Infection of the nervous system Flashcards
What is encephalitis?
Encephalitis means acute inflammation of brain parenchyma, usually viral
What is the most common cause of encephalitis?
Viral
What are viral causes of encephalitis?
- HSV 1 + 2
- Arbovirus
- CMV
- EBV
- VZV
- HIV
- Measles
- Mumps
- Rabies
- West nile virus
- Tick-borne encephalitis
What are non-viral causes of encephalitis?
- Any bacterial meningitis
- TB
- Malaria
- Listeria
- Lyme disease
- Legionella
- Leptospirosis
- Aspergillosis
- Crytococcus
- Schistosomiasis
- Typhus
What would be your differential diagnosis for someone with features of encephalitis?
If no infectious prodrome, think encephalopathy
- Hypoglycaemia
- Hepatic encephalopathy
- Diabetic ketoacidosis
- Drugs
- Hypoxic brain injury
- Uraemia
- SLE
- Wernicke’s encephalopathy
What are autoimmune causes of encephalitis?
Limbic encephalites
- Paraneoplastic limbic encephalitis
- Voltage gated potassium channel limbic encephalitis
- Anti-NMDA receptor antiobody panencephalitis
What are signs and symptoms of encephalitis?
- Bizarre encephalopathic behaviour or confusion
- Decreased GCS/Coma
- Fever
- Headache
- Focal neurological signs
- Seizures
When should you suspect encephalitis?
Whenever someone presents with odd behaviour, decreased consciousness focal neurology or seizure which was preceded by an infectious prodrome
What kind of infectious prodromes would you want to find out about in someone presenting with features of encephalitis?
- Pyrexia
- Rash
- Lymphadenopathy
- Cold sores
- Conjunctivitis
- Meningeal signs
What might cold sore indicate about the cause of a presentation of encephalitis?
Caused by Herpes Simplex virus
What might parotid gland swelling indicate as to the cause of encephalitis?
Caused by mumps
What might be the cause of someone presenting with features of encephalitis, hydrophobia, delusions, hallucinations and anxiety?
Rabies
What investigations would you consider doing in someone with features of encephalitis?
- Bloods - Blood cultures, Viral PCR, Malaria film, Toxoplasma IgM titre, HIV test, Mantoux test
- Contrast enhanced CT
- LP
- EEG
In someone with features of encephalitis, what would focal bilateral temproal lobe involvement on Contrast-enhanced CT indicate ?
HSV encephalitis
What would meningeal enhancement on contrast-enhanced CT suggest in someone with features of encephalitis?
Meningeal involvemnent
What should you do before doing an LP?
CT scan to rule out coning
What are features seen on LP in someone with encephalitis?
- Increased CSF protein
- Increased lymphocytes
- Decreased glucose
What is important to remember when interpreting LP CSF results for someone with suspected encephalitis?
Normal CSF does not exclude ecnephalitis
How would you manage someone with encephalitis?
- Start aciclovir within 30 mins arrival
- Supportive therapy in HDU
- Anticonvulsants for seizures
- Dexamethaose - if raised ICP
What is mortality rate in untreated encephalitis?
70%
What is the mortality rate in treated encephalitis?
10-30%
What are causes of a cerebral abscess?
- Ear/Sinus/dental/peridontal infection
- Skull fracture
- Congenital heart disease
- Endocarditis
- Bronchiectasis
What are the typical causative bacteria implicated in brain abscesses?
- Staph. angiosus (sinus/teeth)
- Bacteriodes (sinus/teeth)
- Staphylococci (penetrating trauma)
What are symptoms of a brain abscess?
- Dull persistent headache
- Symptoms of raised intracranial pressure (e.g., vomiting, papilledema, altered mental status)
- Focal neurological deficits
- Fever
- Generalized or focal seizures
What are signs seen in someone with a cerebral abscess?
- Decreased GCS/Coma
- Signs of sepsis elsewhere
- Fever
- Focal neruology
- Signs of increased ICP
- Meningism may be present
What investigations might you consider doing in someone with a cerebral abscess?
- CT/MRI
- Bloods - FBC, ESR
- Biopsy
What might you see on FBC in someone with a cerebral abscess?
Increased WCC
What might you see on investigation of ESR in someone with a cerebral abscess?
Raised ESR
How would you manage someone with a cerebral abscess?
Urgent neurosurgical referral
- Treat ICP
- High dose ABx - 6-8 weeks
- Surgical resection/decompression
What dose of aciclovir would you start someone on if they presented with encephalitis?
IV acicolvir 10mg/kg 8 hrly for 14-21 days
What antibiotics would you use to treat a cerebral abscess?
- Penicillin/ceftraixone - cover streps
- Metranidazole - anaerobes
What is the morality rate in those with a cerebral abscess?
Treated - 25%
What cerebral problems can occur in those with HIV infection?
- Cerebral toxoplasmosis
- Aseptic meningitis/encephalitis
- Primary cerebral lymphoma
- Cerebral abscess
- Cryptococcal meningitis
- SOL of unkown cause
- Dementia
- Leucoencephalopathy
What infectious organisms can infect the CNS in those with chronic HIV infection?
- Cryptococcus neoformans
- Toxoplasma gondii
- Cytomegalovirus
What is acute disseminated encephalomyelitis?
A rare autoimmune disease marked by a sudden, widespread attack of inflammation in the brain and spinal cord that often follows many types of infection (measles, mycoplasma, mumps, rubella). As well as causing the brain and spinal cord to become inflamed, ADEM also attacks the nerves of the central nervous system and damages their myelin insulation, which, as a result, destroys the white matter.
What are neurological manifestations of lyme disease?
- Mononeuropathy
- Mononeuritis multiplex
- Painful radiculopathy
- Cranial neuropathy
- Myelitis
- Meningoencephalitis
- Encephalomyelitis
What are the main forms of neurosyphillis?
- Asymptomatic neurosyphillis
- Meningovascular syphillis
- Tabes dorsalis
- General paralysis of the insane
What is Meningovascular Neurosyphillis?
Syphillitic infection which causes:
- Subacute meningitis with cranial nerve palsies and papilloedema
- A gumma – a chronic expanding intracranial mass
- Paraparesis – a spinal meningovasculitis.
What is asymptomatic neurosyphillis?
Neurosyphillis with positive CSF but no neurological signs
What is tabes dorslis?
Demyelination in dorsal roots causes a complex deafferentation syndrome. The elements of tabes:
- Lightning pains
- Ataxia, stamping gait, reflex/sensory loss, wasting
- Neuropathic (Charcot) joints
- Argyll Robertson pupils
- Ptosis and optic atrophy
What is general paralysis of the insane?
Dementia and weakness associated with neurosyphillis, in addition to:
- Seizures
- Brisk reflexes
- Extensor plantar reflexes
- Tremor
- Argyll-Robertson pupils
How would you manage someone with neurosyphillis?
Benzylpenicillin
What are features of Sporadic/Variant CJD?
- Rapidly progressive dementia with early behavioural abnormalities
- Myoclonus
- Cerebellar ataxia
- Extrapyramidal and pyramidal signs
- Cortical blindness
- Seizures
What is variant CJD linked to?
Bovine spungiform encephalopathy
What is the following?
Cerebral abscess
