Chapter 20 Infections of the Nervous System

Signs versus Symptoms

Differential Diagnosis

Definitive DX

RX

HX

  1. Anatomy, Physiology and Immunity of the Nervous System

     A. CNS - Brain and  Spinal Cord

            1. Meninges

            2. CSF

            3. CNS immune cells neuroglial cells

            4. Portals of Infection

    B. Enclosed by bone, close to blood - sterile

            1. Blood brain barrier

            2. Nerve cell damage through infection

    C. Diagnosis through CSF - Gram Stain, Culture & Sensitivity (C&S), and CSF chemistry

     

  2. Infections of the Nervous System
Disease Etiologic Agent Pathogenesis Symptoms Transmission Prevention and treatment
Bacterial Infections of the Nervous System
Meningitis Neisseria meningitidis
GNDC
attach via fimbrae
capsules
petechiae = septicemia

epidemic
13 strains A,B,C & W135
 

Mild cold, severe headache, stiff-neck, high fever, nausea, vomiting, WBC in CSF decrease in CSF glucose, may lead to brain damage, hearing loss Inhaling microorganism through respiratory tract or associated ear or sinus infections Chloramphenicol
Cephalosporins + Rifampin for
Prophylaxis for family members

Vaccination

Streptococcus pneumoniae
GPDC
pneumococci
capsule evades immune system, invasion via blood Ceftriaxone
Vaccination
leading cause in adults
Haemophilus influenzae
GNCB
Ceftriaxone
Vaccination HiB
Streptococcus agalactiae (Group B)
GPC cl
predominantly  inoculation in vagina during delivery Ampicillin +Cefotaxime
Screening in OBGYN visits
leading cause in newborns
Listeria monocytogenes
GPR psychrophiles
GI tract to blood and brain, miscarriage foodborne
common epidemics from food products
Ampicillin + Gentamicin
Peripheral Nerves Mycobacterium leprae  AFB Very long generation time = chronic, slow infection

preferentially attacks nerves, infection mediated by T cell immunity (possibly inhibition of immunity allows spread.)

tingling and decreased sensation in extremities, pain, then loss of feeling as nerves become involved, wasting, damage- cartilaginous changes respiratory and close contact

l

Dapsone, rifampin, clofazimine

early treatment essential

vaccine?

Botulism
Neural Intoxication
Clostridium botulinum Intoxication
anaerobe found in improperly canned foods, other anaerobic conditions

Foodborne -ingestion of toxin

Infant botulism

Wound botulism

 

toxin binds to Ach site preventing muscle contraction =

flaccid paralysis

Botox

heat labile 7 different exotoxins
18-36 hour
(8hrs-4days)

GI symptoms, diplopia, difficulty swallowing and flaccid paralysis, inability to breathe

 

Botulinum Ig
antibiotics and antitoxin for wound and infant botulism

proper food preparation & cooking

Antitoxin

canned corn, peppers, green beans, soups, beets,asparagus, mushrooms, ripe olives, spinach, tuna fish, chicken and luncheon meats, ham, sausage, lobster, smoked & salted fish

Tetanus Clostridium tetani

GPR endospore former

 

Wound infection and toxin production neurotoxin binds preventing release of AChe and muscle relaxation anaerobic wounds contaminated with endospores Prevention with vaccination

toxoid

Disease Etiologic Agent Pathogenesis Symptoms Transmission Prevention and treatment
Viral Infections of the Nervous System
Viral meningitis Aseptic meningitis
(Coxsackie, Echo, & Mumps virus)
infect throat -> lymph-> viremia

mild disease

abrupt onset, fever, headache, stiff neck, light sensitivity, CSF shows lymphs CSF glucose normal contact, food no treatment

vaccines prevent mumps

Sporadic Viral Encephalitis Herpes, Mumps, Measles etc invade nerves to brain nasal nerves antivirals
Acyclovir
Epidemic Viral Encephalitis Equine encephalitis
WEE, VEE, SLE
West Nile Virus
invade from bite to blood

serious disease

epidemics
mosquito via reservoirs
mosquito abatement
sentinel chickens
no treatment
Polio
http://phil.cdc.gov/phil/
detail.asp?id=996

Illustration of polio virus.
poliovirus - picornavirus

3 types

selective destruction of motor neurons-> permenant paralysis headache, fever, stiff neck, nausea
post polio syndrome
oral portal water vaccination

Sabin and Salk

Rabies Rabies virus

ssRNA

Saliva and body fluids,long incubation, Amount of virus, distance form brain, Negri bodies pain at bite, fatigue, inability to swallow (hydrophobia), vomiting, CNS involvement, seizures, coma saliva via a bite, bat guano animal control, vaccine, post exposure vaccine, hyper immune globulin
Trypanosomiasis African Trypanosoma species Enters skin and spreads to blood - parasitemia, goes to brain headache, sleepiness, coma bite of tsetse fly suramin (early), melarsoprol (late infections)
Disease Etiologic Agent Pathogenesis Symptoms Transmission Prevention and treatment
Other the Nervous System disease from infectious agents
Mad cow = BSE, C-J, Kuru,

 

Prion Proteinaceous Infectious Particle eaten, pathogenesis unknown, no inflammatory or immune response anxiety, insomnia, fatigue, muscle jerks, dementia undercooked meat, transplant, blood FATAL

highly resistant

Disease Etiologic Agent Pathogenesis Symptoms Transmission Prevention and treatment
Fungal Infections of the Nervous System
Cryptococcal meningitis Cryptococcus neoformans opportunist in immunosuppressed mild disease inhaled in dust, usually eliminated in lungs Amphotericin B
Disease Etiologic Agent Pathogenesis Symptoms Transmission Prevention and treatment
Protozoal Infections of the Nervous System
Amoebic Meningitis Naegleria fowleri Enters through nasal passage infects brain headache Swimming pools, lakes, and other water sources Flagyl

Chapter 20 Infections of the Nervous System

1. Describe the protective and immune barriers found in the Nervous System.

2. Compare and contrast Meningicoccal meningitis, Haemophilus meningitis, Listeriosis, Botulism, and Leprosy (Hansen's Disease) with regards to transmission, treatment and control.

3. Describe the transmission routes, pathogenesis, diagnosis, treatment and prevention of the various types of viral encephalitis agents including WNV,WEV, EEV.

4. Describe the transmission routes, pathogenesis, diagnosis, treatment and prevention rabies.

5. Describe the transmission routes, pathogenesis, diagnosis, treatment and prevention of opportunistic infections with Cryptosporidiosis.

6. Describe the transmission routes, pathogenesis, diagnosis, treatment and prevention Trypanosomiasis.

7. Describe the transmission routes, pathogenesis, diagnosis, treatment and prevention Prion diseases such as Kuru, Crutzfeld-Jakob, and Mad Cow disease.

8. Compare and contrast the clinical picture involved in viral, fungal, and bacterial nervous system infections.

9. When given a patient with Nervous symptoms indicating a potential infection, evaluate and analyze the evidence to determine a differential diagnosis, additional testing needed, and a probable diagnosis and treatment for the patient with the information provided.

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Date last updated 11/02/2010
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