Emery-Dreifuss muscular dystrophy: contractures, weakness and the heart

Most muscular dystrophies are recognised by weakness. In EDMD, stiffness comes first. Children develop contractures, which are shortened muscles and tendons that limit joint movement, particularly at the elbows, which cannot straighten, the heels, which pull the child onto tiptoe, and the back of the neck, which limits bending the head forward. The spine can become rigid.

Weakness follows later and has a humeroperoneal pattern: the upper arms and the front and outer lower legs. The pattern can be slow enough that adults are diagnosed after an unexpected heart rhythm problem or a pacemaker implant. That is why neuromuscular specialists check the elbows and neck of any adult with an unexplained conduction disorder.

MedlinePlus states that cardiac complications develop in nearly all adults with the condition, including rhythm disturbances and conduction defects that can cause fainting, heart failure or sudden death if untreated. The risk does not track how weak the limbs are, so someone with very mild muscle involvement can still have significant heart disease.

Typical findings are slow heart rates, atrial rhythm problems that start in early adult life, and heart block. People with these features may need a pacemaker or, in selected cases with LMNA variants, an implantable defibrillator, because LMNA disease carries a particular risk of dangerous ventricular rhythms. Decisions are made jointly by cardiology and neuromuscular teams.

• Fainting, near-fainting, or an unusually slow pulse needs prompt assessment

• Palpitations and breathlessness are reasons to be seen urgently

• Collapse, chest pain or severe breathlessness is a 999 emergency

• Annual or more frequent ECG and ambulatory monitoring are usual

The proteins made from these genes sit in or near the nuclear envelope, the double membrane that surrounds the cell nucleus, which is why EDMD is sometimes called a nuclear envelope disease. Emerin is encoded by EMD, FHL1 acts in muscle structure, and lamin A/C by LMNA supports the nuclear scaffold.

Inheritance depends on the gene. X-linked forms mostly affect males, and carrier women may have cardiac conduction problems later in life even without muscle weakness. Autosomal dominant LMNA disease affects both sexes and each child of an affected parent has an even chance of inheriting it. The autosomal recessive form is rare, with only a handful of reported cases worldwide, according to MedlinePlus.

Diagnosis begins with clinical recognition. Creatine kinase is normal or mildly raised, electromyography shows a myopathic pattern, and muscle MRI can help. The NHS lists blood tests, genetic screening, electromyography, muscle biopsy and MRI among the tests used for muscular dystrophy, and genetic panels now usually include EMD, FHL1 and LMNA.

Because the genetic cause is unknown in more than half of cases, a negative test does not rule out the condition. Cardiac review should not wait for genetic results. NHS genetic testing is free when arranged by a hospital specialist, and counselling is offered alongside it.

Management focuses on preventing and treating complications. Physiotherapy stretches tight joints, and orthopaedic surgery to release Achilles tendons is sometimes used. Physiotherapists and orthopaedic teams watch the spine, since rigid spine syndrome can limit breathing. Respiratory function should be checked periodically, and the NHS notes that respiratory support may be needed in muscular dystrophy when appropriate.

Heart rhythm monitoring and devices are the most important interventions. Heart failure medicines may be added when the heart muscle weakens. Anaesthesia needs prior cardiac and respiratory planning. Female relatives who carry X-linked changes or LMNA variants are usually offered cardiac assessment as well.