Neurological - Patho Feb 5.pdf

Neurological - Patho Feb 5 Explain the pathophysiology of focal and diffuse traumatic brain injuries Focal Traumatic Brain Injury Focal brain injuries are localized to a specific area of the brain. These typically occur when the head experiences direct impact or force, causing damage to a particu...

Neurological - Patho Feb 5 Explain the pathophysiology of focal and diffuse traumatic brain injuries Focal Traumatic Brain Injury Focal brain injuries are localized to a specific area of the brain. These typically occur when the head experiences direct impact or force, causing damage to a particular region of the brain. 2 types of focal injuries include: Cerebral contusions and Hematomas. 1. Coup and Contrecoup Injuries: o Coup injury: This occurs at the site of impact. For example, if the head strikes a hard surface, the brain impacts the skull directly beneath the point of impact o Contrecoup injury: This is the injury on the opposite side of the impact. The brain is thrown against the skull, causing damage on both sides. (think car accident- “cont/cant-recoup from that”) 2. Mechanisms: o Focal injuries often involve contusions (bruising of the brain tissue), lacerations, or hemorrhage (bleeding), often associated with a skull fracture. o Hematomas (e.g., epidural or subdural) may form from ruptured blood vessels. The increase in intracranial pressure (ICP) due to blood accumulation can lead to herniation of brain tissue, which can be life-threatening. o Types of hematomas: epidural, subdural and intracerebral 3. Pathophysiology: o In focal injuries, there’s direct cellular injury at the site of impact, causing neuronal death, disruption of the blood-brain barrier, and edema (swelling). o Necrosis and axonal injury (damage to nerve fibers) can occur, leading to dysfunction of the affected brain region. o Hemorrhages can cause compression of surrounding structures, impairing normal function. Diffuse Traumatic Brain Injury Diffuse injuries are more widespread and involve multiple regions of the brain. These injuries typically result from shearing forces, such as in high-velocity impacts, and are not confined to a specific point of injury (football... head on head) 1. Axonal Injury: o Diffuse axonal injury (DAI) is the hallmark of diffuse TBI. The rapid acceleration or deceleration of the head causes stretching and tearing of the axons (the long, threadlike parts of nerve cells). o This leads to disruption of axonal transport and cellular apoptosis (cell death), which impairs communication between neurons. o The injury often occurs in areas where the brain is most vulnerable to acceleration-deceleration forces, like the corpus callosum and the brainstem. 2. Mechanism:  o The shear forces cause brain tissue deformation and widespread microvascular damage, leading to cerebral edema, increased ICP, and potential herniation. o In DAI, cerebral blood flow is often compromised, leading to areas of ischemia (lack of blood flow) in the brain. 3. Pathophysiology: o Glutamate and other excitatory neurotransmitters are released in excessive amounts due to injury, which can lead to neurotoxic effects (excitotoxicity) and secondary cell death. o Mitochondrial dysfunction and oxidative stress are also seen, contributing to further neuronal injury. o Diffuse injury tends to cause widespread functional impairment, affecting cognition, motor control, and consciousness, often leading to coma or persistent vegetative states. Key Differences: Focal injury tends to cause localized deficits based on the area of the brain affected, while diffuse injury causes more global dysfunction. Focal injury may involve bleeding or contusions, while diffuse injury primarily involves axonal shearing and widespread cellular damage. Describe the clinical manifestations of traumatic brain injuries. Mild TBI (Concussion) Symptoms: o Headache o Dizziness or balance problems o Nausea (feeling sick to your stomach) o Confusion or feeling "dazed" o Trouble concentrating or remembering things o Sensitivity to light or noise o Mood changes like irritability or anxiety o Sleep problems (too much or too little) How long it lasts: Symptoms usually go away in a few days to weeks. Prognosis: Most people recover completely, but some may have lingering issues (called post-concussion syndrome). Glasgow Coma Scale (GCS): 13-15 (mild impairment of consciousness) Imaging: Typically normal on CT/MRI; no visible structural damage. 2. Moderate TBI Symptoms: o Loss of consciousness (could last from minutes to hours) o Confusion and disorientation for a long time o Memory problems  o Slurred speech or difficulty talking o Weakness or numbness in parts of the body o Problems with balance or coordination o Mood swings or emotional changes How long it lasts: Symptoms can last for weeks to months. Glasgow Coma Scale (GCS): 8-13 (moderate impairment of consciousness) Duration of Post-traumatic Amnesia (PTA): Between 24 hours and 7 days. Prognosis: Some people recover fully, but others might have long-term cognitive or emotional issues. Rehabilitation might be needed. Imaging: CT or MRI may show some focal lesions (contusions, hemorrhage, or swelling), but not to the degree of severe TBI. There may be edema (swelling) or signs of microbleeding, which are significant but not life-threatening. 3. Severe TBI Symptoms: o Loss of consciousness for long periods (hours to days) o Coma or vegetative state (not aware of surroundings) o Severe weakness or paralysis (on one side or the whole body) o Vision problems (like losing sight in one eye) o Difficulty speaking or understanding speech o Severe headache o Increased intracranial pressure (ICP): Signs include bradycardia, hypertension, and irregular breathing patterns (Cushing's triad). o Breathing problems (may need ventilation) o Seizures (like MMA or massive hockey/football hit) o Severe confusion or not being able to recognize people or surroundings How long it lasts: Symptoms are long-lasting and may be permanent. Prognosis: People may experience life-long disabilities, like paralysis, difficulty speaking, or memory loss. The prognosis depends on the severity of the injury. Glasgow Coma Scale (GCS):