What is the cause of lightheadedness a day after falling off a bicycle?

Lightheadedness After Bicycle Fall: Differential Diagnosis and Evaluation

The most critical concern in a patient with lightheadedness one day after a bicycle fall is intracranial injury, particularly delayed intracranial hemorrhage or concussion, which requires immediate neurological assessment and consideration of head CT imaging based on specific risk factors. 1

Primary Diagnostic Considerations

1. Post-Traumatic Intracranial Injury (Highest Priority)

The temporal relationship between trauma and lightheadedness mandates evaluation for:

• Delayed intracranial hemorrhage - can present with lightheadedness, altered mental status, or neurological deficits hours to days after seemingly minor head trauma 1
• Concussion - causes a neuro-metabolic cascade leading to physical symptoms including lightheadedness, even without loss of consciousness at time of injury 2

Critical red flags requiring immediate head CT imaging include: 1

• Glasgow Coma Scale (GCS) score < 15
• Any focal neurological deficit
• Signs of basilar skull fracture
• Vomiting (Odds Ratio 3-5 for intracranial lesion)
• Loss of consciousness at time of fall
• Post-traumatic amnesia
• Dangerous mechanism (high-speed bicycle crash, collision with vehicle)
• Anticoagulant use

Important caveat: Even patients without loss of consciousness or amnesia can have clinically significant intracranial injury, particularly if other risk factors are present 1

2. Post-Concussive Presyncope/Orthostatic Hypotension

Lightheadedness specifically describes presyncope - extreme lightheadedness with visual changes ("tunnel vision" or "graying out") and variable degrees of altered consciousness without complete loss of consciousness 1

Evaluate for orthostatic hypotension: 1

• Sustained drop in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg within 3 minutes of standing
• Can be delayed (>3 minutes to develop)
• May be exacerbated by dehydration from trauma/reduced oral intake

3. Traumatic Benign Paroxysmal Positional Vertigo (BPPV)

Post-traumatic BPPV has higher recurrence rates than spontaneous BPPV and should be considered 3

Key diagnostic features: 4

• Positional vertigo triggered by head movements
• Diagnosed with Dix-Hallpike maneuver
• BPPV following trauma is particularly common

4. Cardiac Syncope/Presyncope

Though less likely given temporal relationship to trauma, cardiac causes must be excluded 1:

• Arrhythmias (bradycardia or tachycardia)
• Structural cardiac disease causing low cardiac output

Immediate Evaluation Algorithm

Step 1: Neurological Assessment 1

• GCS score (if <15, obtain head CT immediately)
• Focal neurological deficits (if present, obtain head CT)
• Signs of basilar skull fracture (Battle's sign, raccoon eyes, hemotympanum, CSF rhinorrhea/otorrhea)
• Post-traumatic amnesia or confusion
• Vomiting episodes

Step 2: Mechanism and Risk Factor Assessment 1

• Dangerous mechanism of injury (high-speed crash, struck by vehicle, fall from height)
• Anticoagulant or antiplatelet medication use
• Age >65 years (higher risk for occult injury) 1

Step 3: Orthostatic Vital Signs 1

• Supine BP and heart rate
• Standing BP and heart rate at 1 and 3 minutes
• Assess for orthostatic hypotension (BP drop ≥20/10 mmHg) or orthostatic tachycardia (HR increase ≥30 bpm)

Step 4: Vestibular Examination 4

• Dix-Hallpike maneuver for BPPV
• Evaluation for nystagmus
• Gait and balance assessment

Imaging Decision

Obtain non-contrast head CT if ANY of the following: 1

• GCS <15
• Focal neurological deficit
• Vomiting
• Signs of basilar skull fracture
• Loss of consciousness at time of injury
• Post-traumatic amnesia
• Dangerous mechanism
• Anticoagulant use
• Age >65 with any concerning features

Note: The sensitivity for neurosurgical lesions is 94-96% when these criteria are applied, though 0.3-3.5% of mild TBI patients require neurosurgery 1

Management Based on Findings

If intracranial injury identified: Neurosurgical consultation and admission 1

If concussion without intracranial hemorrhage: 2

• Individualized symptom management
• Cognitive and physical rest initially
• Gradual return to activity as tolerated
• Close outpatient follow-up

If orthostatic hypotension: 1

• Volume repletion
• Review and adjust medications if contributing
• Alpha agonists or mineralocorticoids if persistent

If BPPV diagnosed: 3, 4

• Epley maneuver (canalith repositioning)
• Fall precautions (particularly important given recent trauma)
• Follow-up within 1 month
• Higher recurrence rate expected with post-traumatic BPPV

Critical Safety Considerations

Fall risk is significantly elevated: 1, 3

• Assess home safety and need for supervision
• Consider activity restrictions until symptoms resolve
• Evaluate for assistive devices if balance impaired
• Particularly critical in elderly patients (falls occur in 33% of those >65 years) 1

Red flags requiring immediate return: 3

• Worsening or persistent symptoms
• New neurological symptoms
• Persistent nausea/vomiting
• Gait disturbance
• Subjective hearing loss