on the patient’s upper abdomen for 10 repetitions every waking hour was used to target this issue. Such an intervention was used to target Mr. J's apical breathing pattern and to ensure that Mr. J was receiving enough oxygen with each breath at rest and during exercise. Also, preliminary research in healthy individuals shows the potential of diaphragmatic breathing being associated with improvements in balance as well (Stephens et al. 2017). Therefore, Mr. J may also be receiving this benefit from such an intervention as well.

Strengthening- isometric exercises were chosen as the starting point for Mr. J due to his muscle atrophy and weakness. Supine self-resisted (with-opposite foot) ankle dorsiflexion, supine sustained neck extension, and sustained finger flexion squeezes were prescribed to address the main muscular weaknesses that Mr. J presents with. The exercises were prescribed at 5-10 second contractile holds, for 15-25 repetitions, for 2 sets with no more than 2-minute rests between each set. Mr. J was instructed to complete the exercises above 2-3 days a week and that they should be completed to muscular fatigue, not failure. Mr. J then progressed to isometric exercises targeting the same musculature under endurance strength training parameters. In the literature there seems to be the possibility of those with DM1 to present with skeletal muscle growth (Roussel et al. 2019) and that strength in DM11 patients can be increased when following an exercise program (Brady et al. 2014).  

Balance- patients with DM1 are seen as similar falls risks to elderly individuals (de Die-Smulders CE, 1998) and have impaired ankle strategy usage when balance is lost due to weakness of the ankle musculature (Exercise Guide for People Living with Myotonic Dystrophy). Also, the drop foot that a person with DM1 presents with puts them at an increased risk of tripping when walking (Exercise Guide for People Living with Myotonic Dystrophy). Therefore, the isometric dorsiflexion exercise as listed above may improve balance as well, but balance exercises were also provided to Mr. J. Based on Mr. J’s presentation, a prescription of narrow stance static standing holds for 10 seconds for 10 repetitions daily were provided. As Mr. J's balance improved, exercises progressed to more challenging interventions (tandem stance) and then to more mobile and task-specific interventions (reaching outside base of support). However, given Jermey’s falls risk, such exercises were completed in parallel bars and under contact supervision of the therapist. Recent research has also suggested that post-balance intervention with DM1 patients is likely to result in a self-reported increase in balance confidence (Hammarén et al. 2015).

Coordination- In order to improve Mr. J’s coordination, task-specific interventions were used. These interventions included tasks that Mr. J deemed meaningful such as: typing, washing the dishes, dressing himself, and being able to open the drawers in his house. Coordination exercises were initially blocked prior to progressing to more random practice as Mr. J improved. In addition, time was provided to Mr. J after each task for self-reflection and to allow Mr. J to problem solve as well as identify any errors in his task completion prior to him receiving feedback of the results from the physical therapist. However, thumb and finger tapping were also provided to Mr. J for at home completion.

Gait training- gait training was a substantial portion of Mr. J’s therapeutic intervention. However, for such a condition, therapists used a bandwidth feedback approach and allowed the patient time to self-reflect prior to providing feedback on the knowledge of results. Mr. J also completed body weight supported treadmill training in a closed environment in order to help facilitate more coordinated gait movements prior to being progressed to gait training in more open environments with great variability (without a balance system) to provide more generalizability to his life environment and to increase his endurance.  

Orthotics/Gait aids - however, given the progressive nature of the condition, Mr. J was placed in an AFO to help address his foot drop as well as being properly fit, educated, and taught how to use a 2 wheeled walker. Both changes were implemented to help improve Mr. J’s stability while ambulating. An Occupational Therapist (OT) was consulted in order to ensure all aids provided were appropriate for Mr. J’s condition.  

In addition, a referral was also made to a Speech Language Pathologist to help target Mr. J’s facial and oral musculature weakness. Throughout the intervention process, constant education was provided to Mr. J regarding several concepts. Some of these concepts included: his condition, the reason why intervention techniques were chosen, any potential risks or benefits from a given intervention, any alternative intervention strategies, and how DM1 may progress and continue to affect his mobility. The goal of this was to ensure Mr. J properly understood the therapy being provided to him and to properly prepare him for what may be his future reality.