Neurological Infections Flashcards
Brain abscess Meningitis Encephalitis Herpes Zoster Malaria
Define Brain Abscess
A localized collection of pus in the brain parenchyma caused by infection, often bacterial or fungal.
What are the 3 different ways Brain Abscesses spread?
Direct, Haematogenous, Post surgical/ Traumatic
How are Brain Abscesses directly spread?
From sinusitis, otitis media, or dental infections.
How are Brain Abscesses spread Haematogenously?
From a distant infection (e.g., infective endocarditis, lung abscess).
How are Brain Abscesses spread post-surgery/traumatically?
Penetrating head injuries or neurosurgical procedures.
Name 3 risk factors for developing a Brain Abscess
Immunosuppression (e.g., HIV, chemotherapy).
Poorly controlled diabetes.
Congenital heart disease (e.g., right-to-left shunts).
Clinical features of Brain Abscess
Fever: May be absent in immunosuppressed patients.
Headache: Persistent and localized.
Neurological deficits: Focal symptoms such as hemiparesis, aphasia.
Signs of raised ICP: Vomiting, papilledema, confusion.
Seizures: Common presentation.
Ix for Brain Abscess
Neuroimaging:
MRI brain with contrast: Gold standard for diagnosis.
CT brain: May show ring-enhancing lesion.
Blood cultures:
Identify causative organisms.
Lumbar puncture:
Contraindicated in raised ICP.
Other tests:
Full blood count, inflammatory markers, and testing for immunosuppression (e.g., HIV).
Management of Brain Abscess
Medical:
Empirical antibiotics: Ceftriaxone + metronidazole ± vancomycin (tailored once cultures are available).
Dexamethasone: To reduce cerebral edema.
Surgical:
Aspiration or drainage: For larger abscesses (>2.5 cm) or those causing mass effect.
Monitoring:
Repeat imaging to assess response to treatment.
The most common imaging modality for diagnosing a brain abscess is ________.
MRI with contrast.
True or False: Lumbar puncture is routinely performed in patients with suspected brain abscess.
False. Lumbar puncture is contraindicated if there are signs of raised intracranial pressure.
What is the initial empirical antibiotic regimen for a brain abscess?
Ceftriaxone + metronidazole ± vancomycin.
Define Meningitis
Inflammation of the meninges surrounding the brain and spinal cord, usually caused by infection.
Name 4 causes of Meningitis
Bacterial, viral, fungal, non-infectious
Bacterial causes of Meningitis
Neisseria meningitidis (meningococcal).
Streptococcus pneumoniae (pneumococcal).
Listeria monocytogenes (in neonates, elderly, immunocompromised).
Viral causes of Meningitis
Enteroviruses, herpes simplex virus (HSV).
Fungal causes of Meningitis
Cryptococcus neoformans (common in HIV).
Non-infectious causes of Meningitis
Autoimmune diseases, malignancies.
Classic triad of Meningitis symptoms
Fever, neck stiffness, altered mental status.
Other clinical features of Meningitis
Photophobia, headache, nausea/vomiting, seizures, and rash (purpuric rash in meningococcal meningitis).
Ix for Meningitis
Lumbar Puncture. Blood Cultures + PCR testing, Imaging
What would a lumbar puncture show for bacterial meningitis?
High WBC count (neutrophils), low glucose, high protein.
What would a lumbar puncture show for viral meningitis?
High WBC (lymphocytes), normal glucose, normal or slightly raised protein.
What are blood cultutes and PCR testing for when investigating Meningitis?
Identify causative organisms.
What type of imaging is used in Meningitis?
CT/MRI: Rule out contraindications to lumbar puncture (e.g., mass effect).
Management of Meningitis
Empirical antibiotics:
Ceftriaxone + ampicillin (covers Listeria).
Add dexamethasone to reduce inflammation.
Supportive care:
Fluids, seizure management, and close monitoring.
True or False: A purpuric rash is commonly associated with pneumococcal meningitis.
False. It is associated with meningococcal meningitis.
Bacterial meningitis typically shows ______ glucose and ______ protein levels in cerebrospinal fluid analysis.
Low glucose and high protein.
What are the first-line antibiotics for bacterial meningitis in adults?
Ceftriaxone and ampicillin (to cover Listeria).
What is the purpose of dexamethasone in bacterial meningitis treatment?
To reduce inflammation and the risk of long-term complications such as hearing loss.
Define Encephalitis
Inflammation of the brain parenchyma, most commonly caused by viruses.
Causes of Encephalitis
Viral: HSV-1 (most common), varicella-zoster virus, enteroviruses.
Non-viral: Autoimmune (anti-NMDA receptor encephalitis).
Clinical features of Encephalitis
Altered mental status: Confusion, agitation.
Seizures.
Focal neurological deficits.
Fever and headache.
Ix for Encephalitis
MRI brain:
Key for identifying areas of inflammation.
Lumbar puncture:
Lymphocytic pleocytosis, normal glucose, elevated protein.
PCR testing:
Detects viral DNA/RNA (e.g., HSV).
Management of Encephalitis
Empirical antiviral therapy: Acyclovir started promptly.
Supportive care: Airway management, seizure control, fluids.
True or False: PCR testing on cerebrospinal fluid is the gold standard for diagnosing HSV encephalitis.
t
Fill-in-the-blank:
HSV encephalitis is often associated with abnormalities in the ________ lobe on MRI.
Temporal
What is the initial treatment for suspected viral encephalitis?
Intravenous acyclovir.
Name two non-infectious causes of encephalitis.
Autoimmune encephalitis (e.g., anti-NMDA receptor encephalitis) and paraneoplastic syndromes.
What is Herpes Zoster Virus (shingles)?
Reactivation of the varicella-zoster virus (VZV), causing a painful vesicular rash in a dermatomal distribution.
Clinical Features of HZV
Prodrome:
Tingling, itching, or pain in the affected dermatome.
Rash:
Vesicular lesions along a single dermatome, unilateral.
Complications:
Postherpetic neuralgia, ophthalmic involvement, Ramsay Hunt syndrome.
Managment of HZV
Antiviral therapy: Acyclovir, valacyclovir (within 72 hours).
Analgesia: NSAIDs, gabapentin for neuralgia.
Vaccination: Shingles vaccine for prevention.
Fill-in-the-blank:
The dermatomal rash seen in herpes zoster is caused by reactivation of the _______ virus.
Varicella-zoster virus.
True or False: Antiviral therapy is only effective if started within 7 days of rash onset.
False. It is most effective within 72 hours.
What is the most common complication of herpes zoster?
Postherpetic neuralgia.
Name one vaccine used to prevent herpes zoster in adults.
Shingrix or Zostavax.
What is Malaria?
A parasitic disease caused by Plasmodium species, transmitted by Anopheles mosquitoes.
Causes of Malaria
Plasmodium falciparum (most severe).
Plasmodium vivax, P. ovale, P. malariae, P. knowlesi.
Clinical features of Malaria - prodrome
Fever, malaise, headache, myalgia.
Classic triad of Malaria
Cyclical fever (every 48-72 hours), anemia, splenomegaly.
Severe Malaria features
(P. falciparum): Altered consciousness, respiratory distress, multi-organ failure.
Ix for Malaria
Blood smear microscopy: Giemsa staining to identify parasite.
Rapid diagnostic tests (RDTs).
FBC: Anemia, thrombocytopenia.
Management of uncomplicated Malaria
Artemisinin-based combination therapy (ACT).
Chloroquine (if sensitive).
Management of severe malaria
IV artesunate.
Prevention of Malaria
Prophylaxis (e.g., atovaquone-proguanil, doxycycline).
Use of insecticide-treated bed nets.
Name the five species of Plasmodium that cause malaria in humans.
Plasmodium falciparum.
Plasmodium vivax.
Plasmodium ovale.
Plasmodium malariae.
Plasmodium knowlesi.
True or False: Plasmodium falciparum is the most severe form of malaria.
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Fill-in-the-blank:
Malaria is transmitted by the bite of an infected ________ mosquito.
Anopheles.
