Does a positive Rhomberg sign indicate a Posterior Cerebral Artery (PCA) stroke?

Romberg Sign and Posterior Cerebral Artery Stroke

A positive Romberg sign is not a specific indicator of posterior cerebral artery (PCA) stroke, but rather suggests proprioceptive pathway dysfunction, most commonly associated with posterior column spinal cord disorders or peripheral neuropathy.

Understanding the Romberg Sign

The Romberg sign is a clinical test that evaluates proprioceptive function and postural stability. It involves:

• Having the patient stand with feet together and arms at sides
• Observing for stability with eyes open
• Then having the patient close their eyes
• A positive test occurs when the patient maintains balance with eyes open but becomes unstable or falls when visual input is removed

The traditional Romberg test assesses the integrity of proprioceptive pathways in the posterior columns of the spinal cord. A positive sign indicates that the patient relies heavily on visual input to maintain balance due to compromised proprioception 1.

Walking Romberg Test

A modified version called the "walking Romberg sign" has been shown to be more sensitive than the traditional test:

• Patient walks 5 meters with eyes open
• Then repeats with eyes closed
• Swaying, instability, or inability to complete the walk with eyes closed constitutes a positive test
• This modification detected proprioceptive deficits in 74.5% of patients with cervical myelopathy compared to only 34% with the traditional test 1

PCA Stroke Clinical Features and Diagnosis

PCA strokes typically present with:

1. Visual field defects - Homonymous hemianopia is the most common manifestation (67-89% of cases) 2, 3, 4
2. Sensory deficits - Present in approximately 6.8-14% of cases 2, 3
3. Motor deficits - Usually mild unless the stroke extends to involve the midbrain 2
4. Neuropsychological symptoms - Including memory impairment (17.5%), dysphasia (14.5%), visual agnosia (8.5%), and prosopagnosia (6%) 3
5. Headache - Common presenting symptom that may mimic migraine 2

The diagnosis of PCA stroke relies primarily on:

• Neuroimaging (CT or MRI) showing infarction in the PCA territory
• Clinical symptoms consistent with PCA territory involvement
• Vascular imaging (CTA/MRA) to identify the mechanism of stroke 5

Why Romberg Sign Is Not Specific for PCA Stroke

1. Anatomical basis: The Romberg sign tests proprioceptive pathways in the posterior columns of the spinal cord, which are not directly affected by PCA territory infarcts 1.

2. PCA territory function: The PCA primarily supplies:

   • Visual cortex (occipital lobe)
   • Inferior and medial temporal lobes
   • Thalamus (posterior portions)
   • Parts of the midbrain 2, 3, 4

3. Clinical correlation: In studies of PCA stroke, the predominant findings are visual field defects (homonymous hemianopia), not proprioceptive deficits 2, 3, 4.

Conditions Associated with Positive Romberg Sign

A positive Romberg sign is more commonly associated with:

• Cervical myelopathy (posterior column dysfunction) 1
• Peripheral neuropathy (especially sensory)
• Vitamin B12 deficiency (subacute combined degeneration)
• Tabes dorsalis (neurosyphilis)
• Posterior column tumors or lesions
• Friedreich's ataxia

Diagnostic Approach for Suspected PCA Stroke

When PCA stroke is suspected:

1. Urgent neuroimaging: Non-contrast CT or MRI to rule out hemorrhage 5
2. Vascular imaging: CTA or MRA to identify vessel occlusion or stenosis 5
3. Diffusion-weighted imaging (DWI): Most sensitive for early detection of ischemic changes 5
4. Visual field testing: To document the extent of visual field defects 6
5. Neuropsychological assessment: To identify cognitive deficits, particularly with left PCA territory infarcts 6, 3

Clinical Pearls and Pitfalls

• Don't rely on Romberg sign for PCA stroke diagnosis: A positive Romberg sign should prompt investigation of posterior column or peripheral nerve pathology, not PCA stroke.

• Visual symptoms may be subtle: Patients with PCA stroke may not initially recognize their visual field defect or may describe it vaguely as "blurry vision" 4.

• Consider stroke mimics: Migraine with aura, posterior reversible encephalopathy syndrome (PRES), and seizures can mimic PCA stroke symptoms 2.

• Evaluate for cardiac sources: Cardioembolism is the most common cause of PCA territory infarcts (43.5-50% of cases) 2, 3.

• Look beyond visual symptoms: The presence of sensory symptoms, mild motor deficits, or cognitive changes may help localize the lesion more precisely within the PCA territory 2, 3, 4.