Neuroanatomy: Meninges and Brain Trauma

Meninges

• Meninges are membranes that cover the brain and spinal cord
• Three layers: dura mater, arachnoid mater, and pia mater
• Dura mater is the outermost layer, closely attached to the skull
• Arachnoid mater is the middle layer, separated from the dura by the subdural space
• Pia mater is the innermost layer, closely adhered to the brain and spinal cord tissue
• Arachnoid trabeculae support the arachnoid mater by providing structural support
• Subarachnoid space is the space between the arachnoid and pia maters, which contains cerebrospinal fluid (CSF)

Trauma

• Hemorrhage is bleeding
• Herniation is the displacement of brain tissue
• Case Study 1: this section details symptoms, diagnoses, and testing that relates to brain trauma
• Case Study 2: similar to Case Study 1, this is related to brain injuries and diagnosis

Ventricles, Choroid, CSF

• Ventricles are fluid-filled cavities within the brain
• Choroid plexus lines the ventricles and produces cerebrospinal fluid.
• Cerebrospinal fluid (CSF) is a clear liquid that circulates through the ventricles and around the brain and spinal cord

Hydrocephalus

• Hydrocephalus is a condition involving an abnormal buildup of CSF in the brain, potentially leading to increased intracranial pressure.

Cisterns

• Cisterns are large subarachnoid spaces
• Specifically designed for CSF to pass through for circulation

Brain Herniation

• Herniation is the displacement of brain tissue due to increased intracranial pressure.
• Different types of herniation exist such as midline and transtentorial

Head Trauma

• Coup and countercoup injuries occur when the brain impacts both the side of injury, (coup), and the opposite side (countercoup).
• Concussion occurs when the brain experiences changes in consciousness
• Contusion involves brain tissue injury
• Hemorrhage leads to lesions (which are damaged/ruptured blood vessels) and axonal damage
• Post-traumatic hydrocephalus and dementia are possible outcomes of traumatic head injuries
• Displaced skull fractures or changes in skull thickness can occur

Hematomas

• Epidural hematoma: bleeding between the skull and the dura mater (meningeal artery tearing)
• Subdural hematoma: bleeding between the dura and arachnoid mater (meningeal vein tearing)
• Subarachnoid hemorrhage: bleeding into the subarachnoid space (typically aneurysm rupture)
• Intra-parenchymal hemorrhage: bleeding within the brain tissue, damaging the underlying structure, and affecting neural function.

Meningitis

• Meningitis is inflammation of the membranes (meninges) surrounding the brain and spinal cord
• It's often caused by bacterial, viral or fungal infections, or environmental factors (trauma/medications).
• Diagnostic tools include collecting CSF samples to identify the source of meningitis.
• Common symptoms include fever, headache, stiff neck (nuchal rigidity), etc.
• Potential long-term effects are cranial nerve palsies, sensory loss, and ataxia

CSF

• CSF flows through the ventricles allowing for fluid exchange and shock absorption.
• CSF circulates to areas of the brain where other functions occur.

Ventricles

• The ventricles are chambers within the brain that contain cerebrospinal fluid (CSF).
• Lateral ventricles, third ventricle, fourth ventricle
• CSF fluid produces various substances that allow communication and further circulation of CSF

Development of Ventricles and Communication Spaces

• Brain development occurs in stages
• Ventricles expand and form distinct spaces allowing for further communication of CSF inside the brain that extends outside of the brain.

CT and MRI scans

• CT and MRI scans are diagnostic imaging tools in observing injuries
• Observing hematomas, tumors, and other pathologies
• Observing ventricular structures in different views to determine extent of damage or illness

Autopsy/Case Studies

• Examining tissue to determine cause of death, observe injuries or damages, and identify potential pathologies.

Herniation

• Midline herniation - subfalcine herniation
• Transtentorial herniation - uncal herniation
• Tonsillar herniation
• Types of herniation are identified in accordance with the site of the brain displacement from the effect of outside trauma
• The symptoms vary based on the specific site of pressure and herniation

Hydrocephalus

• Developmental disorders can lead to hydrocephalus, including aqueductal stenosis as well as enlargement of the cranium
• Ex vacuo hydrocephalus results from reduced brain tissue, leading to larger ventricles.
• Obstructive hydrocephalus can be present in adults and lead to various symptoms, including seizures.
• Pseudotumor cerebri is another form of hydrocephalus that occurs in response to issues like hypertension.
• Normal pressure hydrocephalus occurs when there's pressure buildup in the brain despite normal spinal fluid measures. This often leads to symptoms including gait imbalance, incontinence, and dementia.

Case Study Details

• Specific patient data can be collected from Case Studies which include age, gender, symptoms, and diagnoses.
• Diagnosis/treatment can be assessed through various methods and tools to be administered in the case study.