In a patient who developed new headache, blurry vision and bilateral peripheral visual‑field loss two days before a cardiac arrest (with a limited head CT ordered for headache/neuro deficit) and then suffered a prolonged hypoxic‑ischemic injury after the arrest, what is the most likely cause of the pre‑arrest visual deficit, and is the current peripheral‑field loss a continuation of that pre‑arrest lesion, a result of the post‑arrest anoxic injury, or a combination of both? Additionally, was a brain MRI performed after the limited CT?

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Last updated: October 5, 2026 • View editorial policy

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Pre-Arrest Neurologic Deficit Likely Represents a Distinct Pathologic Process That Requires Urgent MRI Evaluation

The pre-arrest visual and neurologic symptoms (headache, bilateral peripheral vision loss, documented "neuro deficit" prompting CT on [DATE]) represent a separate pathologic event from the post-arrest anoxic injury, and the current peripheral field loss is most likely a continuation or combination of both insults rather than purely anoxic injury.

Critical Timeline Separation

Your timeline establishes two distinct neurologic events that must be evaluated independently:

Pre-Arrest Period ([DATE]–[DATE])

  • New-onset headache with bilateral peripheral vision loss (family-reported)
  • Documented "headache, neuro deficit" severe enough to warrant head CT on [DATE]
  • Limited CT with radiologist recommendation for MRI if clinical concern persisted 1, 2
  • Progressive deterioration with decreased command-following, dilated pupils, rigid extremities before re-intubation

Post-Arrest Period ([DATE] onward)

  • Prolonged CPR with subsequent anoxic brain injury concern
  • Small cerebellar vermis abnormality (possible SAH with edema)
  • Later CT suggesting subacute ischemia with petechial hemorrhage
  • Persistent bilateral peripheral vision loss now verbalized by patient

Most Likely Pre-Arrest Diagnosis

The pre-arrest constellation of acute headache + bilateral peripheral vision loss + rapid neurologic deterioration suggests several possibilities that were inadequately evaluated:

  1. Posterior circulation stroke or vertebrobasilar insufficiency affecting occipital cortices bilaterally
  2. Posterior reversible encephalopathy syndrome (PRES) if hypertension was present 3
  3. Pituitary apoplexy (though typically causes bitemporal hemianopsia, not peripheral loss) 4
  4. Cerebellar pathology (given the later finding of cerebellar vermis abnormality)

The critical failure was not obtaining the MRI recommended after the [DATE] limited CT. This represents a missed diagnostic opportunity before the confounding anoxic injury occurred 2.

Current Visual Deficit: Dual Pathology

The patient's current bilateral peripheral vision loss likely represents both:

  1. Continuation of the pre-arrest lesion (never diagnosed, never treated)
  2. Superimposed anoxic injury to occipital cortices from prolonged CPR

Post-cardiac arrest patients commonly develop hypoxic-ischemic brain injury (HIBI) affecting watershed territories, including occipital cortices 5, 6. However, delayed-onset cortical blindness can appear days to weeks after cardiac arrest even in initially neurologically intact patients 7. Your patient had pre-existing visual symptoms before the arrest, making pure anoxic etiology insufficient to explain the full clinical picture.

Immediate Clinical Actions Required

1. Obtain Brain MRI Urgently

  • MRI with diffusion-weighted imaging (DWI), FLAIR, and gradient-echo sequences to:
    • Identify pre-arrest lesions (subacute ischemia, PRES, structural pathology)
    • Characterize post-arrest anoxic injury patterns
    • Evaluate the cerebellar vermis abnormality more definitively
    • Assess for delayed posthypoxic leukoencephalopathy 7

2. Document Specific Visual Deficits

  • Formal visual field testing (confrontation or automated perimetry if patient can cooperate)
  • Fundoscopic examination to exclude papilledema or optic nerve pathology
  • Pupillary responses (already documented as reactive, but reassess)
  • Blink-to-threat testing (previously absent on [DATE], recheck now)

3. Multimodal Neuroprognostication

Per Canadian Cardiovascular Society guidelines, neuroprognostication after cardiac arrest requires a systematic multimodal approach delayed ≥72 hours from ROSC or achieving normothermia 2. This includes:

  • Neurologic examination (motor response, brainstem reflexes)
  • EEG for seizures and background activity
  • Serum biomarkers (NSE, S100B if available)
  • Neuroimaging (MRI superior to CT for HIBI) 1, 2

Do not attribute all current deficits to anoxic injury when pre-arrest pathology was documented but never fully investigated.

Documentation Strategy

Avoid labeling this as "cortical blindness from anoxic injury" without qualification. Instead, document:

"Patient with bilateral peripheral vision loss of unclear etiology. Timeline complicated by two distinct neurologic events:

  1. Pre-arrest ([DATE]–[DATE]): New headache, bilateral peripheral vision loss, documented 'neuro deficit' prompting head CT on [DATE]. CT limited by artifact; radiologist recommended MRI if concern persisted. MRI was never obtained. Patient deteriorated with decreased command-following and dilated pupils before re-intubation.

  2. Post-arrest ([DATE]): Prolonged CPR with subsequent anoxic brain injury. Cerebellar vermis abnormality noted on imaging (subacute ischemia vs. petechial hemorrhage). EEG showing diffuse slowing consistent with cortical dysfunction.

Current bilateral peripheral vision loss likely represents continuation of pre-arrest pathology (never diagnosed) with superimposed anoxic injury. Urgent brain MRI needed to characterize both components and guide prognosis."

Prognosis Considerations

  • Visual recovery from pure anoxic injury can occur but is variable 7
  • Delayed-onset cortical blindness after cardiac arrest may improve over weeks 7
  • Pre-arrest lesions (if ischemic) may have permanent deficits depending on location and extent
  • The combination of pre-existing pathology + anoxic injury worsens overall prognosis 8, 9

Critical Pitfall to Avoid

The most dangerous error is assuming all current deficits are anoxic when pre-arrest symptoms were documented but inadequately evaluated. This leads to:

  • Premature withdrawal of life-sustaining therapy based on perceived "poor anoxic prognosis"
  • Missed opportunity to identify treatable pre-arrest pathology
  • Inaccurate prognostication for family discussions

The [DATE] CT recommendation for MRI was never followed. This must be prominently documented as a gap in care that prevented diagnosis of the pre-arrest neurologic event.

Specific Neurology Consultation Questions

When consulting neurology, frame the question precisely:

  1. What caused the pre-arrest headache and bilateral peripheral vision loss documented on [DATE]–[DATE]?
  2. Was the recommended MRI after the [DATE] limited CT ever obtained? If not, obtain it now.
  3. Is the current peripheral field loss a continuation of the pre-arrest deficit, a consequence of anoxic injury, or both?
  4. What is the prognosis for visual recovery given dual pathology?
  5. Does the cerebellar vermis abnormality explain any of the pre-arrest symptoms?

References

3
Research

[Acute bilateral loss of vision in posterior reversible encephalopathy syndrome].

Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft, 2013

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