DiagnosticTree/RadialForearm
{
"model": "bayesian_lr_scoring",
"version": "1.0",
"region_label": "Radial Forearm Pain",
"description": "Probabilistic scoring model for pain along the radial (thumb-side) forearm. Five equal-prior sources: the brachioradialis - the local radial-forearm muscle, referring from the lateral epicondyle down the radial forearm to the thumb web - together with four muscles whose pain reaches the radial forearm from a distance: supraspinatus (lateral shoulder to the forearm with a lateral-epicondyle accent), infraspinatus (deep anterior shoulder down to the lateral forearm and radial hand), scaleni (neck driver of the radial chain), and subclavius (a radial skip pattern from beneath the clavicle). Structural differential led by radial tunnel syndrome and posterior interosseous nerve compression, with lateral epicondylitis, radial sensory nerve entrapment, intersection syndrome, and de Quervain's (Moradi 2015; Shamrock & Das; Buchanan 2023; Calotta & Dellon 2022; Shehab & Mirabelli 2013).",
"thresholds": {
"early_exit_posterior": 0.55,
"early_exit_gap": 0.18,
"pairwise_trigger": 0.15
},
"muscles": {
"brachioradialis": {
"label": "Brachioradialis",
"prior": 0.2,
"page": "Muscle:Brachioradialis",
"key_trp_note": "The one muscle here whose belly lies in the radial forearm itself; refers from the lateral epicondyle down the radial forearm to the base of the thumb and the thumb web. Activated by forceful, repetitive gripping (it stabilises the wrist under a strong grip). A common overlooked contributor to lateral elbow and radial-forearm pain; examine with the supinator and the radial wrist extensors, which share the same territory, and screen for radial tunnel syndrome, which occupies the same dorsoradial proximal forearm.",
"subtitle": "Pain at the lateral epicondyle running down the RADIAL forearm to the base of the thumb and web; worse with forceful gripping; the local radial-forearm source, often misdiagnosed as tennis elbow"
},
"supraspinatus": {
"label": "Supraspinatus",
"prior": 0.2,
"page": "Muscle:Supraspinatus",
"key_trp_note": "Refers a deep ache to the mid-deltoid (lateral shoulder) that extends down the lateral arm, often to the forearm, and characteristically concentrates AT THE LATERAL EPICONDYLE - a feature that usefully separates it from the infraspinatus, which does not refer to the epicondyle. Onset is gradual from sustained or repetitive loading (carrying a heavy bag with the arm at the side, prolonged overhead work). Pain runs throughout the abduction arc; sleep disturbance is only mild. Almost always co-active with infraspinatus and upper trapezius.",
"subtitle": "Deep ache over the OUTER (mid-deltoid) shoulder running down the lateral arm to the forearm, often concentrating AT THE LATERAL EPICONDYLE; gradual onset from carrying heavy loads or overhead work; pain throughout raising the arm"
},
"infraspinatus": {
"label": "Infraspinatus",
"prior": 0.2,
"page": "Muscle:Infraspinatus",
"key_trp_note": "The principal myofascial source of deep anterior shoulder-joint pain, with spillover radiating down the anterolateral arm to the lateral forearm and, in a minority, the radial hand - which is how it reaches this region. Onset is typically acute (a reach-and-twist incident the patient recalls). Sleep is disturbed on either side, and behind-the-back reaching is severely restricted (positive Hand-to-Shoulder-Blade test). Unlike the supraspinatus it does NOT concentrate pain at the lateral epicondyle; the forearm pain is distant spillover, so the deep anterior-shoulder findings are the tell.",
"subtitle": "Deep pain in the FRONT of the shoulder joint that radiates down the front-outer arm to the lateral forearm and sometimes the radial hand; acute onset the patient can pin to an incident; cannot sleep on either side; behind-the-back reach severely restricted"
},
"scaleni": {
"label": "Scaleni",
"prior": 0.2,
"page": "Muscle:Scalene",
"key_trp_note": "The scalene complex refers pain down the arm and is a key driver of satellite trigger points throughout the forearm, so its referred pain reaches the radial forearm and it perpetuates the local muscles. The neck must be examined whenever a radial-forearm trigger point is found, because treating the forearm without addressing a scalene driver leads to recurrence. May contribute to a thoracic-outlet-type picture.",
"subtitle": "Neck-origin pain spreading down the arm toward the forearm; a key driver of satellite trigger points throughout the forearm muscles; examine the neck whenever a radial-forearm trigger point is found"
},
"subclavius": {
"label": "Subclavius",
"prior": 0.2,
"page": "Muscle:Subclavius",
"key_trp_note": "A small muscle beneath the clavicle whose referral runs down the radial side of the arm and forearm, characteristically SKIPPING the elbow and wrist, and reappears on the radial hand at the thumb, index, and middle fingers. Its shortening draws the clavicle toward the subclavian vessels, a vascular (reduced-radial-pulse) mechanism distinct from the neurological scalene pattern. Routinely overlooked because it is palpated through the pectoralis major, with which it is almost always co-active.",
"subtitle": "Front-of-shoulder pain running down the RADIAL arm and forearm, SKIPPING the elbow and wrist, reappearing on the thumb, index, and middle fingers; may reduce the radial pulse (vascular pattern); almost always with pectoralis major"
}
},
"questions": [
{
"id": "q_zone",
"text": "Where does the pain seem to come from?",
"sublabel": "The dominant origin of the whole pattern",
"type": "choice",
"answers": [
{
"id": "forearm_elbow",
"label": "The RADIAL FOREARM or outer elbow itself",
"sublabel": "Local radial forearm / elbow",
"lr": {
"brachioradialis": 6.5,
"supraspinatus": 1.2,
"infraspinatus": 0.8,
"scaleni": 0.7,
"subclavius": 0.8
}
},
{
"id": "outer_shoulder",
"label": "The OUTER shoulder (over the deltoid), running down the arm",
"sublabel": "Lateral shoulder source",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 6.0,
"infraspinatus": 1.5,
"scaleni": 0.7,
"subclavius": 0.8
}
},
{
"id": "deep_front_shoulder",
"label": "DEEP in the FRONT of the shoulder joint, radiating down the arm",
"sublabel": "Deep anterior shoulder source",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 1.2,
"infraspinatus": 6.0,
"scaleni": 0.8,
"subclavius": 2.0
}
},
{
"id": "neck",
"label": "The NECK, spreading down the arm",
"sublabel": "Neck source",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 0.7,
"infraspinatus": 0.9,
"scaleni": 7.0,
"subclavius": 0.9
}
},
{
"id": "front_shoulder_skip",
"label": "The FRONT of the shoulder, with a column down the arm that skips the elbow",
"sublabel": "Anterior shoulder, skip column",
"lr": {
"brachioradialis": 0.7,
"supraspinatus": 0.8,
"infraspinatus": 1.2,
"scaleni": 0.8,
"subclavius": 6.5
}
}
]
},
{
"id": "q_onset",
"text": "How did the pain start?",
"sublabel": "The onset pattern separates the shoulder sources from one another",
"type": "choice",
"answers": [
{
"id": "gradual_loading",
"label": "Gradually, from repeated gripping, carrying, or overhead work",
"sublabel": "Gradual overload",
"lr": {
"brachioradialis": 3.5,
"supraspinatus": 4.0,
"infraspinatus": 0.6,
"scaleni": 1.0,
"subclavius": 1.2
}
},
{
"id": "acute_incident",
"label": "Suddenly, after a specific reach-and-twist or balance-grab incident I can recall",
"sublabel": "Acute recalled incident",
"lr": {
"brachioradialis": 0.8,
"supraspinatus": 0.8,
"infraspinatus": 6.0,
"scaleni": 0.7,
"subclavius": 0.7
}
},
{
"id": "neck_posture",
"label": "With neck trouble, or after carrying a heavy shoulder bag / poor posture",
"sublabel": "Neck / postural",
"lr": {
"brachioradialis": 0.7,
"supraspinatus": 0.8,
"infraspinatus": 0.8,
"scaleni": 5.0,
"subclavius": 2.0
}
}
]
},
{
"id": "q_provocation",
"text": "Which activity most reliably brings on the pain?",
"sublabel": "Choose the single strongest aggravator",
"type": "choice",
"answers": [
{
"id": "forceful_gripping",
"label": "Forceful or sustained gripping (tools, a racquet, a steering wheel)",
"sublabel": "Forceful gripping",
"lr": {
"brachioradialis": 6.5,
"supraspinatus": 0.8,
"infraspinatus": 0.7,
"scaleni": 0.7,
"subclavius": 0.7
}
},
{
"id": "carry_overhead",
"label": "Carrying a heavy bag with the arm at the side, or working/reaching overhead",
"sublabel": "Carrying / overhead load",
"lr": {
"brachioradialis": 0.8,
"supraspinatus": 6.0,
"infraspinatus": 1.5,
"scaleni": 0.8,
"subclavius": 0.9
}
},
{
"id": "reach_behind_back",
"label": "Reaching behind the back (to a pocket or to fasten clothing)",
"sublabel": "Behind-the-back reach",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 1.0,
"infraspinatus": 6.0,
"scaleni": 0.8,
"subclavius": 0.9
}
},
{
"id": "neck_movement",
"label": "Neck movement, or carrying a heavy strap/bag on the shoulder",
"sublabel": "Neck / strap load",
"lr": {
"brachioradialis": 0.7,
"supraspinatus": 0.8,
"infraspinatus": 0.8,
"scaleni": 6.0,
"subclavius": 1.5
}
},
{
"id": "front_shoulder_reach",
"label": "Reaching forward, or deep front-of-shoulder load",
"sublabel": "Anterior shoulder load",
"lr": {
"brachioradialis": 0.7,
"supraspinatus": 1.0,
"infraspinatus": 1.5,
"scaleni": 0.8,
"subclavius": 5.0
}
}
]
},
{
"id": "q_epicondyle",
"text": "Does the pain concentrate AT or feel like it is IN the lateral elbow (the bony point on the outer elbow)?",
"sublabel": "Supraspinatus refers to the lateral epicondyle; infraspinatus does not - a key separator between the two shoulder muscles",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - there is a clear pain focus at the outer elbow",
"lr": {
"brachioradialis": 2.0,
"supraspinatus": 4.0,
"infraspinatus": 0.3,
"scaleni": 0.9,
"subclavius": 0.7
}
},
{
"id": "no",
"label": "No - the elbow point itself is not a focus",
"lr": {
"brachioradialis": 0.8,
"supraspinatus": 0.5,
"infraspinatus": 1.6,
"scaleni": 1.05,
"subclavius": 1.1
}
}
]
},
{
"id": "q_sleep_back",
"text": "Is sleep disturbed on EITHER side, with marked difficulty reaching behind the back?",
"sublabel": "Infraspinatus signature - severe bilateral sleep disturbance and restricted behind-the-back reach",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - cannot lie comfortably on either side, and behind-the-back reach is very limited",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 0.8,
"infraspinatus": 6.0,
"scaleni": 0.9,
"subclavius": 0.9
}
},
{
"id": "no",
"label": "No - sleep is not badly disturbed and behind-the-back reach is reasonable",
"lr": {
"brachioradialis": 1.2,
"supraspinatus": 1.2,
"infraspinatus": 0.3,
"scaleni": 1.05,
"subclavius": 1.05
}
}
]
},
{
"id": "q_skip_radial",
"text": "Does the arm pain SKIP the elbow and wrist - present in the arm and again in the radial fingers (thumb, index, middle), but not at the elbow or wrist?",
"sublabel": "The radial skip pattern of the subclavius",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - the elbow and wrist are spared while the arm and radial fingers hurt",
"lr": {
"brachioradialis": 0.6,
"supraspinatus": 0.8,
"infraspinatus": 1.0,
"scaleni": 0.9,
"subclavius": 7.0
}
},
{
"id": "no",
"label": "No - the pain includes the elbow or wrist, or runs continuously",
"lr": {
"brachioradialis": 1.2,
"supraspinatus": 1.05,
"infraspinatus": 1.0,
"scaleni": 1.0,
"subclavius": 0.3
}
}
]
},
{
"id": "q_neck_driver",
"text": "Is there neck pain or tightness with the forearm pain, or does pressing the side of the neck reproduce or worsen the arm pain?",
"sublabel": "Scalene driver screen - scalene trigger points seed satellite trigger points down the forearm",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - neck pain/tightness, or neck pressure reproduces the arm pain",
"lr": {
"brachioradialis": 0.8,
"supraspinatus": 0.9,
"infraspinatus": 1.0,
"scaleni": 6.5,
"subclavius": 1.0
}
},
{
"id": "no",
"label": "No - no neck component",
"lr": {
"brachioradialis": 1.1,
"supraspinatus": 1.05,
"infraspinatus": 1.0,
"scaleni": 0.3,
"subclavius": 1.0
}
}
]
},
{
"id": "q_palpation",
"text": "Where does firm palpation most precisely reproduce the familiar forearm pain?",
"sublabel": "The reproducing tender point - the most specific localiser",
"type": "choice",
"answers": [
{
"id": "brachioradialis_belly",
"label": "In the brachioradialis (the muscle that bunches on the upper radial forearm when you bend the elbow against resistance)",
"sublabel": "Brachioradialis location",
"lr": {
"brachioradialis": 7.0,
"supraspinatus": 0.5,
"infraspinatus": 0.5,
"scaleni": 0.5,
"subclavius": 0.5
}
},
{
"id": "supraspinous_fossa",
"label": "Above the spine of the shoulder blade, in the hollow at the top (through the trapezius)",
"sublabel": "Supraspinatus location",
"lr": {
"brachioradialis": 0.5,
"supraspinatus": 7.0,
"infraspinatus": 0.6,
"scaleni": 0.5,
"subclavius": 0.5
}
},
{
"id": "infraspinous_fossa",
"label": "On the flat of the shoulder blade below its spine, at the back of the shoulder",
"sublabel": "Infraspinatus location",
"lr": {
"brachioradialis": 0.5,
"supraspinatus": 0.6,
"infraspinatus": 7.0,
"scaleni": 0.5,
"subclavius": 0.5
}
},
{
"id": "side_of_neck",
"label": "In the side of the neck (scalene muscles)",
"sublabel": "Scaleni location",
"lr": {
"brachioradialis": 0.5,
"supraspinatus": 0.5,
"infraspinatus": 0.6,
"scaleni": 7.0,
"subclavius": 0.7
}
},
{
"id": "beneath_clavicle",
"label": "Deep beneath the collarbone (through the chest muscle)",
"sublabel": "Subclavius location",
"lr": {
"brachioradialis": 0.5,
"supraspinatus": 0.5,
"infraspinatus": 0.6,
"scaleni": 0.7,
"subclavius": 7.0
}
}
]
}
],
"pairwise": [
{
"id": "pw_supra_infra",
"pair": [
"supraspinatus",
"infraspinatus"
],
"text": "Tiebreaker - Supraspinatus vs Infraspinatus",
"question": "Is the pain over the OUTER shoulder with a focus at the lateral epicondyle and gradual onset (supraspinatus), or DEEP in the front of the shoulder joint with acute onset and disturbed sleep on either side (infraspinatus)?",
"sublabel": "The two rotator-cuff sources - separate by epicondyle focus, onset, and sleep",
"answers": [
{
"id": "supra",
"label": "Outer shoulder, lateral-epicondyle focus, gradual onset - supraspinatus",
"lr": {
"supraspinatus": 6.0,
"infraspinatus": 0.3
}
},
{
"id": "infra",
"label": "Deep front of joint, acute onset, sleepless on either side - infraspinatus",
"lr": {
"supraspinatus": 0.3,
"infraspinatus": 6.0
}
}
]
},
{
"id": "pw_brad_supra",
"pair": [
"brachioradialis",
"supraspinatus"
],
"text": "Tiebreaker - Brachioradialis vs Supraspinatus",
"question": "Is the pain reproduced by forceful GRIPPING with a tender point in the radial forearm (brachioradialis), or does it come from the OUTER SHOULDER and run down to the elbow (supraspinatus)?",
"sublabel": "Local radial-forearm source vs shoulder source referring to the forearm/epicondyle",
"answers": [
{
"id": "brad",
"label": "Forceful gripping, radial-forearm tender point - brachioradialis",
"lr": {
"brachioradialis": 6.0,
"supraspinatus": 0.3
}
},
{
"id": "supra",
"label": "Outer shoulder running down to the elbow - supraspinatus",
"lr": {
"brachioradialis": 0.3,
"supraspinatus": 6.0
}
}
]
},
{
"id": "pw_scal_subcl",
"pair": [
"scaleni",
"subclavius"
],
"text": "Tiebreaker - Scaleni vs Subclavius",
"question": "Does the arm pain originate at the NECK (reproduced by neck pressure), or run from beneath the collarbone down the RADIAL arm while SKIPPING the elbow and wrist?",
"sublabel": "Neck driver vs the subclavius radial skip pattern",
"answers": [
{
"id": "scal",
"label": "Neck origin, reproduced by neck pressure - scaleni",
"lr": {
"scaleni": 6.0,
"subclavius": 0.3
}
},
{
"id": "subcl",
"label": "Radial arm, skips elbow and wrist to thumb/index/middle - subclavius",
"lr": {
"scaleni": 0.3,
"subclavius": 6.0
}
}
]
},
{
"id": "pw_brad_infra",
"pair": [
"brachioradialis",
"infraspinatus"
],
"text": "Tiebreaker - Brachioradialis vs Infraspinatus",
"question": "Is the pain a LOCAL radial-forearm ache reproduced by gripping (brachioradialis), or does it come from DEEP in the front of the shoulder and radiate down to the forearm (infraspinatus)?",
"sublabel": "Local forearm source vs deep anterior shoulder source with forearm spillover",
"answers": [
{
"id": "brad",
"label": "Local radial-forearm ache, worse gripping - brachioradialis",
"lr": {
"brachioradialis": 6.0,
"infraspinatus": 0.3
}
},
{
"id": "infra",
"label": "Deep anterior shoulder radiating to the forearm - infraspinatus",
"lr": {
"brachioradialis": 0.3,
"infraspinatus": 6.0
}
}
]
}
],
"treatment_dag": {
"edges": [
{
"from": "scaleni",
"to": "brachioradialis",
"type": "key_satellite",
"label": "Scalene trigger points seed satellite forearm trigger points; treat the neck first"
},
{
"from": "supraspinatus",
"to": "infraspinatus",
"type": "functional_unit",
"label": "The supraspinatus-infraspinatus rotator-cuff team develops trigger points together; examine and treat both"
},
{
"from": "infraspinatus",
"to": "brachioradialis",
"type": "secondary_load",
"label": "Shoulder-girdle trigger points can refer to and overload the radial forearm; address the shoulder source when forearm treatment gives incomplete relief"
},
{
"from": "subclavius",
"to": "brachioradialis",
"type": "secondary_load",
"label": "Subclavius is a deep residual radial source (co-active with pectoralis major); treat after the primary muscles"
}
],
"edge_type_labels": {
"key_satellite": "Treat first - key TrP driving satellite",
"functional_unit": "Treat concurrently in same session",
"secondary_load": "Treat after primary resolves",
"antagonist_risk": "Treat in alternating cycles - reactive activation risk"
}
},
"emergency": [
{
"id": "rf-e1",
"label": "Acute compartment syndrome of the forearm",
"question": "Severe, disproportionate, worsening forearm pain unrelieved by rest or elevation? Pain sharply increased by passive finger or wrist movement? Tense or woody forearm? Paraesthesia, pallor, or weakness of the hand? Recent fracture, crush, tight cast, or circumferential burn?",
"source": "Standard limb-emergency screen"
},
{
"id": "rf-e2",
"label": "Septic arthritis of the elbow / forearm joint",
"question": "An acutely hot, swollen, exquisitely tender elbow or wrist with severe restriction of all movement and forearm rotation? Fever or systemically unwell? Recent bacteraemia, penetrating injury, IV drug use, or immunosuppression?",
"source": "Standard joint-sepsis screen"
}
],
"urgent": [
{
"id": "rf-u1",
"label": "Posterior interosseous nerve (PIN) compression syndrome",
"question": "Progressive WEAKNESS of finger and thumb extension (and weak wrist extension that drifts radially), with or without dorsoradial forearm aching? Unlike radial tunnel syndrome (pain only), PIN compression syndrome causes true motor loss from injury to the nerve's myelinated fibres. Examine finger/thumb extension carefully - progressive weakness needs prompt referral, electrodiagnostic study, and consideration of decompression.",
"source": "Shamrock & Das; Buchanan, Maini & Varacallo 2023"
},
{
"id": "rf-u2",
"label": "Radial neuropathy at the spiral groove / proximal radial nerve injury",
"question": "Wrist drop (weak wrist and finger extension) after a humeral shaft fracture, prolonged arm compression ('Saturday night palsy'), or trauma, with sensory change over the dorsal forearm/hand? A proximal radial nerve lesion needs distinguishing from the radial-tunnel/PIN entrapments and from a myofascial source.",
"source": "WikiMSK (radial neuropathy at the spiral groove)"
},
{
"id": "rf-u3",
"label": "Radial head / forearm fracture",
"question": "Significant trauma, fall, or axial load with bony tenderness, deformity, or a painful, limited, or blocked forearm rotation? A radial head fracture with ulnar-sided wrist pain may signal an Essex-Lopresti injury (interosseous membrane disruption) - image the wrist as well as the elbow.",
"source": "WikiMSK (radial head fractures)"
},
{
"id": "rf-u4",
"label": "Cervical radiculopathy (C6-C7) / thoracic outlet syndrome",
"question": "Neck pain with dermatomal radial forearm/thumb pain, sensory deficit, reflex change (depressed brachioradialis/biceps reflex), or myotomal weakness? Positive Spurling's? A proximal driver must be excluded - and scalene trigger points frequently coexist with and drive a thoracic-outlet picture.",
"source": "Buchanan, Maini & Varacallo 2023; standard radiculopathy screen"
}
],
"broad_differential": [
{
"id": "bd-1",
"condition": "Radial tunnel syndrome",
"confidence": "uncommon",
"mimics": "Aching dorsoradial proximal-forearm pain, often called 'resistant tennis elbow' - overlaps the brachioradialis and supraspinatus epicondylar referral directly",
"distinguishing_feature": "Pain WITHOUT motor or sensory loss, from intermittent compression of the posterior interosseous nerve in the radial tunnel (most often at the arcade of Frohse). The point of maximal tenderness is 5 cm DISTAL to the lateral epicondyle over the mobile wad - not on the epicondyle itself, which is the lateral-epicondylitis point. Pain is reproduced by resisted supination and resisted middle-finger extension, and by wrist flexion with forearm pronation; it is often worse at night. The Rule-of-Nine test localises tenderness to the two proximal lateral circles. EMG/nerve conduction studies are typically normal. Trigger-point pain is reproduced by muscle palpation and is not maximal 5 cm distal to the epicondyle.",
"action": "Largely a clinical diagnosis of exclusion. A diagnostic local anaesthetic block into the radial tunnel (taking care it does not track to the epicondyle) that relieves the pain supports it. Activity modification (avoid sustained elbow extension with forearm pronation and wrist flexion), splinting, NSAIDs, and a radial-tunnel corticosteroid injection first; surgical decompression of the arcade of Frohse and the whole supinator for recalcitrant cases (modest 60-70% success, delayed recovery). Treat coexisting brachioradialis and forearm trigger points, which can be the dominant pain source.",
"source": "Moradi, Ebrahimzadeh & Jupiter 2015; Shamrock & Das"
},
{
"id": "bd-2",
"condition": "Lateral epicondylitis (tennis elbow)",
"confidence": "common",
"mimics": "Lateral elbow and proximal radial-forearm pain - overlaps the brachioradialis and supraspinatus epicondylar referral, and coexists with radial tunnel syndrome",
"distinguishing_feature": "Tenderness localised DIRECTLY on the lateral epicondyle (1-2 cm distal at the common extensor origin), with pain on resisted wrist and middle-finger extension (Cozen's). The point tenderness is on the epicondyle, in contrast to radial tunnel syndrome (5 cm distal). The two coexist in a meaningful minority - radial tunnel syndrome is present in about 5% of those diagnosed with tennis elbow, and lateral epicondylitis is found alongside 21-41% of radial tunnel cases. Trigger-point referral may drive the enthesopathy via taut-band tension in the radial extensors.",
"action": "Examine for the central trigger point and screen for a coexisting radial tunnel before labelling it isolated epicondylitis. Load modification, counterforce strap, eccentric loading, trigger-point release; surgery only after prolonged failed conservative care.",
"source": "Moradi 2015; Shamrock & Das; WikiMSK (lateral elbow tendinopathy)"
},
{
"id": "bd-3",
"condition": "Posterior interosseous nerve compression syndrome",
"confidence": "uncommon",
"mimics": "Deep dorsoradial proximal-forearm pain that progresses to extensor weakness - overlaps the radial-forearm referrers but adds motor loss",
"distinguishing_feature": "Compression of the posterior interosseous nerve distal to the supinator causing true WEAKNESS of finger and thumb extension, with the wrist drifting into radial deviation on attempted extension (extensor carpi radialis longus is spared). This is the motor counterpart of radial tunnel syndrome - the same nerve, but with myelinated-fibre injury and demonstrable weakness rather than pain alone. Trigger-point pain produces no true motor loss.",
"action": "Examine finger/thumb extension; EMG/nerve conduction studies confirm motor involvement; imaging for a compressive ganglion, lipoma, or synovitis. Activity modification and trigger-point treatment first; surgical decompression for progressive motor loss.",
"source": "Shamrock & Das; Buchanan, Maini & Varacallo 2023"
},
{
"id": "bd-4",
"condition": "Radial sensory nerve entrapment (Wartenberg's syndrome / cheiralgia paraesthetica)",
"confidence": "uncommon",
"mimics": "Burning dorsoradial forearm and wrist pain with sensory change - runs the length of the radial forearm and overlaps the whole region",
"distinguishing_feature": "Burning or electric pain with paraesthesia/numbness over the dorsoradial forearm, wrist, and thumb-index web, worsened by ulnar wrist flexion and forearm pronation (which tighten the nerve where it emerges between brachioradialis and the radial wrist extensor) and by tight watch straps, with a positive Tinel over the nerve in the mid-forearm. In up to 75% of people the lateral antebrachial cutaneous nerve overlaps the radial sensory territory, so residual pain after a radial-nerve block points to that second nerve. Trigger-point pain produces aching without objective sensory loss.",
"action": "Differential diagnostic nerve blocks (radial sensory nerve, then lateral antebrachial cutaneous nerve) localise the generator. Remove external compression, activity modification, neural gliding; neuroma resection with muscular implantation for refractory cases.",
"source": "Buchanan, Maini & Varacallo 2023; Calotta & Dellon 2022"
},
{
"id": "bd-5",
"condition": "Intersection syndrome",
"confidence": "uncommon",
"mimics": "Dorsoradial forearm pain and crepitus - sits in the distal radial forearm within this region",
"distinguishing_feature": "Pain, swelling, and sometimes audible crepitus about 4-6 cm proximal to the wrist on the dorsoradial forearm, where the first extensor compartment muscles cross over the radial wrist extensors - more proximal than de Quervain's. Associated with repetitive wrist extension (rowing, weightlifting). Trigger-point pain is reproduced by muscle palpation and is not localised to this crossover point.",
"action": "Clinical diagnosis (the proximal location and crepitus distinguish it from de Quervain's); ultrasound or MRI if uncertain. Activity modification, splinting, NSAIDs, occasionally corticosteroid injection. Treat coexisting radial-forearm trigger points.",
"source": "Calotta & Dellon 2022; Shehab & Mirabelli 2013"
},
{
"id": "bd-6",
"condition": "De Quervain's tenosynovitis",
"confidence": "common",
"mimics": "Radial pain at the distal forearm/wrist - the distal end of the radial-forearm zone",
"distinguishing_feature": "Tenderness and sometimes swelling over the radial styloid and the first extensor compartment tendons, with a positive Finkelstein test and a negative grind test. More a wrist than a forearm entity, but the pain can be felt up the distal radial forearm. Trigger-point pain has no focal first-compartment tendon tenderness and a negative Finkelstein.",
"action": "Finkelstein and grind tests; the diagnosis is clinical. Splinting, activity modification, corticosteroid injection; release if refractory.",
"source": "Shehab & Mirabelli 2013"
},
{
"id": "bd-7",
"condition": "Radial head fracture / proximal radioulnar pathology",
"confidence": "uncommon",
"mimics": "Lateral and proximal radial-forearm pain after a fall - overlaps the proximal referrers",
"distinguishing_feature": "Radial head tenderness and painful, limited forearm rotation after a fall on the outstretched hand. A radial head fracture with ULNAR-sided wrist pain suggests an Essex-Lopresti injury (interosseous membrane disruption). Trigger-point pain has no bony tenderness or rotation block.",
"action": "Radiographs of the elbow AND wrist; assess the distal radioulnar joint. Orthopaedic referral for displaced or unstable fractures or suspected Essex-Lopresti.",
"source": "WikiMSK (radial head fractures)"
},
{
"id": "bd-8",
"condition": "Cervical radiculopathy (C6-C7) / rotator cuff and shoulder pathology",
"confidence": "uncommon",
"mimics": "Radial forearm pain referred from the neck or shoulder - overlaps the scalene, supraspinatus, and infraspinatus contributions",
"distinguishing_feature": "C6-C7 radiculopathy gives dermatomal pain to the radial forearm/thumb or middle finger with reflex change (brachioradialis/biceps or triceps) and myotomal weakness; positive Spurling's. Rotator cuff disease gives a painful abduction arc and weakness on cuff testing. Trigger-point referral produces no reflex change or true dermatomal deficit and IS reproduced by muscle palpation - and supraspinatus/infraspinatus/scalene trigger points are themselves commonly mistaken for radiculopathy.",
"action": "Full neurological and upper-quarter examination; Spurling, cuff testing. MRI cervical spine or shoulder and EMG/nerve conduction studies if neurological or structural signs. Treat coexisting shoulder-girdle and scalene trigger points concurrently - they may be the dominant or driving source.",
"source": "Buchanan, Maini & Varacallo 2023; Shehab & Mirabelli 2013"
}
]
}