Muscular Dystrophy

Question 1

Epidemiology

Answer 1

1/3500 births, Male only X-linked

Question 2

Aetiology

Answer 2

inherited disease of mucle resulting in degenerative change in muscle fibres.

Question 3

Pathophysiology

Answer 3

duchennes is the most common type
absent dystrophin is the reason

dystrophin provides support fo the membrane of the muscle fiber it is part of the cytoskeleton
Without support the membrane allows Ca+ enters the cell resulting in its death

Beckers Muscular Dystrophy is milder due to dystrophin being somewhat function

Suspected if any child has delayed motor development
speech may also be delayed

Question 4

Natural History

Answer 4

affects proximal muscles first

premature death

Question 5

Clinical Manifestations

Answer 5

Clinically manefests at 5 years or earlier
leading to wheel chair.

Becker 2nd common manifests later/milder

Question 6

Symptoms

Answer 6

Clumsy with poor balance.

Weak muscles? tiptoeing, prutruding abdominals, spine hyperextension

Question 7

Signs

Answer 7

Beckers - ankle jerk reflex present rest are absent.

pseudomuscular hypertrophy due to the replacement of fat/fibrous tissue in place of degenerated fibres

Question 8

Complications

Answer 8

Duchennes

Joint contractures.
Respiratory complications:
Respiratory muscle failure is progressive, leading to hypoventilation, loss of coughing, and respiratory infections.
Respiratory failure is the usual cause of death.

Cardiac complications:
The severity of cardiomyopathy and congestive heart failure may not parallel the severity of skeletal muscle disease.

Atrial and ventricular arrhythmias may be life-threatening. The degree of hypoventilation and pulmonary dysfunction also affects cardiac function in muscular dystrophy.

Only a minority of patients die from cardiac complications.

Smooth muscle can also be affected, causing gastrointestinal symptoms such as gastric dilation or pseudo-obstruction.

Educational: about 20% of DMD patients have learning difficulty. This is nonprogressive and may affect verbal ability more than other performance.

Complications of immobility and/or steroids - eg, constipation, osteoporosis, obesity, hypertension.

Weight loss can occur in the late stage of DMD.
Anaesthetic complications (see 'Presentation' and 'Management', above).

Beckers - milder

Question 9

Prognosis

Answer 9

Duchennes = complications in all 18 +
usually die from respiratory or cardiac complications in their 20s or 30s

Beckers = survive to 30-40s