Infections of the Nervous System Flashcards by Erin Sanderson

What is meningitis?

Inflammation/infection of the meninges

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What is encephalitis?

Inflammation/infection of brain substance

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What is myelitis?

Inflammation/infection of the spinal cord

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What is the classic triad of meningitis?

Fever
Neck Stiffness
Headache

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What are the classic signs of meningitis?

Fever 
Neck stiffness
Photophobia 
Nausea 
Vomiting 
Headache

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How is neck stiffness examined?

By passively bending the neck forward

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Describe GCS in meningitis patients

Often a little lower than normal

<14 in 69%

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What type of rash is seen in meningitis?

Petechial rash

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What test should be done on a petechial skin rash in suspected meningitis?

Tumbler test

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What is non-blanching petechial skin rash a hallmark sign of?

Meningococcal meningitis

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What are the common bacterial causes of meningitis?

Neisseria meningititis (meningococcus)

- Streptococcus pneumoniae (pneumococcus)

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What do viral causes of meningitis include?

Enterioviruses

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What are the clinical features of encephalitis?

Flu like prodrome 
Progressive headaches with fever
\+/- meningism 
Cerebral dysfunction 
Altered brain function - confusion, abnormal behaviour, memory disturbance, depressed conscious level 
Seizures 
Focal symptoms

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What is a distinguishing feature between encephalitis and meningitis?

Onset of encephalitis is generally slower than for bacterial meningitis and cerebral dysfunction is a more prominent feauture

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What investigations should be carried out for meningitis?

Blood cultures
Lumbar puncture
No need for imaging if no contraindications to LP

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What investigations should be carried out for encephalitis?

Blood cultures
Imaging (CT scan+/- MRI)
LP
EEG

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What are the contraindications for a lumbar puncture?

Focal symptoms or signs that suggest a focal brain mass
Reduced conscious levels suggesting raised ICP
GCS <10
Severely immunocompromised state
New onset seizures

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What is opening pressure?

The pressure of CSF that is detected just after a needle is placed into the spinal canal

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Describe opening pressure in meningitis and encephalitis

Meningitis - increased

Encephalitis - normal/increased

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Describe cell count in meningitis and encephalitis

Meningitis - high, mainly neutrophils

Encephalitis - high, mainly lymphocytes

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Describe glucose in meningitis and encephalitis

Meningitis - reduced

Encephalitis - normal

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Why is glucose reduced in meningitis?

Because the bacteria consume the glucose 1

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What do you have to do when testing glucose in encephalitis and meningitis?

Have to take a 3rd blood sample to compare to the red of the body cannot compare to a ‘normal’ figure

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What is the first line of treatment in suspected meningitis?

IV ceftriaxone

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What should you do if the patient is presenting clinically septic or pyrexial?

Do a LP | But do not do a blood culture

What is the commonest cause of encephalitis in europe?

Herpex simplex encephalitis

What investigation should you do for HSV encephalitis?

What is the lab diagnosis for HSV encephalitis?

PCR of CSF for viral DNA

What is the Rx for HSV encephalitis?

AciclovirIV

When should aciclovir be given in HSV encephalitis?

On clinical suspicion - don't wait for lab confirmation

What general things does herpes simplex cause?

Cold sores | Genital herpes

Where does herpes simplex virus lay dormant?

Dorsal route ganglion

What type of HSV causes encephalitis?

Nearly all caused by type 1 other than in neonates

What common virus can encephalitis be a rare complication of?

HSV

What is meant by neurotropic?

a virus, toxin, or chemical) tending to attack or affect the nervous system preferentially.

What do enteroviruses tend to attack?

Nervous system

How are enteroviruses spread?

Faecal-oral route

What are examples of enteroviruses?

Polioviruses, coxsackieviruses, echoviruses

What is a brain abscess?

Localised area 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

How does subdural empyema present?

With a high pressure headachw

What can be the features of an underlying source of subdural empyema?

Dental, sinus or ear infection

What are the differential diagnosis for brain abscess?

An focal lesion More commonly a tumour Subdural haeatoma

What are the causes for brain abscess and empyema?

Penetrating head injury Spread from adjacent infection (dental, sinusitis, otitis media) Blood borne infection Neurosurgical procedure

How is diagnosis for brain abscess and empyema made?

CT or MRI Investigating source Blood cultures Biopsy

What is the most common organisms present in a brain abscess?

Often a mixture of organisms present | Streptococci in 70% of cases

What is the management of brain abscess?

Surgical drainage if possible | Penicillin of ceftriaxone AB

Why are HIV positive patients susceptible to infection?

Because their immune system is compromised

What is the suspicion when a patient presents with cerebral toxoplasmosis?

That they have HIV

What is the most common cause of brain abscess in patients with HIV?

Cerebral toxoplasmosis

What is the diagnosis for HIV brain infection?

What does toxoplasmosis serology IgG suggest?

Past infection

What does toxoplasmosis serology IgE suggest?

Acute infection

What does borrelia burgoferi cause?

Lyme disease

Which organisms causes syphilis?

Trepomena pallidum

What is the vector for lyme disease?

Tick

What are the 3 spirochaetes in the CNS?

Lyme Disease (Borrelia burgorferi) Syphilis (Trepomena pallidum) Leptospirosis (Leptospira interrogans)

Describe stage 1 of lyme disease?

``` Early localised infection Characteristic rash at the site of the tick bite 50% flu like symptoms fatigue myalgia Arthralgia Headache Fever Chills Neck stiffness ```

Describe stage 2 of lyme disease infection

Early disseminated infection (weeks – months) One or more organ systems become involved Haematologic or lymphatic spread Musculoskeletal and neurologic involvement most common

Describe stage 3 lyme disease

``` Chronic infection Occurring after a period of latency Musculoskeletal and neurological involvement most common Subacute encephalopathy Encephalomyelitis ```

Does lyme disease cause chronic fatigue syndrome?

What s the investigation for lyme disease?

``` Complex range of serology tests CSF lymphocytosis PCR of CSF MRI brain/spine Nerve conduction studies EMG if there is PNS involvement ```

What is the treatment for lyme disease?

Prolonged AB treatment IV ceftriaxone Oral doxycycline

What are the 3 stages of neurosyphilis?

Primary Secondary Latent

In which stage of neurosyphilis is there neuro involvement?

Tertiary

How is neurosyphilis diagnosed?

Serology

Which antibody tests should be carried out for neurosyphilis?

Treponema - specific | Non specific treponemal

What is the treatment for neurosyphilis?

High dose penicillin

What type of virus are poliovirus?

Enterovirus

What are the 3 types of poliovirus?

Types 1,2,3

Where does poliovirus infect in poliomyelitis?

Anterior horn cells of lower motor neurons

What are the motor features of poliomyelitis?

Asymmetric, flaccid paralysis esp in the legs

What % of polio viruses are asymptomatic?

99%

What are the sensory features of poliomyelitis?

No sensory features

What does the polio vaccination contain?

All 3 types of polio

What is rabies?

Acute infectious disease of CNS affecting almost all mammals

How is rabies transmitted?

By bite or salivary contamination of open lesions

What type of virus is rabies?

Neurotropic

How does the rabies virus progress?

Enters PNS and migrates to CNS

What are the symptoms of rabies?

Paraesthesiae at the site of origin | Ascending paralysis and encephalitis

Who is at risk of rabies in the UK?

Bat handlers

How is rabies diagnosed?

Culture Detection Serology

What are important sources of human infection of rabies?

Dogs in africa/asia

What is pre-exposure prevention of rabies?

Active immunisation with killed vaccine

What is the post-exposure treatment for rabies?

Wash wound Give active rabies immunisation Give human rabies immunoglobulin if high risk

What is tetanus infection with?

Clostridium tetanis

Where do toxins in tetanus act?

The the neuromuscular junction

How do toxins in tetanus affect the neuro-muscular junction?

Blocks the inhibition of motor neurons | Keep firing

What is the signs of tetanus

Rigidity and spasms

How is tetanus prevented?

Immunisation

Which organisms causes botulism?

Clostridium botulinum

How does botulism act as a neurotoxin?

Binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions Toxin binding blocks Ach release

How is there recovery from botulism?

Sprouting new axons

What is the clinical presentation of botulism?

Incubation period of 4-14 days Descending symmetrical flaccid paralysis Pure motor Respiratory failure Autonomic dysfunction (usually pupil dilation)

What is the diagnosis for botulism?

Nerve conduction studies | Culture from debrided wound

What is the treatment for botulism?

anti-toxin (A,B,E) Penicillin Radical wound debridement

What is CJD?

rare, degenerative, invariably fatal brain disorder.

Forms of CJD

Sporadic New variant Familial CJD Acquired

Who should sporadic CJD be considered in?

Rapidly progressing dementia

What are the clinical features of sporadic CJD?

Insidious onset Early behavioural abnormalities Rapidly progressing dementia Myoclonus

What signs suggest global neurological decline in CJD?

``` Motor abnormalities Cerebellar ataxia Extrapyramidal: tremor, rigidity, bradykinesis, dystoinia Pyramidal: weakness, spaciticity Cortical blindness Seizures may occur ```

What is the progression for sporadic CJD?

Rapid progression | Death often within 6 months

What is the onset age for new variant CJD?

<40 | Younger onset

What are the investigations for new variant CJD?

MRI EEG CSF

What can be seen in MRI in new onset CJD?

Pulvinar sign

What can be seen on MRI in sporadic CJD?

Often no specific changes are seen

What is seen on CSF in new variant CJD?

normal or raised protein

What is the most common form of CJD?

Sporadic

What protein can be detected in CJD that is not specific but is very helpful in correct clinical context of CJD?

Immunoassay 14-3-3 brain protein

What is the treatment for CJD?

There is no treatment that can control or cure CJD

What is there an infiltration of in CJD?

Prions

Infections of the Nervous System Flashcards

(111 cards)