Muscle weakness and Fever

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Differential Diagnosis of Muscle Weakness and Fever

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
Endocrine	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
Inflammatory/ Rheumatologic	Dermatomyositis	40s−50s Can affect children	Proximal	+	+	−	−	−	−	+	−	Rash Dyspnea Weight loss Cough	Viral infections Cancer	Heliotrope rash on face and hands Telangiectasia Erythema Mechanic's hands Gottron's sign ( violaceous scaly eruption )	↑↑ ESR ↑↑ CRP	↑↑	Perimysial mononuclear infiltrate	Myopathic
	Polymyositis	> 18 years	Proximal	+	+	−	−	−	−	+	−	Similar to dermatomyositis without mucous and skin involvement	N/A	N/A	↑↑ ESR ↑↑ CRP	↑↑	Endomysial mononuclear infiltrate Patchy necrosis
	Polymyalgia Rheumatica	50s	Diffuse	+	+	−	−	−	−	+	−	Weight loss	History of joints stiffness, worse in the morning	Restricted shoulder motion	↑↑ ESR ↑↑ CRP	Normal	Normal	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
Infectious	Lyme disease	Variable	Proximal	+	+	−	+/−	+	−	−	−	Erythema Migrans Flu−like symptoms Lyme arthritis Neurological manifestations	H/o tick bite Hiking trip	Target−like lesions HSM	Clinical diagnosis +Serology	N/A	N/A	N/A
	Influenza	Variable	Proximal and Distal	+	+	−	+	−	−	−	+	Fever Malaise Rhinorrhea Muscle pain worse with movement	Cold weather H/o Ill contacts	Muscle weakness, tenderness, and swelling.	↑↑ Liver enzymes Positive PCR	↑↑	N/A	N/A
	Pyomyositis	Variable	Proximal & Distal	+	+	−	−	−	−	+	−	Fever Malaise Psoas abscess	Immunocompromised	Muscles are painful, swollen, tender, and indurated. Depending on the site of involvement, it may mimic appendicitis (psoas muscle), septic arthritis of the hip (iliacus muscle), or epidural abscess (piriformis muscle).	Leukocytosis Elevated ESR	N/A	N/A	N/A