myalgia

DEFINITION of myalgia

Myalgia is the sensation of discomfort or pain originating from skeletal muscle tissue, ranging from mild soreness to debilitating pain. It is distinguished from arthralgia (joint pain) by its origin within the muscle belly or myofascial structures, and from neuralgia (nerve pain) by the character of the pain—usually dull, cramping, or aching rather than sharp, shooting, or burning. The underlying mechanism involves activation of muscle nociceptors by chemical mediators (bradykinin, prostaglandins), mechanical stretch, ischemia, or inflammation, often triggered by trauma, infection, overuse, or metabolic stress. Myalgia can be physiological (e.g., delayed-onset muscle soreness after unaccustomed exercise) or pathological (e.g., viral myositis, fibromyalgia, statin-induced myopathy, or polymyalgia rheumatica). Clinically relevant site‑specific forms in coding include M79.11 (mastication muscle), M79.12 (neck), and M79.18 (other site), while generalized myalgia is coded as M79.10. It is commonly confused with fibromyalgia (a centralized pain‑regulation disorder with widespread pain and tender points but normal muscle histology) and with myositis (true muscle inflammation with elevated CK and weakness).

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ETYMOLOGY of myalgia

greek

Component	Origin	Meaning
my- / o	Greek μῦς (mys)	“muscle” — combining form denoting relationship to muscle
-algia	Greek ἄλγος (álgos)	“pain” — noun‑forming suffix, “condition of pain”

The word entered English in the mid‑19th century (circa 1840s) as myalgia (noun), borrowed from New Latin, from Greek mys (“muscle”) + algos (“pain”) — literally “muscle pain.” The adjective myalgic appears by the late 19th century. The root my‑ (“muscle”) connects myalgia to the entire -myo family: myopathy (disease of muscle), myositis (inflammation of muscle), and myocardium (heart muscle). The suffix -algia is highly productive in medical terminology, appearing in terms such as arthralgia, neuralgia, and mastalgia.

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🔀 ALIASES / ALTERNATE TERMS

• Myalgic (adjective form — e.g., “myalgic encephalomyelitis,” “myalgic symptoms”)
• Muscle pain (lay term; standard in patient history and review of systems)
• Myodynia (clinical synonym; from myo- + -odynia, “muscle pain”)
• Muscle ache (common colloquial term, often used for mild or post‑exertional discomfort)
• Muscle soreness (descriptive term, especially for delayed‑onset muscle soreness [DOMS])
• Myalgic spot (localized tender area; may refer to a trigger point)
• Polymyalgia (pain in many muscles; often used for polymyalgia rheumatica, ICD‑10‑CM M31.5)

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🔗 RELATED TERMS

• Analgesia — absence of pain; opposite state of myalgia.
• neuralgia — pain in the distribution of a nerve; distinguished from myalgia by its neuropathic, often electrical quality.
• Arthralgia — joint pain; differentiated by location over the joint line and findings on articular examination.
• Myositis — inflammation of muscle tissue, typically with elevated creatine kinase (CK) and objective weakness; pain may be a feature.
• Fibromyalgia — chronic widespread pain syndrome with central sensitization, fatigue, and tender points; coded M79.7.
• Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) — multisystem illness with post‑exertional malaise and prominent myalgia; ICD‑10‑CM G93.3.
• Myopathy — primary muscle disease, often genetic or toxic; pain is variable; multiple ICD‑10‑CM codes under G71‑G72.
• Rhabdomyolysis — rapid muscle breakdown releasing myoglobin, causing severe pain and risk of renal failure; ICD‑10‑CM M62.82.
• Trigger point — hyperirritable band within a muscle that refers pain; key feature of myofascial pain syndrome.
• Myofascial pain syndrome — regional pain disorder with trigger points; often coded to site‑specific myalgia codes (M79.1x).
• Polymyalgia rheumatica — inflammatory condition of older adults with proximal muscle pain and stiffness; ICD‑10‑CM M31.5.
• Statin‑induced myopathy — medication‑related muscle damage; may present with myalgia.

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CODING CORNER

🏥 ICD-10-CM CODES

Myalgia by Site (M79.1x)

Code	Description
M79.10	Myalgia, unspecified site
M79.11	Myalgia of mastication muscle
M79.12	Myalgia, neck
M79.18	Myalgia, other site

Related Systemic Pain / Fatigue Syndromes

Code	Description
G93.3	Postviral fatigue syndrome / benign myalgic encephalomyelitis
M79.7	Fibromyalgia
M62.82	Rhabdomyolysis

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🔧 COMMON CPT CODES (Myalgia-Related Diagnosis & Treatment)

CPT Code	Description
20552	Injection(s); single or multiple trigger point(s), 1 or 2 muscle(s)
20553	Injection(s); single or multiple trigger point(s), 3 or more muscles
97140	Manual therapy techniques, 1 or more regions, each 15 minutes
97124	Massage, including effleurage, petrissage and/or tapotement, 1 or more areas, each 15 minutes
97110	Therapeutic procedure, therapeutic exercises to develop strength and endurance, range of motion and flexibility, each 15 minutes

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⚠️ Coding Note: myalgia codes (M79.1x) require the highest level of site specificity — never default to M79.10 if the location is documented. When myalgia is a manifestation of a known underlying condition (e.g., influenza, lupus, statin use), sequence the underlying disease first and use the myalgia code as an additional diagnosis only if it meets the criteria for a secondary code. A common undercoding pitfall is using unspecified myalgia M79.10 for what is actually fibromyalgia M79.7; any note of widespread pain, tender points, or fatigue should prompt a query for fibromyalgia or G93.3 (ME/CFS). For trigger point injections, ensure the number of muscles injected is clearly documented to support 20552 vs. 20553.

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DERIVATIONS of myalgia

TABLE definition AS Definition
FROM #medterm 
WHERE length(filter(roots, (word) => econtains([[myalgia]].roots, word))) > 0 AND file.name != [[myalgia]].file.name
SORT file.name ASC

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Query functionality

TABLE definition AS Definition
FROM #medterm 
WHERE length(filter(definition, (word) => econtains([[myalgia]].definition, word))) > 0 AND file.name != [[myalgia]].file.name

Med roots dictionary Appendix A Prefixes Appendix B Combining Forms Appendix C Suffixes Appendix D Suffix forms