Week 19 - Meningitis Flashcards
what type of hearing loss can meningitis cause?
sensorineural deafness
fault in the inner ear or auditory nerve
permenant
mild to profound
one or both ears
caused by:
- infection spreading to cochlea and damaging hair cells
- inflammation of auditory nerves
how can meningitis induce seizures?
- increased intracranial pressure
- irratition of the brain = can disrupt normal electrical activity of the brain
- fever = can lower seizure threshold in people already predisposed
- metabolic disturbances = electrolyte imbalance, change in blood glucose
- sepsis
how can meningitis cause motor defecits?
- inflammation of brain and spinal cord
- increased intracranial pressure
- direct neural damage
- seizures
how can meningitis cause cognitive impairment?
- inflammation of the brain = leading to encephalitis
- increased intracranial pressure
- hypoxia
- seizures
- delirium
how can meningitis cause hydrocephalus?
- inflammation and obstruction
- scarring and fibrosis
- impaired CSF absorption
- overproduction of CSF
what are some perminant neurological sequelae seen after meningtitis?
hearing loss
seizures
motor defecit
cognitive impairment
hydrocephelus
visual disturbances
what are some differential diagnosis of a headache?
- Tension headaches
- Migraines
- Cluster headaches
- Sinusitis
- Giant cell arteritis → (temporal arteritis). Form of vasculitis commonly causing inflamed temporal arteries
- Glaucoma → acute angle closure glaucoma. Due to reduced drainage of aqueous humor in the eye - leads to raised intraocular pressure
- Intracranial haemorrhage
- Venous sinus thrombosis → blood clot in dural venous sinuses. May happen during pregnancy.
- Subarachnoid haemorrhage
- Hormonal headache
- Cervical spondylosis
- Trigeminal neuralgia
- Raised intracranial pressure
- Brain tumours
- Meningitis
- Encephalitis
- Brain abscess
- Pre-eclampsia → high blood pressure and protein in urine
what is acute angle glaucoma?
due to reduced drainage of aqueous humor in the eye leading to raised intraocular pressure
what is DIC?
disseminated intravascular coagulation
response to an illness or disease which results in dysregulated blood clotting
both bleeding and thrombosis simultaneously
what is the pathophysiology leading to DIC?
- A trigger leads to intravascular activation of the coagulation cascade throughout the body
a. Sepsis and trauma -> lead to a release of pro-inflammatory cytokines in a systemic inflammatory response
b. Other conditions -> expression of certain pro-coagulant factors is upregulated- Microvascular thrombosis results due to formation of fibrin webs and the activation and aggregation of platelets within small vessels
a. These small thrombi can lead to multi-organ failure due to tissue ischaemia - However, widespread activation of coagulation leads to a reduction in conc of circulating coagulation factors
a. This is known as consumptive coagulopathy, where clotting factors are consumed by intravascular thrombosis - The fall in conc of clotting factors leads to a risk of bleeding and as all platelets are being used within the circulation there is thrombocytopenia which also increases risk of bleeding
- Microvascular thrombosis results due to formation of fibrin webs and the activation and aggregation of platelets within small vessels
how does sepsis and trauma lead to DIC?
through release of pro-inflammatory cytokines in a systemic inflammatory respose
what causes multi-organ failure in DIC?
microvascular thrombosis due to formation of fibrin webs and activation and aggrigation of platelets in small vessels
how is there a risk of bleeding in DIC?
reduction in conc of circulating coagulation factors
thrombocytopenia from all platelets being used in thrombosis
what are the major causes of DIC?
shock
sepsis/severe infection
major trauma/burns
malignancies
obstetric emergencies
severe immune-mediated reactions
severe organ dysfunction
what are some complications of DIC?
- Multi-organ failure
- Life-threatening haemorrhage
- Cardiac tamponade
- Haemothorax
- Intracranial haemorrhage
Gangrene and loss of digits
what are the symptoms of DIC?
- Bleeding from unusual sites:
○ ears, nose, gastrointestinal tract, genitourinary tract, respiratory tract or sites of venepuncture or cannulation.
○ Bleeding from three unrelated sites is highly suggestive of DIC.- Widespread or unexpected bruising without a history of trauma
New confusion or disorientation: a sign of microvascular thrombosis affecting cerebral perfusion
- Widespread or unexpected bruising without a history of trauma
what are the clinical signs of DIC?
- Signs of haemorrhage: bleeding from cannula sites/venepuncture sites, melaena, haematemesis, rectal bleeding, epistaxis, haemoptysis, haematuria
- Petechiae or purpura
- Livedo reticularis: a mottled lace-like patterning of the skin
- Purpura fulminans: widespread skin necrosis
- Localised infarction and gangrene for instance of the digits
- Confusion
Oliguria, hypotension and/or tachycardia: signs of circulatory collapse, which is associated with DIC
what is prothrombin time a measure of?
extrinsic and common pathways of coagulation
what is APTT (activated partial thromboplasting clotting time) a measure of?
intrinsic and common pathways of coagulation
what test measures intrinsic pathway of coagulation?
APTTw
what test measures the extrinsic pathway of coagulation?
PT
how does sepsis occurs?
At the site of infection the endothelium suffers microvascular damage, which in turn activates coagulation and complement cascades which further exacerbate vascular injury, leading to capillary leak and decreased peripheral vascular resistance. When this happens systemically it can result in organ damage, loss of haemodynamic stability and other cardinal signs of septic shock.
what is warm shock?
Clinically, patients, have a dynamic precordium with tachycardia and bounding peripheral pulses. They are warm to the touch and have a reduction in capillary refill . This is described as warm shock.
what is cold shock?
As shock progresses, elevated catecholamine (adrenaline etc) production leads to an increase in peripheral vascular resistance as the body attempts to shunt blood away from non-vital tissues GI tract, kidneys, muscle, and skin to the vital tissues (brain and heart). This is described as cold shock.
what are some risk factors that predispose to sepsis?
- Diabetes
- Malignancy
- Chronic kidney and liver disease
- Use of corticosteroids
- Immunosuppressed state
- Burns
- Major surgery
- Trauma
- Presence of indwelling catheters and lines
- Prolonged hospitalization
- Haemodialysis
- old age
what is the sepsis 6?
Taking 3:
* blood cultures
* lactate
* urine output
Giving 3:
* Antibiotics
* oxygen (to maintain SpO2 >94%)
Fluids -
what are the 4 paired paranasal sinuses?
maxillary
frontal
sphenoid
ethmoid
what cells line the paranasal sinuses?
ciliated pseudosratified epithelium
interspursed with mucus-secreting goblet cells
what are the various functions of the paranasal sinuses?
Lightening the weight of the head
Supporting immune defence of the nasal cavity
Humidifying inspired air
Increasing resonance of the voice
how many ethmoid sinuses are there and what are the names?
3
anterior
middle
posterior
where do the ethmoid sinuses open into?
- Anterior – Opens onto the hiatus semilunaris (middle meatus)
- Middle – Opens onto the lateral wall of the middle meatus
Posterior – Opens onto the lateral wall of the superior meatus
where do the maxillary sinuses drain to?
the nasal cavity at the hiatus semilunaris, underneath the frontal sinus opening
how can sinusitis cause toothache?
because maxillary nerve supplies both the maxillary sinus and the maxillary teeth
how do the frontal sinuses drain?
via the frontonasal duct. It opens out at the hiatus semilunaris, within the middle meatus of the nasal cavity.
what nerve supplies the frontal sinuses?
supraorbital nerve (a branch of the ophthalmic nerve)
what is the arterial supply of the frontal sinuses?
via the anterior ethmoidal artery (a branch of the internal carotid)
how do the sphenoid sinuses open to the nasal cavity?
open out into the nasal cavity in an area supero-posterior to the superior cocha – known as the spheno-ethmoidal recess.
what are the sphenoid sinuses innervated by?
posterior ethmoidal nerve (a branch of the ophthalmic nerve), and branches of the maxillary nerve.
where do the sphenoid sinuses recieve their arterial supply from?
pharyngeal branches of the maxillary arteries.
List the 12 cranial nerves
I Olfactory
II optic
iII Oculomotor
IV trochlear
V trigeminal
VI abducens
VII facial
VIII vestibulocochlear
IX glossopharyngeal
X vagus
CI accessory
XII hypoglossal
What is the function of the olfactory nerve?
Smell
What is cranial nerve I and is it sensory or motor?
Olfactory
Sensory
Where does the olfactory nerve pass through the skull?
Cribriform plate
What is the function of the optic nerve?
Vision
What is cranial nerve II and is it sensory or motor?
Optic nerve
Sensory
Which nerves are responsible for the pupillary eye reflex?
Optic nerve = afferent
Occulomotor = efferent
Where does the optic nerve pass through the brain?
Optical canal
What is cranial nerve III and is it sensory or motor?
Occulomotor
Motor
What is the function of the occulomotor nerve?
Eye movement
Acts on extraocular and pupillary constrictor muscles
Where does the occulomotor nerve pass through the skull?
Superior orbital fissure
What is cranial nerve IV and is it sensory or motor?
Trochlear
Motor
What is the function of the trochlear nerve?
Eyeball movement
Movement to extraocular superior oblique muscle
Assists in depressing and abducting the eye
What is cranial nerve V and is it sensory or motor?
trigeminal
both
what is the function of the trigeminal nerve?
facial movement
chewing
temperature
touch
pain
what are the 3 divisions of the trigeminal nerve and what are their functions?
opthalmic V1 = sensory above lower eyelid
maxillary V2 = sensory lower eyelid to upper lip
mandibular V3 = sensory below upper lip and motor muscles of mastication
What is cranial nerve VI and is it sensory or motor?
abducens
motorw
what is the function of the abducens nerve?
eyeball movement
innervates the lateral rectus muscles for eye abduction
What is cranial nerve VII and is it sensory or motor?
facial nerve
both
what is the function of the facial nerve?
taste
saliva
tears
facial movement e.g. expressions
What is cranial nerve VII and is it sensory or motor?
vestibulocochlear
sensory
what is the function of the vestiulococlear nerve?
hearing
equilibrium
What is cranial nerve IX and is it sensory or motor?
glossopharyngeal
both
what is the function of the glossopharyngeal nerve?
swallowing
monitoring blood pressure/O2/CO2
What is cranial nerve X and is it sensory or motor?
vagus
both
what is the function of the vagus nerve?
smooth muscle control
digestive enzyme secretion
parasympathetic innervation of viscera
What is cranial nerve XI and is it sensory or motor?
accessory
motor
what is the function of the accessory nerve?
swallowing
head/shoulder movement (efferent fibres to trapezius and sternoclidomastoid)
What is cranial nerve XII and is it sensory or motor?
hypoglossal
motor
what is the function of the hypoglossal nerve?
tongue movement
speech
swallowing
what are the red flag symptoms of a headache?
2SNOOP
systemic signs and disorders
neurological symptoms
onset new/changed and patient over 50
onset is thunderclap
papilloedema, pulsatile tinitus, positional provokation, precipiated by exercise
what are the expected findings of bacterial meningitis?
high WBC
low glucose
neutropjils
what is the main cause of bacterial meningitis?
neisseira meningitidis
what does xanthochromia suggest?
raised bilirubin in LP
from breakdown of haem
e.g. subarachnoid haemorrhage
what are some differentials for unilateral face pain?
trauma
trigeminal neuralgia
dental abscess
infection e.g. sinusitis, ear
corneal abscess
periorbital cellulitis
TMJ
patients eye is pulled down and outward. a lesion in which nerve could cause this?
CN III - oculomotor
it has function to pull eye in every other direction if this is lost then only down and out left
what is right homonymous hemianopia?
no vision in each right visual field
usually lesion in nerves supplying left half of brain
right nasal and left temporal visual fields
what nerve is affecting in changes in voice and difficulty swallowing?
glossopharyngeal
in which group of people is live vaccines contraindicated?
immunosuppressed
