What is the differential diagnosis for a patient presenting with intermittent blurred vision, difficulty with word finding, and unsteady gait?

Differential Diagnosis for Intermittent Blurred Vision, Word-Finding Difficulty, and Unsteady Gait

This triad of symptoms—intermittent blurred vision, word-finding difficulty (anomia), and unsteady gait—demands urgent evaluation for cerebrovascular disease, particularly posterior circulation stroke or transient ischemic attacks, which can present with fluctuating neurological symptoms affecting vision, language, and balance. 1, 2

Life-Threatening Conditions (Rule Out First)

Posterior Circulation Stroke/TIA

• Vertebrobasilar insufficiency presents with intermittent symptoms affecting vision, speech, and balance due to fluctuating perfusion to posterior brain regions 3
• Look for additional brainstem signs: diplopia, dysarthria, dysphagia, or crossed sensory/motor findings 3
• The intermittent nature suggests episodic hypoperfusion rather than completed infarction 3

Hypertensive Emergency with End-Organ Damage

• Acute severe hypertension can manifest first with visual symptoms (hypertensive chorioretinopathy) before other organ involvement 4
• Check blood pressure immediately; values >180/120 mmHg with neurological symptoms constitute emergency 4
• Associated findings: retinopathy, serous retinal detachment, abnormal urinalysis, elevated troponin 4

Neurodegenerative Conditions

Alzheimer's Disease and Related Dementias

• Progressive amnesic syndrome with word-finding difficulty (anomia) is characteristic of AD, often accompanied by executive dysfunction 1
• Gait disturbance occurs in moderate-to-advanced stages, presenting as unsteady, cautious walking 1, 2
• Visual symptoms can include difficulty with visual perception despite intact acuity (posterior cortical variant) 1
• Obtain corroborative history from reliable informant about decline in cognition, function, and behavior 2
• Use structured cognitive assessment: MoCA, Clock Drawing Test, and informant-based tools (AD8, ECog, IQCODE) 2

Lewy Body Dementia

• Progressive cognitive-behavioral-parkinsonism syndrome presents with fluctuating cognition, visual hallucinations, and parkinsonism 1
• Fluctuating levels of cognitive impairment explain intermittent symptoms 1
• REM sleep behavior disorder often precedes other symptoms 1
• Visual hallucinations are typically well-formed and recurrent 1

Parkinson's Disease

• Associated with convergence insufficiency causing intermittent blurred vision and diplopia at near 1
• Gait disturbance includes shuffling, freezing, and postural instability 1
• Cognitive changes include executive dysfunction and word-finding difficulty in later stages 1

Multiple Sclerosis

• Causes intermittent visual impairment (optic neuritis, internuclear ophthalmoplegia), language difficulties, and ataxic gait 1
• Symptoms fluctuate with relapses and remissions 1
• Look for other neurological signs: sensory changes, bladder dysfunction, heat sensitivity 1

Ophthalmologic Causes with Neurological Overlap

Myasthenia Gravis

• Variable incomitant strabismus worsens with fatigue, causing intermittent diplopia and blurred vision 1
• Ptosis that worsens with prolonged upgaze and improves with rest (ice pack test positive) 1
• Bulbar involvement causes dysarthria that may be mistaken for word-finding difficulty 1
• Ocular saccades are characteristically slow 1
• Perform ice pack test: apply ice over closed eyes for 2-5 minutes; reduction in ptosis/misalignment is highly specific 1

Convergence Insufficiency

• Causes intermittent blurred vision, eyestrain, and diplopia specifically during near work/reading 1
• Associated with concussion history or Parkinson's disease 1
• Exophoria or exotropia at near with normal distance alignment 1
• Does not explain gait disturbance or word-finding difficulty unless concurrent pathology 1

Functional/Orthostatic Causes

Hemodynamic Orthostatic Dizziness

• Episodes triggered by standing, relieved by sitting/lying down 5
• Accompanied by blurred vision, difficulty concentrating, generalized weakness, and unsteadiness 5
• Document orthostatic vital signs: measure blood pressure and heart rate supine, then at 1 and 3 minutes standing 5
• Orthostatic hypotension (≥20 mmHg systolic or ≥10 mmHg diastolic drop) or postural tachycardia (≥30 bpm increase) confirms diagnosis 5

Functional Gait Disorder

• Gait pattern shows inconsistency (varies in ways incompatible with organic lesion) and incongruity (bizarre patterns not seen in organic disease) 6
• Look for buckling, waddling, or antalgic patterns that vary with distraction 6
• Critical caveat: Can coexist with organic neurological disease; does not exclude concurrent pathology 6

Acquired Brain Injury Sequelae

Post-Concussion/Traumatic Brain Injury

• Over 50% experience visual dysfunction: reading difficulties, photosensitivity, blurred vision, visual field disorders 7
• Convergence insufficiency develops or worsens after concussion 1
• Cognitive symptoms include word-finding difficulty, attention deficits, processing speed reduction 7
• Balance problems and unsteady gait are common 7
• Many patients don't recognize symptoms as vision-related; use structured questionnaire 7

Diagnostic Workup Algorithm

Immediate Assessment

1. Vital signs with orthostatic measurements to rule out hypertensive emergency or orthostatic hypotension 4, 5
2. Focused neurological examination: cranial nerves, motor/sensory, cerebellar testing, gait assessment 2
3. Fundoscopic examination if hypertension present to assess for retinopathy 4
4. Cognitive screening: MoCA or MMSE to quantify cognitive impairment 2

Laboratory Testing

• TSH, free T4, Vitamin B12, folate to exclude reversible causes 2
• Complete metabolic panel, urinalysis if hypertensive 4
• Consider acetylcholine receptor antibodies if myasthenia suspected 1

Neuroimaging

• MRI brain with and without contrast is preferred over CT, especially for detecting vascular lesions, demyelination, or posterior fossa pathology 2
• Obtain urgently if acute/subacute presentation suggesting stroke/TIA 2

Specialized Testing Based on Clinical Suspicion

• Ice pack test if myasthenia suspected (2 minutes for ptosis, 5 minutes for strabismus) 1
• Convergence testing and near point of convergence measurement if convergence insufficiency suspected 1
• Orthostatic vital signs with tilt table testing if orthostatic symptoms prominent 5
• Neuropsychological testing to characterize cognitive deficits objectively 2

Critical Pitfalls to Avoid

• Don't dismiss intermittent symptoms as benign: Fluctuating neurological symptoms can herald stroke, particularly in posterior circulation 3
• Don't overlook visual dysfunction in brain injury: Patients often don't recognize visual problems as such; use structured screening 7
• Don't assume functional gait excludes organic disease: Functional and organic gait disorders frequently coexist 6
• Don't rely on symptom quality alone: The timing and triggers approach (acute vs. episodic, spontaneous vs. triggered) is more diagnostically useful than symptom descriptors 3
• Don't forget to obtain informant history: Cognitive decline assessment requires corroborative information from someone who knows the patient well 2