Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Synonyms: Landouzy-Dejerine muscular dystrophy, facioscapuloperoneal muscular dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) is a common type of adult muscular dystrophy and is divided into types 1 and 2 based on genetic mutation. Both FSHD types often show asymmetrical and progressive muscle weakness affecting initially the face, shoulder and arms followed by the distal then proximal lower extremities. Approximately 95% of patients (FSHD1) have a deletion of a key number of repetitive elements on chromosome 4q35. The remaining 5% (FSHD2) have no deletion on chromosome 4q35.
Patients with FSHD1 carry a large deletion in the polymorphic D4Z4 macrosatellite repeat array at chromosome 4q35 and present with 1-10 repeats whereas non-affected individuals possess 11-150 repeats.[2, 3]
- FSHD1 is dominantly inherited.
- The estimated prevalence of FSHD is 1:20,000.
- In the majority of cases, FSHD (FSHD1) results from a heterozygous partial deletion of a critical number of repetitive elements (D4Z4) on chromosome 4q35. No causal gene has yet been identified.
- Frequency is higher in males but asymptomatic cases are more common in females.
FSHD usually presents in the first and second decades of life but may present at any age.Onset as early as infancy has been described but is rare. As many as one third of patients are asymptomatic. FSHD presents classically with facial and shoulder girdle weakness but may also present with dyspnoea and myopathic electromyogram (EMG) changes. Usually, FSHD muscle involvement starts in the face and then progresses to the shoulder girdle, the humeral muscles and the abdominal muscles, and then the anterolateral compartment of the leg. Disease severity is very variable and progression is very slow.
- The degree of weakness or disability can vary widely between different affected members in a family but can show even greater variation between people in different families.
- Muscle pain is a frequent complaint, often in the early stages.
- Weakness may affect not only the facial muscles and shoulders and/or upper arms but also the neck, forearms, wrists, fingers, hips, legs, ankles and the back muscles. Weakness may be asymmetrical.
- The disease tends to progress from the face downwards, with initial weakness starting in the muscles around the eye (orbicularis oculi), mouth and cheek. The extraocular and pharyngeal muscles are spared.
- Weakness of facial muscles can be suspected if the eyes remain slightly open when asleep, particularly in young children, or if the eyelids cannot be screwed tightly enough to bury the eyelashes.
- Difficulties with pursing the lips to whistle, drinking through a straw or blowing up balloons are also suggestive.
- Winging of the scapula is the most characteristic sign. The scapula is more lateral than normal and moves upwards with shoulder abduction. There is selective weakness of the thoracoscapular muscles which may spare other shoulder muscles such as the deltoid muscle. This imbalance results in significant winging and loss of shoulder function.
- The anterior axillary fold slopes upwards due to weakness of the pectoralis major.
- Excessive aching around the shoulders, rounded shoulders and thin upper arms may be the first presenting signs or symptoms in teenagers and adults.
- Weakness of foot dorsiflexion and foot drop due to weakness of the tibialis anterior muscle are very characteristic. The posterior leg muscles are spared. The pelvic girdle muscles are also often spared.
- Associated non-skeletal muscle manifestations include high-frequency hearing loss as well as retinal telangiectasias, both of which are rarely symptomatic.
Asymmetry and selective muscle group involvement help to distinguish this condition from other muscular dystrophies. Extraocular muscles, bulbar muscles, deltoids and respiratory muscles are usually spared.
- Amyotrophic lateral sclerosis.
- Chronic inflammatory demyelinating polyradiculoneuropathy.
- Congenital muscular dystrophies.
- Congenital myopathies.
- Diabetic neuropathy.
- Endocrine myopathies.
- Inherited metabolic disorders.
- Limb-girdle muscular dystrophy.
- Scapuloperoneal dystrophy.
- Elevated serum creatine kinase (CK).
- Imaging studies show a selective destructive process involving the anterior compartment muscles of the leg.
- Gene testing: one of the genes has been localised to chromosome band 4q35, but the affected gene or genes are still unknown. Molecular diagnosis has 98% accuracy.
- Electrodiagnostic studies may reveal myopathic potentials.
- Muscle biopsy is important to rule out other possible differential diagnoses if genetic testing is negative.
Molecular diagnostic techniques are available for prenatal diagnosis.
- No definitive therapy is available. However, defining the genetic and molecular defects offers the potential for therapeutic intervention in the future.[12, 13]
- There is no strong evidence of significant benefit with operative scapular fixation. Any benefit as shown in some observational studies has to be balanced against postoperative immobilisation, need for physiotherapy and potential complications.
- There is no evidence from randomised controlled trials to support any drug treatment. However, both strength training and albuterol (equivalent to salbutamol) appear safe with limited benefit on muscle strength and volume. The consequences of long-term use are currently unknown.
- The effectiveness of simple analgesia combined with anti-inflammatory agents for muscle pain is variable.
- A reported association with heart rhythm disorders in some cases suggests that a cardiovascular review every few years (looking particularly for ECG abnormalities, hypertension and heart muscle thickening) is important.
- A periodic eye check may also be appropriate. If troublesome inflammation of the eyes occurs as a result of them remaining open at night, surgery to bring the eyelids closer can be offered if artificial tears alone are insufficient. Research on involvement of the retina may give clues to the pathogenesis of the muscle dysfunction.
- Driving licences, especially LGV or PCV, may be issued for a limited duration, with renewal subject to a satisfactory medical examination.
- Coats' syndrome: retinal vasculopathy with telangiectasia, exudation and retinal detachment. Seen in 49-75% of affected individuals. If detected early, retinal photocoagulation may prevent serious consequences.
- Hearing loss: sensorineural deafness, which may be unilateral or bilateral.
- Mental impairment and epilepsy: either or both may be seen in those patients with early onset.
- Cardiac complications: a single case report found ECG abnormalities - eg, bundle branch block, as well as left ventricular myocardial thickening.[18, 19]
- As many as 20% of patients eventually become wheelchair-bound.
- However, up to one third of patients remain unaware of symptoms at least into old age but may have subtle detectable clinical signs. The majority of affected people come between these two extremes.
- Males tend to develop symptoms earlier and more severely at a given age than females. By age 30 virtually all males with FSHD exhibit symptoms but only two thirds of females do.
- Life expectancy is not affected, except perhaps in the most severe cases with greatly impaired mobility and consequent greater risk of chest infections.
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