DiagnosticTree/FrontalHeadache

{

 "tree_id": "frontal-headache",
 "region": "Frontal Headache",
 "start": "agg-1",

 "redflags": {
   "emergency": [
     {
       "id": "rf-e1",
       "label": "Thunderclap headache",
       "question": "Did the headache reach maximum intensity within seconds to a minute — described as 'the worst headache of my life' or like a blow to the head?",
       "rationale": "Subarachnoid haemorrhage presents as thunderclap headache. Any instantaneous-onset severe headache is an emergency until proven otherwise.",
       "action": "Call emergency services immediately. Do not proceed with musculoskeletal assessment."
     },
     {
       "id": "rf-e2",
       "label": "Signs of raised intracranial pressure",
       "question": "Is there headache that is worse on waking, progressively worsening over days or weeks, or associated with vomiting, visual changes, or altered consciousness?",
       "rationale": "Progressive headache with morning predominance or vomiting suggests raised ICP — may indicate intracranial mass, hydrocephalus, or venous sinus thrombosis.",
       "action": "Emergency medical referral. CT head urgently required."
     },
     {
       "id": "rf-e3",
       "label": "Meningism",
       "question": "Is there neck stiffness with fever, photophobia, or a non-blanching rash?",
       "rationale": "Meningitis or encephalitis must be excluded immediately. Neck stiffness with fever is a medical emergency.",
       "action": "Call emergency services immediately."
     },
     {
       "id": "rf-e4",
       "label": "Acute angle-closure glaucoma",
       "question": "Is there frontal or periorbital pain with sudden visual blurring, halos around lights, nausea, or a hard red eye?",
       "rationale": "Acute angle-closure glaucoma presents as severe frontal or periorbital pain with visual symptoms and is a sight-threatening emergency.",
       "action": "Emergency ophthalmology referral same day."
     }
   ],
   "urgent": [
     {
       "id": "rf-u1",
       "label": "Temporal arteritis",
       "question": "Is the patient aged 50+ with jaw claudication (pain building with chewing then easing), scalp tenderness, or a non-pulsatile tender temporal artery?",
       "rationale": "Temporal arteritis can cause irreversible blindness if untreated. Jaw claudication is pathognomonic. Same-day ESR required.",
       "action": "Same-day GP referral + ESR and CRP. Do not delay for musculoskeletal assessment."
     },
     {
       "id": "rf-u2",
       "label": "Cervical instability",
       "question": "Is there a history of significant trauma to the head or neck combined with arm symptoms, gait disturbance, or headache worsened by neck loading?",
       "rationale": "Odontoid fracture or cervical instability can produce occipital and frontal head pain. Manual therapy is contraindicated until cleared.",
       "action": "Urgent spinal assessment — no manual therapy or cervical stretch until cleared."
     },
     {
       "id": "rf-u3",
       "label": "New headache in immunocompromised patient",
       "question": "Is the patient immunocompromised (HIV, cancer, immunosuppressants) with a new or changing headache pattern?",
       "rationale": "Opportunistic intracranial infection such as cryptococcal meningitis or toxoplasmosis can present as progressive frontal headache.",
       "action": "Urgent medical referral."
     }
   ]
 },

 "nodes": {

   "agg-1": {
     "type": "choice",
     "question": "What is the PRIMARY pattern of the frontal headache?",
     "clinical_rationale": "This first split separates the five muscles by mechanism. SCM clavicular produces frontal headache via neck and postural loading, or with dizziness. SCM sternal produces frontal headache via cheek and orbital referral with autonomic phenomena. Semispinalis capitis produces an encircling band that reaches the temple and sweeps forward over the eye, worsened by neck flexion. The facial satellite muscles — frontalis and zygomaticus major — produce local forehead or nasal arc patterns without a prominent neck component.",
     "options": [
       {
         "label": "Neck movement, posture, or head load aggravates — or dizziness accompanies the frontal headache",
         "sublabel": "Turning the head, looking down, carrying a bag, sustained forward head position, or balance disturbance alongside the pain",
         "next": "scm-split-1"
       },
       {
         "label": "Band-like headache encircling from the occiput through the temple and forward over the eye",
         "sublabel": "Worsened by sustained neck flexion — reading, computing, sewing; often bilateral or sub-occipital at onset",
         "next": "semispinalis-screen-1"
       },
       {
         "label": "Frontal pain that stays local to the forehead — OR a curved nasal arc from cheek up along the nose to mid-forehead",
         "sublabel": "No prominent neck component; pain localised to the forehead itself, or tracing an arc up the side of the nose",
         "next": "facial-split-1"
       }
     ]
   },

   "scm-split-1": {
     "type": "symptom",
     "question": "Alongside the frontal headache, are there ipsilateral AUTONOMIC phenomena — profuse tearing, rhinitis (watering or congested nose), conjunctival redness, or apparent drooping of the eyelid on the same side?",
     "symptom_name": "Autonomic phenomena — tearing, rhinitis, palpebral narrowing",
     "muscles_implicated": ["SCM (Sternal Division)"],
     "muscles_excluded": ["SCM (Clavicular Division)"],
     "clinical_rationale": "This single question separates the two SCM divisions. Autonomic phenomena are specific to the sternal division — the clavicular division produces postural dizziness and frontal headache without tearing, rhinitis, or palpebral changes. Tearing is often the most alarming symptom to the patient and is frequently misattributed to eye disease.",
     "yes": "exam-scm-sternal-1",
     "no": "exam-scm-clavicular-1"
   },

   "exam-scm-clavicular-1": {
     "type": "examination",
     "question": "Does flat palpation of the clavicular head of the SCM — from the medial clavicle upward toward the mastoid — reproduce the frontal headache or provoke dizziness?",
     "exam_type": "palpation",
     "landmark": "With the patient supine and head rotated slightly toward the opposite side, use flat palpation of the clavicular (posterior) head, which lies deep and posterior to the sternal head. Palpate from the medial clavicle upward. Use the sternal head as a landmark and palpate just posterior to it. Ask the patient to report reproduction of the familiar headache OR any dizziness or imbalance sensation.",
     "positive_finding": "Reproduces ipsilateral frontal headache, dizziness, or sensation of imbalance",
     "muscles_implicated": ["SCM (Clavicular Division)"],
     "yes": "result-scm-clavicular",
     "no": "semispinalis-screen-1"
   },

   "exam-scm-sternal-1": {
     "type": "examination",
     "question": "Does pincer palpation of the sternal head — grasping the full muscle belly between thumb and forefinger from mastoid to sternum — reproduce the cheek, orbital, or frontal pain? And does the SCM Compression Test resolve a concurrent sore throat on swallowing?",
     "exam_type": "palpation",
     "landmark": "Patient supine, head rotated slightly toward the TrP side to relax the muscle. Grasp the full sternal belly in a pincer grip from the mastoid process down to the sternum. SCM Compression Test: firmly grip the belly and ask the patient to swallow — resolution of pharyngeal pain with compression is pathognomonic of a sternal central TrP. Also note palpebral fissure width: narrowing on the TrP side (apparent ptosis without miosis) is a confirmatory sign.",
     "positive_finding": "Reproduces cheek, orbit, vertex, or frontal pain. SCM Compression Test may relieve concurrent sore throat.",
     "muscles_implicated": ["SCM (Sternal Division)"],
     "yes": "result-scm-sternal",
     "no": "semispinalis-screen-1"
   },

   "semispinalis-screen-1": {
     "type": "rom",
     "question": "Is cervical flexion restricted or does it reproduce the headache? Ask the patient to slowly lower the chin toward the chest — is the range reduced, or does flexion provoke or intensify the frontal or band-like pain?",
     "movement": "Cervical flexion",
     "direction": "aggravating",
     "muscles_implicated": ["Semispinalis Capitis"],
     "clinical_rationale": "Semispinalis capitis acts as a checkrein during neck flexion — even slight forward head posture chronically loads it. Normal cervical flexion brings the chin within one to two finger-breadths of the sternum. Restriction or reproduction of the headache at less than this range is clinically significant.",
     "yes": "exam-semispinalis-1",
     "no": "facial-split-1"
   },

   "exam-semispinalis-1": {
     "type": "examination",
     "question": "Does flat palpation of the semispinalis capitis — alongside the nuchal ligament from C₁ down to C₄, and at the enthesopathy zone at the nuchal line — reproduce the encircling or temporal headache?",
     "exam_type": "palpation",
     "landmark": "Location 1 (enthesopathy zone): 1–2 cm lateral to midline at the superior nuchal line — usually exquisitely tender; driven by taut bands from TrPs lower in the muscle. Location 2 (upper-third TrP): at or just above C₁ level, 1–3 cm lateral to midline — DO NOT inject here (vertebral artery proximity). Location 3 (middle-third TrP): approximately C₃–C₄ level, 2–3 cm lateral to midline. Also examine upper trapezius and splenius capitis — these are key TrPs that frequently activate semispinalis as a satellite.",
     "positive_finding": "Tenderness at the nuchal line (Location 1) or midbelly (Locations 2 or 3) that reproduces the band-like temporal or frontal headache",
     "muscles_implicated": ["Semispinalis Capitis"],
     "yes": "result-semispinalis",
     "no": "facial-split-1"
   },

   "facial-split-1": {
     "type": "choice",
     "question": "Which pattern best describes the frontal or forehead pain?",
     "clinical_rationale": "At this point the neck-dominant muscles have been screened. The remaining two muscles are distinguished by referral geometry. Frontalis TrPs stay local to the forehead itself — the referred pain does not leave the muscle territory. Zygomaticus major TrPs produce a distinctive nasal arc (cheek to nose side to mid-forehead) and often restrict jaw opening by 10–20mm. Both are nearly always satellites of SCM or masticatory TrPs — treating the key TrP first often resolves both.",
     "options": [
       {
         "label": "Pain spreads upward and over the forehead — localised to the forehead itself",
         "sublabel": "Stays within the forehead region; no referral to the cheek or along the nose; patient may have a habitually furrowed brow",
         "next": "exam-frontalis-1"
       },
       {
         "label": "Pain traces an arc from the cheek, up along the side of the nose, to the mid-forehead",
         "sublabel": "The nasal arc pattern — curved path from cheek through nose bridge to forehead; jaw opening may be mildly restricted",
         "next": "exam-zygomaticus-1"
       }
     ]
   },

   "exam-frontalis-1": {
     "type": "examination",
     "question": "Does flat palpation of the frontalis belly — pressing through the forehead skin above the eyebrow — reproduce the frontal headache? Also note: does the patient have a habitually furrowed brow or persistently raised eyebrows at rest?",
     "exam_type": "palpation",
     "landmark": "Frontalis lies in the subcutaneous fascia with no bony attachment anteriorly. Press firmly with the pad of the index finger through the forehead skin, moving systematically from above the medial eyebrow laterally. TrP tenderness will be focal and reproduce the familiar pain. Note brow position at rest — a habitually elevated or furrowed brow indicates chronic frontalis overload.",
     "positive_finding": "Focal tenderness in the forehead belly reproducing the frontal headache. Habitually furrowed or raised brow at rest.",
     "muscles_implicated": ["Frontalis (Occipitofrontalis)"],
     "clinical_note": "Frontalis TrPs are nearly always satellites of SCM clavicular division TrPs — check and treat SCM first. If the forehead pain has a neuritic burning or stinging quality above the medial eyebrow, suspect supraorbital nerve entrapment by frontalis taut bands.",
     "yes": "result-frontalis",
     "no": "result-overlap"
   },

   "exam-zygomaticus-1": {
     "type": "examination",
     "question": "Does flat palpation of the zygomaticus major — along the diagonal from the zygomatic bone to the angle of the mouth — reproduce the nasal arc pain? Is jaw opening mildly restricted?",
     "exam_type": "palpation",
     "landmark": "Palpate with the index finger pad along the muscle's diagonal course from the malar prominence of the zygomatic bone to the angle of the mouth. The muscle is superficial and ribbon-like. Pincer palpation is possible with a gloved intraoral finger against the cheek. Measure interincisal opening — TrP tightness may reduce opening by 10–20mm. Inactivating the TrPs should restore opening immediately, which serves as an intratreatment confirmation.",
     "positive_finding": "Tenderness along the diagonal belly reproducing the nasal arc pattern. Jaw opening possibly reduced by 10–20mm.",
     "muscles_implicated": ["Zygomaticus Major"],
     "clinical_note": "Zygomaticus major TrPs develop as satellites of SCM sternal division or masticatory TrPs. Always identify the key TrP — the satellite often resolves without direct treatment.",
     "yes": "result-zygomaticus",
     "no": "result-overlap"
   },

   "result-scm-clavicular": {
     "type": "result",
     "diagnosis": "SCM Trigger Point — Clavicular Division",
     "confidence": "high",
     "wiki_page": "Muscle:Sternocleidomastoid",
     "chapter_ref": "Travell & Simons Vol.1 — Ch.7 Sternocleidomastoid",
     "notes": "The clavicular division is the chief myofascial source of ipsilateral frontal headache. Any one of three presentations may dominate: frontal headache, postural dizziness or imbalance, or dysmetria (disturbed weight perception). The headache is aggravated by neck posture and head loading — carrying a bag on the same shoulder, lying without pillow support, or rapid head rotation. There are NO autonomic phenomena — the absence of tearing and rhinitis is the key distinguishing feature from the sternal division. Hearing may rarely be impaired on the same side.",
     "treatment_hint": "Flat palpation and spray and stretch of the clavicular head from clavicle upward. Correct forward head posture — the single most important perpetuating factor. Advise the patient to roll the head on the pillow when turning in bed rather than lifting it. Treating the clavicular SCM often resolves frontalis satellite TrPs without direct treatment.",
     "also_consider": ["SCM Sternal Division", "Semispinalis Capitis", "Scalene muscles", "Splenius Cervicis"],
     "less_likely": [
       { "muscle": "SCM Sternal Division", "reason": "No autonomic phenomena — absent tearing, rhinitis, and palpebral narrowing" },
       { "muscle": "Semispinalis Capitis", "reason": "No encircling band quality and no neck flexion aggravation on examination" },
       { "muscle": "Frontalis", "reason": "Clavicular SCM is the key TrP — frontalis is its satellite; treat SCM first" }
     ],
     "confirmatory": [
       "Frontal headache reproduced by flat palpation of the clavicular head — familiar headache reproduction, not just local tenderness",
       "Straight-line walking test: patient veers toward the TrP side while walking toward a fixed point — confirms clavicular division involvement",
       "Dizziness worsened by lying without pillow or by quick head rotation — non-vestibular character",
       "Romberg negative and nystagmus absent — distinguishes from vestibular pathology",
       "No autonomic phenomena — no tearing, rhinitis, or palpebral narrowing on the headache side",
       "Weight perception test: same object may feel heavier when held on the unaffected side (dysmetria)"
     ],
     "satellite_trps": ["Frontalis", "Orbicularis Oculi", "Scalene muscles", "Sternalis"],
     "landing_page_topics": [
       "Dizziness differentiation — vestibular vs non-vestibular: Romberg, nystagmus, straight-line walk",
       "Hearing restoration manoeuvre — rotate head toward affected side, tilt chin down",
       "Dysmetria and weight perception testing",
       "Car sickness, sea sickness, and nausea as clavicular TrP features",
       "Satellite TrP sequence — SCM clavicular before frontalis"
     ],
     "related_pages": [
       { "label": "Frontalis / Occipitofrontalis →", "page": "Muscle:Occipitofrontalis" },
       { "label": "Scalene TrPs →", "page": "Muscle:Scalene" }
     ]
   },

   "result-scm-sternal": {
     "type": "result",
     "diagnosis": "SCM Trigger Point — Sternal Division",
     "confidence": "high",
     "wiki_page": "Muscle:Sternocleidomastoid",
     "chapter_ref": "Travell & Simons Vol.1 — Ch.7 Sternocleidomastoid",
     "notes": "The sternal division refers to the cheek, supraorbital ridge, temple, occiput, and vertex — the frontal component is part of a wider pattern. Cardinal features are ipsilateral autonomic phenomena: profuse tearing (often more alarming to the patient than the pain itself), rhinitis, and apparent ptosis via palpebral fissure narrowing without true miosis. Head tilts toward the TrP side due to pain on holding the head upright. The patient prefers to lie with a pillow supporting the head so the sore face does not bear weight. A cough TrP near the sternal attachment may produce a dry tingling cough.",
     "treatment_hint": "Pincer palpation and spray and stretch superior to inferior. SCM Compression Test confirms sternal central TrP. Correct forward head posture. Treating the sternal SCM often resolves zygomaticus major and orbicularis oculi satellite TrPs without direct treatment.",
     "also_consider": ["SCM Clavicular Division", "Semispinalis Capitis", "Zygomaticus Major (satellite)"],
     "less_likely": [
       { "muscle": "SCM Clavicular Division", "reason": "Autonomic phenomena are present — tearing and rhinitis are specific to the sternal division" },
       { "muscle": "Semispinalis Capitis", "reason": "No encircling band quality; autonomic phenomena are specific to SCM sternal" },
       { "muscle": "Zygomaticus Major", "reason": "Sternal SCM is the key TrP driving zygomaticus as a satellite — treat SCM first" }
     ],
     "confirmatory": [
       "SCM Compression Test positive — pharyngeal pain on swallowing resolves when the sternal belly is firmly gripped; pathognomonic of sternal central TrP",
       "Profuse ipsilateral tearing — often the most alarming symptom; specific to the sternal division",
       "Rhinitis on the TrP side — ipsilateral nasal congestion or watering without infection",
       "Apparent ptosis without miosis — palpebral fissure narrowing; confirm pupils equal and reactive to exclude true Horner syndrome",
       "Head tilts toward the TrP side; patient lies on sore side with pillow supporting the face",
       "Visual disturbance with strongly contrasted vertical lines (venetian blinds, window frames) — not blurred or double vision"
     ],
     "satellite_trps": ["Zygomaticus Major", "Orbicularis Oculi", "Frontalis", "Masseter", "Temporalis"],
     "landing_page_topics": [
       "Horner syndrome exclusion — pupils, ciliospinal reflex, enophthalmos",
       "CN XI entrapment and trapezius weakness monitoring",
       "Cough TrP — dry tingling cough from sternal attachment",
       "Venetian blinds visual phenomenon",
       "Sleep posture and pillow advice",
       "Satellite TrP treatment sequence — SCM sternal before facial muscles"
     ],
     "related_pages": [
       { "label": "Zygomaticus Major TrP →", "page": "Muscle:Zygomaticus_Major" },
       { "label": "Orbicularis Oculi TrP →", "page": "Muscle:Orbicularis_Oculi" }
     ]
   },

   "result-semispinalis": {
     "type": "result",
     "diagnosis": "Semispinalis Capitis Trigger Point",
     "confidence": "high",
     "wiki_page": "Muscle:Semispinalis_Capitis",
     "chapter_ref": "Travell & Simons Vol.1 — Ch.16 Semispinalis Capitis",
     "notes": "The defining referral is a band-like headache that encircles the head halfway, reaches maximum intensity at the temple, and continues forward over the eye. Tenderness at the nuchal line (Location 1) is enthesopathy driven by taut bands from a TrP in the upper-third midbelly (Location 2) — palpate the midbelly to find the causal TrP. Greater occipital nerve entrapment by taut bands produces a superficial tingling and hot prickling scalp pain distinct from the deep aching myofascial referral — both may coexist. The checkrein loading mechanism means sustained reading, computing, or sewing with a forward head posture chronically activates TrPs.",
     "treatment_hint": "Spray and stretch with neck extension and contralateral rotation. Moist heat. DO NOT inject Location 2 (vertebral artery proximity at C₁ level). Identify and treat upper trapezius and splenius capitis key TrPs first — semispinalis capitis is frequently their satellite and may resolve without direct treatment.",
     "also_consider": ["Upper Trapezius (key TrP)", "Splenius Capitis (key TrP)", "Semispinalis Cervicis", "Suboccipital Group"],
     "less_likely": [
       { "muscle": "SCM Clavicular Division", "reason": "Encircling band with neck flexion aggravation is specific to semispinalis; dizziness not dominant" },
       { "muscle": "SCM Sternal Division", "reason": "No autonomic phenomena; encircling band pattern does not arise from SCM" },
       { "muscle": "Frontalis", "reason": "Pain encircles from occiput through temple to forehead — not localised to the forehead muscle itself" }
     ],
     "confirmatory": [
       "Band-like headache encircling from occiput through temporal region forward over the eye — the defining pattern of semispinalis capitis TrPs",
       "Cervical flexion reproduces or intensifies the headache — the checkrein mechanism; reduced chin-to-chest range",
       "Enthesopathy tenderness at the nuchal line (Location 1) — 1–2 cm lateral to midline at the superior nuchal line",
       "Midbelly TrP (Location 2 or 3) reproduces the band headache on palpation — this is the causal TrP, not the nuchal line tenderness",
       "Greater occipital nerve entrapment: coexisting superficial tingling or hot prickling in scalp distribution — distinct from the deep aching referral",
       "Aggravated by sustained forward head posture activities: reading, computing, sewing, writing"
     ],
     "satellite_trps": ["Semispinalis Cervicis", "Suboccipital Group", "Multifidi", "Upper Trapezius"],
     "landing_page_topics": [
       "Three TrP locations — palpation technique, injection caution for Location 2",
       "Greater occipital nerve entrapment — deep aching vs superficial tingling distinction",
       "Occipital neuralgia differentiation — treat TrPs before neuroablative procedures",
       "Posture correction — reading stands, screen height, laptop use"
     ],
     "related_pages": [
       { "label": "Upper Trapezius TrPs →", "page": "Muscle:Trapezius/Upper" },
       { "label": "Splenius Capitis TrP →", "page": "Muscle:Splenius_Capitis" }
     ]
   },

   "result-frontalis": {
     "type": "result",
     "diagnosis": "Frontalis Trigger Point (Occipitofrontalis — Frontal Belly)",
     "confidence": "moderate",
     "wiki_page": "Muscle:Occipitofrontalis",
     "chapter_ref": "Travell & Simons Vol.1 — Ch.14 Occipitofrontalis",
     "notes": "Frontalis TrPs produce pain that spreads upward and over the forehead on the same side — the referral stays local to the muscle, similar to TrPs in the deltoid. There is no referral to the eye or occiput. A habitually furrowed brow or persistently raised eyebrows at rest are the cardinal clinical signs of chronic frontalis overload. Frontalis TrPs are nearly always satellites of clavicular division SCM TrPs — treating SCM first is essential and often resolves the frontalis without direct treatment. If the frontal headache has a neuritic burning or stinging quality above the medial eyebrow, supraorbital nerve entrapment by frontalis taut bands should be suspected.",
     "treatment_hint": "Treat SCM clavicular division TrPs first — frontalis is almost always a satellite. If direct treatment is needed: spray and stretch upward over the forehead; ischemic compression over focal taut bands. Address habitual facial expression habits (frowning, raised brows).",
     "also_consider": ["SCM Clavicular Division (key TrP)", "Occipitalis belly", "Semispinalis Capitis"],
     "less_likely": [
       { "muscle": "SCM Clavicular Division", "reason": "SCM is the key TrP — frontalis is the satellite. Examine and treat SCM regardless." },
       { "muscle": "Zygomaticus Major", "reason": "No nasal arc pattern; pain localised to the forehead itself" },
       { "muscle": "Semispinalis Capitis", "reason": "No encircling band quality; pain does not spread from occiput through temple" }
     ],
     "confirmatory": [
       "Focal tenderness in the frontalis belly above the eyebrow reproducing the familiar frontal headache",
       "Pain stays local to the forehead — no referral to the eye, cheek, or occiput; this localisation distinguishes frontalis from all other muscles in this region",
       "Habitually furrowed brow or raised eyebrows at rest — visible clinical sign of chronic overload",
       "Supraorbital nerve entrapment suspected if neuritic burning or stinging quality above the medial eyebrow",
       "Confirm clavicular SCM TrPs regardless — frontalis is almost invariably a satellite"
     ],
     "satellite_trps": ["Occipitalis", "SCM Clavicular Division (key TrP)", "Temporalis"],
     "landing_page_topics": [
       "Supraorbital nerve entrapment — neuritic vs myofascial frontal headache",
       "Occipitalis belly — through-the-skull referral and pillow intolerance",
       "Satellite relationship with SCM clavicular division",
       "Facial expression habits and frontalis overload"
     ],
     "related_pages": [
       { "label": "SCM TrPs →", "page": "Muscle:Sternocleidomastoid" },
       { "label": "Occipitofrontalis page →", "page": "Muscle:Occipitofrontalis" }
     ]
   },

   "result-zygomaticus": {
     "type": "result",
     "diagnosis": "Zygomaticus Major Trigger Point",
     "confidence": "moderate",
     "wiki_page": "Muscle:Zygomaticus_Major",
     "chapter_ref": "Travell & Simons Vol.1 — Ch.13 Zygomaticus Major",
     "notes": "Zygomaticus major TrPs refer in a distinctive nasal arc: from the cheek, along the lateral side of the nose, across the nasal bridge, and up to the mid-forehead. This is readily mistaken for tension headache or sinus pain. TrP tightness restricts jaw opening by 10–20mm — inactivating the TrPs should restore opening immediately, which serves as intratreatment confirmation. Unilateral palpebral fissure narrowing may be present on the affected side. Zygomaticus major TrPs are nearly always satellites of SCM sternal division TrPs (which refer to the cheek — the zygomaticus major lies within this referral zone) or severe masticatory muscle dysfunction.",
     "treatment_hint": "Treat SCM sternal division or masticatory TrPs first — zygomaticus major frequently resolves without direct treatment. If direct treatment is needed: spray and stretch along the diagonal muscle course; ischemic compression from zygomatic bone to the angle of the mouth. Immediate restoration of jaw opening confirms TrP inactivation.",
     "also_consider": ["SCM Sternal Division (key TrP)", "Masseter", "Buccinator", "Zygomaticus Minor"],
     "less_likely": [
       { "muscle": "SCM Sternal Division", "reason": "Sternal SCM is the key TrP for zygomaticus — always examine and treat before direct satellite treatment" },
       { "muscle": "Frontalis", "reason": "No nasal arc pattern — frontalis pain stays local to the forehead" },
       { "muscle": "Semispinalis Capitis", "reason": "No encircling band; nasal arc is specific to zygomaticus major" }
     ],
     "confirmatory": [
       "Focal tenderness along the diagonal from zygomatic bone to angle of mouth reproducing the nasal arc pattern",
       "Jaw opening restricted 10–20mm and improves immediately on TrP inactivation — intratreatment confirmation",
       "Nasal arc referral confirmed: cheek to lateral nose to nasal bridge to mid-forehead",
       "Unilateral palpebral fissure narrowing on the affected side from masticatory venous territory involvement",
       "Confirm SCM sternal division TrPs — zygomaticus is almost invariably a satellite"
     ],
     "satellite_trps": ["Zygomaticus Minor", "Orbicularis Oris", "Buccinator", "SCM Sternal (key TrP)"],
     "landing_page_topics": [
       "Nasal arc referral — clinical misdiagnosis as sinusitis or tension headache",
       "Jaw opening restriction — immediate improvement on TrP inactivation as confirmation test",
       "Palpebral fissure narrowing — venous mechanism in masticatory territory",
       "Satellite relationship with SCM sternal and masticatory muscles"
     ],
     "related_pages": [
       { "label": "SCM TrPs →", "page": "Muscle:Sternocleidomastoid" },
       { "label": "Buccinator TrP →", "page": "Muscle:Buccinator" }
     ]
   },

   "result-overlap": {
     "type": "overlap",
     "text": "Findings are inconclusive. Multi-muscle involvement is common in frontal headache — SCM is frequently the key TrP driving one or more satellite muscles in the face and scalp. Perform a systematic screen in order of clinical priority.",
     "screen_these": [
       "SCM both divisions — pincer palpation full length for the sternal head; flat palpation posterior to the sternal head for the clavicular head; SCM Compression Test for the sternal division",
       "Semispinalis capitis — palpation at the nuchal line (Location 1) and midbelly (Locations 2 and 3); assess neck flexion range and reproduction of headache",
       "Frontalis — flat palpation across the forehead above the eyebrow; note habitual brow position at rest",
       "Zygomaticus major — flat palpation along the diagonal from zygomatic bone to angle of mouth; measure jaw opening"
     ],
     "wiki_page": "Differential:Frontal_Headache"
   }

 },

 "broad_differential": [
   {
     "id": "bd-1",
     "condition": "Tension-type Headache",
     "confidence": "uncommon",
     "mimics": "Bilateral pressing or tightening frontal pain — overlaps strongly with semispinalis capitis and bilateral SCM TrP patterns",
     "distinguishing_feature": "Tension-type headache has a very high probability of myofascial TrP involvement (Ch.5, Table 5.1). The pressing quality of tension headache closely matches the steady deep aching of myofascial TrP pain. EMG studies do not support elevated muscle contraction as the mechanism — pericranial muscle tenderness consistent with TrPs is the consistent finding.",
     "action": "Systematic TrP examination of all pericranial and cervical muscles. All five muscles in this algorithm should be screened. Myofascial treatment with perpetuating factor correction is first-line."
   },
   {
     "id": "bd-2",
     "condition": "Migraine Without Aura",
     "confidence": "uncommon",
     "mimics": "Unilateral or bilateral frontal or temporal headache — overlapping referral patterns from SCM, semispinalis capitis, and masticatory TrPs produce a typical migraine picture",
     "distinguishing_feature": "Migraine patients have pericranial TrP tenderness even between attacks, and tenderness increases with attack intensity. Injection of these sites produces complete headache relief in 60% of patients. The myofascial and vascular components coexist — TrPs should be identified and treated alongside standard migraine management.",
     "action": "Screen for pericranial TrPs in all migraine patients. Address perpetuating factors. TrP treatment reduces the myofascial trigger component without replacing migraine medication."
   },
   {
     "id": "bd-3",
     "condition": "Cervicogenic Headache",
     "confidence": "uncommon",
     "mimics": "Predominantly unilateral frontal headache precipitated by neck movement — overlaps with SCM and semispinalis capitis patterns",
     "distinguishing_feature": "Consistent unilaterality, precipitation by specific neck movements or sustained postures, and associated shoulder or arm pain. Most cervicogenic headache patients have myofascial TrPs that reproduce their headache. Reduced cervical segmental mobility accompanies the TrPs.",
     "action": "Conservative myofascial TrP management first. Treat TrPs before attributing restriction to fibrous fixation or proceeding to invasive treatments."
   },
   {
     "id": "bd-4",
     "condition": "Sinusitis",
     "confidence": "uncommon",
     "mimics": "Frontal pressure and pain — zygomaticus major and masseter TrPs commonly produce maxillary pain described as sinus pain; SCM sternal TrPs produce rhinitis",
     "distinguishing_feature": "True sinusitis has fever, purulent nasal discharge, and radiographic mucosal thickening. TrP-referred sinus pain has normal radiographs, no fever, no discharge, and is reproduced by palpating the relevant TrPs.",
     "action": "Palpate the relevant TrPs and confirm referral pattern. Request sinus imaging only if clinical features make true sinusitis plausible."
   },
   {
     "id": "bd-5",
     "condition": "Occipital Neuralgia",
     "confidence": "rare",
     "mimics": "Occipital and frontal pain with burning or shooting quality — overlaps with semispinalis capitis referral and greater occipital nerve entrapment",
     "distinguishing_feature": "Paroxysmal stabbing with aching between attacks, radiating to the frontal region. The greater occipital nerve may be entrapped by semispinalis capitis taut bands — producing both neuritic pain and myofascial TrP aching simultaneously. Always treat TrPs before any neuroablative procedure.",
     "action": "Treat semispinalis capitis TrPs first. If neuritic component persists after adequate TrP treatment, refer to neurology. Neuroablative treatments should be a last resort."
   },
   {
     "id": "bd-6",
     "condition": "Analgesic Rebound Headache",
     "confidence": "uncommon",
     "mimics": "Daily or near-daily frontal headache in patients using frequent analgesics — most also have active myofascial TrPs",
     "distinguishing_feature": "Daily analgesic use more than 10–15 days per month. Headache becomes refractory and prophylactic medications lose effectiveness. Most analgesic rebound patients have active TrPs — detoxification must accompany TrP treatment.",
     "action": "Refer for medication detoxification protocol alongside TrP assessment. Time-contingent dosing with 20% weekly reduction. TrP treatment begins concurrently."
   },
   {
     "id": "bd-7",
     "condition": "Post-traumatic Headache",
     "confidence": "uncommon",
     "mimics": "Frontal headache following whiplash or closed head injury — semispinalis capitis and SCM are the most commonly activated TrPs after motor vehicle accidents",
     "distinguishing_feature": "History of trauma. Posttraumatic headache is clinically indistinguishable from tension-type headache and is likely driven by the same myofascial TrP mechanism. Semispinalis capitis and splenius capitis are most commonly involved regardless of impact direction.",
     "action": "Systematic TrP screen with special attention to semispinalis capitis, SCM, upper trapezius, and splenius capitis. Address perpetuating factors. Refer if neurological symptoms suggest brainstem or vestibular involvement."
   },
   {
     "id": "bd-8",
     "condition": "Cluster Headache with myofascial component",
     "confidence": "rare",
     "mimics": "Severe unilateral frontal or orbital headache with autonomic features — overlaps with SCM sternal division tearing and rhinitis",
     "distinguishing_feature": "Classic cluster: strictly unilateral, periorbital, 15–180 minutes, autonomic features, clustered in bouts. The Ch.5 case illustrates chronic cluster with an SCM TrP as a contributing and triggering factor — the TrP referred to the suboccipital region and induced nasal stuffiness mimicking cluster features. Treatment of the SCM TrP significantly reduced frequency.",
     "action": "Examine for SCM TrPs in all cluster headache patients, especially chronic cluster. Myofascial treatment may reduce frequency without replacing prophylactic cluster medications."
   }
 ]

}