Infections of the Nervous System Flashcards
Meningitis?
Inflammation of meninges
Encephalitis?
Inflammation/infection of brain substance
Myelitis?
Inflammation/infection of spina cord
What is the classical triad of symptoms for meningitis?
Fever, neck stiffness, altered mental state
Meningtism?
Clinical syndrome of neck stiffness, photophobia, nausea and vomiting
The conscious state can be measured using the Glasgow Coma Scale.
In those with meningitis, what is the GCS usually?
<14
What else can occur in those with meningitis?
Cranial nerve palsies
Seizures
Focal neurological deficits
What is a hallmark of meningococcal meningitis?
Non-blanching skin rash
->may occur in viral meningitis so not completely specific to bacterial
Name three causes of infective meningitis.
Bacteria
Virus
Fungus
Name a cause of inflammatory meningitis.
Sarcoidosis
Name a cause of drug induced meningitis.
NSAIDs
IVIG
What are some malignant causes of meningitis?
Metastasis
Name the two bacterial which can cause bacterial meningitis.
Neisseria meningitidis
Streptococcus pneumoniae
What are the viral causes of meningitis?
Enteroviruses
What usually occurs 4-10 days before neurological features of encephalitis start to occur?
Flu-like illness
In encephalitis, which symptoms occur after the flu-like illness?
Progressive headache
Fever
Progressive cerebral dysfunction
Seizures
Focal symptoms
List some of the aspects of the altered cerebral dysfunction seen in those with encephalitis.
Confusion
Abnormal behaviour
Memory disturbance
Depressed conscious level
Which has a slower onset; meningitis or encephalitis?
Encephalitis
What is the infective cause of encephalitis?
Viral, most commonly HSV (herpes simplex virus).
What are some inflammatory causes of encepalitis?
Limbic encephalitis
ADEM
What are some of the metabolic causes of encephalitis?
Hepatic cause
Uraemic cause
Hyperglycaemic cause
What are some malignant causes of encephalitis?
Metastatic
Parneoplastic
What other issue can present like encephalitis?
Migraine
-> patient is less unwell though and the migraine will usually resolve by itself.
Name the two types of auto-immune encephalitis.
Anti-VGKC (voltage gated potassium channel)
Anti-NDMA receptor
What would be seen in a patient with Anti-VGKC autoimmune encephalitis?
Frequent seizures
Amnesia
Altered mental state
What would be seen in a patient with Anti-NMDA receptor autoimmune encephalitis?
Flu like illness
Prominent psychiatric features
Altered mental state and seizures
What could Anti-NMDA receptor autoimmune encephalitis lead to?
Movement disorder and coma
Which investigations are required in meningitis?
Blood cultures
Lumbar puncture
Which investigations are required in encephalitis?
Blood cultures
Imaging (CT +/-MRI)
Lumbar puncture
EEG
Why is imaging carried out before a lumbar puncture in encephalitis?
To ensure there is no contraindication for carrying out the lumbar puncture
What would be a contraindication to a lumber puncture?
Swelling/mass in the brain
What would focal symptoms or signs suggest?
A focal brain mass
What would a reduced conscious level suggest about ICP?
Raised intracranial pressure
Which circumstances would a CT scan be required before carrying out a lumbar puncture?
Seizures
Abnormal conscious state
Papilledema
In the sample of CSF taken in a lumbar puncture, what would be the predominant type of cells found within it if the patient had bacterial meningitis?
Neutrophils
In the sample of CSF taken in a lumbar puncture, what would be the predominant type of cells found within it if the patient had viral meningitis/encephalitis?
Mainly lymphocytes
What would the glucose levels be like in a sample of CSF of a patient with bacterial meningitis?
Reduced glucose
What would the glucose levels be like in a sample of CSF of a patient with viral meningitis or encephalitis?
Normal
What would the protein levels be like in a sample of CSF of a patient with bacterial meningitis?
High
What would the protein levels be like in a sample of CSF of a patient with viral meningitis or encephalitis?
Slightly increased
Why are neutrophils higher in bacterial infections?
Neutrophils fight bacterial infections
Polymorths?
Neutrophils
->these can be used interchangeably
Monocytes?
Lymphocytes
->these can be used interchangeably
What is the most common cause of encephalitis in Europe?
Herpes Simplex Virus
How is herpes simplex encephalitis diagnosed in a lab?
PCR of CSF
What is the treatment for herpes simplex encephalitis?
Aciclovir
->if suspicious, prescribe this, it can be stopped if you get lab results confirming diagnosis of something else
Herpes simplex is one of the herpes viruses. Name some others.
Varicella zoster virus
Epstein-Barr virus
There is type one and two or herpes simplex virus. Which type do more people come into contact with?
Type 1 herpes simplex
What can type 1 herpes simplex virus cause?
Cold sores
Can herpes virus be treated?
No, lies latent in body for the rest of life
What can type 2 herpes simplex cause?
Genital herpes
->can also be caused by type one but type two is more common
Enteroviruses are a large family of RNA viruses which can cause CNS infections. How are they spread?
Faecal-oral route
Give some examples of enteroviruses.
Poliovirus
Coxsachievirus
Echovirus
How are arbovirus encephalititides, a cause of encephalitis, spread?
Transmitted to man by a vector e.g. mosquito or tick
Which type of history is especially important in terms of arbovirus encephalitides?
Travel history
What is a brain abscess?
A localised collection of pus within the brain
What is a subdural empyema?
Thin layer of pus between the dura and arachnoid membranes over the surface of the brain
What are the clinical features of a brain abscess/ subdural empyema?
Fever
Headache
Raised intracranial pressure
Meningism, especially in empyema
What are some signs of raised intracranial pressure?
Papilloedema
Depressed conscious level
What is the differential diagnosis for brain abscess and empyema?
Any focal lesion, commonly a tumour
Subdural haematoma
What are some causes of a brain abscess/empyema?
Penetrating head injury
Spread from adjacent infection
Blood borne infection
Neurosurgical procedure
What can be used for the diagnosis of brain abscess and empyema?
Imaging- CT or MRI
Blood cultures
Biopsy- drainage of pus
->MRI will be a lot better quality and give more information but CT usually initial investigation
Brain abscesses can be polymicrobial, meaning there are many different microorganisms present in the pus sample.
Which microorganism is commonly found?
Streptococci- particularly penicillin-sensitive Strep.milleri group
What is the management of a brain abscess?
Surgical drainage of pus if possible
Antibiotics to cover strep. bacteria
Which antibiotics may be given?
Penicillin or ceftriaxone to cover strep. bacteria
Metronidazole for anaerobes
Which antibiotic would be used the target organism is not known?
Ceftriaxone
Which system does HIV affect?
Immune system
Spirochaetes in the CNS can cause infection.
They are not seen on staining or bacterial cultures.
Give some examples of spirochaete caused conditions.
Lyme disease
Syphilis
Leptospiroisis
Which species causes Lyme disease?
Borrelia burgdorferi
Which species causes syphilis?
Treponema pallidum
Which species causes laptospirosis?
Leptospira interrogans
Ticks are the vectors for lyme disease. In which type of conditions are ticks more prominent?
Wooded areas
There are three stages of Lyme’s disease. What happens in stage one?
-Target rash expanding from site of tick bite
-50% get flu like symptoms within the first week (fever, chills, headache, neck stiffness, fatigue).
There are three stages of Lyme’s disease. What happens in stage two?
Spreads to affect other organ systems
Which organ systems are most commonly affected by Lyme’s Disease?
Musculoskeletal and neurological
In Lyme’s disease, if there is neurological involvement, is it more likely to be in the CNS or PNS?
PNS
There are three stages of Lyme’s disease. What happens in stage three?
Chronic infection which can last years
Occurs after a period of latency
Again, musculoskeletal and neurological involvement most common
List some of the potential neurological involvement in stage 2 of Lyme’s disease.
Mononeuropathy
Myelitis
Meningo-encephalitis
Cranial neuropathy
What are the investigations used in the diagnosis of Lyme’s disease?
Complex serology
CSF lymphocytosis
MRI brain/spine if CNS involvement
Nerve conduction studies if PNS involvement
What is the treatment for Lyme’s disease?
Prolonged antibiotic treatment -> oral doxycycline and IV ceftriaxone
Neurosyphilis also has three stages of presentation.
How long does it take for the tertiary stage of the disease take to occur after the primary infection?
Years/decades
What is the treatment for neurosyphilis?
High dose penicillin
Which type of cells would be increased in CSF of someone with neurosyphilis?
Lymphocytes
Polio is a virus which affects the CNS. What causes polio?
Polio virus type 1, 2 or 3.
All three types are nerteroviruses
What is a rare complication of polio and why does it happen?
Paralytic disease can occur in <1% of those with polio as infects the anterior horn cells of LMN
What are the symptoms for the majority of individuals with polio?
Asymptomatic in 99%
What is rabies?
Acute infectious disease of the CNS affecting almost all mammals
How is rabies transmitted?
By bite or salivary contamination of open lesion
What are the initial signs of rabies?
Paraesthesia at site of original lesion
What can rabies go on to cause?
Ascending paralysis
Encephalitis
Which investigations are used for the diagnosis of rabies?
PCR and serology
What are the most common sources of rabies virus?
Dogs in Africa/Asia
Bats in developed world
What is the rabies post-exposure treatment?
Wash wound
Give active rabies immunisation
Give human rabies immunoglobulin immunisation if high risk
Which microorganism causes tetanus?
Clostridium tetani
Tetanus does not cause a wound but the microorganism releases a toxin. Where does this toxin act upon and what does it do?
Neuro-muscular junction- blocks inhibition of motor neurons.
When the toxin blocks the inhibition of motor neurons, what can this cause?
Muscle rigidity and spasm
What is used in the prevention of tetanus?
Immunisation
Given with other antigens e.g. DTaP
->penicillin and immunoglobulins given for high risk wounds/patients
Botulism is a rare but serious illness causing breathing difficulty, muscle paralysis and even death.
Which microorganism causes it?
Clostridium botulinium
What dos the neurotoxin do in botulism?
Binds irreversibly to presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions.
This blocks the release of acetylcholine
Where is Clostridium botulinum naturally present?
Soil, dust, aquatic environments
Name the three modes of infection of botulism.
Infantile via intestinal colonisation
Food-borne
Wound, usually by injection in IVDU
In Botulism, there is an initial incubation period for 14 days. Describe the clinical presentation after this incubation period.
Descending symmetrical flaccid paralysis
Resp. failure
Autonomic dysfunction, usually pupil dilation
Which investigations can be used in the diagnosis of botulism?
Nerve conduction studies
Culture from debrided wound (dead tissue)
What is the treatment of botulism?
Anti-toxin A, B, E
Prolonged treatment of penicillin/metronidazole
Radical wound debridement (process of removing dead tissue from a wound)
Which type of microorganism causes Creutzfeldt-Jakob Disease?
Prions
There are many different types of CJD. How does sporadic CJD present?
Early behavioural abnormalities
Rapidly progressive dementia
Myoclonus (sudden, brief involuntary movement)
Motor abnormalities
Cortical blindness
Seizures may occur
When should sporadic CJD be considered?
In rapidly progressing dementia
What are some of the differential diagnosis’s for sporadic CJD?
Alzheimer’s with myoclonus
Subacute sclerotising panencephalitis
CNS vasculitis
Inflammatory encephalopathies
What is the prognosis of sporadic CJD like?
Rapid progression, death often within 6 months
When is new variant CJD linked to?
Ingestion of infected meat
->e.g. mad cow disease, eating beef after that was a bit more risky
Which investigations are looked at in CJD?
MRI
EEG
CSF
