nervous system Flashcards
Multiple sclerosis
- A chronic inflammatory disease involving degeneration of CNS myelin, scarring, and loss of axons -
Cause: autoimmune response to self or microbial antigens in genetically susceptible individuals
Treatments: immunosuppressants, corticosteroids
No cure, but try to mitigate exacerbations and progressions
Risk factors:
Smoking
Vitamin D deficiency
Epstein-Barr virus infection
Cause:
Autoreactive T and B cells cross the BBB and recognize myelin and oligodendrocyte autoantigens, triggering inflammation and loss of oligodendrocytes (produce myelin)
Activation of microglia cells (brain macrophages) contributes to inflammation ad injury with plaque formation and axonal degeneration
Loss of myelin disrupts nerve conduction with subsequent death of neurons and brain atrophy
Clinical manifestations:
Paresthesias of the face, trunk, or limbs
Weakness
Impaired gait
Visual disturbances
Urinary incontinence
Nystagmus
Ataxia
Weakness with all four limbs
Intention tremor
Slurred speech
Meningitis
Inflammation of the brain or spinal cord
Cause: bacteria, virus, fungi, parasites, toxins
Classified as: acute, subacute, or chronic
Fungal meningitis:
chronic and less common
Produces a granulomatous reaction
Can extend along perivascular sites in the subarachnoid space and into the brain tissue
Leads to arteritis with thrombosis, infarction, and communicating hydrocephalus
Clinical manifestations:
Dementia symptoms
Communicating hydrocephalus
Afebrile
Viral Meningitis:
AKA aseptic or nonpurulent meningitis
No identifiable bacterium
Usually enteroviral virus, arboviruses, and herpes simplex type 2
Virus enters the NS by:
Crossing the BBB
Direct spread along peripheral nerves
Through the choroid plexus epithelium
Virus activates inflammatory response
Similar symptoms to those of bacterial meningitis
Bacterial Menginitis
An infection of the pia mater and arachnoid layers, the arachnoid space, the ventricular system, and the CSF
Bacteria: Meningococci & Pneumococci
Transmission: respiratory droplets or contact with droplets
Treatments: antibiotics and prophylactic vaccines
Most common
Common bacteria:
Meningococci (Neisseria meningitis), when the infection is caused by this bacteria it can be called meningococcemia
Pneumococi (Streptococcus penumoniae)
Most common in children
Can be carriers and spread the virus without symptoms
Bacteria enter bloodstream and cross the BBB to infect the meninges. Causing neutrophils to enter subarachnoid space and exhibit inflammatory response. This thickens CSF, interfering with normal CSF function causing hydrocephalus. Blood vessels also engorge.
CM:
Systemic infection symptoms
Severe throbbing HA
Severe photophobia
Nuchal rigidity
Positive Kernig and Brudzinski signs
Decrease in LOC
Cranial nerve palsies
Focal neurologic deficits
Seizures
Projectile vomiting
Specifically for meninogococcal meningitis you may have petechial or purpuric rash covering the skin and mucus membranes
Complication: purpura fulminans
Brain or Spinal cord Abscess
Localized collections of pus form within the parenchyma of the brain or spinal cord
Very rare
Classifications: epidural, subdural, or intracerebral
Commonly found in drug abuser who share needles or immunosupressed
Treatment: antibiotics, aspiration/decompression
Epidural is associated with osteomyelitis in a cranial bone, but in the spine the osteomyelitis occurs in the vertebrae.
Subdural brain abscesses arise from a sinus infection or a vascular source.
Intracerebral brain abscesses arise from a vascular source.
Clinical manifestations of brain abscess:
low-grade fever
Headache
N/V
Neck pain and stiffness
Confusion
Drowsiness
Sensory deficits
Communication deficits
Decreased attention span
Memory deficits
Decreased visual acuity
Narrowed visual fields
Papilledema
Ocular palsy
Ataxia
Dementia
Seizures
Clinical manifestations of spinal abscess:
Spinal aching
Severe root pain, back spasms and stiffness
Weakness caused by progressive cord compression
Paralysis
Encephalitis
An acute febrile illness, usually of viral origin, with nervous system involvement
Causes: mosquito, tick or fly bites, Herpes SImplex type 1, or complications of systemic viral diseases
Treatments: antiviral agents (acyclovir), steroids, sometimes antibiotics
Systemic viral diseases:
Poliomyeltitis
Rabies
Mononucleosis
Rubella
Varicella
Rubeola
Yellow fever
Can occur after vaccination with a live attenuated virus.
Viruses gain access to the CNS through:
Bloodstream
Olfactory bulb
Choroid plexus
Intraneuronal route from peripheral nerves
Viruses cause widespread nerve cell degeneration leading to edema, necrosis and increased ICP.
Mild symptoms:
Malaise
HA
Body aches
N/V
Severe symptoms:
Fever
Delirium
Confusion/unconsciousness
Difficulty finding words
Seizure activity
Cranial nerve palsies
Paresis & paralysis
Involuntary movement and abnormal reflexes
Guillain-Barré Syndrome
Rare demyelinating disorder caused by a humoral and cell-mediated immunologic reaction directed at the peripheral nerves
Cause: complication of respiratory tract or GI viral infection
Treatment: IV immunoglobulin or plasmapheresis and aggressive rehab
Recovery can take weeks to 2 years
Manifestations:
Ascending motor paralysis
Paresis of legs to complete quadriplegia
Paralysis of eye muscles
Respiratory insufficiency
Autonomic NS instability
Sensory symptoms (pain, numbness, paresthesias)
Respiratory arrest or cardiovascular collapse
Stroke Syndromes
Ischemic Strokes
Transient Ischemic Attacks
Thrombotic strokes
Embolic stroke
Lacunar strokes
Hemodynamic stroke
Hemorrhagic stroke
Intracranial aneurysm
Subarachnoid hemorrhage
Risk factors:
HTN
Type 2 diabetes mellitus
High cholesterol
Smoking
Polycythemia and thrombocythemia
CHF
Peripheral vascular disease
Atrial fibrillation
Ischemic Strokes
Occurs due to an obstruction in arterial blood flow to the brain
Causes: thrombus formation, an embolus, or hypoperfusion related to decreased blood volume or heart failure
Result; ischemia of brain tissue which can lead to infarction of brain tissue
Types: TIAs, Thrombotic strokes. Embolic strokes. Lacunar strokes, Hypoperfusion stroke
Cerebral infarction occurs when an area of the brain loses its blood supply because of vascular occlusion.
When occlusion occurs the necrotic tissue become infiltrated with macrophages and the tissue becomes phagocytized. It heals but you still have a cavity present and glial scarring
Transient Ischemic Attacks
Episodes of neurologic dysfunction lasting no more than 1 hour and resulting from focal cerebral ischemia
Clinical manifestations:
Weakness
Numbness
Sudden confusion
Loss of balance
Sudden severe headache
__At risk of a stroke in the near future__
Thrombotic Strokes (cerebral thromboses)
Stroke that arise from arterial occlusions caused by thrombi formation in arteries supplying the brain or intracranial vessels
Caused by conditions that increase coagulation or cause inadequate cerebral perfusion
Dehydration, hypotension, prolonged vasoconstriction from
malignant hypertension
Usually occur at branches or curvature in cerebral circulation
Can grow for many years (artherosclerosis)
Embolic Strokes
Strokes that are caused by fragments that break from a thrombus formed outside the brain
Also can be fat, air, tumor, bacterial clumps, and foreign
bodies
Involve small brain vessels and obstruct at bifurcations or other points of narrowing….Usually occurs in the branches of the middle cerebral artery
Middle cerebral artery is the largest cerebral artery.
Risk factors:
Atrial fibrillation
Left ventricular aneurysm or thrombus
Left atrial thrombus
Recent MI
Endocarditis
Rheumatic valve disease
Mechanical valvular protheses
Atrioseptal defects
Patent foramen ovale
Primary cardiac tumors
Lacunar Strokes
Strokes caused by occlusion of a single, deep perforating artery that supplies small penetrating subcortical vessels
Cause ischemic lesions predominantly in basal ganglia, internal capsules, and pons
Very rare
Symptoms: pure motor or sensory deficits
Hemodynamic
Associated with systemic hypoperfusion caused by cardiac failure, pulmonary embolism, or bleeding that results in inadequate blood supply to the brain
Symptoms: bilateral and perfuse
Clinical manifestations of ischemic strokes
Carotid artery occlusion:
Dysphasia
Contralateral motor and sensory deficits
Middle cerebral artery occlusion:
Conjugate ipsilateral eye deviation
Contralateral sensory deficits
Vertebrobasilar system syndromes:
Dizziness
Ataxia
Quadriplegia
Coma
Reason for contralateral deficits – motor tracts originate in the cortex and cross over at the medulla.
Hypoxic Brain Injury
Caused by: stroke, cardiac arrest, strangulation, severe anemia, hypotension, smoke inhalation, shock
All of the causes lead to inadequate amounts of oxygen to meet the metabolic demands of the brain
Usually starts after 4 minutes of anoxia
Hemorrhagic stroke
Occur in the intraparenchyma or subarachnoid or subdural spaces
Primary cause: HYPERTENSION
Characterized by: massive, small, slit or petechial
Subarachnoid hemorrhage is associated with ruptured aneurysms or arteriovenous malformations or brain trauma.
Subdural hemorrhage is usually associated with brain trauma.
Hypertensive hemorrhagic strokes involve smaller arteries and arterioles:
putamen of the basal ganglia
Thalamus
Cortex and subcortex
Pons
Caudate nucelus
Cerebellar hemispheres
Massive = centimeters
Small = 1-2 cm
Slit = subcortical area
Petechial = pinhead bleed
Typically, cerebral hemorrhages resolves through reabsorption by macrophages and astrocytes and usual leave a glial scar.
Parkinsons disease
Complex motor disorder accompanied by systemic nonmotor and neurologic symptoms.
Cause: degeneration of basal ganglia with dysfunctional or misfolded alpha-synuclein protein and loss of dopamine-producing neurons in the substantia nigra and dorsal striatum. This results in depletion of cholinergic (excitatory) activity in the feedback circuit are manifested by hypertonia and akinesia. Dementia can also occur.
Clinical manifestations:
- resting tremor
Rigidity
Bradykinesia – slowness of voluntary movements
Akinesia – decrease in voluntary and associated movements
Postural disturbances
Dysarthria
Dysphagia
Typically bilateral presentation of symptoms
Sleep disorders
Meds:
Levodopa
Deep brain stimulation
Strabismus
one eye deviates from the other when the person is looking at an object
Due to weak or hypertonic muscle in one eye
Deviate up, down, in, out
Biggest symptom is diplopia(double vision)