Neuromuscular disorder is a broad term but it encompasses several syndromes and diseases. These syndromes and diseases impair the function of the skeletal muscles directly or indirectly. The problem can be with the muscle structure itself (muscle disease) or it can be with the signal sent to the muscle (motor neuron disease).
Below are some of the neuromuscular disorders in children and a brief overview of each.
Congenital Muscular Dystrophy (CMD)
The group of muscular dystrophies that becomes apparent near birth or at birth is called congenital muscular dystrophy or CMD.
In general, muscular dystrophies are genetic.
These conditions primarily affect the voluntary muscles and are considered degenerative in nature.
Congenital muscular dystrophy often results in overall muscle weakness.
Joint looseness or stiffness may also manifest.
Depending on the type, other symptoms may include:
- Respiratory insufficiency
- Spinal curvature
- Eye defects
- Learning disabilities
Throughout the changing course of the disease, well-coordinated multidisciplinary care, strong provider-patient relationship and an individualized care plan is recommended.
Typically, the treatment plan will adopt a multidisciplinary approach and will include help and guidance from pediatric orthopaedics specialists, cardiologists, pulmonologists, physiotherapists or rehabilitation specialists (to help optimize the patient’s quality of life), among others.
Emery-Dreifuss Muscular Dystrophy (EDMD)
Emery-Dreifuss muscular dystrophy (EDMD) is one of the 9 types of muscular dystrophy that affects the voluntary muscles. The condition is named after Fritz Dreifuss and Alan Emery, the physicians who first described the disorder in a Virginia family in the 1960s.
Emery-Dreifuss muscular dystrophy is characterized by weakness and wasting of the muscles in the upper arms, shoulders and calf muscles. One telltale indicator of the condition is the stiffening of the joints (contractures) in the heels, elbows and neck. Another common feature of EDMD is the development of a heart condition known as cardiac conduction block.
Contractures often manifest in the early stages of the condition and can get worse over time even if muscle strength does not change. While preventing contractures is difficult, maintaining a range of motion through physical therapy has been known to help slow down its development. Surgical release of contractures is also considered challenging because the symptom has a tendency to recur. Cardiac conduction block develops when the heartbeat’s rhythm is disrupted. The disruption can be attributed to the electrical impulses not communicating properly between the heart’s lower and upper chambers. The condition may lead to sudden cardiac arrest when left untreated. Cardiac problems are life-threatening. Treatment interventions can include medication, although a pacemaker might be required in some cases.
Ideally, patients diagnosed with EDMD are regularly monitored for possible signs of cardiac conduction block.
Becker Muscular Dystrophy (BMD)
Becker muscular dystrophy (BMD) is a variant of Duchenne muscular dystrophy (DMD) and was named after a German doctor, Peter Emil Becker who first described the condition in the 1950s.
In some ways, BMD is similar to DMD but the voluntary muscles function better in the latter.
The onset of the condition is often in late childhood or adolescence. Compared to DMD, the course of the condition is also more gradual and less predictable.
The most common symptom of the condition is a generalised weakness that affects the muscles of the shoulders, thighs, hips and the pelvic area. The calves will also become enlarged.
Thanks to medical advances (especially in the field of cardiology), patients diagnosed with Becker muscular dystrophy are living longer in the 21st century compared to decades prior. Braces (otherwise known as orthoses) are sometimes used to support the ankle and the foot. Ankle-foot orthoses are also sometimes recommended for nightwear to keep the Achilles tendon stretched and to prevent the feet from pointing downward.
However, some patients with BMD may ultimately require scooters or wheelchairs.
While some may consider the devices as symbols of disability, many users attest they are more independent, mobile, and energetic using a wheelchair than merely relying on very weak legs.
Cardiomyopathy or the deterioration of the heart muscle is also often associated with Becker MD. The American Academy of Pediatrics recommends cardiac evaluations every other year (beginning at age 10) for patients diagnosed with BMD.
Limb-Girdle Muscular Dystrophy (LGMD)
Limb-girdle muscular dystrophy (LGMD) does not refer to one disease alone. It actually refers to a group of disorders that affect the voluntary muscles, primarily those around the shoulders and the hips. The bony structure that surrounds the shoulder area is called the shoulder girdle while the bony structure surrounding the hips is called the pelvic girdle.
Collectively, they are referred to as the limb girdles. The muscles connected to the limb girdles are affected in LGMD.
Just like many other muscular dystrophies, LGMD is a disorder of the voluntary muscles. Voluntary muscles are the muscles used to move the neck, limbs, trunk, and other body parts that are under voluntary control.
Over time, muscle atrophy and weakness can result in inability to raise the arms above the shoulders and limited mobility. Fortunately, the involuntary muscles, (except the heart) are not affected by LGMD. Bowel, bladder, digestion, and sexual function also remain normal. The intellect, senses, and brain are also not affected. However, cardiopulmonary complications can sometimes develop especially in the late stages of the condition.
As weakness progresses, using simple devices like a long-handled reacher or a cane can help make things easier for patients. A scooter or power wheelchair will be ideal when weakness manifests in the upper legs and the pelvic girdle. While the heart can be affected by LGMD, it does not occur as often as it does in other forms of muscular dystrophy. Heart problems can be in the form of cardiomyopathy (weakness of the heart muscle) or conduction abnormalities or arrhythmias (abnormal transmission of the signals that regulates the heartbeat).
When needed, medications or devices (i.e. pacemakers) will be used to help manage the condition. Occupational and physical therapy programs are also considered an integral component in the treatment of LGMD.