pathophys2test3: CNS Infections, Seizures, Head Trauma & Movement Disorders ppt

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Questions and Answers

What is the primary mechanism of diffuse axonal injury?

Penetrating injury to the brain

Blast waves damaging the brain

Direct impact on the basal skull surfaces

Shifting/rotation of the brain within the skull during trauma (correct)

What is the common location of focal cerebral contusions?

Cerebral cortex

Basal frontal and temporal areas (correct)

Brainstem

Cerebellum

What is the result of free-radical injury to cell membranes in secondary brain injury?

Electrolyte imbalances

Mitochondrial dysfunction

Neuronal cell death (correct)

Inflammation

What type of hemorrhage occurs between the dura mater and the skull?

Epidural hematoma Signup and view all the answers

What is the term for the injury caused by abrupt deceleration?

Coup contrecoup Signup and view all the answers

What is the result of shearing/tearing forces in TBI?

All of the above Signup and view all the answers

What is the characteristic of primary brain injury?

Caused by external mechanical forces Signup and view all the answers

What is the result of secondary ischemia from vasospasm in TBI?

Neuronal cell death Signup and view all the answers

What is the primary function of the thalamus in the context of motor signals?

To relay motor signals from the basal ganglia to the cortex Signup and view all the answers

What is the primary neurotransmitter involved in the regulation of movement by the basal ganglia?

Dopamine Signup and view all the answers

Which of the following is NOT a characteristic of hyperkinetic movement disorders?

Decreased movement Signup and view all the answers

What is the primary genetic defect responsible for Huntington's disease?

Mutation in the Huntingtin gene leading to triplet repeat expansion Signup and view all the answers

What is the primary mechanism of action of Levodopa in the treatment of Parkinson's disease?

Crossing the blood-brain barrier to increase dopamine levels Signup and view all the answers

Which of the following is NOT a characteristic of Parkinson's disease?

Hyperkinetic movements Signup and view all the answers

What is the primary function of the substantia nigra in the context of movement?

Production of dopamine Signup and view all the answers

What is the primary mechanism of action of Carbidopa in the treatment of Parkinson's disease?

Inhibition of peripheral decarboxylase Signup and view all the answers

What is the primary clinical manifestation of Huntington's disease?

Chorea movements Signup and view all the answers

What is the primary pathway affected in Parkinson's disease?

Both direct and indirect pathways Signup and view all the answers

What type of brain injury is characterized by a temporary impairment of neurologic function, with symptoms including memory loss, attention deficits, and headache?

Mild traumatic brain injury (mTBI) Signup and view all the answers

What is the primary reason why concussed cells become vulnerable to further damage?

Metabolic insults from the trauma Signup and view all the answers

What is the term for the infection of the brain parenchyma itself, which is not always clinically distinguishable from meningitis?

Encephalitis Signup and view all the answers

What is the primary function of the substantia nigra, a part of the basal ganglia?

Initiating voluntary motor movement Signup and view all the answers

What is the term for the progressive neurological disorder that often presents like dementia, and can also have motor disorders, resulting from repetitive closed-head injuries?

Chronic Traumatic Encephalopathy Signup and view all the answers

What is the primary mechanism by which bacteria invade the meninges in bacterial meningitis?

All of the above Signup and view all the answers

What is the primary reason why steroids like Decadron are used in the treatment of bacterial meningitis?

To reduce inflammation Signup and view all the answers

What is the term for the group of subcortical nuclei responsible primarily for motor control, which includes the substantia nigra, caudate nucleus, and putamen?

Basal Ganglia Signup and view all the answers

What is the primary function of carbidopa in levodopa therapy?

Preventing the conversion of levodopa into dopamine outside the brain Signup and view all the answers

What percentage of ALS cases are accounted for by the sporadic form?

90-95% Signup and view all the answers

What is the primary pathology observed in the spinal cord of ALS patients?

Atrophy of the spinal cord Signup and view all the answers

What is the typical cause of death in ALS patients?

Respiratory failure from paralysis of respiratory muscles Signup and view all the answers

What is the mechanism of action of riluzole in ALS treatment?

Blocking the release of glutamate Signup and view all the answers

What is the typical duration of survival after diagnosis in ALS patients?

2-5 years Signup and view all the answers

Study Notes

Head Trauma

Traumatic Brain Injury (TBI) is an alteration in brain function or evidence of brain pathology caused by external force
Common mechanisms of TBI include direct impact, rapid acceleration/deceleration, penetrating injury, and blast waves
The external mechanical forces are transferred to intracranial contents, causing damage to the brain, including focal contusions and hematomas, shearing of white matter tracts, and possible cerebral edema
The injury can be focal or diffuse, depending on the mechanism of injury

TBI Pathophysiology: Primary Brain Injury

Diffuse Axonal Injury is caused by shearing/tearing of neuronal axons due to shifting/rotation of the brain within the skull during trauma
Seen in "coup contrecoup" injuries; abrupt deceleration causes the brain to collide with the skull
Can be seen on neuroimaging as multiple small lesions within white matter tracts
Focal Cerebral Contusions are the most common lesions, commonly seen in the basal frontal and temporal areas due to direct impact on basal skull surfaces in the setting of acceleration/deceleration injuries
Intracranial hemorrhage can occur, including epidural hematomas, subdural hematomas, or subarachnoid hemorrhage

TBI Pathology: Secondary Brain Injury

Cascade of molecular injury mechanisms that start at the time of injury and continue for hours to days
Free-radical injury to cell membranes, electrolyte imbalances, mitochondrial dysfunction, inflammatory responses, apoptosis, and secondary ischemia from vasospasm lead to neuronal cell death and cerebral edema
It is critical to avoid secondary brain insults after an initial TBI due to the cells being vulnerable to further damage

Concussion

Mild traumatic brain injury (mTBI)
Temporary impairment of neurologic function
Memory loss, attention deficits, headache, altered mental status
Neuronal dysfunction happens due to metabolic insults from the trauma rather than an actual structural abnormality
Concussed cells become very vulnerable, and if a second concussion is sustained during this period, damage can be irreversible
Hallmark symptoms are confusion and amnesia with or without loss of consciousness

Chronic Traumatic Encephalopathy

Repetitive closed-head injuries, like in boxers, football players
Progressive neurological disorder that often presents like dementia, can also have motor disorders

CNS Infections

Meningitis

Infection of the meninges resulting in inflammation
Can be viral, bacterial, or fungal

Bacterial Meningitis

Virulence factors of a pathogen overcome host defense mechanisms
Common pathogens include Group B streptococcus, Neisseria meningitidis, Streptococcus pneumoniae, H. influenza, and E. coli
Invasion of bacteria into the meninges through the bloodstream or direct extension from local infection
Clinical manifestations include fever, neck stiffness, and altered mental status
Treatment includes empiric antibiotics, antivirals, and steroids to reduce inflammation

Neurodegenerative & Movement Disorders

Basal Ganglia

Group of subcortical nuclei responsible primarily for motor control
Made up of the substantia nigra, caudate nucleus, putamen, and others
Functions include initiating voluntary motor movement, suppressing unwanted movement, and procedural learning
Substantia Nigra contains dopamine and projects to the striatum

Movement Disorders

Group of neurologic conditions that cause abnormal movements
Can be either increased movements (spasms, tremors, etc.) or decreased/slow movement
Can affect both voluntary and involuntary movements
Common disorders include ataxia, chorea, dystonia, tremor, Huntington's disease, and Parkinson's disease

Huntington's Disease

Rare autosomal dominant genetic disorder
Clinical manifestations include dementia, psychiatric symptoms, chorea movements, and progressive neuronal degeneration
Genetic mutation in Huntingtin (HTT) gene causes triplet repeat expansion of a particular DNA sequence responsible for coding for glutamine
Accumulations of this abnormal protein lead to neuronal death/dysfunction as well as dysfunction of glutamate/dopamine signaling in the basal ganglia
Treatment focuses on symptom management, usually aimed at trying to help suppress the abnormal chorea movements to improve quality of life

Parkinson's Disease

Degenerative disorder of the substantia nigra
Progressive degeneration of dopamine-producing neurons in the substantia nigra
Symptoms include "pill-rolling" tremor at rest, rigidity, masked facies, shuffling gait, bradykinesia, and dementia in later stages
Clinical correlation: Parkinson's treatment includes Levodopa/Carbidopa to increase dopamine levels in the brain

Amyotrophic Lateral Sclerosis (ALS)

Progressive neurodegenerative disorder of upper and lower motor neurons
Etiology is unknown, with some genetic susceptibility
Sporadic form accounts for 90-95% of cases, and familial forms make up 5-10% of cases
Pathophysiology includes motor neuron degeneration and death, cortical motor neuron death, spinal cord atrophy, and loss of large myelinated fibers in motor nerves
Unfortunately, no cure exists, and it is always fatal, usually within five years of diagnosis

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Description

This quiz covers the basics of traumatic brain injury, its causes, and effects on the brain. It includes the mechanisms of injury, types of damage, and more.