Infections Flashcards
What is prion disease
Group of neurodegenerative diseases caused by prions which accumulate and damage nerve cells
What is the most common prion disease
CJD
What causes CJD
Sporadic - protein -> prion
New variant - consuming meat from cow with bovine spongiform encephalopathy
Familial - genetic
Acquired - infection
How does sporadic present
Rapidly progressive dementia Myoclonic jerks >60 Behaviour abnormality Cerebellar ataxia Parkinsonism - Tremor / rigid / bradykinesia Weakness Hyperreflexia / UMN sign Seizure Blidness
What is prognosis
Death in 6 months
13 if new variant
How does new variant present
Younger onset
Early behaviour change
Anxiety / withdrawal / dysphonia
Better prognosis
How do you Dx
MRI = hyperextense
EEG
CSF = usually normal
Immunoassay for brain protein
How do you Rx
No treatment currently
What are differentials
Viral encephalitis PML HIV dementia Lyme's / neurosyphillis Whipple's Alzheimer's Lewybody Tumour
What is Reye’s
Fatty infiltration of liver, pancreas, kidney and brain
What causes Reye’s
Post viral infection
Aspirin use
Common in children
What are the symptoms
Severe progressive encephalopathy Confusion Seizures N+V Cerebral oedema Coma Abnormal LFT Hypoglycaemia
How do you treat
Supportive
What are other rare infections in brain / affect nerves
Poliomyelitis Lyme's Neurosyphillis Rabies Tetanus Botulism
What does poliovirus 1,2,3 (enterovirus) cause and where does it affect
Poliomyelitis
Affects anterior horn cell to affect LMN
How do you prevent
Vaccine
What happens in rabies
Humans bitten by infected animal
Virus enters PNS
Migrates to CNS
What does it cause
Ascending paralysis
Paraesthesia
Encephalitis
How do you Dx
Nerve conduction
Culture of wound
Serology
How do you Rx
Immunisation killed vaccine if high risk area before travel
If bitten Clean and disinfect wound Immunisation active vaccine to boost Human rabies Ig Consider Ax
What causes tetanus
Clostridium tetani Anaerobic gram +ve Toxin acts at TMJ and blocks inhibition of motor neurones Prevents release of GABA Present in soil and can enter body
How does it present
Fever Lethargy Hedache Trismus - locked jaw Spasms Rigidity Arched back and hyperextended neck Dysphagia due to spasm
How do you prevent
Immunisation x5
Penicillin and Ig if high risk wounds
How do you treat
Ventilatory support
Muscle relaxant
IM Ig for high risk wounds
Metronidazole
What causes botulism
Clostrodium botulinum
Anaerobic gram +Ve
Binds to pre-synaptic membranes of peripheral NMJ
Block Ach release
What are symptoms
Flaccid paralysis Resp failure Autonomic dysfunction - Urinary retention - Dry mouth - Dilated fixed pupils Diplopia Ataxia Bulbar palsy - Dysphagia - Dysphonia
How do you Dx botulism / tetanus
Nerve conduction
Wound culture
Mouse neutralisation bioassay
How do you treat
Anti-toxin ABE
Prolonged penicillin
Wound debridement
What are considered high risk tetanus wound requiring prophylaxis with IM Ig + muscle relxant
Burns requiring surgery >6 hour wait Soil containation FB Compound fracture Systemic sepsis
Meningitis and encephalitis
See infection
What is most common cause of encephalitis
Viral
- HSV / VZV
What is another cause
Autoimmune
What are general encephalitis features
Fever Altered mental status Seizure Flu like prodrome Meningitis can become
How do you Dx and Rx
CT head
MRI
LP if no focal
Rx
- Aciclovir
- Anticonvulsant
What does HSV cause
Temporal lobe change and multi-focal haemorrhage
How does autoimmune present
Confusion Siezure Movement disorder Psychosis Cognitive change Low GCS Often fluctuating
Increasingly recognised as acute / subacute mental status change in the young
How do you Dx
Ab
- NMDA receptor Ab
- Voltage gated K channel (low Na)
- Anti-Hu
MRI head
EEG
PET CT
What is important to do in autoimmune
Cancer screen as can be parenoplatic - PET CT
Ovarian = NMDA
SCLC = anti-Hu
How do you Rx
Steroid
IV Ig if required
