1️⃣ Transient brain ischemia (TIA)
• Transient episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction.
• A history of TIA (especially more than one) in the same territory as the stroke strongly favors the presence of a local vascular lesion (thrombosis). Attacks in more than one vascular territory suggest brain embolism from the heart or aorta.
• TIAs are not a feature of brain hemorrhage.
• the physician must ask directly about specific symptoms. "Did your arm, hand, or leg ever transiently go numb?" "Did you
ever have difficulty speaking?" "Did you ever lose vision? If so, in which part of your vision? Was it in one eye and, if so, which one?

2️⃣ Hemorrhagic subtypes (20%)

▪️Intracerebral hemorrhage (ICH)
• Bleeding directly enters the brain, forming a localized hematoma that spreads along white matter pathways.
• Accumulation of blood occurs over minutes or hours.
• Neurologic symptoms usually increase gradually over minutes or a few hours.
• does not improve during the early period; it progresses gradually during minutes or a few hours.
• In contrast to brain embolism and SAH, the neurologic symptoms do not begin abruptly and are not maximal at onset.

• The most common causes:
- hypertension,
- trauma,
- bleeding diatheses,
- amyloid angiopathy,
- illicit drug use (mostly amphetamines and cocaine),
- vascular malformations

🔺Clinical suspicion for ICH is based upon features such as acute onset of gradually worsening symptoms and increasing neurologic deficit, particularly if accompanied by severe headache, vomiting, severe hypertension, and decreased level of consciousness or coma.

▪️Subarachnoid hemorrhage (SAH)
• Rupture of arterial aneurysms is the major cause of SAH.
• The blood spreads quickly within the CSF, rapidly increasing ICP.

• Symptoms of SAH:
- Begin abruptly,develops in an instant, occurring at night in 30 percent of cases.
- The primary symptom is a sudden, severe headache (97 percent of cases) classically described as the "worst headache of my life." The headache is lateralized in 30 percent of patients, predominantly to the side of the aneurysm.
- The onset of the headache may or may not be associated with a brief loss of consciousness, seizure, nausea, vomiting, focal neurologic deficit, or stiff neck.
- There are usually no important focal neurologic signs at presentation unless bleeding occurs into the brain and CSF simultaneously.(Focal brain dysfunction is less common).

🔺CT or MRI can miss small SAH. LP may be needed to make the
diagnosis in such patients(high clinical suspicion and negative(inconclusive imaging for SAH).

3️⃣ Ischemia subtypes (80%)

▪️Thrombotic stroke
• Thrombosis-related symptoms often fluctuate, varying between normal and abnormal or progressing in a stepwise or stuttering fashion with some periods of improvement.
• Penetrating artery occlusions usually cause symptoms that develop during a period of hours or at most a few days, compared with large artery-related brain ischemia, which can evolve over a longer period.

▪️Embolic stroke
• Since the process is not local (as with thrombosis), local therapy only temporarily solves the problem; further events may occur if the source of embolism is not identified and treated.
• most often occur suddenly. The deficits indicate focal loss of brain
function that is usually maximal at onset.
• Rapid recovery also favors embolism.
• Unlike thrombosis, multiple sites within different vascular territories
may be affected when the source is the heart.
• Four categories of embolic stroke:
- known cardiac source,
- possible cardiac or aortic source based on the echocardiographic findings,
- arterial source,
- truly unknown source

▪️Systemic hypoperfusion
• Can be due to cardiac pump failure or hypoxemia

❌the distinction between brain hemorrhage and ischemia cannot be made on the basis of clinical characteristics alone, imaging is critical.