CNS Infections & Nerve & Muscle Flashcards
What are the 3 general pathways that viruses can enter the CNS?
- Neural
- Olfactory
- Hematogenous
What condition does this describe:
– Inflammation of the lining of the brain
Meningitis
– Aseptic meningitis is NOT caused by bacteria
What is the major type of virus that causes aseptic meningitis?
80% enterovirus
10% HSV-1&2
10% arboviruses
<1% other viruses
Nuchal rigidity is a sign of what CNS condition?
Nuchal rigidity is a sign of meningitis
• “Brudzinski’s sign” is a symptom of meningitis.
• The neck is so stiff that the knees flex when the
neck is flexed.
What is the distinguishing feature of meningitis that differentiates it from encephalitis?
In meningitis, the patients mental status is NORMAL
What is the distinguishing feature of encephalitis that differentiates it from meningitis?
Mental status is altered in encephalitis and you get intracerebral hemmorage
Encephalitis is URGENT if unrespeonsive/coma, seizure or paralysis
How to diagnose aseptic meningitis?
Tx:
Spinal tap
Elevated white blood cell count in spinal fluid (no bacteria)
– Viruses may be detected in CSF
tx: supportive care, drugs exist for HSV, funcal and mycobacterial infections
How to diagnose encephalitis?
Tx:
Spinal tap indicates inflammation in CSF, blood may be present and viruses may be detected → PCR is gold standard for definitive diagnosis
– EEG is suggestive of seizures
– Brain MRI or CT scan may show foci of inflammation or hemorrhage
Tx: supportive care and symptom relief (acyclovir if caused by herpesvirus)
Postinfectious encephalitis follows viral infection by 1-2 weeks
This is called what?
Acute disseminated encephalomyelitis (ADEM)
-Associated with measles, mumps, VZV, influenza, parainfluenza viruses
– Autoimmune disorder
What type of viruses infect via neuronal spread?
Herpesvirus (alphaherpesviruses)
What type of viruses infect via fecal-oral spread?
Picornaviruses (enteroviruses)
What type of viruses infect via insect vectors (arboviruses)
Flaviviruses
Togaviruses
If infected with HSV, which type (HSV 1 or 2) will more often cause meningitis during their primary infection?
HSV-2»_space; HSV-1 primary infections often cause meningitis
• Recurrent HSV-1 infections can also cause encephalitis
• Other herpesviruses: VZV, CMV, EBV meningitis occur
more often in immunocompromised patients
• In a weak host, these CNS infections often progress to severe encephalitis
• Treat HSV and VZV aggressively with acyclovir!
What is the route of infection for HSV-1
-Primary HSV-1 in the oropharynx → trigeminal nerve → CNS
– Recurrent HSV-1 → trigeminal nerve → CNS
HSV-1 is the most common cause of sporadic viral encephalitis.
How to diagnose HSV-1 Encephalitis?
Remember that an altered mental state is characteristic of encephalitis (NOT meningitis)
Gold standard: PCR of CSF for HSV and other viruses
– Brain imaging: MRI shows predominantly
unilateral temporal lobe abnormalities
If you have a very young or very old patient with encephalitis in the summer time, which virus should you most suspect?
Enterovirus, but also think arboviruses with seasonal vectors
Viral infections of the central nervous system cause meningitis, encephalitis, or both, and have many common symptoms. What is a distinguishing characteristic of encephalitis?
A. Virus detected in the CSF by culture or PCR
B. Intracerebral hemorrhage.
C. Stiff neck, also known as Brudzinski’s Sign
D. Headache.
E. Prognosis may be good, with few sequelae
B. Intracerebral hemorrhage.
A patient diagnosed with viral encephalitis in the summer is most likely infected with what type of virus? A. Enterovirus B. Cytomegalovirus C. Herpes Simplex Virus Type 2 D. Rabies virus E. Mumps virus
A. Enterovirus
Viremia can result in skin rashes, congenital infections, and CNS infections. What is an alternate route for viruses to enter the CNS?
A. Extravasation through meningeal or cerebral capillaries
B. Implantation of an organ from a donor infected with HSV-1
C. Retrograde transport from peripheral nerve endings or nasal mucosal
D. Bites from Aedes, Culex, or Culiseta mosquitos carrying Togaviruses
C. Retrograde transport from peripheral nerve endings or nasal mucosal
Repetitive brief unilateral headaches lasting 15min-3h. Excruciating periorbital pain with lacrimation and rhinorrhea. More common in males.
What is tx?
Cluster headache
tx: 100% O2, sumatriptan, DHE
Bilateral headaches lasting >30min (typically 4-6h); constant, steady pain with no photophobia or phonophobia. No aura
Tx:?
Tension headache
Tx: analgesic NSAIDs, (aspirin, acetaminophen, naproxen, ibuprofen)
Prevention tx: amitriptyline, SSRIs (fluoxetine, paroxetine, sertraline)
Unilateral pulsating pain with nausea, photophobia, or phonophobia. May have
“aura.” Due to irritation of CN V, meninges, or blood vessels (release of substance P, calcitonin gene–related peptide, vasoactive peptides).
Tx:?
Migraine
Tx: Sumatriptan-take early
Ergotamine
Dihydroergotamine (DHE)-works in later stages of migrane
Opiates (codeine) can be used for acute tx of migraines
A healthy 16 year-old girl has been suffering from continuous bi frontal pressure like headache of mild to moderate intensity for a year. No associated migraine symptoms. Not taking any pain medicines. P/E and Neurological, Normal. Which one of the following is the preferred treatment for Headache Prevention? A. Propranolol B. Amitriptyline C. Discontinue analgesics D. Sumatriptan E. Indomethacin
Answer: B. Amitriptyline.
Amitriptyline is still the premier drug for chronic tension-type headache.
A 40 year-old woman seeks help for migraines that became daily several months ago and are requiring more frequent daily doses of ibuprofen or Excedrin to enable her to function. Which one of the following is the preferred treatment for preventing headache development? A. Propranolol B. Amitriptyline C. Discontinue analgesics D. Sumatriptan E. Indomethacin
Answer: C. Discontinue analgesics
Rebound migraines won’t disappear without withdrawal from the overused analgesics
The frequent daily doses of ibuprofen and excedrin can result in rebound headaches (medication-overuse headaches), which are caused by regular, long-term use of medication to treat headaches, such as migraine. Pain relievers offer relief for occasional headaches. … Rebound headaches usually stop when you stop taking the pain medication
