WHAT IS DUCHENNE MUSCULAR DYSTROPHY?
Duchene Muscular Dystrophy, which is the most common type of neuromuscular disease in childhood, is a hereditary disease with a recessive transition due to the X chromosome and a prevalence of approximately 1/3600-6000 live male births. The cell called dystrophin is a disease characterized by the deficiency of membrane protein, and dystrophin deficiency causes progressive loss in skeletal muscles, respiratory and cardiac muscle strength and functional skills with continuous degeneration of  muscle fibrils. DMD is also characterized by progressive muscle weakness in the proximal muscles.

Although no symptoms are observed at birth and in early  infancy, there are signs of muscle weakness in the early period, such as hypotonia and difficulty in holding the head. Symptoms in children begin to occur between the ages of 2-5 and with gait disturbance. Abnormal walking, climbing stairs and difficulty in running, Gower’s symptom can be counted as early symptoms of the disease. Patients balance the weakness of the gluteus maximus muscle with lordotic posture while standing. As a result of bilateral muscle weakness, duck-like walking, tiptoe walking, frequent falls and difficulties in climbing stairs occur when starting to walk. Due to weakness of knee and hip extension, Gower’s sign is observed at the age of 3. In addition, pseudohypertrophy occurs in the calf muscles. When patients fall from the ground, they come to the knee- elbow position to get up, they bring their hands and feet closer together by extending their elbows and knees, and they suddenly get up from the ground in the form of climbing with one hand on their knees. This typical movement is called the Gower’s sign (maneuver ).

The diagnosis of the disease is usually made around the age of 4, where symptoms also occur. Motor skills and muscle strengths are generally preserved until the age of 6, but proximal muscle strength loss becomes evident in the later period, and patients lose their walking functions around the age of 11-12 and start to use wheelchairs.Especially after the transition to wheelchair, upper extremity muscle strength is important for independence in daily life.As a result of secondary problems such as the development of scoliosis, respiratory problems and cardiomyopathy with the loss of ambulation, they die at the age of patients. Today, there is no clear treatment that eliminates the disease, but physiotherapy rehabilitation approaches including steroid use, exercise and orthosis applications are being tried to improve their quality of life.

CLINICAL PROPERTIES
Although children with DMD start to walk late compared to their peers, most of them walk around 18 months. They have a hard time walking on tiptoe.

• Muscle Weakness : It starts with the proximal lower extremity and trunk muscles and then the weakness of the upper extremity and distal muscles is added .Neck flexors are mostly weak from the onset of the disease. Duck-like gait , enlargement of the calf muscles, and increased lumbar lordosis are observed in patients.
• Respiratory Problems : Patients have chronic respiratory failure due to restrictive lung disease.Vital capacity, which is normal until the age of 10, begins to decrease after the age of 10.

• Cardiac Problems : The problems that can be seen are dilated cardiomyopathy, rhythm and conduction disorders due to cardiac fibrosis. The age at which cardiomyopathy is first seen is around 10 years of age, and the incidence increases with age, and it occurs in most patients over 18 years of age.

• Osteoporosis : Patients with DMD have low mineral density. It is thought that this may be due to the fact that they are immobile earlier than their peers. Traumatic fractures of long bones are common in people with DMD, and fractures in the lower extremity affect independent ambulation.
• Nutrition and Gastrointestinal Problems : Weight control is very important. While some patients struggle with weakness, some patients struggle with obesity. Weight gain can be observed as respiratory disturbance increases and mobility decreases. One of the most common symptoms is loss of appetite, which is accompanied by weight loss. The most common complication of steroid  use is weight gain.In the later stages of the disease, swallowing problems may occur, which may result in malnutrition. Necessary nutritional support and advice should be provided to patients.
• Learning and Speech Disorders : Patients usually have a normal IQ between 85-115, but there is also a below-normal standard deviation. The learning skills of patients with DMD are very extensive and have some typical features.Progress in learning problems can be prevented and improved over time.

Performance in Duchenne Muscular Dystrophy: Factors such as muscle weakness, fatigue, locomotion problems, exercise deficiency, pain and weight are factors that affect functional capacity, reduce the quality of life and lead to sedentary life. 6 min walking test and duration performance tests ( 10 m walking, lifting (Gowers), stair climbing and descending times) are the tests used to evaluate performance in DMD. The 6-minute gait test was modified for patients with DMD. The results of the test provide important inferences about the course of the disease and functional capacity. Increases in walking distance can be seen under the age of 7, but decreases in walking distance can be seen as the age increases. A patient with DMD walking less than 350 m is a sign of the onset of ambulation loss. The 6-minute gait test can also be explained as a measure of ambulation function affected by decreased lower extremity strength, biomechanical deficiencies during gait, decreased endurance, and cardiorespiratory status. Timed performance tests are also one of the important performance criteria.

Energy Consumption in Duchenne Muscular Dystrophy: Muscle weakness seen in patients leads to a decrease in gait endurance and an increase in energy consumption by causing patients to get tired during gait. Reducing the excess energy consumed by patients with DMD during gait is one of the main goals of the treatment.In a study conducted by Brehm et al. in 2014, they investigated the relationship between walking energy consumption and age in patients with 12-month ambulated DMD during the 6-minute walking test and concluded that the natural walking speed of children with DMD decreased with age and their energy consumption during walking also increased.

Gait and Balance in Duchenne Muscular Dystrophy: Patients with DMD exhibit an abnormal gait pattern primarily due to muscle weakness and muscle shortness and joint limitations. Due to weaknesses in the extensor muscles, the center of gravity passes through the posterior of the hip, in front of the knee and ankle, and due to this situation, patients begin to try to maintain internal and flexion moments in the lower extremity joints. As a result, patients with DMD provide body support and progress by utilizing the strength in the hip flexors, the posterior structures of the knee joint and the ankle plantar flexors. With the progression of the disease, muscle weaknesses and contractures progress, and as a result, patients begin to fall. The gaits of patients with DMD are characteristic and mostly show a duck-like gait pattern with difficulty in maintaining balance, increased lordosis, crop in the ankle, standing inversion , and wide sole gait.

EVALUATION

In DMD, the evaluation is made to determine the rehabilitation program for contractures or deformities that may occur from the beginning of the disease and the course of the disease and to determine the effectiveness of the rehabilitation program. Patient evaluation begins with observation from the moment the patient meets the patient. Following this, physical measurements such as taking the story, determining the normal joint movement limit and muscle strength, periodic performance tests, evaluation of quality of life and participation in activities, and ambulation evaluation come .

North Star Ambulatory Assessment is a motor function scale developed specifically for DMD and applied to patients who walk 10 meters independently from the age of 3. This scale, which consists of 17 items together with two period performance items, is scored as‘ 0=cannot, 1= is done with compensation and 2= is done without compensation ’.

Performance of Upper Limb (FAS) is a personalized test consisting of 3 levels: high (shoulder), middle (elbow) and lower (wrist) in order to evaluate the functionality of the upper extremity in children with DMD. In this test, which is used in patients with walking and DMD who have lost their ability to walk, high scores show high function. The tools used to evaluate cognitive functions in patients with DMD are the Bayley-III and Griffiths Mental Developmental Scale . It is recommended that evaluations be made every 4-6 months in order to monitor the changing physical and functional capacity with the rehabilitation program.

PHYSICAL THERAPY AND REHABILITATION

The physiotherapy and rehabilitation program should be started immediately after diagnosis and shaped according to the needs of the patient. The objectives of DMD can be expressed as reducing the complications on joint or spinal deformities, protecting and improving cardiac and respiratory functions, and preventing contractures (3,5). It is not possible to completely eliminate the patient’s symptoms, but functionality is tried to be preserved. We can consider the rehabilitation program in 3 periods in general.

EARLY PERIOD: Intense exercise program is not recommended for a patient with DMD in this period. While preparing the rehabilitation program, primarily abdominals ,hip extensors and abductors ,knee extensor muscles should be emphasized . The operation of the upper extremity muscles from the early period also plays an important role in preventing functional restrictions that may occur in the future. Standing or walking for at least 2-3 hours a day should be recommended to the patient. Resistant and eccentric exercises should be avoided in every period of the treatment program. Respiratory exercises should also be included in the program as they slow down the loss of vital capacity. It can be applied to the patient in the form of play activities such as balloon inflation and candle blowing. One of the primary approaches is to prevent contracture. For this, exercises are applied to maintain positioning and range of motion. Gastrocnemius-soleus and tensor fascia lath stretching exercises are initially given to maintain range of motion. Ankle ,knee,hip flexor stretches should also be added to the rehabilitation program in line with the need. Primarily, the reason for its application to these muscles is that contractures cause gait problems such as tiptoeing and enlargement of the support surface in the future. Stretching exercises were recommended to be completed in a total of 10-20 minutes with 5-10 repetitions by waiting for 10 seconds 1-2 times a day. Stretches should be applied slowly and should not cause pain. In addition to stretching exercises, night splints are recommended to prevent the formation of dorsiflexor contractures in the ankle. Scoliosis is rarely seen in children with early DMD, but evaluation of scoliosis should be done regularly.

 

 MIDDLE PERIOD : The objectives of the middle period can be listed as ensuring the fulfillment of daily life activities, self-care, prevention of scoliosis, and transition to wheelchair mobility. With the increase in muscle weakness and contracture formation, the patient’s ambulation has weakened. The patient has problems in daily life activities, so he/she also needs a work-occupation therapist. Active assisted NEH and manual stretching exercises are considered appropriate in this period. Manual stretching exercises to the hip flexors, tensor fascia lata and ankle are important. In order to prevent the development of hip and knee contractures, lying in the prone position is recommended. In addition, hamstring stretching should be added to the program. Knee-ankle-foot orthosis (KAFO) is preferred to maintain late ambulation, standing in the early non-ambulation period or limited ambulation. The standing stand can also be used to prevent contractures. The choice of the appropriate wheelchair is important in terms of preventing scoliosis and secondary problems that may occur.

LATE PERIOD: Late period for DMD is defined as the period when the child is between the ages of 12-14, can only walk or stand thanks to help or long walking device, needs help to balance, or becomes dependent on a wheelchair or bed, and the independence decreases in transfer and daily life.Combating scoliosis constitutes an important part of rehabilitation. Keeping the spine in a neutral or slightly elongated position delays the formation of scoliosis. Spinal surgeries are performed to reduce pain, protect respiratory functions and prevent worsening of spinal deformity. Stretching exercises should be added for active movements , shoulder flexion and abduction, elbow, wrist and finger extensor limitation to protect upper extremity functions. Resting splint can be recommended for the extremity distal. The majority of patients have difficulty changing positions and may feel the need to rotate at night. Positioning, mobilization and stretching exercises prevent bed sores. Since head and body control is reduced due to progressive weakness, a high spacing seating arrangement can also be used. Respiratory exercises, postural drainage or intermittent pressurized respiratory therapy should be added according to the needs of the patients in pulmonary rehabilitation. In this process, postural drainage techniques should be taught to the family.

In order to maintain and improve muscle strength, the degree of weakness and exercise intensity should be considered as much as possible when planning the exercise program. It has been observed that when muscle strength is too weak to resist gravity, exercises do not have a strengthening effect, and passive exercises should be used when these muscles weaken in this stream. The most recommended types of exercises are aerobic exercises, exercises for muscle strengthening, and specific exercises for respiratory muscles. Typical aerobic exercises recommended include walking , walking band or cycling exercises for 30 minutes or more in 60% of the maximal heart rate. In a study conducted with children with DMD, it was concluded that cycling exercises were safer than exercises performed under the supervision of a physiotherapist. Strengthening exercises can be started for muscles with a strength of +3 and above by using a pound of weights or a pint of water bottle, and necessary adjustments are made according to the patient’s performance.

In a study conducted in 2014, in patients with early stage Duchenne muscular dystrophy (DMD), exercise was performed with an arm ergometer under the supervision of a physiotherapist in one of the groups divided to investigate the effects of 2 different upper extremity exercise training on upper extremity function, strength, durability and ambulation, while strengthening joint range of motion exercises were performed for 8 weeks under the supervision of their families in the other group. As a result of the study, ambulation scores, endurance and arm functions and proximal muscle strength improved in the arm ergometer group. The results show that upper extremity study with an arm ergometer is more effective in maintaining and improving the functional level of early stage DMD patients compared to ROM exercises alone.

Electrical stimulation can also be used to strengthen the muscle. In DMD, electrotherapy slows the degeneration of affected muscle fibrils and increases the rate of regeneration. Low intensity electrical stimulation is recommended to patients.

Since ankle dorsiflexion range of motion is one of the first body regions showing contracture, its gait affects functionality and may cause pain and skin disorders. Various interventions are available to reduce reductions in ankle dorsiflexion range of motion, such as stretching, orthosis, serial plastering, and surgical intervention. M.Kiefer et al.  The aim of his  study with 332 DMD patients was to investigate the progressive loss of ankle dorsiflexion range of motion, its relationship with functional decline and its effects on physical therapy management. For this, data for age, number of visits, ankle dorsiflexion measurements and North Star Outpatient Assessment (NSAA) scores were investigated and recorded. According to the findings, ankle dorsiflexion movement ranged from -32.5 to 25 degrees. The result of the study describes the progression of ankle contractures and functional decline in DMD. It is important to help prevent the progression of contractures and loss of functionality in patients with DMD, and to make timely decisions about intervention and equipment needs.

The objectives oforthosis applications are to support weakened muscles, to prevent contractures, to ensure the stability of the joints, to maintain biomechanics, and to maintain functionality.AFO is recommended to be used as night splint to prevent dorsiflexion weakness, ambulation and plantar flexion contracture.Knee-foot-ankle orthosis (KAFO) is applied to prevent contractures and deformities in the late period of ambulation in order to perform standing and weak ambulation.The passive standing device can be used to prevent contractures in the hip, knee and ankle joints. Today, wheelchairs that can be driven are used instead of CAFO. In scoliosis, posture is badly affected in many ways. In the treatment of scoliosis, spinal orthoses are used to prevent the progression of deformities and to protect the sitting posture in patients with severe deformities. However, patients do not have the muscle strength required to maintain proper posture and exercise in orthosis. It is useful to use thermoplastic orthoses to correct the sitting posture. In this method, leaving the diaphragm exposed relieves breathing.

Hydrotherapy is very beneficial for patients with DMD.Active assisted, passive exercises and respiratory physiotherapy can be applied in water. The temperature of the water should be well adjusted , and the patient should not be cold.

Respiratory physiotherapy is important for the protection and development of respiratory functions. Loss of walking ability also adversely affects the functioning of respiratory muscles. Abdominal muscle weakness causes effective coughing and the risk of infection increases. Decreases in FVC value also lead to respiratory failure. Patients have problems expelling secretions due to these problems. The use of techniques such as percussion, shaking or vibration helps breathing. When the assisted coughing device and  assisted coughing are combined, the air and expiratory flow entering the lungs increase and more effective coughing is performed. Glassopharyngeal respiration is an individual technique, but the main  purpose is to open the throat and force air into the trachea by moving the trachea and laryngeal cartilage downwards, thus allowing air to be swallowed.

 

DMD management should be multidisciplinary and adapted to the patient’s profile and clinical progression. In order to improve the quality of life of patients, treatment and physiotherapy targeting gastrointestinal, respiratory, cardiac and orthopedic problems should be provided. Cases of genetic studies play a key role in the management of the disease in identifying potential carriers and characterizing the associated mutation and developing new therapies.