deck_3051775 Flashcards
How can you get CNS infections?
Direct spread e.g. trauma, middles ear infectionBlood borne e.g. sepsis, infective endocarditisIatrogenic e.g. ventriculoperitoneal shunt, lumbar puncture
How can you get a temporal lobe abscess?
Untreated middle ear infection
Define meningitis
Inflammation of the meninges
Give the causative organism for meningitis in a neonate
E coli, L monocytogenes
Give the causative organism for meningitis in a 2-5 year old
Haemophilus influenzae type B
Give the causative organism for meningitis in a 5-30 year old
Neisseria meningitidis
Give the causative organism for meningitis in an over 30 year old
Streptococcus penumoniae
How does meningitis present?
HeadacheNon-blanching rashNeck stiffnessPhotophobia
Define chronic meningitis
Has a chronic clinical course.Presents with: sub-acute headaches, increasing confusion, neurological signs
Give the common cause of chronic meningitis
Mycobacterium tuberculosis, causing granulomatous inflammation and fibrosis of the meninges. This leads to entrapment of the cranial nerves.
Give some complications of meningitis
Death - swelling and increased ICPCerebral infarctionCerebral abscessSubdural empyema
What is a subdural empyema?
Infection between dura mater and arachnoid mater
Describe encephalitis
Infection of the brain tissue. Usually a viral causes. Brain cells become haemmorhagic
Give some causes of encephalitis
Herpes virus - temporal lobePolio = spinal cord Rabies = brain stemLymphocytic inflammation reaction- signs of perivascular cuffing w/ lymphocytes in spaces around vessels in the brainCytomegalovirusToxoplasmosis
Describe the process involved in cytomegalovirus infection
Viral replication takes over cell body machinery. Causes eventual cell body destruction and death. Have Owl’s Eye inclusions
Describe the process involved in toxoplasmosis
Have toxoplasms in cells bodiesDestruction of cell body and death of neurone.
What is the cause of toxoplasmosis?
Caused by intracellular protein parasite Toxoplasm Gondii. Lives in guts of cats and humans are infected via contaminated cats faeces.
Describe prion diseases
Acts like an infection but isnt an infection. Prion proteins are found normally in the synapses. Mutations in these bins to normal PrPs, and undergo a post translational conformational change, to create more mutated prion proteins. This causes aggregates to form, which leads to neuronal death and holes in the grey matter
Describe the process of infection with a prion disease
Bovine spongiform encephalopathies in cowsNew variant creutzfeld-Jacob disease- infects humans if they have ingested mutated PrP from cows with BSE
Give some different types of dementia
AlzheimersVascular dementiaLewy Body DementiaPick’s Disease
Give some characteristics of alzheimers
Exaggerated ageing processLoss of cortical neurones- decreased brain weight and cortical atrophy- caused by neuronal damage- neurofibrillary tangles caused by twisted filaments of Tau proteins- senile plaques due to amyloid deposition
How does the intracranial pressure stay stable?
Change in volume of one component must be accompanied by an equal and opposite change in the volume of the other two. - brain- CSF fluid- blood
What is normal intracranial pressure?
0-10 mmHg- rise to 20 mmHg when coughing or straining
What are the three areas involved in compression and herniation with raised ICP?
Cingulate gyrusUncusCerebellar tonsils
What are Tau proteins?
Proteins that normally bind and stabilise microtubules. They become hyperphosphorylated in Alzheimer’s disease.
Describe senile plaques
Are foci of enlarged axons, synaptic terminals and dendrites.
What can lead to a raised intracranial pressure?
Expanding foalc lesions- tumours, haematoma, abscess, infarction with oedemaGlobal increase in brain mass- oedema, inflammation, trauma
Give the characteristics that will be seen with an expanding lesion
Deformation/destruction of brain around lesionSulci flattened against the skullDisplacement of midline structuresBrain shift, due to internal herniation
Define hernia
A protrusion of an organ or part of an organ through the wall that normally contains it
Describe a subfalcine/cingulate herniation
Occurs when ICP pushes cingulate gyruns under the free edge of the falx cerebri - ischaemia of middle parts of frontal and parietal lobe and corpus callosum- compression of anterior cerebral artery
Describe a tentorial/uncal herniation
Uncus is pushed through the tentorial notch
What is damaged in an uncal/tentorial herniation?
Damage to occulomotor nerve on same side- compression of cerebral peduncles- occlusion of blood flow in post. cerebral and sup. cerebellar arteriesCommonly is fatal due to secondary haemmorhage into the brainstem (midbrain or pons)
Describe a tonsillar herniation
Cerebellar tonsils are pushed down into the foramen magnum and compress the brainstem
Describe a central herniation
Dienchepalon and temporal lobes are pushed down through the tentorial notch.
Give the clinical signs for RICP
HeadacheVomitingPapilloedemaAcute phase- occulomotor nerve compression (dilation of pupil)- brainstem compression (coma)Compression of the cerebral peduncles leads to hemiparesis
What is the name of a benign brain tumour?
Meningioma
Give the name of a malignant brain tumour
Astrocytoma- Grade 1 to grade 4(grade 4 is the most aggressive, few months to live)- Spreads along the nerve tracts and through the sub-arachnoid space - Commonly presents with spinal secondaries- Never metastasise outside the CNS
What are the two phases of head injury?
Primary damage- due to force causing the injurySecondary damage- reaction to the primary damage causes further damage
Describe primary damage
Due to movement of brain inside the skullFocal damage- bruising of brain as it hits the inner surface of the skullDiffuse damage- direct tearing to axons (Diffuse Axonal Injury)- tearing of nerves and small vessels, as well as to the pituitary stalk- heals by gliotic scarring
What are the bones that make up the pterion?
Frontal ParietalSphenoidalTemporal
Give the characteristics that you will see on imaging for a subdural haematoma
Midline shiftCompressed ventricleFlattened gyriCrescent shaped bright lesion
Why do subdural haematomas occur?
Head trauma leads to tearing of bridging vessels as they pass from the cerebral hemispheres to the dura. Causes venous bleeds. Blood accumulate slowly, leading to a gradual rise in the ICP.
Which type of people are particularly vulnerable to subdural haematomas?
Elderly and alcoholics- due to shrinking of the brain
What are the three main patterns of MS?
Relapsing-remitting MSSecondary Progressive MSPrimary Progressive MS
What is the main type of MS?
Relapsin-remitting- symptoms occur in attackts- onset over day, recovery in weeks- average of one relapse a year
Describe secondary progressive MS
Late stage of MS- gradually worsening disability- slowly progresses over the years- relapsing-remitting will lead to this in 75% of cases
Describe primary progressive MS
Last common form- gradually worsening disability with no relapses- typically presents later- associated with fewer inflammatory changes on MRI
What are the common symptoms in MS?
Visual changesSensory symtpoms- water trickling down skin- reduced vibration sensationAtaxiaBladder hyper-reflexiaNeuropathic painFatigueSpasticityTemperature sensitivity- worsening of symptoms with increasing temperature
What can occur with HIV that affects the CNS?
EncephalopathyNeuropathy
