What are the differential diagnoses and recommended management for a 74‑year‑old woman presenting with acute dizziness and photopsia?

Acute Dizziness with Photopsia in a 74-Year-Old Woman

Immediate Priority: Rule Out Posterior Vitreous Detachment and Retinal Detachment

The flashing colored lights (photopsia) in this 74-year-old woman represent a potential ophthalmologic emergency requiring urgent ophthalmology evaluation within 24 hours to exclude retinal tear or detachment, while the dizziness warrants simultaneous assessment for posterior circulation stroke given her age. 1, 2

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Differential Diagnosis

For Photopsia (Flashing Lights)

The photopsia component demands immediate attention because:

• Posterior vitreous detachment (PVD) accounts for 39.7% of photopsia cases and typically presents with quick, white/silver flashes in the temporal visual field, often triggered by eye movements and seen preferentially in dark environments 2
• Retinal tear (8.9% of photopsia cases) presents similarly to PVD but requires urgent intervention to prevent progression to detachment 2
• Rhegmatogenous retinal detachment (7.5% of cases) shows similar photopsia characteristics to PVD but with more non-temporal location (40% vs 14%) 2
• Vertebrobasilar insufficiency (2.8% of photopsia cases) can cause both visual phenomena and dizziness simultaneously 2, 3

For Dizziness in a 74-Year-Old

Given her age, the dizziness differential must prioritize:

• Posterior circulation stroke/TIA – accounts for 25% of acute vestibular syndrome presentations overall, but rises to 75% in high-risk vascular cohorts (age >50 with hypertension, diabetes, atrial fibrillation, or prior stroke) 4
• Benign paroxysmal positional vertigo (BPPV) – most common peripheral cause (42% of vertigo cases), but episodes last <1 minute and are triggered by specific head position changes 4
• Vestibular neuritis – 41% of peripheral vertigo, presents with continuous severe vertigo lasting days 4
• Vestibular migraine – 14% of vertigo cases, can present with visual aura and photopsia, episodes last minutes to hours 4

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Management Plan

Step 1: Immediate Ophthalmology Referral (Same Day or Next Morning)

• Arrange urgent dilated fundoscopic examination to evaluate for retinal tear, detachment, or PVD 1, 2
• Do not delay – retinal tears require immediate laser photocoagulation or cryotherapy to prevent detachment 1
• If new-onset floaters accompany the photopsia (85% of PVD cases), this further elevates urgency 2

Step 2: Vascular Risk Assessment

Document presence of:

• Hypertension, diabetes, atrial fibrillation, prior stroke/TIA, smoking 4, 5
• If any vascular risk factors are present, posterior circulation stroke becomes the leading concern even with normal neurologic exam, as 75-80% of posterior circulation strokes present without focal deficits 4

Step 3: Focused Neurologic Examination

Perform and document:

• HINTS examination (if trained): Head impulse test, nystagmus pattern, test of skew 4

  • Normal head impulse + direction-changing nystagmus + skew deviation = central cause requiring urgent MRI 4
  • Caveat: HINTS is only 100% sensitive when performed by trained neuro-otology specialists; emergency physicians achieve inadequate sensitivity 4

• Observe for spontaneous nystagmus 6

  • Pure vertical (up-beating or down-beating) without torsional component = central pathology 7
  • Horizontal with rotatory component, unidirectional, suppressed by visual fixation = peripheral 7

• Dix-Hallpike maneuver (if vertigo is positional) 4, 6

  • Positive: 5-20 second latency, torsional upbeating nystagmus, resolves <60 seconds = BPPV 4
  • Immediate onset, persistent, purely vertical = central cause requiring MRI 4

• Complete neurologic exam for dysarthria, dysmetria, dysphagia, limb weakness, sensory deficits, diplopia, Horner's syndrome 7

Step 4: Imaging Decision Algorithm

Obtain urgent MRI brain without contrast (with diffusion-weighted imaging) if ANY of the following:

• Age >50 plus any vascular risk factor (even with normal neuro exam) – 11-25% harbor posterior circulation stroke 4
• Abnormal HINTS examination suggesting central cause 4
• Any focal neurologic deficit 4
• Severe postural instability with falling 4
• New severe headache accompanying dizziness 4
• Pure vertical nystagmus without torsional component 7
• Nystagmus not suppressed by visual fixation and does not fatigue 7
• Failure to respond to appropriate peripheral vertigo treatment 7

Do NOT order imaging if:

• Typical BPPV with positive Dix-Hallpike, no vascular risk factors, normal neuro exam 4
• Clear peripheral vestibular syndrome in low-risk patient 4

Imaging modality specifics:

• MRI sensitivity for posterior circulation stroke: 4% 6
• CT sensitivity: <1% – CT misses most posterior circulation infarcts and should not substitute for MRI 4
• If MRI unavailable and stroke suspected, CT may be used initially but recognize its 10-20% sensitivity for posterior fossa strokes 4

Step 5: Treatment Based on Diagnosis

If BPPV confirmed:

• Perform Epley maneuver immediately – 80% success after 1-3 treatments, 90-98% with repeat maneuvers 4, 6
• Avoid vestibular suppressants (meclizine, dimenhydrinate) – they delay central compensation 4
• Counsel on fall risk (12-fold increase in elderly), recurrence risk (10-18% at 1 year) 4, 6

If vertebrobasilar insufficiency/TIA:

• Aggressive medical management: antiplatelet therapy, statin, risk factor modification 8
• Obtain CTA or MRA head and neck to evaluate vertebral and basilar arteries 4

If vestibular migraine:

• Migraine prophylaxis and lifestyle modifications 4
• Differentiate from Ménière's by absence of fluctuating hearing loss 4

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Critical Pitfalls to Avoid

• Do not assume normal neurologic exam excludes stroke – 75-80% of posterior circulation strokes lack focal deficits 4
• Do not rely on patient description of "spinning" vs "lightheadedness" – focus on timing, triggers, and associated symptoms 4
• Do not delay ophthalmology referral – retinal tears can progress to detachment within hours to days 1
• Do not order CT instead of MRI when stroke is suspected – CT misses the majority of posterior circulation infarcts 4
• Do not rely on HINTS alone in the ED – obtain MRI for high-risk patients regardless of HINTS results 4
• Do not overlook vertebrobasilar insufficiency – isolated transient vertigo may precede stroke by weeks to months 7, 3, 8

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Specific Photopsia Characteristics to Elicit

Ask the patient to describe:

• Laterality: Unilateral suggests retinal pathology; bilateral simultaneous suggests migraine or vertebrobasilar insufficiency 2
• Morphology: Lightning/flash (96% in PVD), zig-zag (migraine), strobe 2
• Color: White/silver (87% in PVD), colored patterns (migraine or neovascular AMD) 2
• Location: Temporal (86% in PVD), central (83% in neovascular AMD) 2
• Duration: Quick (<1 second in PVD), prolonged (migraine aura) 2
• Triggers: Eye/head movements (60% in PVD), none (84% in neovascular AMD) 2
• Associated symptoms: New floaters (85% in PVD), headache (migraine), vertigo (vertebrobasilar insufficiency) 2, 3