Muscle weakness and Atrophy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Iqra Qamar M.D.[2]

Differential Diagnosis of Muscle weakness and Atrophy

Organ system	Disease	Symptoms												History	Physical Examination	Diagnosis
		Age of onset	Muscle weakness	Fever	Myalgia	Contractures	Gait abnormality	Neuropathy	Atrophy	Stiffness	Myoglobinuria	Other features	Laboratory Findings			Creatine Kinase	Muscle Biopsy	Electromyogram
Medication−induced	Corticosteroids	Variable	Proximal	−	+	−	−	−	+	−	−	Central obesity Excessive sweating Insomnia Reduced libido  Amenorrhea Infertility  Psychological disturbances	Positive h/o medications	Facial and sphincter muscles are usually spared	Positive ACTH stimulation test 24-hour urine cortisol Low dose dexamethasone suppression test	Normal	Normal	Normal
Endocrine	Cushing's disease	25 −45	Proximal	−	−	−	−	−	+	−	−	Decreased libido Obesity/weight gain Plethora Round face Menstrual changes Hirsutism Hypertension Ecchymoses Lethargy Depression Dorsal fat pad Abnormal glucose tolerance	N/A	Facial and sphincter muscles are usually spared Overweight Straie Moon face HTN Hyperpigmentation	Positive ACTH stimulation test 24-hour urine cortisol Low dose dexamethasone suppression test	Normal	Atrophy of type 2 muscle fibers, especially type 2B	Normal
	Hyperthyroidism	40	Proximal	−	−	−	−	−	+	+	+	Signs of hyperthyroidism	H/o of weight loss	Sweating Tremor Neck swelling	Decreased TSH	↑↑	Non specific	Myotonic
	Hypothyroidism	55	Proximal	−	+	+	−	−	+	+	+ Rhabdomyolysis	Signs of hypothyroidism	H/o weight gain	Myxoedema  Muscle pseudohypertrophy	Increased TSH	↑↑	Nonspecific	Normal
	Diabetic infraction	45	Proximal	+	+	−	−	+	+	−	−	Cramps Sudden onset of pain Anterior thigh muscles are most commonly involved	H/O long standing diabetes	Swelling Tenderness	Elevated ESR Leukocytosis	Normal	Necrosis Edema	Normal
Organ system	Disease	Age of onset	Muscle weakness	Fever	Myalgia	Contractures	Gait abnormality	Neuropathy	Atrophy	Stiffness	Myoglobinuria	Other features	History	Physical Examination	Laboratory Findings	Creatine Kinase	Muscle Biopsy	Electromyogram
Genetic	Becker muscular dystrophy	<13yrs	Proximal	−	−	+	+	−	+	−	−	Milder form of Duchenne	Growth delay Age of onset of symptoms is much delayed than duchenne	Positive Grower sign	Decreased amount of dystrophin.	↑↑	Muscle fibril degeneration, regeneration Isolated fiber hypertrophy Muscle replacement with fat and connective tissue	Myopathic
	Duchenne muscular dystrophy	<13 yrs	Proximal	−	−	+	+	−	+	−	−	Calf psedohypertrophy Cardiomyopathy Kyphoscoliosis Cognitive impairment	Early onset	Positive Grower sign	Errors in the Xp21 gene. Absence of dystrophin.	↑↑
	Limb−girdle muscular dystrophies	<15 yrs	Proximal	−	+	+	+	−	+	−	−	Calf hypertrophy Scapular winging Cardiomyopathy Cardiac arrhythmias Respiratory muscle weakness	Autosomal dominant Deterioration of ability to run/walk	Muscle weakness is generally symmetric	LMNA gene CAV3 gene	↑↑	N/A	Myopathic
	Glycogen storage disease	Variable	Proximal	−	−	−	−	−	+	−	−	AR Faituge Hypoglycemia	Exercise intolerance	Hypotonia Hepatomegaly	Lactic acidosis Elevated liver enzymes Ketosis	↑↑	Normal	Normal
Infectious	Polio	<5 yrs	Proximal	−	−	−	+	+	+	−	−	Asymmetrical paralysis Muscle atrophy Tremors Skeletal deformities	History of skipped immunization.	Normal Meningeal signs Asymmetrical flaccid paralysis Pharyngeal paralysis	Isolation from pharyngealsecretions, CSF Positive serology	N/A	N/A	Neurological pattern
Neurologic	ALS	>35	Proximal & Distal Distal	−	−	−	−	+	+	+	−	Dysphagia Spasticity Hyperreflexia Babinski's +	N/A	Both upper and lower motor neuron signs	Clinical diagnosis	Normal	Nonspecific findings of chronic denervation with reinnervation	Neuropathic
	Stroke	>65	Proximal & distal	−	−	−	+	+	+	−	−	Dysphagia Unilateral/Bilateral weakness	H/o HTN, dyslipidaemia DM	Weakness of the involved arm	Head CT	Normal	Normal	Neuropathic