Distal muscle weakness

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

Differential diagnosis of distal muscle weaknes

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	Hyperaldosteronism with myopathy	50	Proximal & distal	−	−	−	−	−	−	−	+ Rhabdomyolysis	Palpitations Hypertension	Episodes of increased heart beats	Hyperpigmentation	Hypokalemia	Normal	Normal	Normal
Inflammatory/ Rheumatologic	Inclusion body myositis	50s	Proximal & distal	−	−	−	−	−	−	−	−	Dysphagia Asymmetric weakness	Retrovirus (most common)	N/A	Antibodies to cytoplasmic 5'−nucleotidase	↑↑	Inflammatory cells Invading muscle cells Vacuolar degeneration Inclusions or plaques	Neurogenic
	Fibromyalgia	40−50s	Generalized	−	−	−	−	+	−	−	−	Anxiety or depression features Fatigue Sleep disturbance Numbness Muscle spasms	History of depression	Tenderness in the soft tissue anatomical location	Normal	Normal	Normal	Normal
	Polymyalgia Rheumatica	50s	Diffuse	+	+	−	−	−	−	+	−	Weight loss	History of joints stiffness, worse in the morning	Restricted shoulder motion	↑↑ ESR ↑↑ CRP	Normal	Normal	Normal
Genetic	Myotonic dystrophy	<18 years	Proximal & distal	−	−	+	+	−	−	+	−	Myotonia Cataracts Diabetes mellitus Frontal balding Cardiac arrhythmias Cholecystitis Pregnancy Eyelid ptosis	Positive family history	Muscles often contract and are unable to relax	Mutations in the DMPK gene	N/A	N/A	Myopathic
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	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
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
Neurologic	ALS	>35	Proximal & 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
	Multiple Sclerosis	30's	Proximal & distal	−	−	−	+	+	−	−	−	Ocular findings Urinary incontinence Problems with speech or swallowing	Attacks or exacerbation	Localized weakness Focal sensory disturbances Hyper reactive reflexes Increased tone or stiffness	Head CT ologo−clonal bands	Normal	N/A	Neuropathic
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
Neuromuscular	Botulinum	Variable	Distal	−	−	−	+	−	−	+	−	Double vision Blurred vision Drooping eyelids Slurred speech Difficulty swallowing	H/O food exposure	Hyporeflexia Decreased strength	+Toxin	Normal	N/A	Myopathic
	Lambert−Eaton syndrome	Variable	Distal	−	−	+	+	−	−	+	−	Weakness of the bulbar muscles Ocular Limb weakness	Weaknessa is often relieved temporarily after exertion or physical exercise.		Antibodies against voltage−gated calcium channels