Meningitis/Encephalitis Flashcards
Causes of Meningitis? [4]
- Infective
- Inflammatory e.g. Sarcoid
- Drugs Induced e.g. NSAIDs
- Malignant (Metastatic or Leukemia)
How do we approach meningitis? [3]
- Blood Cultures & Gram Stain
- LP (CSF culture & Microscopy)
- Only image if LP is contraindicated
How do we approach encephalitits? [4]
- Blood Culture
- CT/MRI
- LP (PCR of the CSF for viral DNA)
- EEG
When would an LP be contraindicated? [6]
You don’t do it if there’s sign of a mass or swelling as the pressure [1] could cause herniation and death.
- Focal Neuro deficits
- New Seizures
- Papilloedema
- GCS<10
- Severe Immunocompromisation
Causes of Encephalitis? [5]
- Infective (HSV is main cause of encephalitis, Enterovirus etc)
- Inflammatory (i.e. autoimmune)
- Metabolic (Hepatic, uraemic, hyperglycaemic)
- Malignant, either a metastases or a paraneoplastic syndrome
- Post Ictal (After Seizure)
What microorganisms cause infective meningitis? [2]
Neisseria Meningitidis (Meningococcus) Streptococcus Pneumoniae (Pneumococcus) Enteroviruses
How do we treat viral encephalitis?
Aciclovir based on clinical suspicion of Viral encephalitis.
Generally speaking, viral meningitis is self-limiting, with symptoms improving over the course of 7 - 14 days and complications are rare in immunocompetent patients.
How does HSV cause encephalitis? [2]
Initial infection resolves and becomes latent eg residing in trigeminal ganglion [1]
It reactivates later and can cause encephalitis - Type 1 HSV [1]
Name some enteroviruses [3] and how you spread and test for them in encephalitis? [2]
Polioviruses, coxsackie virus, echovirus
Faecal-oral spread
Do PCR of a stool sample if you suspect
Other than HSV and Enteroviruses what else causes infectious encephalitis? [1]
Arbovirus Encephalitides
Common in other parts of the world they are vector-transmitted (tick or mosquito) so a travel history is important
E.g. West Nile Virus (Location name viruses dont relate to current geographical distribution)
How does Meningitis Present? [5]
Classic triad of Fever, neck stiffness and altered mental status
Also:
- Short history of headache
- Meningism (Stiff neck, photophobia, N&V)
Cerebral dysfunction e.g. confusion is common and many have a lowered GCS
Cranial Nerve Palsies, Seizures and focal neuro deficits can occur
What presentation of meningitis is specific to which cause? [1]
Petechial Skin Rash
A hallmark of meningococcal meningitis (But can occur in viral)
How does Encephalitis Present? [6]
Flu-like Prodrome for 4-10 days
- Progressive Headache with Fever
- ~Meningism
- Progressive cerebal dysfunction (Seen as confusion, memory issues, behaviour etc)
- Seizures
- Focal Signs
How is viral encephalitis different from bacterial meningitis? [2]
It has a slower onset and more prominent cerebral dysfunction…generally
Describe the types of auto-immune encephalitis? [2]
Anti-VGKC (Voltage Gated K Channel) antibodies:
- Seizures, Amnesia & Altered mental state
Anti-NMDA receptor antibodies:
- Flu like prodrome
- Prominent Psych features
- Altered Mental state & Seizures
- Progresses to a movement disorder then coma
Indications for an LP? [6]
To Diagnose:
- Meningitis/Meningoencephalitis
- Subarachnoid Haemorrhage
- Malignancy (diagnose & Treat)
- Idiopathic Intracranial Hypertension
- Detect Oligoclonal bands to indicate CNS inflammation e.g. MS
To infuse drugs or contrast
Contraindications for a LP? [4]
- Patient has cardiovascular or respiratory Instability
- Infection in skin or soft tissue over puncture site
- Unstable bleeding disorder (diagnosed, low platelets or low clotting factors)
- Raised ICP (CT first to spot a mass which may herniate), obstructive hydrocephalus
What are the types of LP needle? [2]
- Spinal needles usually 22 gauge
- Atraumatic needles (Cause less spinal headaches but cost more)
What is used to anaesthetize for an LP? [2]
Topical anaesthetic to injection site such as EMLA
Lidocaine 1%
4mg per kg is maximum dose
OR lidocaine inserted intradermally, then carried through on needle
In what positions are an LP performed? [2]
Lateral (Decubitus) position:
- Lying on left side with maximally flexed spine (particularly at hips)
Sitting (Infants):
- Infants hands held between its flexed legs using one hand and the other hand flexes its head
What vertebral level is an LP performed? [2]
L3-4 in adults and L4-5 in infants
Procedure for an LP [8]
- ~Anaesthetize topically 30 mins before
- Adopt position
- Clean skin with Povidone Iodine to 10cm from puncture site and allow to dry
- Drape below patient and around site
- ~Anaesthetize with lidocaine
- Insert spinal needle + Stylet with bevel upwards (90 to spinal cord)
- Aim Cephalad to get through slanted lamina
- Pop of sudden lack of resistance means your in, remove stylet and collect CSF
What do you do if theres no fluid? [3]
- Rotate the needle 90 degrees
- Reinsert stylet and advance needle again
- Compress jugular
How is CSF pressure measured? [1]
With a Manometer in the lateral position only, once CSF starts to flow
How much CSF do you collect on an LP?
14mls is needed
Count the drops
2ml microbiology, 2ml biochemistry, 2ml immunology
4ml cytology
How is the LP ended? [3]
Measure closing pressure with manometer if you want
- > Reinsert Stylet
- > Smoothly remove needle
- > Cleanse and cover puncture site
What is the Paramedian or Lateral Approach? [2]
What are the benefits of this approach? [3]
Approaching the spine at an angle not quite in the midline (10-15 degrees out) [1]
This passes through the erector spinae & Ligamentum flavum rather than Supraspinal/interspinal ligaments [1]
Helps in patient with calcifications, anatomical abnormalities or just to reduce Spinal Headaches (hole through dura &arachnoid wont overlap)
Complications of a LP? [8]
- Headache
- Apnea
- Back pain, bleeding or leaking
- Infection or Haematoma
- Subarachnoid Epidermal cyst (Carried Skin cells through to meninges)
- Nerve Trauma, Ocular Muscle Palsy
- Brainstem Herniation
Describe a spinal headache?
SOCRATES
Risk factors [3]
A common complication of LPs
More likely in women, young people, low BMIs and people with a history of headaches
Its bilateral and improves with lying down
It can last hours to weeks
How do we treat a spinal headache? [3]
We can help with:
- Hydration
- Caffeine (PO/IV)
- Epidural Blood Patch to stimulate healing
How do we prevent a spinal headache? [3]
1) Keep needle bevel parallel to spinal cord to minimise tearing
2) Replace stylet before removing needle
3) Use small diameter or atraumatic needles
How would a nerve root trauma complication present in an LP [1] and what do you do if you cause it [3]?
Sudden electric shocks of dysaesthesia, its rarely permanent
WHAT TO DO:
You should withdraw immediately
If the pain or weakness is persistant you may have caused irritation warranting CCSs
After that nerve conduction studies and EMG may be necessary to investigate further
How does a herniated brainstem appear when caused by LP? [3]
What must you do? [5]
Altered mental status -> Cranial nerve abnormalities -> Cushing’s Triad
It can often be rapidly fatal
You must:
- Remove needle
- Raise head of bed to drain venous blood
- 3% saline (hypertonic so draws fluid into blood, reducing ICP)
- Intubate & Hyperventilate
- Call neurosurgeon
What options are there should your LP fail? [3]
- Get someone else
- Radiographic guided LP with US, Fluoroscopy or CT
- Cisterna Magna Tap (C1/2)
Describe the results from a normal LP? [5]
Describe color, opening pressure, protein, glucose, WCC
- Clear & Colourless
- Opening pressure 6-16 mm Hg
- 35 mg protein
- 60% glucose as in blood
- WCC<5
What should you do when sending CSF to the lab? [2]
Send with Blood sample to compare glucose
Put it in a brown envelope or the sunlight damages the sample and they all come back diagnosed with SAH
Bacterial meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
Viral meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
TB meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
Management of bacterial meningitis
- Initial empirical therapy aged < 3 months
- Initial empirical therapy aged 3 months - 50 years
- Initial empirical therapy aged > 50 years
- Initial empirical therapy aged < 3 months Intravenous cefotaxime + amoxicillin
- Initial empirical therapy aged 3 months - 50 years
Intravenous cefotaxime - Initial empirical therapy aged > 50 years Intravenous cefotaxime + amoxicillin
Management of bacterial meningitis
- Meningococcal meningitis
- Pneumococcal meningitis
- Meningitis caused by Haemophilus influenzae
- Meningitis caused by Listeria
- Meningococcal meningitis- Intravenous benzylpenicillin or cefotaxime
- Pneuomococcal meningitis- Intravenous cefotaxime
- Meningitis caused by Haemophilus influenzae- Intravenous cefotaxime
- Meningitis caused by Listeria- Intravenous amoxicillin + gentamicin
Describe appearances on MRI
HSV encephalitis imaging
VZV encephalitis
CMV encephalitis
HSV - Increased signal in temporal lobe seen in 80%
VZV - multifocal areasw of haemorrhage and ischaemic infarction
CMV encephalitis - ventriculomegaly
HSV encephalitis management
Aciclovir 10mg/kg IV every 8 hours for 14-21 days
With proof of cure by repeating CSF-PCR.
Management of tuberculous meningitis
RIPE Rifampicin, Isoniazid, pyrazinamide, ethambutol + pyridoxine for 8 weeks
Sensitivities will come back and ethambutol can be stopped if not needed
Continue R+I for another 6-12 months depending on CSF monitoring
A course of dexamethasone for HIV immunocompromised
Chronic encephalitis
Progressive multifocal leukoencephalopathy
Multifocal areas of demyelination throughout brain sparing spinal cord and optic nerves
Changes in brain cell structures
Presentation
* homonymous hemianopia
* mental impairment
* weakness
* ataxia
* seizures
Immunosuppressed population
PML diagnosis
CSF PCR for JCV
MRI demonstrating multifocal asymmetric white matter lesions
Chronic encephalitis
Subacute sclerosing panencephalitis
Primary history of measles infection at 2 years old
6-8 years later then develop neuro signs
Diagnosis at 5-15 years old
CNS viral infection presentation with progressive neurological deterioration
Diagnosed with MRI + CSF results, raised antimeasles antibody levels
Treatment: isoprinosine
Pathophysiology
Brain Abscess
- Direct spread from cranial site of infection like sinus or OM.
- Head trauma or neurosurg procedure
- Haematogenous spread from remote iste of infection
25% cryptogenic source
Brain abscess disease course
- Day 1-3 cerebritis, oedema
- Late cerebritis, pus formation, enlarged necrotic centre, thin capsule
- Day 10-13 early capsule formation seen as ring enhancing
- Late capsule formation - well defined necrotic centre, dense collagenous capsule, surrounding gliosis
Presentation of brain abscess
Headache - dull aching constant, hemicranial/generalised
Signs of infection
Seizure
Focal neurologic deficit, weakness, speech problems, visual changes
Not common to have meningism
Brain abscess investigations
MRI > CT especially early cerebritis
Blood culture +ve in 10%
LP contraindicated as increases risk of herniation
Brain abscess management
- Empirical antibiotics, ceftriaxone + metronidazole
Penetrating head trauma, neurosurg procedure > cover for pseudomonas and staph with ceftazidime + vancomycin. - Aspiration and drainage under stereotactic guidance
- Duration 6-8 weeks MINIMUM
- Prophylactic anticonvulsant for 3 months after resolution of abscess
Herpes simplex meningitis vs herpes simplex encephalitis
Difference in presentation and treatment
Presentation of encephalitis has no meningism symptoms.
Treatment of herpes simplex meningitis:
* supportive measures like fluids and early discharge
Treatment of encephalitis:
* If there are any suggestions of encephalitis such as changes in personality, behaviour or cognition or altered conscious level intravenous aciclovir should be given for suspected HSV encephalitis
