MYOPATHIES,MYOTONIA,CARDIOMYOPATHIES.

Presenter: Dr Eva F. Mujuni (Resident-Internal Medicine)

Facilitator: Dr B.L. Mtinangi

Overview1.Introduction2.Myopathies Definition Causes Classification Pathophysiology Clinical presentation Diagnosis Treatment

Overview…

3.Myotonia Definition Causes Treatment

4.Cardiomyopathies Definition Causes Types Pathophysiology Clinical Presentation Diagnosis Treatment

5.References

Myopathies

A myopathy is a muscular disease in which the muscle fibers do not function for any one of many reasons, resulting in muscular weakness.

It can occur in heart muscle, skeletal muscles, or muscles of various organs (for example, the stomach or intestines).

Myopathies Winged scapulae

Myopathies…

Depending on the causes Myopathies can be classified as:

GeneticInflammatoryEndocrine Toxic Idiopathic

Myopathies…

Classification of Myopathies…

Genetic myopathies

Caused by a genetic defect. The most common muscular dystrophies, Duchenne

and Becker muscular dystrophy, result from a genetic defect on the X chromosome.

Myopathies… Classification of Myopathies…

Other Genetic Myopathies include:

• Central core disease • Centronuclear (myotubular) myopathy • Myotonia congenita • Nemaline myopathy • Paramyotonia congenita • Periodic paralysis (hypokalemic and hyperkalemic forms) • Mitochondrial myopathies

Myopathies… Classification of Myopathies…

Inflammatory myopathies

They are autoimmune disorders

Healthy muscle fibres are attacked by the body's immune system and become inflammed , this in turn damages the muscle.

Example in: Polymyositis (PM) Dermatomyositis (DM) is characterised by a skin rash as well as

muscle symptoms of PM

Myopathies… Classification of Myopathies…

Endocrine myopathies

Caused by the over or underproduction of hormones.

Examples are: Hyperthyroid myopathy is caused by the thyroid gland

producing too much thyroxine. Hypothyroid myopathy is caused by the underproduction of

thyroxine.

Myopathies… Classification of myopathies…

Endocrine myopathies…

Cushing's disease, characterized by overproduction of hormones produced by the pituitary and adrenal glands.

Excess parathyroid hormone results in hypercalcemia, which causes proximal muscle pain and weakness.

Hormone-secreting tumors can also cause endocrine disorders that cause myopathies.

Myopathies… Classification of myopathies…

Toxic myopathies

They are caused by exposure to certain medications and chemicals.

Excessive alcohol intake . Drugs and chemicals - Anesthetics (eg. lidocaine,

mepivacaine, ethyl chloride) Cholesterol lowering medication (eg. clofibrate, genfibrozil,

lovastatin, simivastatin, niacin)

Myopathies…

Classification of myopathies…

Toxic myopathies…

Glucocorticoids (eg. triamcinolone, dexamethasone, betamethasone)

Narcotics (eg. cocaine, heroin, meperidine) Other drugs (eg. zidovudine, D-penicillamine,

procainamide, chloroquine, gallamine) Herbicides, insecticides

Myopathies…

Clinical Presentation of Myopathies

Symmetric proximal muscle weaknessMalaiseFatiguePatient may note dark colored urine and/or fever.No sensory complaints or paresthesias are noted with myopathies.Atrophy and hyporeflexia are very late findings in most patients with myopathy. The early presence of these findings usually implicates neuropathies.

Myopathies…

Diagnosis of MyopathiesMedical historyThorough physical examCK with isoenzymesElectrolytes- calcium, magnesiumSerum myoglobinSerum creatinine and BUN

Myopathies…

Diagnosis of Myopathies…Urinalysis: Myoglobinuria is indicated by

positive urinalysis with few RBCs on microscopic evaluation.

Complete blood countErythrocyte sedimentation rateThyroid function tests

Myopathies…

Diagnosis of Myopathies…Muscle tissue biopsyElectromyogram

Myopathies…

Treatment:Corticosteroids. Immunosuppressive drugs - cyclosporine,

tacrolimus , mycophenolate mofetil and rituximab .

Physical therapy. Treating the underlying condition

Myotonia

A symptom of several muscular disorders characterized by:

Increased muscular irritability and contractility

Slow relaxation of the muscles after voluntary contraction or electrical stimulation.

Myotonia…

Causes of Myotonia Abnormality in the muscle membrane—

specifically, the ion channels that controls the contraction of muscle fibers.

Examples are:myotonic muscular dystrophy myotonia congenita

Myotonia…

Myotonia congenita This disease is caused by mutations in the

gene for a chloride channel that is necessary for shutting off the electrical excitation that causes muscle contraction.

The Becker type is inherited in an autosomal recessive pattern.

The Thomsen type is autosomal dominant.

Myotonia…

Treatment of Myotonia Mexelitine Quinine Phenytoin Physical therapy

Cardiomyopathies

Cardiomyopathy is a chronic disease of the heart muscle (myocardium), in which the muscle is abnormally enlarged, thickened, and/or stiffened.

Cardiomyopathies…

Common types:

Dilated cardiomyopathy (DCM)Hypertrophic cardiomyopathy (HCM)Restrictive cardiomyopathy (RCM)

Dilated cardiomyopathy (DCM)

Dilated cardiomyopathy is a condition characterized by dilatation and impaired systolic function of the left and/or right ventricle.

In majority,the cause is idiopathic

DCM

Causes of dilated cardiomyopathy

Genetic eg: Autosomal dominant DCM, X-limked cardiomyopathy

Inflammatory eg: Post-infective, autoimmune, connective tissue diseases( such as SLE and systemic sclerosis)

Metabolic eg: Glycogen storage diseasesNutritional eg: Thiamin and selenium

deficiency

Causes of dilated cardiomyopathy…

Endocrine eg Acromegaly, Thyrotoxicosis, Diabetes mellitus

Infiltrative eg: Hereditary haemochromatosisNeuromuscular eg: Muscular dystrophy,

mitochondrial myopathiesToxic eg: Due to Alcohol,cocaine,

CyclophosphamideHaematological eg: Sickle cell anemia,

Thrombotic thrombocytopenic purpura

DCM

Pathophysiology25% of the idiopathic cases are familialIn the majority of familial cases the

inheritence is autosomal dominantThe responsible genes are the genes encoding

cytoskeletal or associated myocyte proteins(dystrophin,actin,desmin,troponin,lamin)

DCM

DiagnosisChest x-rayECGEchocardiographyTesting for cause as indicatedDiagnosis is by history, physical examination,

and exclusion of other common causes of ventricular failure (eg, systemic hypertension, primary valvular disorders, MI

DCM

ManagementAnticoagulation (EF <30%, hx of embolic

events,atrial fibrillation)Limit activity based on functional statusSalt restriction Fluid restriction Medical therapy– ACE inhibitors, diuretics– Digoxin– Beta blockers

DCM

Management…

Cardiac transplantation • This disorder is the most common indication for

cardiac transplantation

Left Ventricular Reduction Procedures• LV-reshaping

Hypertrophic cardiomyopathy (HCM)

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart muscle becomes thick.

Characterized by variable myocardial hypertrophy most commonly involving the interventricular septum

Majority of cases are familial,autosomal dominant

HCM

With HCM, the sarcomeres (contractile elements) in the heart increase in size, which results in the thickening of the heart muscle.

In addition, the normal alignment of muscle cells is disrupted, a phenomenon known as myocardial disarray.

HCM is most commonly due to mutations in the genes encoding sarcomeric proteins.

HCM

• Beta myosin heavy chain mutations cause elaborate ventricular hypertrophy

• Troponin mutations cause less hypertrophy but more disarray and abnormal vascular response eg.hypotension,hence liable to sudden deaths.

HCM

HCM

Clinical features :Asymptomatic• Echocardiographic findings only

Symptomatic• Dyspnea • Chest pain• Fatigue, pre-syncope, syncope • Palpitation, PND, CHF, dizziness• Cardiac arrythmias,Sudden death

HCM TreatmentThe primary goal of medications is to relieve

symptoms such as chest pain, shortness of breath, and palpitations.

Beta blockers are considered first-line agents, as they can slow down the heart rate.

Nondihydropiridine calcium channel blockers such as verapamil can be used

HCM

Treatment…

Surgical myectomyAlcohol septal ablationVentricular pacingCardiac transplantation

Restrictive cardiomyopathies It is a disease of the myocardium characterized

by restrictive filling and reduced diastolic volume of either or both ventricles, with normal or near-normal systolic function.

May be classified as: Primary (e.g., endomyocardial fibrosis, Löffler's

endocarditis, idiopathic restrictive cardiomyopathy)

Secondary

Restrictive cardiomyopathies

Causes of secondary restrictive cardiomyopathy include:

Infiltrative diseases (e.g., amyloidosis, sarcoidosis)

Storage diseases (e.g., hemochromatosis, glycogen storage disorders, Fabry's disease).

Restrictive cardiomyopathies

Rigid ventricular wall with impaired ventricular filling

Much less common than DCM or HCM outside the tropics, but frequent cause of death in Africa, India, South and Central America and Asia primarily because of the high incidence of endomyocardial fibrosis in those regions

Restrictive cardiomyopathies

The idiopathic form may be familial Associated with mutations in the sarcomeric

protein troponin I

Restrictive cardiomyopathies

Clinical manifestations:Dyspnea Fatigue Symptoms of right and left heart failure Elevated Jugular Venous Pulse

Restrictive cardiomyopathy

Management:

No satisfactory medical therapy .Cardiac failure should be treated.Cardiac transplantation

References

• Kumar and Clark,Clinical Medicine 6th edition• Review of medical Physiology,W.Ganong 21st

edition• Textbook of Medical Physiology,Guyton and

Hall,10th edition• Medscape references-Drugs,diseases and

procedures• http:www.health of children.com• Wikipedia