Infections of the Nervous System Flashcards
Define Meningitis
Inflammation/infection of meninges
What is the classic triad of meningitis
Fever
Neck stiffness
Altered mental status
What is the clinical features associated with meningitis
Short history of a
Progressive headache with fever and meningism
Cerebral dysfunction
Cranial nerve palsy
seizures
focal neurological deficits
Petechial skin rash
A tumbler test indicates a petechial skin rash, what does this usually indicate
Meningococcal meningitis
What is the differential diagnosis for meningitis
Infective
Inflammatory - sarcodosis
Drug induced (NSAIDs, IVIG)
Malignant
What bacterial cause meningitis
Neisseria meningitidis (meningococcus) Streptococcus pneumoniae (pneumococcus)
What virus cause meningitis
enteroviruses
Define encephalitis
Inflammation/ infection of brain substance
What is the clinical features of encephalitis
Flu like prodrome
Progressie headache with associated fever
Progressive cerebral dysfunction
seizures
focal symptoms
What is the similarities to encephalitis and meningitis
Both have classic triad of meningism symptoms but encephalitis has more brain problems and is a more prominent feature
What is the differential diagnosis of encephalitis
Infective - viral
Inflammatory
(limbic encephalits,
Acute disseminated encephalomyelitis)
Metabolic
(Hepatic, uraemic, hyperglycaemic)
malignant
(metastatic, paraneoplastic)
migraine
After seizure
What is the most common cause of encephalitis
Herpes simplex virus
What are two important antibodies causing autoimmune encephalitis
Anti VGKC (voltage gates potassium channel)
Anti NMDA receptor
What is the the investigation for meningitis
Blood cultures (bacteraemia)
Lumbar puncture (CSF culture/microscopy)
When would imaging be needed in investigating meningitis
If there was contradictions to lumbar puncture
What is the CSF finding in Bacterial meningitis
Increased opening pressusre
High cell count - mainly neutrophils
Reduced glucose
High protein
What is the CSF findings in viral meningitis
Opening pressure is normal or increased
High cell count- mainly lymphocytes
Normal glucose levels
Protein slightly increased
What occurs after CSF findings
Gram stain and culture
how is bacterial meningitis diagnosed from gram stain and culture (blood/CSF)
Gram stain shows - gram positive cocci in chains
= streptococci
Culture and check is allergic to penicillin
= streptococcus pneumonia
What is the first line treatment for suspected meningitis
IV ceftriaxone
What is the investigations for encephalitis
Blood culture
Imaging (CT scan +/- MRI)
Lumbar punture
EEG
What is first line treatment of suspected herpes simplex encephalitis
Aciclovir
How do you specifically diagnose herpes simplex encephalitis
Lab diagnosis by PCR of CSF for viral DNA
Where does herpes simplex virus lay dormant after primary infection
Trigeminal or sacral ganglion
then patients is always affected with virus becoming active again when patient is under immune pressure
Enterovirus, has a tendency to cause what
CNS infections
eg non -paralytic meningitis
How do enteroviruses spread
Faecal-oral route
no animal reservoir - only human
How do diagnose enterovirus
Stool sample
What additional virus groups can cause encephalitis
Arbovirus encephalitis which is transmitted to man by a non human vector
What part of the history is important in arbovirus encephalitis
Travel history
Arborvirus encephalitis organisms are named dependant on where they were first described, name 5 arbovirus encephalitis
West Nile virus
St Louis Encephalitis
Western Equine
Encephalitis
Tick Borne Encephalitis
Japanese B Encephalitis
Define Brain abscess
localized area of pus within the brain
Define subdural empyema
thin layer of pus between the dura and arachnoid membranes over the surface of the brain
What is the symptoms of brain abscess
Fever
headache
Focal symptoms
Papilloedema
Depressed conscious level
Meningism
What symptoms are particulate present in empyema
Meningism
- neck stiffness, -photophobia,
- headache
What is the pathological affect of brain abscess and subdural empyemma
Raised intracranial pressure
What is the differential diagnosis of brain abscess and empyema
Any focal lesion - tumour
Subdural haematoma
What is the potential causes of brain abscess and empyema
Penetrating head injury
Spread from adjacent infection
Blood borne infection
e.g. Bacterial endocarditis
Neurosurgical procedure
How do you diagnose brain abscess and empyema
Imaging: CT or MRI
investigate source
blood cultures
Biopsy (drainage of pus)
What is the contradiction with taking a biopsy in brain abscess diagnosis
Depends where abscess is as brain stem has a higher threshold for taking biopsy compared to the periphery
What is the microbiology of brain abscess
Often a mixture of organisms present
Streptococci:
“strep milleri” group
Anerobes:
Bacteriodes, prevotella
What is the management of brain abscess
Surgical drainage
Antibiotics
What antibiotics are given in brain abscess based on the microbiology
Streps - penicillin or ceftriaxone
Anaerobes - metronidazole
High dose required for penetration
What gives a useful guid on how to manage brain abscess
Culture and sensitive tests on aspirate sample
What are three different forms of streptococci in the penicillin sensitive strep milleri group
Strep anginosus,
strep intermedius ,
strep constellatus
What is the characteristic of strep miller groups
Causes many abscess elsewhere
What are 8 examples of neurological illnesses that can result from HIV
Cerebral toxoplasmosis
Aseptic meningitis /encephalitis
Primary cerebral
lymphoma
Cerebral abscess
Cryptococcal meningitis
Space occupying lesion of unknown cause
Dementia
Leucoencephalopathy
What cells does the HIV virus affect, and what does this result in
HIV virus kills CD4 cells, this result in HIV patients becoming immunocompromised
What is the main cause of morality in HIV patients
Opturmistic infection on the immunocompromised patient
What are the brain infection that can occur in a HIV patient with low CD4 count
Cryptococcus neoformans
Toxoplasma gondii
Progressive multifocal leukoencephalopathy (PML)
Cytomegalovirus (CMV)
HIV-encephalopathy
What brain infections can lead to HIV associated dementia
HIV - encephalopathy
What is the diagnostic for infection in HIV patients
India Ink, cryptococcal antigen
Toxoplasmosis serology (IgG)
JC virus PCR
CMV PCR
HIV PCR
What is the JC virus an early indication of
Progressive leukoecnephalopathy
What is the main cause of cryptococcal infection
Cryptococcal neoformans (in soil and avian habitats) and rarely C.gatti (trees) Inhaled as airborne organisms (spores and yeast) into the lungs
What is the clinical presentation of cryptococcal infections
Patient present with Cryptococal Meninigencephalitis
Has defects in immune function
What is a major risk factor in cryptococcal infections
AIDS
How do you diagnose cryptococcal infections
Mucicarmine stain
-pink stained fungi
India ink stain
-add drop to CSF, blue stain to confirm the morphology
Name three spirochetes disease (spiral twisted bacteria) in the CNS
Lyme disease
Syphilis
Leptospirosis
What causes Lymes
The bacterial species borrelia burgdorferi which is found in ticks
How does lymes disease become a multi system disease
due to Skin, rheumatological, neurological / neuropsychiatric, cardiac and ophthalmological involvement
What can be seen in stage 1 lymes disease (
Early localised infection
Characterised by expanding rash at the site of the tick bite
Flu like symptoms
What occurs in stage 2 lymes disease
Early disseminated infection
One or more organ system become involved
Musculoskeletal and neurological involvement most common
How does lymes disease spread from stage 1 to stage 2
haematological or lymphatic spread
What does the neurological involvement of lymes disease potentially cause
Mononeuropathy
Mononeuritis multiplex (peripheral neuropathy)
Painful radiculoneuropathy
Cranial neuropathy
Myelitis
Meningo-encephalitis
What occurs in stage 3 lymes disease
Chronic infection
(months - years, or occurring after period of latency)
musckuloskeletal and further neurological involvement
does not cause chronic fatigue symptoms
What is the further neurological involvement in stage 3 lymes disease
Subacute encephalopathy
Encephalomyelitis
What is the overall investigations for Lymes disease
Complex range of serological tests
CSF lymphocytosis
PCR of CSF
MRI brain / spine (if CNS involvement)
Nerve conduction studies / EMG (if PNS involvement)
What is the treatment of lymes disease
Prolonged antibiotic treatment (3-4 weeks)
Intravenous cefrtriaxone
oral doxycycline
What cause syphilis
The spirochaete bacterium treponema pallidum
How many stage presentation does syphils have
Primary
Secondary
Latent /tertiary
When does syphilis become neurosyphilis
In the territory disease, years and decades later after primary disease
How do you diagnose syphilis
Serology-Treponema specific and non-treponemal specific (VDRL) antibody tests
PCR
What is indication of syphilis in testing
CSF lymphocytes increased
Evidence of intrathecal antibody production (CSF)
What is the treatment for syphilis
High dose penicillin
What is the cause of leptospirosis
The spirochaete bacterium leptospira interrogans
What is 3 important vaccines for the the nervous system
Polio immunisation
Rabies immunisation
Tetanus immunisation
What causes poliomyelitis
Poliovirus types 1,2 and 3 which are all enteroviruses
99% of poliovirus infections are asymptomatic, what happens in the 1%
Paralytic disease as affects the anterior horn cells of the lower motor neurones
What is the symptoms of poliomyelitis
Asymmetric
flaccid paralysis especially legs
no sensory features
What occurs in rabies, and how does it occur
Acute inflammation disease of CNS affecting almost all mammals, transmitted to human by bite or salivary contamination of open lesion
How is rabies a neurotropic virus
enters peripheral nerves and migrates to the CNS
What is the effect of rabies
Parathesia at site of original lesson
ascending paralysis and encephalitis
How do you diagnose rabies encephalitis
Culture
detection
serology
No useful diagnostic test before clinical disease is apparent
How do we prevent rabies
Rabies pre-exposure prevention through active immunisation with killed vaccine
Who is given rabies immunisation
bat handlers
regular handlers of imported animals
selected travellers to enzootic areas
What is the treatment of rabies post exposure
Wash wound
Give active rabies immunisation
Give human rabies immunoglobulin (passive immunisation) if high risk
What causes tetanus
Infection of clostridium tetani - an aerobic gram positive bacillus (spore forming) coming into contact with a wound
What is the pathology of tetanus
The bacterium releasing toxin at nerve-muscular junction blocking the inhibition of motor neurones
resulting in rigidity and spasms
How is tetanus prevented
Immunisation which contains toxoid and combined with other antigens (DTaP)
What is given to high risk wound/patients for prevention of tetanus
Penicillin and immunoglobulin
What causes botulism
Clostridium botulinum
an anaerobic spore producing gram postive bacillus naturally present in soil, dust and aquatic environment
What is the affect of clostridium botulinium
Is a neurotoxin
Binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions
and toxin binding blocks acetylcholine release
How does the nervous system recover form the neurotoxin affects of botulism
Recovery is by sprouting new axons
What is the three modes of infection from clostridium botulinum
Infantile (intestinal colonization)
Food-borne (outbreaks)
Wound: Almost exclusively
injecting or “popping” drug users
What is the symptoms of botulism
Descending symmetrical flaccid paralysis
Respiratory failure
Autonomic dysfunction
How do you diagnose botulism
Nerve conduction studies
Mouse neutralisation bioassay for toxin in blood
Culture from debrided wound
How long is the incubation period for botulism
4-14 days
What is the treatment for botulism
Anti-toxin (A,B,E)
Penicillin / Metronidazole (prolonged treatment)
Radical wound debridement
What is a post infective inflammatory syndrome of the CNS
Acute disseminated encephalomyelitis (ADEM)
- rare autoimmune disease marked by a sudden, widespread attack of inflammation in the brain and spinal cord (encephalitis)
What is a post infective inflammatory syndrome of the PNS
Gullian barre syndrome
-an acute autoimmune disorder of the peripheral nerves, often preceded by a respiratory infection, causing weakness and often paralysis of the limbs (radiculoneuropathy)
How does post infective inflammatory syndromes arise
Due to preceding infection (viral, bacterial) or through immunisation
causing a latent arrival between precipitating infections and onset of neurological symptoms due to autoimmune disorder
What is the cause of Creutzfeldt-Jakob Disease (CJD)
Prion - a transmissible proteinaceous particle
disease causing small infectious particle
What is the aetiology of Creutzfeldt-Jakob Disease (CJD) prion
Sporadic CJD
New variant CJD
Familial CJD (10-15%)
Acquired CJD (<5%)
What aetiology of CJD is considered in rapid progressive dementia
Sporadic CJD
What is the clinical presentation of sporadic CJD
Insidious onset - gradual with detrimental affects
Early behavioural abnormalities
Rapidly progressive dementia
Myoclonus
Progressing to global neurological decline
Motor abnormalities
cortical blindness
seizures
What is the motor abnormalities seen in CJD
Cerebellar ataxia - loss of movement
Extrapyramidal:
tremor, rigidity, bradykinesis, dystonia
Pyramidal: weakness, spacticity, hyper-refexia
What is a differential diagnosis to sporadic CJD
Alzheimer’s disease with myoclonus
Subacute sclerosing panencephalitis (SSPE)
(Very rare, chronic infection with defective measles virus)
CNS vasculitis
Inflammatory encephalopathies
What is the difference between sporadic CJD and Alzheimer’s
Alzheimers us usually more prolonged
What is the prognosis of sporadic CJD
Rapid progression
Death often within 6 months
When is usually the onset for sporadic CJD
Over 60 years
What is the difference between new variant CJD and sporadic CJD
New variant CJD has younger onset (<40 years)
early behavioural changes more prominent
Longer prognosis course - average 13 months
may be genetically susceptibility
What is new variant CJD linked to
Bovine spongiform encephalopathy in cattle
- eating this infected material
What is the investigations for CJD
MRI
EEG
CSF
What can be seen in a MRI of CJD
Pulvinar sign in variant CJD
Often no specific changes
in sporadic CJD
What is typical in an EEG of CJD
Generalised periodic
complexes
Often normal / non-specific in initial stages
What can be seen in a CSF sample of CJD
Normal or raised protein
Immunoassay 14-
3-3 brain protein (non-specific, but very helpful in correct clinical context)
How does acquired CJD arise
- Cadeveric Growth Hormone
- Dura matter grafts
- Blood transfusion
