DR MOHAMMAD A.S KAMIL

CONSULTANT NEUROLOGIST

NEUROSCIENCES HOSPITAL

• MYOPATHIES ARE A HETEROGENEOUS GROUP OF DISORDERS THAT CAN BE

CHALLENGING TO DIAGNOSE.

• THE PURPOSE OF THIS REVIEW IS TO PROVIDE A DIAGNOSTIC APPROACH BASED

PREDOMINANTLY ON THE CLINICAL HISTORY AND NEUROLOGIC EXAMINATION.

• IN APPROACHING THE EVALUATION OF A PATIENT WITH A SUSPECTED

MYOPATHY, ONE OF THE MOST IMPORTANT COMPONENTS IS A COMPREHENSIVE

MEDICAL HISTORY.

MYOPATHIES ARE DISORDERS AFFECTING

channel

structure

Metabolism

of skeletal

muscle

Drug-induced myopathies

Endocrine myopathies

Inflammatory/immune myopathies

Myopathies associated with other systemic illness

Toxic myopathies

•Acquired

Channelopathies

Congenital myopathies

Metabolic myopathies

Mitochondrial myopathies

Muscular dystrophies

Myotonias

•Hereditary

Which ‘‘positive’’ and/or ‘‘negative’’ symptoms does the patient experience?

What is the temporal evolution (presentation,episodic,constant,acute)

Does the patient have a family history of a myopathic disorder?

Are there precipitating factors that trigger episodic weakness or stiffness (drugs,exercise,fever,high carbohydrate,cold)

Are any associated systemic symptoms or signs present (cardiac,respiratory,hepatomegaly,cataract,rash)

What is the distribution of weakness?

SYMPTOMS ASSOCIATEDWITH MYOPATHIESA

Negative

•Exercise intolerance

•Fatigue

•Muscle atrophy

•Weakness

Positive

•Cramps

•Contractures

•Muscle hypertrophy

•Myalgia

•Myoglobinuria

•Stiffness

MUSCLE DISEASES ASSOCIATED WITH MYALGIASEosinophilia-myalgia syndrome

Hypothyroid myopathy

Inflammatory myopathies (dermatomyositis, polymyositis)

Infectious myositis (especially viral)

Mitochondrial myopathies

Myoadenylate deaminase deficiency

Toxic myopathies (statins, chloroquine)

Tubular aggregate myopathyX-linked myalgia and cramps (Becker dystrophy

variant)

MYOPATHIES ASSOCIATED WITH MUSCLE CONTRACTURES

Brody disease

Glycolytic/glycogenolytic enzyme defects

Hypothyroid myopathy

Paramyotonia congenita

Rippling muscle disease

MYOPATHIESASSOCIATED WITH MUSCLE STIFFNESS

Hyperkalemic periodic paralysis

Hypothyroid myopathy

Myotonia congenita

Myotonic dystrophy

Paramyotonia congenita

Proximal myotonic myopathy

CAUSES OF MYOGLOBINURIAA

Drugs and toxins (especially alcohol)

Heatstroke

Inflammatory myopathies (rare)

Limb-girdle muscular dystrophy types 2C, 2D, 2E, and 2F (sarcoglycanopathies) and 2I (FKRP)

Neuroleptic malignant syndrome

Metabolic myopathies

Prolonged, intensive exercise

Severe metabolic disturbances, including prolonged fever

Trauma (crush injuries)

Viral and bacterial infections

DRUGS THAT CAN CAUSE TOXICMYOPATHIES

Inflammatory

• Cimetidine

• D-penicillamine

• Procainamide

• L-tryptophan

• Levodopa

Non inflammatory

Necrotizing or

Vacuolar

• Alcohol

• Cholesterol-lowering

agents

• Chloroquine

• Colchicine

• Cyclosporine and

tacrolimus

• Emetine

• (-aminocaproic acid

• Isoretinoic acid

(vitamin A analogue)

• Labetalol

• Vincristine

Rhabdomyolysis and

Myoglobinuria

• Alcohol

• Amphetamine

• Cholesterol-lowering

drugs

• Cocaine

• Heroin

• Toluene

• (-aminocaproic acid

Myosin Loss

• Non depolarizing

neuromuscular

blocking agents

• Steroid

Pattern

recognition

approach to

myopathy

Proximal Limb-Girdle

Distal Weakness

Distal Arm/Proximal Leg Weakness

Proximal Arm/Distal Leg (Scapuloperoneal) Weakness

Ptosis With or Without Ophthalmoparesis

Extensor Weakness Prominent Neck

Bulbar Weakness

Episodic pain,weakness and myoglobinurea

Episodic weakness delayed or unrelated to execise

stiffness and Decreased Ability to Relax

MYOPATHIESCHARACTERIZED BY PREDOMINANTLY DISTAL

WEAKNESS

Centronuclear myopathy

Debrancher deficiency

Hereditary inclusion body myopathy

Inclusion body myositis

Myofibrillar myopathy

Myotonic dystrophy

Distal myopathies (Welander, Markes bery/Udd,Nonaka,Miyoshi,Liang)

SCAPULOPERONEALPATTERN OF WEAKNESS

Acid maltase deficiency

Central core myopathy

Emery-Dreifuss humeroperoneal dystrophy

Facioscapulo humeral dystrophy

Limb-girdle dystrophy 2A(calpain), 2C-F (sarcoglycans),2I (FKRP)

Nemaline myopathy

Scapuloperoneal dystrophy

MYOPATHIES WITHPTOSIS OR OPHTHALMOPARESIS

Ptosis Without

Ophthalmoparesis

Congenital myopathies

Nemaline myopathy

Central core myopathy

Desmin (myofibrillary) myopathy

Myotonic dystrophy

Ptosis With

Ophthalmoparesis

Centronuclear myopathy

Mitochondrial myopathy

Multicore disease

Oculopharyngeal muscular dystrophy

Oculopharyngodistal myopathy

Neuromuscular junction disease

(myasthenia gravis Lambert-Eaton

myasthenic syndrome, botulism(

MYOPATHIESWITH PROMINENT NECK EXTENSOR

WEAKNESS

Isolated neck extensor myopathy

Dermatomyositis

Polymyositis

Inclusion body myositis

Carnitine deficiency

Facioscapulohumeral dystrophy

Myotonic dystrophy

Congenital myopathy

Hyperparathyroidism

MYOPATHIESWITH EPISODIC PAIN, WEAKNESS,

AND MYOGLOBINURIA/RHABDOMYOLYSISARelated to

Exercise

‘‘Couch

potato’’

syndrome

Glycogenoses (eg,

McArdle disease)

Lipid disorders (carnitine

palmitoyltransferase deficiency)

Not Related

to Exercise

Central non-neuromuscular causes :

neuroleptic malignant ,status epilepticus

Drugs/toxins

Malignant hyperthermia

Polymyositis/dermatomyositis (rarely)

Viral/bacterial infections

EPISODIC WEAKNESS DELAYEDOR UNRELATED TO EXERCISE

Periodic paralysis

Ca++ channelopathies (hypokalemic)

Na++ channelopathies (hyperkalemic)

Andersen-Tawil syndrome

Secondary periodic paralysis

(thyrotoxicosis)

Other: Neuromuscular junction

diseases

STIFFNESS/DECREASED ABILITY TO RELAX

Improves With

Exercise

Myotonia: Na or

Cl channelopathy

Worsens With

Exercise/Cold

Paramyotonia:

Na

channelopathy

Brody disease

With Fixed

Weakness

Myotonic

dystrophy (DM 1)

Proximal

myotonic

myopathy (DM2)

Becker disease

(AR Cl

channelopathy)

Other

Malignant

hyperthermia

Neuromyotonia

Rippling muscle

Stiff-person

syndrome

DR MOHAMMAD A.S KAMIL

CONSULTANT NEUROLOGIST

NEUROSCIENCES HOSPITAL