Horner's Syndrome (Acute)MANAGEMENT

SYSTEMIC AND MISCELLANEOUS PRESENTATIONS · 12 SECTIONS

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564 items

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Endocrine and Metabolic Presentations45▾

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

Allergic Transfusion Reaction Anaphylaxis Angioedema Benedikt's Syndrome Cannabis-induced hyperemesis Eczema (acute flare)Gradenigo's Syndrome Horner's Syndrome (Acute)Huntington's Disease (Acute Presentation)Kanavel's Signs Lemierre's Syndrome Procedural sedation Radiation exposure Retained products of conception Sever's Disease Urticaria Venous air embolism

01Approach to the Critical Patient/attcp33

Immediate priorities

›Life-threatening cause exclusion

›Carotid artery dissection

›Ipsilateral neck or facial pain with acute Horner is dissection until proven otherwise

›Cerebral or retinal ischemia develops in 50-95% of dissection cases after initial warning symptoms

›Brainstem stroke (lateral medullary syndrome)

›Crossed neurological deficits, ataxia, vertigo, dysphagia

›First-order neuron involvement

›Pancoast tumor

›Shoulder and arm pain, weight loss, smoking history

›Second-order neuron compression at lung apex

›If acute neurological deficits present, activate stroke protocol immediately

›IV tPA eligibility window assessment

›Thrombectomy eligibility assessment

Monitoring and stabilization

›Initial stabilization steps

›IV access and continuous cardiac monitoring

›Telemetry if dissection or stroke suspected

›ECG for atrial fibrillation as alternative embolic source

›Neurological status monitoring

›GCS baseline

›Cranial nerve function trend

›NPO status if stroke or surgical cause suspected

›Swallow assessment before oral intake

Consultation triggers

›Immediate consults

›Neurology for acute stroke, brainstem infarction, or dissection with neurological deficit

›Stroke team if thrombolysis window open

02History/hx68

Symptom onset and character

›Timing and onset

›Exact time of symptom onset

›Sudden versus gradual

›Duration of ptosis and anisocoria

›Pain character

›Ipsilateral headache present in approximately 65% of carotid dissections

›Ipsilateral neck pain present in approximately 50% of carotid dissections

›Orbital or facial pain

›Associated neurological symptoms

›Limb weakness or numbness

›Speech difficulty or aphasia

›Vertigo or dysphagia

Alarm features

›High-risk historical features

›Trauma history

›Head, neck, or chest trauma even if minor

›Chiropractic manipulation

›MVA, sports injury, coughing, or vomiting

›Neurological deficits

›Hemiparesis or hemisensory loss suggesting stroke from dissection

›Brainstem signs: ataxia, diplopia, crossed deficits

›Pulsatile tinnitus

›Present in approximately 8% of carotid dissections

›Visual symptoms

›Amaurosis fugax suggesting carotid territory ischemia

›Visual obscurations

03Physical Exam/exam44

Ocular examination

›Pupillary assessment

›Pupil size in light and in darkness

›Anisocoria greater in dark is classic for Horner syndrome

›Dilation lag on the affected side in dim light

›Ptosis character

›Typically 1-2 mm upper lid ptosis

›Lower lid reverse ptosis (upside-down ptosis)

›Pseudoenophthalmos

›Apparent enophthalmos from ptosis and reverse ptosis

›True enophthalmos uncommon

Neurological examination

›Cranial nerve survey

›CN IX, X assessment

›Dysphagia, hoarseness, uvular deviation

›CN XII assessment

›Tongue deviation suggests carotid dissection compressing nerve

›CN VI assessment

›Lateral gaze palsy with cavernous sinus lesion

›Motor and sensory exam

›Hemiparesis ipsilateral or contralateral

›Distinguish central from peripheral pattern

›Hemisensory loss pattern

›Crossed deficit: ipsilateral face, contralateral body in Wallenberg

›Cerebellar and gait testing

›Ataxia or dysdiadochokinesia

›Lateral medullary syndrome pattern

›Nystagmus

04Differential Diagnosis/ddx52

Life-threatening causes

›Vascular emergencies

›Carotid artery dissection

›ICD-10 I77.71

›Most common nonprocedural cause of acute Horner syndrome

›Pain plus Horner is highly suggestive

›Vertebral artery dissection

›ICD-10 I77.74

›Posterior neck pain, occipital headache

›Lateral medullary infarction (Wallenberg syndrome)

›ICD-10 I63.89

›First-order neuron; crossed findings, ataxia, vertigo, dysphagia

›Malignant causes

›Pancoast tumor (superior sulcus tumor)

›ICD-10 C34.10

›Second-order neuron at lung apex

›Shoulder and arm pain from brachial plexus invasion

›Mediastinal lymphoma or other malignancy

›ICD-10 C85.90

›Weight loss, night sweats

Other structural causes

›Central nervous system lesions

›Brainstem demyelination

›ICD-10 G37.3

›Multiple sclerosis plaque at first-order neuron level

›Hypothalamic or thalamic lesion

›Hemorrhage or infarction

›Cervical cord lesion

05Laboratory Tests/lt29

Core labs

›Baseline investigations

›Complete blood count

›Leukocytosis if infectious cause considered

›Thrombocytopenia affecting anticoagulation choice

›Basic metabolic panel

›Renal function for anticoagulant dosing

›Glucose for stroke risk assessment

›Coagulation studies

›PT/INR and aPTT prior to anticoagulation

›Baseline if thrombolysis considered

Vascular and inflammatory markers

›Stroke and dissection workup

›Lipid panel

›Atherosclerotic risk stratification

›HbA1c

›Diabetic stroke risk

›ESR and CRP

›Vasculitis or inflammatory arteriopathy

›Hypercoagulability screening

›Selected young patients with dissection and no trauma

›Antiphospholipid antibodies

›Protein C, Protein S, antithrombin III

›Ordered in consultation with neurology or hematology

Pediatric-specific labs

›Neuroblastoma exclusion

›Urine catecholamines

›Vanillylmandelic acid (VMA) and homovanillic acid (HVA)

06Diagnostic Tests/dt77

Scoring Systems

›Horner localization tools

›Anatomical level classification

›First-order (central): hypothalamus to ciliospinal center of Budge (C8-T2)

›Second-order (preganglionic): ciliospinal center to superior cervical ganglion

›Third-order (postganglionic): superior cervical ganglion to iris dilator

›Clinical localization clues

›Anhidrosis pattern guides level: face and body central; face only preganglionic; none postganglionic

›Associated neurological findings guide imaging priority

MRI

›MRI head and neck indications

›Brain MRI preferred sequences

›DWI (diffusion weighted imaging) for acute brainstem or hemispheric infarction

›FLAIR for subacute infarction and demyelination

›T1 fat-saturated for intramural hematoma (crescent sign of dissection)

›MRI advantages over CT

›Superior sensitivity for brainstem infarction

›Better characterization of intramural hematoma in dissection

›No ionizing radiation

›MRA neck for dissection

›Luminal narrowing or occlusion of carotid or vertebral arteries

›Pseudoaneurysm identification

›Limitations

›Longer acquisition time than CT

›Not first-line in acute ED setting when CT faster and widely available

›MRI chest indications

›Pancoast tumor characterization

›Superior sulcus mass with brachial plexus or vascular involvement

›MRI preferred over CT for soft tissue and nerve invasion detail

›Mediastinal mass evaluation

›Lymphoma or thymoma staging adjunct

›First-line ED imaging for acute Horner syndrome

›CT head without contrast

›Excludes hemorrhagic stroke or intracranial mass

›Performed before starting antithrombotics

›Sensitivity for acute ischemic stroke limited in first 6-24 hours

›CTA head and neck with contrast

›Recommended initial imaging per ACR Appropriateness Criteria for acute Horner

›High sensitivity for carotid and vertebral artery dissection

›Short acquisition time suitable for acute presentations

›Coverage from carina to vertex evaluates lung apex, mediastinum, and neck

›CT limitations

›Less sensitive than MRI for brainstem ischemia

›Radiation exposure consideration

›Contrast nephropathy risk assessment required

›CT chest indications

›Pancoast tumor or apical lung mass assessment

›Lung apex mass with rib or vertebral involvement

›Superior sulcus location

›Mediastinal mass evaluation

›Lymphadenopathy extent

›Tracheal deviation

Ultrasound

›Carotid ultrasound role

›Limited primary diagnostic utility for dissection in ED

›Cannot reliably visualize distal internal carotid artery

›Intramural hematoma may be missed

›Adjunct use

›Screening for atherosclerotic disease when dissection excluded

›Plaque characterization

›Point-of-care ultrasound adjuncts

›Cardiac POCUS

›LV function assessment if embolic stroke suspected

›Pericardial effusion screening

›IVC and volume assessment

›Hemodynamic instability evaluation

›Pharmacologic pupil testing

›Apraclonidine 0.5% test

›Reversal of anisocoria confirms Horner syndrome; affected pupil dilates due to denervation supersensitivity

›Sensitivity approximately 93%

›Can be positive as early as 48 hours after onset

›May have reduced sensitivity in hyperacute period

›Cocaine 4-10% test

›Failure to dilate affected pupil confirms Horner

›Sensitivity approximately 40%; harder to obtain

›Hydroxyamphetamine 1%

›Differentiates preganglionic from postganglionic lesions

›Fails to dilate in postganglionic third-order lesions

›Limited availability; not widely used in ED

›Note: Do not delay imaging for pharmacologic testing when clinical suspicion for dangerous cause is high

07Disposition/dispo41

Admission indications

›Criteria requiring admission

›Carotid or vertebral artery dissection

›Neurology admission or monitored step-down

›Initiation of antithrombotic therapy with monitoring

›Acute ischemic stroke or TIA

›Stroke unit admission

›Secondary prevention workup

›Undiagnosed acute Horner syndrome with pain

›Cannot exclude dangerous cause in ED

›Urgent vascular imaging required if not yet obtained

›Any neurological deficit

›Admission for monitoring and evaluation

›ICU indications

›Hemodynamic instability with stroke

›MAP targets for ischemic stroke management

›Airway compromise from mass lesion

›Respiratory monitoring

Discharge criteria

›Safe discharge requirements

›Known benign cause confirmed

›Iatrogenic from regional anesthesia with expected resolution

›Known physiological anisocoria confirmed by photographs

›Complete imaging evaluation performed

›Dangerous vascular and structural causes excluded

›Clear follow-up plan established

›No neurological deficits

›Stable examination during ED stay

08Treatment/t67

Carotid and vertebral artery dissection

›Antithrombotic therapy

›Antiplatelet therapy

›Aspirin 81-325 mg orally daily

›Clopidogrel 75 mg orally daily as alternative

›CADISS trial found no significant difference versus anticoagulation

›Anticoagulation therapy

›Heparin IV bridge to warfarin; target INR 2.0-3.0

›Duration 3-6 months total antithrombotic therapy

›May be preferred with vessel occlusion or severe luminal stenosis

›AHA scientific statement

›Similar efficacy between antiplatelet and anticoagulant therapy

›Anticoagulation may be preferred with vessel occlusion

›Antiplatelet may be preferred with large infarct or hemorrhagic risk

›Contraindications to anticoagulation

›Intracranial extension of dissection

›Large hemorrhagic infarct

›Uncontrolled hypertension with hemorrhage risk

Acute ischemic stroke management

›Thrombolysis

›IV alteplase (tPA) 0.9 mg/kg (maximum 90 mg)

›10% given as IV bolus over 1 minute

›Remaining 90% as IV infusion over 60 minutes

›Within 4.5 hours of symptom onset per AHA Class I recommendation

›Contraindications review

›Recent surgery, hemorrhage, or anticoagulation

›Blood pressure greater than 185/110 mmHg requires pre-treatment

›Blood pressure management in ischemic stroke

09Special Populations/sp47

Pregnancy

›Pregnancy-specific considerations

›Dissection risk

›Increased vascular fragility in peripartum period

›Fibromuscular dysplasia more prevalent in women of reproductive age

›Imaging approach

›CTA acceptable if benefit outweighs radiation risk

›MRI and MRA preferred to avoid radiation when time permits

›Gadolinium contrast avoided unless essential; FDA Category C

›Antithrombotic therapy

›Low molecular weight heparin preferred over warfarin (warfarin teratogenic in first trimester, crosses placenta)

›Aspirin 81 mg daily considered safe after first trimester

›Anticoagulation decisions in conjunction with obstetrics and neurology

›Blood pressure management

›Hypertension associated with increased dissection risk

›Avoid ACE inhibitors and ARBs

›Labetalol or nifedipine preferred antihypertensives in pregnancy

Geriatric

›Older adult considerations

›Atypical presentation

›Minimal or absent pain with dissection

›Greater risk of atherosclerotic versus dissection etiology

›Stroke risk emphasis

›Higher baseline stroke risk from comorbidities

›Atrial fibrillation more prevalent; cardioembolic consideration

›Medication safety

›Anticoagulation bleeding risk higher

›Renal function adjustment for heparin and LMWH

10Background/b61

Epidemiology

›Incidence and prevalence

›At least 40% of all Horner syndrome cases remain idiopathic after evaluation

›Acute onset with pain should never be assumed benign

›Carotid dissection

›Annual incidence approximately 2.5-3 per 100,000 population

›Most common nonprocedural cause of acute Horner syndrome in adults

›Iatrogenic Horner

›Most common overall cause across all settings

›Post-interscalene block, central line, epidural, thoracic surgery

›Age and sex distribution

›Carotid dissection: mean age 40s; slight male predominance

›Pancoast tumor: age over 40, strong smoking association

›Neuroblastoma: pediatric, median age 2 years at diagnosis

›Anatomical pathway

›Three-neuron oculosympathetic pathway

›First-order neuron: hypothalamus to ciliospinal center (C8-T2)

›Second-order neuron: ciliospinal center over lung apex to superior cervical ganglion

›Third-order neuron: superior cervical ganglion along carotid artery to iris dilator and Muller's muscle

›Stroke burden

›Cerebral or retinal ischemia develops in 50-95% of carotid dissection cases after initial warning symptoms

Pathophysiology

›Oculosympathetic disruption

›Sympathetic innervation loss to eye and adnexa

›Iris dilator paralysis produces miosis

›Muller's muscle denervation produces 1-2 mm ptosis and reverse ptosis

›Sweat gland denervation produces anhidrosis at appropriate level

›Carotid dissection mechanism

11Patient Discharge Instructions/pdi26

copy discharge instructions

›Discharge home instructions for Horner syndrome

›Reason for droopy eyelid and small pupil

›Caused by disruption of nerve supply to the eye

›Underlying cause has been evaluated and treated or follow-up arranged

›Medications as prescribed

›Take blood thinners or antiplatelet medications exactly as directed if prescribed

›Do not stop antithrombotic medications without speaking to your doctor

›Warning signs to return to the emergency room immediately

›Sudden weakness or numbness in face, arm, or leg

›Sudden difficulty speaking or understanding speech

›New or worsening vision loss

›Sudden severe headache unlike any previous headache

›Sudden severe neck pain or throat pain

›Difficulty walking, balance problems, or sudden dizziness

›Loss of consciousness or confusion

›Follow-up instructions

›Neurology appointment within 48-72 hours if dissection or stroke diagnosed

›Bring medication list and imaging reports

›Repeat vessel imaging at 3 months to assess healing

›Ophthalmology appointment if eyelid drooping or pupil asymmetry persists

›Primary care follow-up if no specialist arranged

›Lifestyle and activity

›Avoid contact sports, heavy lifting, and activities with risk of neck injury if dissection diagnosed

›Until neurology or vascular surgery clears you

›No driving if vision significantly affected by ptosis or double vision

›Report new shoulder or arm pain to your doctor promptly if Pancoast tumor evaluation is pending

12References/r19

Guidelines and key sources

›Vascular and stroke guidelines

›American Heart Association and American Stroke Association guidelines for management of spontaneous cervical artery dissection

›AHA scientific statement on antithrombotic treatment in cervical artery dissection 2021

›CADISS trial: Cervical Artery Dissection in Stroke Study (antiplatelet vs anticoagulation)

›ACR Appropriateness Criteria

›ACR Appropriateness Criteria for acute onset Horner syndrome recommend CT head without contrast and CTA head and neck as first-line imaging

›Emergency medicine references

›Tintinalli's Emergency Medicine: Horner syndrome evaluation and management

›UpToDate: Horner syndrome workup and treatment

Evidence summaries

›Key studies

›CADISS randomized trial: no significant difference between antiplatelet and anticoagulation in cervical artery dissection

›Carotid dissection natural history: recanalization in 60-90% by 3 months; stroke risk highest in first 2 weeks

›Carotid dissection presenting with headache in 65% and neck pain in 50% of cases

›Apraclonidine 0.5% pharmacologic testing: sensitivity approximately 93% for confirming Horner syndrome

›Coding standards

›ICD-10 G90.2 Horner syndrome

›ICD-10 I77.71 dissection of carotid artery

›ICD-10 I63.89 other cerebral infarction (Wallenberg)

›ICD-10 C34.10 malignant neoplasm of upper lobe bronchus (Pancoast)

Learn More: Horner's Syndrome (Acute)→

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Reviewed by SymptomDx Medical Team · Last reviewed August 18, 2026

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