What is the differential diagnosis for a 57-year-old female patient presenting with sudden onset of rotatory dizziness, frontal headache, and bradycardia, with a history of left frontal cavernous malformation (cavernoma) and hypomagnesemia?

Differential Diagnosis for 57-Year-Old Female with Rotatory Dizziness, Frontal Headache, and Left Frontal Cavernous Malformation

The primary differential diagnosis includes symptomatic cavernous malformation with hemorrhage, BPPV, and symptomatic bradycardia, with the cavernous malformation being the most concerning given the MRI findings and potential for progressive neurological deterioration.

Primary Considerations

1. Symptomatic Cavernous Malformation (Cavernoma)

• The left frontal cavernous malformation identified on MRI is the most critical finding requiring close monitoring, as cavernomas can cause headaches, dizziness, and focal neurological deficits based on anatomic location 1
• Cavernomas present with hemorrhage in 62% of pediatric cases and are associated with seizures, intracerebral hemorrhage, and various neurological disorders 2, 3
• The annual hemorrhage rate per lesion is approximately 1% for asymptomatic lesions, but increases significantly after the first symptomatic hemorrhage 4
• The American Association of Neurological Surgeons recommends conservative management for asymptomatic or minimally symptomatic cavernomas, as the natural history risk of death or nonfatal stroke is approximately 2.4% over 5 years compared to 6% surgical risk 5
• Brain MRI with gradient echo or susceptibility-weighted sequences should be performed annually for follow-up 5

2. Benign Paroxysmal Positional Vertigo (BPPV)

• The unidirectional nystagmus on examination supports BPPV as a concurrent diagnosis, which is the most common cause of peripheral vertigo 6
• BPPV presents with rotatory vertigo triggered by changes in head position relative to gravity, typically lasting less than 30 minutes with no associated hearing loss 6
• The Dix-Hallpike maneuver and supine roll test are essential to confirm BPPV and distinguish it from central causes 6
• The American Academy of Otolaryngology-Head and Neck Surgery emphasizes that failure to respond to particle repositioning maneuvers should raise concern that the underlying diagnosis may not be BPPV 6

3. Symptomatic Bradycardia (HR: 54)

• The documented heart rate of 54 bpm with associated dizziness requires urgent cardiovascular assessment to exclude cardiac arrhythmia as a cause of symptoms 6
• The National Institute for Health and Clinical Excellence recommends 24-hour Holter monitoring when cardiac arrhythmia is suspected, which has been appropriately ordered 6
• If severe bradycardia due to atrioventricular block is identified, urgent cardiac pacing may be required 6

Secondary Considerations

4. Cerebrocerebellar Atrophy

• The MRI finding of cerebrocerebellar atrophy may contribute to chronic imbalance and dizziness 6
• This finding requires correlation with clinical examination for gait disturbance and coordination deficits 6

5. Hypomagnesemia

• Electrolyte imbalances, particularly hypomagnesemia, can contribute to dizziness and neurological symptoms 6
• The treatment plan appropriately includes magnesium sulfate replacement (2.5g in 100cc PNSS x 12 hours for 2 cycles) with repeat magnesium levels 6

6. Cervicogenic Dizziness

• Given the frontal headache and rotatory dizziness, cervical spine pathology should be considered 6
• The American Academy of Otolaryngology-Head and Neck Surgery notes that cervical vertigo may produce symptoms similar to BPPV due to proprioceptive abnormalities, triggered by rotation of the head relative to the body while upright 6

Less Likely Differentials

7. Vertebrobasilar Insufficiency

• The nystagmus pattern and symptom duration make this less likely, as vertebrobasilar insufficiency typically produces nystagmus that does not fatigue and is not easily suppressed by gaze fixation 6
• The absence of other posterior circulation symptoms (diplopia, dysarthria, ataxia) further reduces this likelihood 6

8. Vestibular Neuritis

• The continuous nature of symptoms rather than acute onset with gradual improvement makes vestibular neuritis unlikely 6
• Absence of hearing loss helps distinguish from Meniere's disease 7

Critical Management Points

Seizure precautions are absolutely essential given the frontal cavernoma location, as 35% of pediatric cavernoma patients present with seizures 2

The referral to cardiology (Dr. Dizon) for 24-hour Holter and echocardiography is appropriate and urgent given the symptomatic bradycardia 6

Annual brain MRI with gradient echo sequences is mandatory for cavernoma surveillance, as surgical intervention is primarily indicated after repeated symptomatic hemorrhages 5, 4

Common Pitfalls to Avoid

• Do not attribute all symptoms to BPPV without addressing the cavernoma, as concurrent diagnoses are common and the cavernoma carries higher morbidity risk 6
• Avoid delaying cardiac evaluation - symptomatic bradycardia requires urgent assessment to exclude life-threatening arrhythmias 6
• Do not perform surgical resection of the cavernoma unless there are repeated symptomatic hemorrhages, as conservative management has lower morbidity (2.4% vs 6% at 5 years) 5
• Ensure the patient understands stroke warning signs and has immediate access to emergency care if new focal neurological deficits develop 5, 1