The Brain Lecture 2 Ali B Alhailiy

Brain Anatomy

ANATOMY

ANATOMY

Stroke A stroke, sometimes referred to by the older term cerebrovascular accident (CVA), is the rapid loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood flow) caused by blockage (thrombosis), or a hemorrhage .

Stroke As a result, the affected area of the brain cannot function, which might result in: 1.Inability to move one or more limbs on one side of the body. 2. Inability to understand or formulate speech. 3. Inability to see one side of the visual field.

Risk Factors A stroke is a medical emergency and can cause permanent neurological damage and death.  Risk factors for stroke include old age, high blood pressure, previous stroke, diabetes, high cholesterol, tobacco smoking and atrial fibrillation.  High blood pressure is the most important variable risk factor of stroke. It is the second leading cause of death worldwide

Stroke Symptoms Sudden numbness or weakness of the face, arm, or leg (especially on one side of the body) Sudden confusion, trouble speaking, or difficulty understanding speech Sudden trouble seeing in one or both eyes Sudden trouble walking, dizziness, or loss of balance or coordination Sudden severe headache with no known cause

why we didn’t start with MRI ???? Diagnosis Stroke is diagnosed through several techniques:   1. Physical examination (neurological examination) A physical examination, including taking a medical history of the symptoms and a neurological status, helps giving an evaluation of the location and severity of a stroke. It can give a standard score on e.g., the NIH stroke scale ??????. 2. Imaging For diagnosing ischemic stroke in the emergency setting: A. CT scans (without contrast enhancements) sensitivity= 89%specificity= 100%MRI scan sensitivity= 81%specificity= 100% B. MRI why we didn’t start with MRI ????

Treatment for Stroke The most promising treatment of ischemic stroke is the FDA-approved, clot-busing drug t-PA (tissue plasminogen activator). It must be administered within a four and half hours from the onset of symptoms.   The sooner it is administered, the more effective it is.   It has been used to treat well over 100,000 ischemic stroke patients. Administering t-PA or other clot-dissolving agents is done through an intravenous (IV) line in the arm by hospital personnel over 60 minutes.  If given quickly, t-PA can significantly reduce the effects of stroke and reduce permanent disability.

CALL 997

CT scan slice of the brain showing a right-hemispheric ischemic stroke (left side of image)

CT scan slice of the brain showing a left-hemispheric ischemic stroke (R side of image)

Cerebral infarction (stroke) In MRI PD T2 Stroke Cerebral infarction (stroke) is a major cause of morbidity, mortality, and disability in the elderly population. As newer treatment options are being developed, the early and accurate diagnosis of stroke becomes more critical. MRI is the imaging modality of choice for the detection of cerebral infarction, and also provides vital information concerning the size and location of the infarct. MR also can demonstrate complications of infarction, such as hemorrhage, mass effect, and herniation (movement of the brain from increased pressure in one area). These transverse proton-density (left) and T2-weighted (right) images demonstrate an acute left temporal lobe infarct as swelling and edema of the cortical gray matter (the outermost layer of the brain) along the distribution of a branch of the left middle cerebral artery. Although not used in this case, intravenous contrast is usually administered in the evaluation of infarction since it can both aid in the detection of an early infarct and can help determine the age of the infarct. Although hyperacute hemorrhage (less than 24 hours ago) can be difficult to detect, MR is very sensitive for the detection of even small amounts of hemorrhage after the first day.

Stroke In MRI These transverse proton-density (left) and T2-weighted (right) images demonstrate an acute left temporal lobe infarct. intravenous contrast is usually administered in the evaluation of infarction since it can both aid in the detection of an early infarct and can help determine the age of the infarct. Although hyperacute hemorrhage (less than 24 hours ago) can be difficult to detect in MRI MRI is very sensitive for the detection of even small amounts of hemorrhage after the first day.

Cerebral Hemorrhage A cerebral haemorrhage. It is alternatively called intracerebral hemorrhage (ICH). It can be caused by brain trauma, or it can occur spontaneously in hemorrhagic stroke. Non-traumatic intracerebral hemorrhage is a spontaneous bleeding into the brain tissue. A cerebral hemorrhage could be: intra-axial hemorrhage extra-axial hemorrhage 1- intra-axial hemorrhage that is, it occurs within the brain tissue rather than outside of it. . There are two main kinds of intra-axial hemorrhages: intraparenchymal hemorrhage and intraventricular hemorrhages. intraparenchymal bleeds are a serious medical emergency because they can increase intracranial pressure which if left untreated can lead to coma and death. The mortality rate for intraparenchymal bleeds is over 40%.[

2- The other category of intracranial hemorrhage is extra-axial hemorrhage . It can be classified to: Epidural hematomas Subdural hematomas subarachnoid hematomas, which all occur within the skull but outside of the brain tissue.

Causes of ICH Intracerebral bleeds are the second most common cause of stroke. High blood pressure raises the risks of spontaneous intracerebral hemorrhage by two to six times. Intraparenchymal bleeds are usually due to penetrating head trauma, but can also be due to depressed skull fractures. Rupture of an aneurysm . Arteriovenous malformation(AVM) Bleeding within a tumor are additional causes

Diagnosis Intraparenchymal hemorrhage can be recognized on CT scans because blood appears brighter than other tissue and is separated from the inner table of the skull by brain tissue. The tissue surrounding a bleed is often less dense than the rest of the brain because of edema, and therefore shows up darker on the CT scan. CT angiogram will be performed in order to exclude a secondary cause of hemorrhage

intraventricular hemorrhage

Intraparenchymal hematoma

epidural hemorrhage

subdural hemorrhage

subarachnoid hemorrhage

Brain Tumors A brain tumor, or tumour, is an intracranial solid neoplasm and also defined as an abnormal growth of cells within the brain or the central spinal canal. Brain tumors include all tumors inside the cranium or in the central spinal canal. They are created by an abnormal and uncontrolled cell division, usually in the brain itself, but also in lymphatic tissue, in blood vessels, in the cranial nerves, in the brain envelopes (meninges), skull, pituitary gland, or pineal gland

signs and symptoms Visibility of signs and symptoms of brain tumors mainly depends on two factors 1- tumor size (volume) 2- tumor location Types of brain tumors. Tumors can be benign or malignant. can occur in different parts of the brain, and may or may not be primary tumors, as opposed to ametastatic tumor, which is something that has spread to the brain from another part of the body.  The incidence of metastatic tumors are more prevalent than primary tumors. The most common primary brain tumors are: Gliomas (50.4%) Meningiomas (20.8%) Pituitary adenomas (15%)

Diagnosis by CT & MRI Imaging plays a central role in the diagnosis of brain tumors., especially magnetic resonance imaging (MRI) and computed tomography (CT)-scans. Neoplasms will often show as differently colored masses) in CT or MRI results. Contrast agent uptake can be demonstrated on either CT or MRI-scans in most malignant primary and metastatic brain tumors.

A glioma is a type of malignant  tumor that starts in the brain or spine. Gliomas make up 80% of all malignant brain tumors. WITH CONTRAST WITH OUT CONTRAST

Benign brain tumors often show up as hypodense (darker than brain tissue) mass lesions on cranial CT-scans (Meningiomas)  CT of brain with benign right temporal arachnoid cyst

Pituitary adenomas( Benign ) CT WITH CONTRAST

. On MRI, they appear either hypo- (darker than brain tissue) or isointense (same intensity as brain tissue) on T1-weighted scans

, or hyperintense (brighter than brain tissue) on T2-weighted MRI Brain Tumor Glioblastomas comprise more than 50% of all brain tumors and occur most frequently in middle age. The tumor itself is of varying intensity on different MR images, but frequently shows enhancement from contrast. Surrounding edema (swelling of the brain) is often present and is best seen on T2-weighted images, although it can be difficult to separate the edema from the tumor prior to contrast administration. Mass effect (pressure from the tumor) and hydrocephalus ("water on the brain") are well demonstrated by MR's multiplanar capabilities.

Perifocal edema, or pressure-areas, or where the brain tissue has been compressed also appears hypointense on T1-weighted MRI, they might indicate the presence a diffuse neoplasm (unclear outline) T1 WITH CONTRAST

Thank you