Neuro

Focal Traumatic Brain Injury

• Injuries localized to a specific area of the brain
• Typically occur with direct impact or force, causing damage to a brain region
• Two types include cerebral contusions and hematomas

Coup and Contrecoup Injuries

• Coup Injury happens at the site of impact
• With a coup injury the brain impacts the skull directly beneath the impact point
• Contrecoup Injury occurs on the opposite side of the impact
• With a contrecoup injury the brain is thrown against the skull, causing damage

Mechanisms of Focal Injuries

• Contusions (bruising), lacerations, or hemorrhage (bleeding) are involved
• Often associated with a skull fracture
• Hematomas (epidural or subdural) may form from ruptured blood vessels
• Increased intracranial pressure (ICP) from blood accumulation can lead to life-threatening herniation
• Types of hematomas include epidural, subdural, and intracerebral

Pathophysiology of Focal Injuries

• Direct cellular injury happens at impact site
• This causes neuronal death, blood-brain barrier disruption, and edema (swelling)
• Necrosis and axonal injury can occur
• This leads to dysfunction of the affected brain region
• Hemorrhages can cause compression of surrounding structures and impair normal function

Diffuse Traumatic Brain Injury

• More widespread and involves multiple brain regions
• Typically result from shearing forces, such as in high-velocity impacts

Axonal Injury

• Diffuse axonal injury (DAI) is the hallmark of diffuse TBI
• Rapid acceleration or deceleration of the head causes stretching and tearing of axons
• This leads to disruption of axonal transport and cellular apoptosis (cell death)
• This also impairs communication between neurons
• Injury often occurs in areas most vulnerable to acceleration-deceleration forces
• These areas include the corpus callosum and the brainstem

Mechanism of Diffuse Injuries

• Shear forces cause brain tissue deformation and widespread microvascular damage
• This leads to cerebral edema, increased ICP, and potential herniation
• Cerebral blood flow is often compromised
• This leads to areas of ischemia (lack of blood flow) in the brain

Pathophysiology of Diffuse Injuries

• Glutamate and other excitatory neurotransmitters are released in excessive amounts due to injury
• This can lead to neurotoxic effects (excitotoxicity) and secondary cell death
• Mitochondrial dysfunction and oxidative stress are also seen
• These contribute to further neuronal injury
• Diffuse injury causes widespread functional impairment
• This affects cognition, motor control, and consciousness, often leading to coma or persistent vegetative states

Key Differences Between Focal and Diffuse Injuries

• Focal injury causes localized deficits based on the affected brain area
• Diffuse injury causes more global dysfunction
• Focal injury may involve bleeding or contusions
• Diffuse injury primarily involves axonal shearing and widespread cellular damage

Mild TBI (Concussion) Symptoms

• Headache
• Dizziness or balance problems
• Nausea
• Confusion or feeling "dazed"
• Trouble concentrating or remembering
• Sensitivity to light or noise
• Mood changes such as irritability or anxiety
• Sleep problems

Mild TBI (Concussion) Details

• Symptoms usually resolve in a few days to weeks
• Most people recover completely, but lingering issues (post-concussion syndrome) are possible
• Glasgow Coma Scale (GCS) score is 13-15, indicating mild impairment of consciousness
• CT/MRI imaging is typically normal

Moderate TBI Symptoms

• Loss of consciousness (minutes to hours)
• Confusion and disorientation for an extended time
• Memory problems
• Slurred speech or difficulty talking
• Weakness or numbness in parts of the body
• Problems with balance or coordination
• Mood swings or emotional changes

Moderate TBI Details

• Symptoms can last for weeks to months
• Glasgow Coma Scale (GCS) score is 8-13, indicating moderate impairment of consciousness
• Duration of Post-traumatic Amnesia (PTA) is between 24 hours and 7 days
• Prognosis: Some recover fully; others have long-term cognitive or emotional issues
• Rehabilitation may be needed
• CT or MRI may show some focal lesions, edema, or microbleeding

Severe TBI Symptoms

• Loss of consciousness for long periods (hours to days)
• Coma or vegetative state
• Severe weakness or paralysis
• Vision problems
• Difficulty speaking or understanding speech
• Severe headache
• Increased intracranial pressure (ICP)
• Breathing problems (possible need for ventilation)
• Seizures
• Severe confusion

Severe TBI Details

• Symptoms are long-lasting and may be permanent
• People may experience lifelong disabilities
• The prognosis depends on the injury severity
• Glasgow Coma Scale (GCS) score is less than 8, indicating severe impairment of consciousness
• Duration of Post-traumatic Amnesia (PTA) is greater than 7 days
• CT or MRI will likely show massive brain injury
• This includes hemorrhage, brain contusions, brain swelling, midline shift, and herniation