Differential Diagnosis for Sudden Right-Sided Numbness
Single Most Likely Diagnosis
- Transient Ischemic Attack (TIA): Given the sudden onset of right-sided numbness and the finding of mild reduced caliber of both vertebral arteries on CTA, a TIA is a plausible diagnosis. The reduced caliber could indicate atherosclerotic disease or other processes affecting the vertebral arteries, potentially leading to transient ischemia.
Other Likely Diagnoses
- Stroke (Ischemic): Similar to TIA, but with persistent symptoms. The sudden onset of numbness is a common presentation of ischemic stroke. The involvement of the vertebral arteries could suggest posterior circulation stroke.
- Multiple Sclerosis: Although less common in men and with a typical relapsing-remitting course, multiple sclerosis could present with sudden numbness. However, the absence of other neurological symptoms and the specific finding of reduced vertebral artery caliber makes this less likely.
- Migraine with Aura: Some migraines can present with neurological symptoms such as numbness, but they are usually accompanied by headache and visual disturbances.
Do Not Miss Diagnoses
- Vertebral Artery Dissection: This is a critical diagnosis to consider due to its potential for leading to significant morbidity or mortality if missed. Dissection could explain the reduced caliber of the vertebral arteries and the sudden onset of symptoms.
- Posterior Circulation Stroke due to Other Causes (e.g., Cardiac Embolism, Vasculitis): These conditions could also lead to sudden neurological deficits and require urgent diagnosis and treatment.
Rare Diagnoses
- Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS): A rare condition that can cause stroke-like episodes, but it typically presents in younger individuals and with other systemic symptoms.
- CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy): An inherited condition leading to stroke and dementia, usually presenting in mid-adult life with a family history of similar conditions.
Next Steps
Given the clinical presentation and the findings on CTA, an MRI of the brain is highly suggested as the next step. MRI can provide more detailed information about the brain parenchyma, help identify any areas of infarction, and is more sensitive than CT for detecting early changes of ischemia. Additionally, MRI can help in evaluating the posterior circulation and the vertebral arteries in more detail, potentially identifying dissections or other abnormalities not visible on CTA.