Differential Diagnosis and Initial Assessment
In a patient with dizziness, headache, and occasional arm pain with a negative ECG, the priority is to systematically exclude life-threatening cardiovascular and neurological causes before attributing symptoms to benign etiologies.
Immediate Life-Threatening Differentials to Exclude
Cardiovascular Causes
- Acute coronary syndrome without ST elevation: Despite negative ECG, unstable angina can present with arm pain and associated symptoms; serial troponin measurements at admission and 12 hours later are essential 1
- Cardiac arrhythmia: Intermittent arrhythmias causing cerebral hypoperfusion may not be captured on single ECG; 48-hour ambulatory ECG monitoring is recommended for frequent or sustained symptoms 2
- Structural heart disease: Valvular disease (especially aortic stenosis) or hypertrophic cardiomyopathy can present with dizziness and should be assessed by careful cardiac auscultation and echocardiography if murmur detected 1
Neurological Causes
- Spontaneous intracranial hypotension (SIH): The combination of headache and dizziness warrants specific questioning about orthostatic pattern—ask "Does the headache worsen significantly when standing and improve dramatically when lying flat?" and "Is the headache absent or mild upon waking?" 3
- Cerebral venous thrombosis: A rare but life-threatening complication that can present with headache and dizziness; occurs in approximately 2% of SIH cases and requires CT or MR venography if clinically suspected 1, 3
- Vertebrobasilar insufficiency: Arm pain combined with dizziness may suggest posterior circulation ischemia, particularly if symptoms worsen with neck movements 1
Critical History Elements to Obtain
Headache Characterization
- Orthostatic pattern: Headache absent/mild on waking, appearing within 2 hours of standing, improving >50% within 2 hours of lying flat strongly suggests SIH 3
- Temporal pattern: Continuous versus intermittent; brief 10-15 minute episodes responding to simple analgesics argue against SIH 3
- Associated symptoms: Pulsatile tinnitus, eye pain, nausea, or visual changes 3
Dizziness Characterization
- True vertigo versus lightheadedness: Spinning sensation suggests vestibular cause; lightheadedness suggests cardiovascular or orthostatic cause 4
- Positional triggers: Symptoms with standing suggest orthostatic hypotension or POTS; symptoms with neck turning suggest vertebrobasilar insufficiency 1
- Duration and frequency: Constant versus episodic helps narrow differential 1
Arm Pain Details
- Cardiac versus musculoskeletal: Exertional arm pain radiating from chest suggests cardiac ischemia; unilateral pain with neck movement suggests cervical radiculopathy 1
- Associated palpitations: Suggests arrhythmic cause requiring cardiac monitoring 2
Red Flag Questions
- Syncope or near-syncope episodes 1
- Chest pain or pressure, especially with exertion 1
- Focal neurological symptoms (weakness, numbness, speech changes) 5
- Recent trauma or spinal procedures 3
- Family history of sudden cardiac death or connective tissue disorders 1, 3
Essential Physical Examination
Cardiovascular Assessment
- Orthostatic vital signs: Measure supine heart rate and blood pressure, then at 1,3,5, and 10 minutes of standing to detect:
- Cardiac auscultation: Listen for murmurs suggesting valvular disease or hypertrophic cardiomyopathy 1
- Carotid sinus massage: Consider in older patients or those with symptoms during neck turning 1
Neurological Assessment
- Cranial nerve examination: Sixth nerve palsy may indicate intracranial hypotension 3
- Motor and sensory examination: Assess for focal deficits suggesting stroke or radiculopathy 5
- Cerebellar testing: Gait, finger-to-nose, heel-to-shin to evaluate for posterior fossa pathology 4
- Neck examination: Range of motion, myofascial tenderness, provocation of symptoms with movement 3
Connective Tissue Assessment
- Joint hypermobility: Beighton score to assess for Ehlers-Danlos syndrome or Marfan syndrome, which predispose to SIH 3
- Skin extensibility: Evaluate for connective tissue disorders 3
Initial Diagnostic Workup
Mandatory First-Line Tests
- 12-lead ECG with expert review: Essential for all patients; automated report followed by expert review if abnormalities detected 1
- Targeted laboratory tests based on clinical suspicion rather than comprehensive panels 2:
Cardiac Monitoring Strategy
- 48-hour ambulatory ECG (Holter monitor): Recommended for frequent or sustained palpitations/dizziness 2
- Event recorder or implantable loop recorder: For infrequent episodes 2
- Echocardiography: If murmur detected, abnormal ECG, or clinical suspicion of structural heart disease 1, 2
Neuroimaging Indications
Order MRI brain with IV contrast AND complete spine MRI with fluid-sensitive sequences if:
- Orthostatic headache pattern confirmed (worsens standing, improves lying flat) 3
- Persistent headache with red flags (thunderclap onset, new neurological signs) 3
- Suspected cerebral venous thrombosis (add CT or MR venography) 1, 3
Important caveat: Normal CSF opening pressure does NOT exclude SIH; clinical presentation and imaging findings are more important than measured pressure 3. Additionally, approximately 20% of patients with active CSF leak have normal brain MRI, so negative initial imaging does not rule out SIH when clinical suspicion remains high 3.
Algorithmic Approach
Step 1: Immediate Risk Stratification
- Obtain vital signs including orthostatic measurements
- Perform focused cardiovascular and neurological examination
- Obtain 12-lead ECG
- If any concerning cardiac features (chest pain, exertional symptoms, abnormal ECG, murmur): Admit for serial troponins, continuous monitoring, and cardiology consultation 1
Step 2: Characterize Symptom Pattern
If true orthostatic headache pattern (absent on waking, worsens standing, improves >50% lying flat within 2 hours):
If palpitations or arrhythmic symptoms prominent:
If symptoms non-specific or intermittent brief episodes:
Step 3: Exclude Common Mimics
- Migraine: Triggered by physical movement (not posture), presence of aura, vertigo rather than tinnitus 3
- Cervicogenic headache: Provoked by cervical movement, limited neck range of motion, myofascial tenderness 3
- Tension-type headache: Bilateral squeezing quality, moderate intensity, not truly positional 3
Common Pitfalls to Avoid
- Do not rely on single negative ECG to exclude cardiac arrhythmia; intermittent arrhythmias require prolonged monitoring 2
- Do not order comprehensive laboratory panels without clinical indication; this is not useful and may lead to false positives 2
- Do not exclude SIH based on normal CSF pressure; the problem is CSF hypovolemia, not pressure 3
- Do not perform electroencephalography unless clear features of epilepsy; brief seizure activity can occur during syncope and does not require neurological investigation 1
- Do not attribute symptoms to benign causes without first excluding orthostatic pattern and obtaining orthostatic vital signs 3
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