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 (japanese encephalitis)
- 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
- Taoxoplasmosis gondii (AIDS)
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?
- (Infectious prodome - fever, rash, lymphadenopathy, cold osres, conjunctivitis, meningeal signs)
- Bizarre encephalopathic behaviour or confusion
- Decreased GCS/Coma
- Fever
- Headache
- Focal neurological signs
- Seizures
- Meningitsm - fever, headache, drowsiness
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
How can rabies present?
Features of encephalitis, hydrophobia (water provoked muscle spasms), delusions, hallucinations and anxiety
Acending paralysis of the limbs
Parasthesia at site of lesion
Rabies pre-exposure prevntion
+
Rabies post-exposure treatment
Active immunisation
Wash wound, active rabies immunisation, human rabies immunoglobulin (passive immunisation)
What investigations would you consider doing in someone with features of encephalitis?
-
Bloods
- FBC - reduced WBC (immunopcompromsised)
- U+Es
- Clotting screen
- Septic screen + Blood cultures
- Blood cultures, Viral PCR, Malaria film, Toxoplasma IgM titre, HIV test, Mantoux test
- CXR - TB?
-
Contrast enhanced CT brain
- Focal bilateral temporal lobe involvement is suggesive of HSV encephalitis (areas of oedema)
-
LP
- Obvs CT first
- Send CSF for PCR for HSV (PCR is 95% specific for HSV1)
-
EEG
- Non specific slow wave activity
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
- Oxygen, IV fluids, steroids, phenytoin (for seizures)
- 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%
Whats the difference between a brain abscess and brain empyema?
Abscess - localised area of pus in brain
Brain empyema - thin layer of pus between dura and arachnoid membrains
What are causes of a cerebral abscess?
Direct spread =75%
Haematogenous spread =25%
- Ear/Sinus/dental/peridontal infection
- Skull fracture
- Congenital heart disease
- Endocarditis (blood borne)
- Bronchiectasis
What are the typical causative bacteria implicated in brain abscesses?
- Strep anginosss (sinus/teeth)
- Bacteriodes (sinus/teeth)
- Staphylococci (penetrating trauma)
What are symptoms of a brain abscess?
- Headache - worse on bending over/lying down
- Fever
- Generally unwell
- Seizures
- Signs of raised ICP
- Features of underlying source - dental, sinus, infection
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
LP NOT PERFORMED DUE TO DANGER OF CONING - Bloods - FBC, ESR
- Biopsy (aspiration)
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
- Penicillin or cefriaxone (cover strep)
- Metronidazole (for anaerobes)
- 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 organism causes neurosyphillis
Treponema Pallidum
Describe presentation of primary neurosyphillus
PRIMARY:
- Macule at site of secual contact
- Ulcerates and becomes a painless firm chancre
- Any urogenitcal ulcer or sole is syphillus until proven otherwise
Describe presentation of secondary neurosyphillus
SECONDARY
- After 6 weeks (6 weeks-6 months) post infection appearance of lesion
- Constitutional symptoms (eg fever, sore throat and arthralgia), generalised lymphadenopathy, rash (exceept face), ulcers on mouth and on genetalia (nsal-track ulcers) and condylomata lata (warty perennial lesions) man sites affected (hepatitis, arthritis, menignitis)
Describe presentation of teritary neurosyphillus
TERTIARY
- Latent period of 2 years or more
- Characteristic lesion is Gumma, occuring in skin, bones, liver and testes
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, causes raised ICP and FNS
- Paraparesis – caused by a spinal meningovasculitis
Occurs 3-4 years postinfection
What is asymptomatic neurosyphillis?
Neurosyphillis with positive CSF but no neurological signs
What is tabes dorslis?
Can occur 10-35 years post syphillis
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 - accomodate but dont react
- Ptosis and optic atrophy
What is general paralysis of the insane?
Occurs 10-15 years
Dementia and weakness associated with neurosyphillis, in addition to:
- Seizures
- Brisk reflexes
- Extensor plantar reflexes
- Tremor
- Argyll-Robertson pupils
Investigations neurosyphillus
Blood tests:
- Dark groun microscopy fluid, serological test
-
VDLR (Venereal Disease Research Laboratory)
- Non-treponema specific (cardiolipin antibody)
- Detectable in primary disease but not in late syphillus
- Indicates active disease and becomes negative if treated
-
TPHA (Treponema Pallidum haemogglutination Assay)
- Presents in syphillus and remain positive depite treamtent
- Treponema specific
- Doesnt distinguish between syphillus and other treponemas eg yaws
- PCR
How would you manage someone with neurosyphillis?
Benzylpenicillin
What is Creutzfeld-Jakob Disease
Progressive dementia
Characterised pathologically by spongiform changes in the brain
Caused by prions (proteinaceous infectios particles)
Types of CJD
Sporadic CJD
Variant CJD
Familail CJD
Acquired CJD
Iatrogenic CJD - contaminated material such as corneal grafts
What are features of Sporadic CJD?
- Rapidly progressive dementia with early behavioural abnormalities
- Myoclonus
- Cerebellar ataxia
- Extrapyamidal: tremor, rigidity, bradykinesia, dystonia
- Pyramidal signs: wakenss, spasticity, hyper-reflexia
- Extrapyramidal and pyramidal signs
- Eye signs - supranuclear palsies, complex visual disturbance, hallucinations, cortical blindness
- Seizures
Invetigations CJD
Tonsillar biopsy
CSF Gel elecrophoresis
What are characteristic fatures of CJD?
Younger onset<40,
Early behavioural symptoms
Ataxia
Dementia
What is variant CJD linked to?
Bovine spungiform encephalopathy
How can varient CJD be acquired?
Transmitted via meat contaminated by CNS tissue affected by bovine spongiform encephalopathy
What organism most commonly causes spinal epiderual abscess
Staph aureus
Back pain and gever followed by paraparesis and local root lesions
What are argyll-robertson pupil
Argyll Robertson pupils (AR pupils or, colloquially, “prostitute’s pupils”) are bilateral small pupils that reduce in size on a near object (i.e., they accommodate), but do not constrict when exposed to bright light (i.e., they do not react to light). They are a highly specific sign of neurosyphilis; however, Argyll Robertson pupils may also be a sign of diabetic neuropathy
What are neurological manifestations of lyme disease?
- Mononeuropathy
- Mononeuritis multiplex
- Painful radiculopathy
- Cranial neuropathy
- Myelitis
- Meningoencephalitis
- Encephalomyelitis
What bug causes lyme disease
Borrelia Burgdorferi
Describe the three stages of lyme disease
- STAGE 1
Early localised infection (1-30 days)
Erythema migrans rasg
50% have flu-like symptoms (fatigue, myalgia arthralgia, fever, chills, headache, neck stiffness) - STAGE 2
Early disseminated infection (weeks-months)
One or more organ systems included
MSK -arthritis
CArdiac - myocarditis
neorlogical - meingoencephalitis, cranial or polyneuropathies - STAGE 3
Chronic infection (months- years
May continue to experience fatigue and MSK pain for months - years
Investigations of lymes
Serological - IgM and IgG
Imaging - MRI, CSF lymphocytosis
Management Lyme disease
Oral doxycycline (or amoxicillin)
IV benzyl penicillin or ceftriazone in later stages
What bug causes tetanus?
Clostridium tetani (anaerobic gram positive bacillus, spore forming)
Pathology of tetanus
Toxin acts on MNJ blokcing inhibtion of motor neurones
Presentation of tetanus
Prodrome illness
Trismus )jaw lock)
Risus sardonicus (grin-like posture of hyperteonic facial msucles)
Spasms
What bug causes botulism?
Clostridium Botulinum
How is botulism transmitted
Naturally present in soil, dust, aquaritc and environments.
Modes of infection: food borne, would (ALMOST EXCLUSIVELY IVDU)
Pathology botulism
Toxin binds to presynaptic membranes of peripheral NMJ
Presentation botulism
Incubation of 4-14- days
Descening symmetrical flaccid paralysis
Pure motor
Resp failure
Diagnosis botulism
Culture from debried wound, mouse neutralisation bioassay for toxin in blood, nerve conduction studies.
Mangement botulism
Wound debridement
Anti-toxin
Benzylpenicillin and metrinodazole
