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Pathology - Epidural Hematoma
Pathophysiology
Blunt head trauma can result in an epidural hematoma.
Ruptures of the middle meningeal artery arising from injuries to the temporoparietal area can cause epidural hematomas. This results in a biconvex lens-shaped collection of blood in the epidural space that does not cross suture lines. These individuals frequently experience lucid intervals, which are crucial for an early diagnosis. Some individuals may develop oculomotor palsy (cranial nerve III palsy) as a result of mass effect on the oculomotor nerve, which occurs when the hematoma compresses the brain in the direction of the midline. The mainstay of treatment is surgical blood extraction. Subdural hematomas are different from epidural hematomas in that they often develop more gradually, are caused by injury to the bridging veins, and have a crescent-shaped collection of blood because the suture lines have crossed.
Pathophysiology
Blunt head trauma can result in an epidural hematoma.
Ruptures of the middle meningeal artery arising from injuries to the temporoparietal area can cause epidural hematomas. This results in a biconvex lens-shaped collection of blood in the epidural space that does not cross suture lines. These individuals frequently experience lucid intervals, which are crucial for an early diagnosis. Some individuals may develop oculomotor palsy (cranial nerve III palsy) as a result of mass effect on the oculomotor nerve, which occurs when the hematoma compresses the brain in the direction of the midline. The mainstay of treatment is surgical blood extraction. Subdural hematomas are different from epidural hematomas in that they often develop more gradually, are caused by injury to the bridging veins, and have a crescent-shaped collection of blood because the suture lines have crossed.
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Pathology - Alzheimer's DIsease
Pathophysiology
The hallmark of Alzheimer's disease (AD) is a progressive decline in short-term memory and cognitive function. Amyloid plaques and neurofibrillary tangles are the histopathologic characteristics of AD. Hyperphosphorylated tau proteins, which are the building blocks of neurofibrillary tangles, have an impact on the microtubules that are a component of the neuronal transport system. The neuronal cells are poisoned by the beta-amyloid plaques. Due to the APP gene's location on chromosome 21, individuals with Down syndrome (trisomy 21) are more likely to develop early Alzheimer's disease. AD development is linked to mutations in the presenilin genes and APP, which can be hereditary or spontaneous. Furthermore, abnormalities in the secretase-mediated APP degradation pathway may result in beta-amyloid accumulation. Additionally, there is a correlation between AD and the apolipoprotein E allele's inheritance. Imaging studies of AD patients usually show atrophy of the temporal lobes, which is most likely caused by hippocampal neuron death brought on by a buildup of beta-amyloid plaques. Acetylcholinesterase inhibitors, like donepezil, or cholinergic medications, such galantamine and rivastigmine, are commonly used in treatment.
According to certain research, vitamin E has some utility as an adjuvant but not as a stand-alone treatment.
Pathophysiology
The hallmark of Alzheimer's disease (AD) is a progressive decline in short-term memory and cognitive function. Amyloid plaques and neurofibrillary tangles are the histopathologic characteristics of AD. Hyperphosphorylated tau proteins, which are the building blocks of neurofibrillary tangles, have an impact on the microtubules that are a component of the neuronal transport system. The neuronal cells are poisoned by the beta-amyloid plaques. Due to the APP gene's location on chromosome 21, individuals with Down syndrome (trisomy 21) are more likely to develop early Alzheimer's disease. AD development is linked to mutations in the presenilin genes and APP, which can be hereditary or spontaneous. Furthermore, abnormalities in the secretase-mediated APP degradation pathway may result in beta-amyloid accumulation. Additionally, there is a correlation between AD and the apolipoprotein E allele's inheritance. Imaging studies of AD patients usually show atrophy of the temporal lobes, which is most likely caused by hippocampal neuron death brought on by a buildup of beta-amyloid plaques. Acetylcholinesterase inhibitors, like donepezil, or cholinergic medications, such galantamine and rivastigmine, are commonly used in treatment.
According to certain research, vitamin E has some utility as an adjuvant but not as a stand-alone treatment.
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Pathology - Normal Pressure Hydrocephalus
Pathogenesis
Normal pressure hydrocephalus (NPH) is characterized by the typical trifecta of symptoms: urine incontinence, dementia, and gait abnormalities.
The three Ws stand for wet (urinary incontinence), wacky (dementia), and wobbly (gait disturbance), and are a useful acronym for remembering the trio. Cerebrospinal fluid (CSF) builds up as a result of reduced resorption at the arachnoid villi, causing non-pulmonary hydrolysis (NPH). CSF pressures are elevated but still fall within the normal range. The corticospinal tract fibers that pass through the internal capsule often stretch first, causing gait difficulty. Later in the course of the disease, disinhibition of bladder contractility leads to urinary incontinence. To determine whether the patient's symptoms have improved once the volume of CSF that is circulating is decreased, lumbar punctures can be done. Patients eventually require a ventriculoperitoneal shunt in order to stop the accumulation of CSF.
Pathogenesis
Normal pressure hydrocephalus (NPH) is characterized by the typical trifecta of symptoms: urine incontinence, dementia, and gait abnormalities.
The three Ws stand for wet (urinary incontinence), wacky (dementia), and wobbly (gait disturbance), and are a useful acronym for remembering the trio. Cerebrospinal fluid (CSF) builds up as a result of reduced resorption at the arachnoid villi, causing non-pulmonary hydrolysis (NPH). CSF pressures are elevated but still fall within the normal range. The corticospinal tract fibers that pass through the internal capsule often stretch first, causing gait difficulty. Later in the course of the disease, disinhibition of bladder contractility leads to urinary incontinence. To determine whether the patient's symptoms have improved once the volume of CSF that is circulating is decreased, lumbar punctures can be done. Patients eventually require a ventriculoperitoneal shunt in order to stop the accumulation of CSF.
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Pathology - Absence Seizures
Pathophysiology
Petit mal seizures were the previous name for absence seizures.
The majority of absence seizures occur in childhood and are characterized by brief (few seconds) episodes of altered consciousness that frequently manifest as gazing episodes. Lip-smacking and other automatisms (brief, unconscious activities) may be present in patients. In most cases, they have no postictal confusion and no memory of the incident or the passing of time. The EEG wave pattern and spike at 3 Hz are indicative of this diagnosis. Hyperventilation, which lowers carbon dioxide levels, can also cause seizures. Etosuximide is the preferred medication for the condition. Treatment usually has a positive effect on the patients, and by adulthood, the seizures frequently stop altogether.
Pathophysiology
Petit mal seizures were the previous name for absence seizures.
The majority of absence seizures occur in childhood and are characterized by brief (few seconds) episodes of altered consciousness that frequently manifest as gazing episodes. Lip-smacking and other automatisms (brief, unconscious activities) may be present in patients. In most cases, they have no postictal confusion and no memory of the incident or the passing of time. The EEG wave pattern and spike at 3 Hz are indicative of this diagnosis. Hyperventilation, which lowers carbon dioxide levels, can also cause seizures. Etosuximide is the preferred medication for the condition. Treatment usually has a positive effect on the patients, and by adulthood, the seizures frequently stop altogether.
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Pathology - Herpes Simplex Virus Encephalitis
Pathogenesis
Herpes Simplex Virus (HSV) involvement in the frontotemporal region might result in seizures. The temporal lobes are particularly susceptible to the virus's influence, which results in seizures and the accompanying symptoms of temporary aphasia. The brain parenchyma in the left motor cortex and temporal lobes is implicated in seizures when just the right side of the body is affected. Jacksonian march, or following somatotopic organization, is a seizure pattern that can be seen in primary motor cortex seizures. One of two possible causes of HSV encephalitis is the reactivation of a latent infection or original HSV infection. Predominant lymphocytosis, normal glucose, and normal protein in the CSF study indicate a viral origin (bacteria would induce a reduction in glucose and an increase in neutrophils). Seizures are prevented and acyclovir is used as treatment. This is regarded as a neurological emergency due to the disease's quick progression, and urgent treatment is essential.
Pathogenesis
Herpes Simplex Virus (HSV) involvement in the frontotemporal region might result in seizures. The temporal lobes are particularly susceptible to the virus's influence, which results in seizures and the accompanying symptoms of temporary aphasia. The brain parenchyma in the left motor cortex and temporal lobes is implicated in seizures when just the right side of the body is affected. Jacksonian march, or following somatotopic organization, is a seizure pattern that can be seen in primary motor cortex seizures. One of two possible causes of HSV encephalitis is the reactivation of a latent infection or original HSV infection. Predominant lymphocytosis, normal glucose, and normal protein in the CSF study indicate a viral origin (bacteria would induce a reduction in glucose and an increase in neutrophils). Seizures are prevented and acyclovir is used as treatment. This is regarded as a neurological emergency due to the disease's quick progression, and urgent treatment is essential.
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Pathology - Alcohol Withdrawal Seizures
Pathophysiology
These seizures usually happen six to forty-eight hours after abruptly stopping alcohol use following heavy and sustained consumption. Downregulation of gamma-aminobutyric acid A (GABAA) receptors and overexpression of N-methyl-D-aspartate (NMDA) receptors in the central nervous system cause seizures. Patients typically arrive with widespread tonic-clonic seizures. Additions to the symptoms of alcohol withdrawal syndrome include anxiety, agitation, delirium tremens, and hallucinations.
A patient who presents with delirium or seizures two days after being admitted to the hospital is not uncommon. Benzodiazepines (BZDs) are used to treat seizures and stop them from happening again. GABA is potentiated by BZDs by increasing the frequency of chloride ion channel opening.
Barbiturates function similarly, but they vary in that they prolong the opening of chloride ion channels; yet, the use of barbiturates has been limited due to the substantial danger of fatal respiratory depression.
Pathophysiology
These seizures usually happen six to forty-eight hours after abruptly stopping alcohol use following heavy and sustained consumption. Downregulation of gamma-aminobutyric acid A (GABAA) receptors and overexpression of N-methyl-D-aspartate (NMDA) receptors in the central nervous system cause seizures. Patients typically arrive with widespread tonic-clonic seizures. Additions to the symptoms of alcohol withdrawal syndrome include anxiety, agitation, delirium tremens, and hallucinations.
A patient who presents with delirium or seizures two days after being admitted to the hospital is not uncommon. Benzodiazepines (BZDs) are used to treat seizures and stop them from happening again. GABA is potentiated by BZDs by increasing the frequency of chloride ion channel opening.
Barbiturates function similarly, but they vary in that they prolong the opening of chloride ion channels; yet, the use of barbiturates has been limited due to the substantial danger of fatal respiratory depression.
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Pathology - Open Angle Glaucoma
Pathogenesis
The trabecular meshwork, which typically serves to drain intraocular fluid from the anterior chamber, is obstructed in this kind of glaucoma. The aqueous humor produced by the ciliary body persists and builds up in the anterior chamber, raising intraocular pressure. This is not painful, unlike acute angle-closure glaucoma, as it happens gradually. Damage to the optic nerve as a result increases the disc to cup ratio and impairs vision from the peripheral to the central nervous system. Venous vessel engorgement manifests as vessels with notches on the outside edge of the optic disc. Topical beta-blockers and oral carbonic anhydrase inhibitors can be used to reduce the generation of aqueous humor, whereas topical prostaglandins can be used in treatment to enhance outflow via the trabecular meshwork.
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Pathology - Closed Angle Glaucoma
Pathophysiology
When the iris dilates in patients with narrow angles, or in dimly lit environments, the iris and lens come into touch. The ciliary body continues to produce aqueous humor, but it cannot move from the posterior chamber into the anterior. A rapid increase in intraocular pressure results in conjunctival erythema, lacrimation, and discomfort. Patients may feel queasy, throw up, or have headaches. Halos around lights and diminished visual acuity are examples of visual abnormalities that could quickly lead to total blindness. In narrow-angle glaucoma, intraocular pressures usually surpass 40 mm Hg, although normal intraocular pressures are usually less than 20 mm Hg. This condition is an ophthalmological emergency that needs to be treated right away with acetazolamide, topical beta-blockers, steroids, and reduction of intraocular pressure in order to control inflammation.
Pathophysiology
When the iris dilates in patients with narrow angles, or in dimly lit environments, the iris and lens come into touch. The ciliary body continues to produce aqueous humor, but it cannot move from the posterior chamber into the anterior. A rapid increase in intraocular pressure results in conjunctival erythema, lacrimation, and discomfort. Patients may feel queasy, throw up, or have headaches. Halos around lights and diminished visual acuity are examples of visual abnormalities that could quickly lead to total blindness. In narrow-angle glaucoma, intraocular pressures usually surpass 40 mm Hg, although normal intraocular pressures are usually less than 20 mm Hg. This condition is an ophthalmological emergency that needs to be treated right away with acetazolamide, topical beta-blockers, steroids, and reduction of intraocular pressure in order to control inflammation.
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Pathology - Parkinson's disease
Pathophysiology
The hallmark of this disease is a reduction in dopaminergic activity, which results from a decrease in the activity of the substantia nigra, a region of the midbrain that secretes dopamine.
There is a clear correlation between dopamine levels and motor function, as dopamine reduces inhibition of motor performance. This is consistent with the clinical observations of bradykinesia and cogwheel rigidity, which is jerky resistance to passive range of motion. Furthermore, a decrease in dopamine suppresses emotions via acting on the prefrontal brain, which is exacerbated by facial paralysis (mask-like facies). Parkinson's patients' neurons frequently include Lewy bodies, which are inclusion bodies containing the protein alphasynuclein. Nevertheless, Parkinson's disease is not the only condition that can cause these aggregation of proteins.
Dopamine agonists and carbidopa/levodopa can be used to treat symptoms. In order to avoid undesirable side effects, carbidogopa blocks the peripheral conversion of levodopa to dopamine. Anticholinergic drugs aid in the management of tremor.
Pathophysiology
The hallmark of this disease is a reduction in dopaminergic activity, which results from a decrease in the activity of the substantia nigra, a region of the midbrain that secretes dopamine.
There is a clear correlation between dopamine levels and motor function, as dopamine reduces inhibition of motor performance. This is consistent with the clinical observations of bradykinesia and cogwheel rigidity, which is jerky resistance to passive range of motion. Furthermore, a decrease in dopamine suppresses emotions via acting on the prefrontal brain, which is exacerbated by facial paralysis (mask-like facies). Parkinson's patients' neurons frequently include Lewy bodies, which are inclusion bodies containing the protein alphasynuclein. Nevertheless, Parkinson's disease is not the only condition that can cause these aggregation of proteins.
Dopamine agonists and carbidopa/levodopa can be used to treat symptoms. In order to avoid undesirable side effects, carbidogopa blocks the peripheral conversion of levodopa to dopamine. Anticholinergic drugs aid in the management of tremor.
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Pathology - Achalasia and Dysphagia
Pathophysiology
Dysphagia may arise from an esophageal motility disease or from issues during the oropharyngeal phase of swallowing. Even though the patient can swallow and produce a bolus, the food stops in the esophagus. The most prevalent causes of motility issues in the esophagus are innervation abnormalities or blockages like cancer. Interaction between inhibitory enteric neurons, which emit vasoactive intestinal polypeptide (VIP) and nitric oxide, and excitatory vagal and enteric neurons, which release acetylcholine and substance P as neurotransmitters, is necessary for coordinated peristalsis. Loss of inhibitory neurons is assumed to be the etiology of achalasia, leading to dysregulation of peristalsis and improper relaxation of the lower esophageal sphincter. The majority of cases are idiopathic, however infrequently occurring identified causative factors include cancer and Trypanosoma cruzi, the organism that causes Chagas disease
Pathophysiology
Dysphagia may arise from an esophageal motility disease or from issues during the oropharyngeal phase of swallowing. Even though the patient can swallow and produce a bolus, the food stops in the esophagus. The most prevalent causes of motility issues in the esophagus are innervation abnormalities or blockages like cancer. Interaction between inhibitory enteric neurons, which emit vasoactive intestinal polypeptide (VIP) and nitric oxide, and excitatory vagal and enteric neurons, which release acetylcholine and substance P as neurotransmitters, is necessary for coordinated peristalsis. Loss of inhibitory neurons is assumed to be the etiology of achalasia, leading to dysregulation of peristalsis and improper relaxation of the lower esophageal sphincter. The majority of cases are idiopathic, however infrequently occurring identified causative factors include cancer and Trypanosoma cruzi, the organism that causes Chagas disease
