Understanding Transient Ischaemic Attacks (TIAs) and Strokes

Transient Ischemic Attack (TIA) and Stroke

• A TIA is a focal neurologic symptom that occurs suddenly and resolves within 24 hours.
• If the deficit persists beyond 24 hours, it is considered a stroke.
• Strokes are graded according to the National Institute of Health Stroke Scale (NIHSS).

Crescendo TIA vs Stroke in Evolution

• A crescendo TIA refers to frequent, repetitive neurological attacks with complete resolution of the deficit between episodes, usually within a 24-hour period, resulting in the same neurological deficit.
• A stroke in evolution is characterized by progressive deterioration in neurological function between TIA episodes.
• Crescendo TIA and stroke in evolution are both concerning findings that may indicate a need for emergent intervention.

Aortic Dissection

• Chest pain that extends to the abdomen may be a sign of mesenteric ischemia or aortic tear.
• Chest pain is a common symptom, occurring in 90% of patients, with tearing pain radiating between the shoulder blades.

Risk Factors and Causes

• Presence of multiple false lumens is associated with increased risk of aortic dissection-related death.
• Blunt thoracic aortic injury can also cause aortic dissections.
• Patients with penetrating aortic ulcers and intramural hematomas are at high risk of aortic rupture.

Anatomy and Pathophysiology

• The dissection most commonly extends down to the left common iliac artery rather than the right.
• The celiac trunk, SMA, and right renal artery typically arise from the true lumen, while the left renal artery arises from the false lumen.
• A false lumen can lead to end-organ ischemia by covering the ostia of branching vessels.
• The false lumen can also lead to weakening of the aortic wall, potentially causing rupture if the diameter is larger than 22mm.

Classification and Diagnosis

• Aortic dissections can be classified into two main types: Type A (ascending aorta) and Type B (descending aorta).
• The SVS-STS classification system divides the aorta into zones from 0 (proximally) to 12 (distally in the mid-SFA).
• CT angiography can detect intramural hematomas, penetrating aortic ulcers, and other signs of aortic dissection.

Complications and Prognosis

• High-risk features for early complication or continued growth include a false lumen diameter greater than 22mm.
• Early mortality for untreated Type A dissections is 1-2% per hour, with 20% mortality within 6 hours, 50% within 24 hours, and 70% within the first week.