Landouzy Dejerine Muscular Dystrophy
Landouzy Dejerine muscular dystrophy, also known as facioscapulohumeral dystrophy was first described by Landouzy and Dejerine in 1884. It is a genetic disease, with autosomal dominant transmission in 70% -90% of cases. The genetic defect is located on chromosome 4, but the gene or genes that are affected in facioscapulohumeral dystrophy are still unknown. Landouzy Dejerine muscular dystrophy affects both sexes and rarely has a recessive, X-linked transmission. It is estimated that facioscapulohumeral dystrophy is the third most common muscular dystrophy, affecting 1 in 20,000 persons.
Landouzy Dejerine Muscular Dystrophy Symptoms
Onset usually occurs between the ages of 6 and 12 years, but sometimes it can occur at the age of 30 years, 95% of patients have signs of disease before the age of 20 years. Infantile onset is very rare. The disease is more common in males, but asymptomatic cases are more common in women. Approximately one third of cases are asymptomatic.
The disease has an insidious onset, a slow, progressive evolution and affects facial muscles, starting with orbicularis oculi, orbicularis oris and zygomaticus muscle. Initial symptoms of the disease may go unnoticed, but some symptoms are insidious installed, so that, some patients have difficulties in whistling or in drinking liquid through a straw, while other patients report that they can not properly close their eyes during sleep. Usually, muscle damage is asymmetrical.
Atrophy of facial muscles gives a characteristic appearance, called myopathic mask, muscle atrophies later extend to the scapular-humeral belt, pelvic belt being spared.
The patient presents a dull facies, without physiological folds produced by laughing or crying, eyelids can not be completely close during sleep, due to orbicularis oculi atrophy. By affecting the orbicularis oris and zygomaticus muscle, upper lip becomes proeminent.
It is characteristic transverse laughter: at the attempt of laughing, upper lip will be applied to dental arches and mouth corners are moving back, possible by affecting the zygomaticus muscle. Chewing is difficult, the patient is no longer able to whistle or drink liquid through a straw.
Scapular belt damage occurs later at 82% of symptomatic patients, atrophy extension will affect scapular muscles, chest muscles, trapezius (neck is elongated) and paravertebral muscles. Deltoid is usually spared and atrophy expansion is selective for biceps and triceps muscles, realizing a carcatural aspect of Popeye, due to massive forearm and deltoid muscles, in contrast with atrophic biceps and triceps muscles.
In rare cases, patients present congenital absence of some muscles, especially of the pectoral muscles. In rare cases, muscle atrophy may spread to the legs, anterior tibial muscle being most often affected, while posterior calf muscles are not affected.
Cognitive functions are preserved, cardiac damage is rare and the disease has a slow evolution, sometimes with lasting remissions.
Landouzy Dejerine Muscular Dystrophy Diagnosis
Serum creatine kinase is increased, but in some cases may present normal values.
Nerve conduction velocity is normal.
Electromyography shows diminished or absent spontaneous muscle activity and motor units present an activity of short duration and low amplitude. It is important to examine the most affected muscles, especially facial and scapular muscles.
Muscle biopsy shows variable aspects. This must be done from a symptomatic muscle or a muscle that is presenting electrophysiological changes. Changes seen in muscle biopsy are:
- Multifocal distribution;
- Fiber size variation with central nuclei;
- Endomysial connective tissue proliferation;
- Regenerating, moth-eaten fibers and muscle fibers undergoing phagocytosis;
- Isolated angular atrophic fibers;
- Rimmed vacuoles;
- Focal inflammation in perivascular and perimysial distributions;
- Muscle fibers expressing membrane attack complex;
- Muscle fibers expressing class 1 major histocompatibility antigen.
Landouzy Dejerine Muscular Dystrophy Treatment
There is no specific treatment for Landouzy Dejerine muscular dystrophy. It was noted that administration of beta-2 adrenergic agonists, albuterol, improves muscle strength through non-specific anabolic effects.
Administration of corticosteroids did not improve muscle strength.
Creatine monohydrate, folic acid and methionine supplementation and myostatin inhibition (MYO-29) have been used, but with no clinical benefits.
Physiokinetotherapy can be useful. It was observed that aerobic training may improve muscle performance. A program that consist of twelve weeks of low-intensity aerobic exercises (on a cycle ergometer at a heart rate corresponding to a work intensity of 65% of maximum oxygen volume for 35 minutes daily, 5 times a week, for a period of 4 weeks) can be useful in the treatment of this disease because it was observed that is improving the oxygen uptake and and patients did not present signs of muscle damage.
Evolution of the disease is slowly, progressive, atrophies will extend from facial muscle to scapular belt. Are also described forms with prolonged episodes of remission. Life expectancy of these patients is good. Possible complications of the disease are represented by retinal vasculopathy, hearing loss in 64% of patients, mental retardation in 40% of cases and epileptic seizures that occur more frequently in early-onset cases. Other complications may include hypertension, arrhythmias and dilated cardiomyopathy.