19 Questions
Which part of the nervous system is affected by meningitis?
Meninges
Which of the following is NOT a type of CNS infection mentioned in the text?
Meningitis
What is the most common route of CNS infections?
Haematogenous spread
Which of the following is NOT a clinical presentation of meningitis?
Joint pain
Which of the following is NOT a CSF finding used to classify meningitis?
Causative agents
What is the normal opening pressure of CSF?
Nil
Which of the following is NOT a potential sequelae of CNS infections?
Increased blood pressure
Which of the following is NOT a route of infection for CNS infections?
Ingestion of contaminated food
Which part of the nervous system is affected by encephalitis?
Brain parenchyma
Explain why infections of the central nervous system are considered a medical emergency.
Infections of the central nervous system are considered a medical emergency because they can be life-threatening and lead to severe sequelae such as coma, decreased mental capacity, seizures, and persistent neurological deficits.
Name the different types of CNS infections mentioned in the text.
The different types of CNS infections mentioned in the text are meningitis, encephalitis, meningoencephalitis, and brain abscess.
What is the route of infection for CNS infections through hematogenous spread?
CNS infections can spread through hematogenous spread, which occurs when the causative agents enter the subarachnoid space and/or blood vessels of the brain through the choroid plexus or other blood vessels.
What are the potential routes of direct spread for CNS infections?
The potential routes of direct spread for CNS infections include otitis media, sinusitis, mastoiditis, surgical procedures, trauma, and congenital abnormalities.
Describe the clinical presentation of meningitis.
The clinical presentation of meningitis includes fever, headache, neck stiffness, altered mental status, photophobia, vomiting, seizure, and focal neurological deficits.
How are the CSF findings used to classify meningitis?
CSF findings are used to classify meningitis based on the speed of onset of initial presentation, rate of progression of the illness, causative agents, white blood cell count, predominant cell type, protein level, and glucose level.
What is the normal opening pressure of CSF?
The normal opening pressure of CSF is nil.
What is the definition of encephalitis?
Encephalitis is the inflammation of the brain parenchyma.
What is the least common route of infection for CNS infections?
The least common route of infection for CNS infections is through travel along nerves to the brain, such as in the case of rabies and HSV infections.
What are the potential sequelae of CNS infections?
The potential sequelae of CNS infections include coma, decreased mental capacity, seizures evolving to epilepsy, and persistent neurological deficits.
Study Notes
Neurological Infections
- Infections of the central nervous system (CNS) are medical emergencies that can be life-threatening and have severe sequelae, such as coma, decreased mental capacity, seizure, and persistent neurological deficit.
Anatomy of the Nervous System
- The central nervous system (CNS) consists of the brain and spinal cord.
- The peripheral nervous system (PNS) consists of peripheral nerves, meninges, and the brain parenchyma.
- The subarachnoid space is a region between the meninges and the brain parenchyma.
Types of CNS Infections
- Meningitis: an infection within the subarachnoid space and/or throughout the leptomeninges.
- Encephalitis: inflammation of the brain parenchyma.
- Meningoencephalitis: concomitant meningitis with encephalitis.
- Brain abscess: a localized collection of pus in the brain.
Routes of Infection
- Haematogenous spread: the most common route of CNS infection, through the choroid plexus or other blood vessels of the brain to the subarachnoid space.
- Direct spread: from adjacent infected sites, such as otitis media, sinusitis, and mastoiditis, or through anatomic defects (e.g., surgery, trauma, congenital abnormalities).
- Travel along nerves to the brain: the least common route of CNS infection (e.g., rabies, HSV).
Clinical Presentation of Meningitis
- Fever
- Headache
- Neck stiffness
- Altered mental status
- Photophobia
- Vomiting
- Seizure
- Focal neurological deficits
- Disseminated disease due to causative agents
Classification of Meningitis
- Acute: progression in hours to days
- Subacute or chronic: progression in days to weeks
CSF Findings
- Opening pressure (mmH2O)
- WBC/mm3: white blood cell count
- Predominant cell type
- Protein (mg/dL)
- Glucose (CSF/Blood ratio)
Test your knowledge on neurological infections with this quiz by Dr. Teresa Wang. Learn about different types of CNS infections, routes of acquiring them, interpreting CSF findings in meningitis/meningoencephalitis, and principles of treatment. Understand why CNS infections are a medical emergency.
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