Infections of the Nervous System: Meningitis & Encephalitis

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the estimated percentage of infections in the ICU that are attributed to infections of the nervous system?

4% (correct)

10%

What is a key intervention that should not delay treatment with antibiotics in cases of suspected meningitis?

Performing a lumbar puncture

Urgent brain imaging (correct)

Conducting a mental status examination

Administering intravenous fluids

Which organism is NOT typically associated with CNS infections?

Mycoplasma pneumoniae

Cryptococcus

Roundworm (Ascaris) (correct)

Toxoplasma

What are the classical signs of bacterial meningitis often tested during a clinical examination?

Kernig’s sign and Brudzinski’s sign Signup and view all the answers

Which condition may lead to direct entry of bacteria into the CNS?

Sinusitis Signup and view all the answers

What is a common consequence of bacterial invasion in cases of bacterial meningitis?

Increased intracranial pressure Signup and view all the answers

Which of the following is classified as a chronic virus that can infect the CNS?

Human Immunodeficiency Virus (HIV) Signup and view all the answers

How is bacterial meningitis defined in medical terms?

Inflammation of the meninges, especially the pia and arachnoid Signup and view all the answers

What is the classic CSF profile indicative of acute bacterial meningitis?

Elevated WBC count, high protein, low glucose Signup and view all the answers

Which organism is commonly associated with bacterial meningitis in children due to reduced incidence from vaccination?

Streptococcus pneumoniae Signup and view all the answers

What is the recommended first-line empiric antibiotic for acute bacterial meningitis treatment?

IV Cefotaxime Signup and view all the answers

What symptom can be notably present in a patient with meningococcal infection?

Photophobia Signup and view all the answers

When should a CT scan be performed prior to a lumbar puncture (LP) in suspected meningitis cases?

If papilledema or focal neurology is present Signup and view all the answers

Which CSF stain is used specifically for identifying tuberculosis in immunocompromised patients?

Auramine stain Signup and view all the answers

What is the significance of administering antibiotics promptly in cases of bacterial meningitis?

They prevent potentially life-threatening complications Signup and view all the answers

What type of rash is commonly associated with meningococcal infections?

Non-blanching petechial or purpuric rash Signup and view all the answers

What is a characteristic feature of tabes dorsalis?

Argyll Robertson pupils Signup and view all the answers

Which neurological syndrome is commonly associated with a viral infection in children?

Reye’s syndrome Signup and view all the answers

What defines meningovascular syphilis?

Gumma as a mass lesion Signup and view all the answers

Which condition involves a multifocal perivascular allergic reaction in the CNS?

Acute disseminated encephalomyelitis Signup and view all the answers

What is the treatment regimen for asymptomatic neurosyphilis?

Benzyl penicillin 1 gm daily im for 10 days Signup and view all the answers

What is the age of onset typically associated with Creutzfeldt-Jakob disease?

After 50 years Signup and view all the answers

Which symptom is a hallmark of Guillain-Barre syndrome?

Progressive weakness and numbness Signup and view all the answers

Which condition is characterized by damage to myelin affecting spinal roots and peripheral nerves?

Guillain-Barre syndrome Signup and view all the answers

What does the CSF analysis show in viral encephalitis caused by HSV1?

Elevated RBC count and leucocytosis Signup and view all the answers

What imaging finding is characteristic of cerebral toxoplasmosis in AIDS patients?

Multiple ring-enhancing lesions Signup and view all the answers

Which treatment is indicated for cryptococcal infections?

Amphotericin Signup and view all the answers

Which condition is characterized by vacuolar myelopathy and loss of sensory function in patients with HIV?

HIV-associated Dementia Signup and view all the answers

What typical finding would be seen in the CSF of a patient with Cryptococcal meningitis?

Lymphocyte dominance with elevated protein Signup and view all the answers

What is the typical CSF profile for viral meningitis?

Lymphocyte dominance, elevated protein, normal glucose levels Signup and view all the answers

What is the common route of infection for Cryptococcus neoformans?

Inhalation of spores from contaminated soil Signup and view all the answers

Which organisms are commonly found in brain abscesses?

Aerobic and anaerobic pathogens Signup and view all the answers

What is the standard protocol for treating HSV1 encephalitis?

Intravenous acyclovir for 2 to 3 weeks Signup and view all the answers

What is a common cause of spinal epidural abscess?

Vertebral osteomyelitis Signup and view all the answers

Which organism is the most common cause of fungal meningitis?

Cryptococcus neoformans Signup and view all the answers

What is the recommended duration for anti-TB treatment in cases of TB meningitis?

9 months Signup and view all the answers

What type of imaging is typically used to diagnose a brain abscess?

CT or MRI with intravenous contrast Signup and view all the answers

Which presentation suggests a potential spinal cord infarction related to a spinal epidural abscess?

Acute presentation with fever Signup and view all the answers

Which group of viruses is commonly associated with viral meningitis?

Enteroviruses and arboviruses Signup and view all the answers

What laboratory finding is commonly seen in CSF for TB meningitis?

Leucocytosis with lymphocyte dominance and very low glucose levels Signup and view all the answers

Study Notes

Infections of the Nervous System: Meningitis and Encephalitis

Account for approximately 4% of infections in ICUs, linked to high morbidity and mortality rates.
Early identification and treatment are crucial for improving clinical outcomes.
Urgent brain imaging recommended if there's evidence of increased intracranial pressure (ICP) before lumbar puncture; however, treatment with antibiotics should not be delayed.
Causative organisms can vary by geographical location and patient immune status.

Causes of CNS Infections

Autoimmune Encephalitis: Considered when microbiological tests yield negative results.
Infectious agents include:
- Parasites: Hydatid cysts, cysticercosis
- Protozoa: Toxoplasmosis
- Rickettsiae: Rocky Mountain spotted fever
- Spirochetes: Syphilis, leptospirosis, Lyme disease
- Fungi: Cryptococcus, Candida
- Chronic Mycobacteria: Tuberculosis, leprosy
- Bacteria: Meningococcus, Haemophilus influenzae
- Viruses: Acute (e.g., HSV, H Zoster, Polio) and chronic (e.g., AIDS, SSPE)
- Prions: Creutzfeldt-Jakob disease
- Mycoplasma: Mycoplasma pneumoniae

Bacterial Meningitis

Defined by inflammation of the meninges, typically affecting the pia and arachnoid mater; results from bacterial invasion into the subarachnoid space.
Bacterial invasion often follows high-grade bacteremia, with entry points including highly vascular areas and direct access via sinusitis or traumatic defects.
Symptoms include:
- Classic signs: Kernig’s sign (pain upon knee extension with hip flexed) and Brudzinski’s sign (involuntary hip flexion when neck flexed).
- Other symptoms: Headache, fever, neck stiffness, confusion, seizures, photophobia, vomiting, and potential purpuric rash in meningococcal infections.

Diagnosis and Treatment of Bacterial Meningitis

CSF analysis via lumbar puncture is critical:
- Characteristic findings: Elevated WBC count (predominantly neutrophils), elevated protein, low glucose.
CT scans needed prior to lumbar puncture if papilledema or focal neurological signs are present to prevent brain herniation.
Empirical antibiotic therapy is critical in life-threatening scenarios, usually involving:
- IV Cefotaxime and Ampicillin for those at risk of Listeria.
Meningococcal vaccination is a standard element of childhood immunization.

Tuberculous Meningitis

Affects the basal meninges, potentially leading to cranial nerve palsies and complications like hydrocephalus.
Presents insidiously with malaise and non-specific symptoms.
CSF typically show lymphocytic pleocytosis and low glucose levels.

Brain Abscess and Spinal Epidural Abscess

Brain abscesses may present with headaches, neurological signs, and raised ICP; often require imaging to differentiate from tumors.
Spinal epidural abscess symptoms include neck or back pain, neurological signs of cord compression, and potential urinary dysfunction.
Diagnosis typically confirmed by imaging; prolonged antibiotic treatment is required.

Viral Infections of the CNS

Viral Meningitis: Often caused by enteroviruses; diagnostics reveal lymphocytic CSF profile with normal glucose levels.
Viral Encephalitis: Symptoms include fever, altered consciousness, and seizures; often presents with you elevated RBC count in CSF and positive PCR for HSV.

Fungal and Parasitic Infections

Fungal infections like Cryptococcus neoformans affect both immunocompetent and immunocompromised patients; treatments typically involve amphotericin.
Toxoplasmosis in AIDS patients often results in ring-enhancing lesions on imaging.

Late Complications of HIV Infection

Include HIV-associated dementia, vacuolar myelopathy, and progressive multifocal leukoencephalopathy.

Neurosyphilis

Characterized by varying clinical manifestations, including:
- Asymptomatic forms detected via serology.
- Meningovascular syphilis causing subacute meningitis and cranial nerve palsies.

Transmissible Spongiform Encephalopathy

Creutzfeldt-Jakob Disease presents with progressive dementia and spongiform changes in the brain; diagnosis through biopsy and electrophoresis.

Post-Infective Neurological Syndromes

Acute Disseminated Encephalomyelitis: Follows infections or immunizations; characterized by multifocal neurological deficits.
Guillain-Barre Syndrome: Post-infectious condition leading to progressive weakness and sensory loss, often fully recoverable.
Reye’s Syndrome: Develops in children post-viral infection, linked to aspirin use; presents with severe symptoms including hepatic encephalopathy.
Myalgic Encephalomyelitis: Associated with prolonged fatigue and muscle pain following viral infections.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz focuses on the infections of the nervous system, specifically meningitis and encephalitis. It covers key aspects such as morbidity, mortality, and the importance of early recognition and treatment. Additionally, it discusses urgent brain imaging protocols and the impact of geographic location on these infections.