Chapter 20 Nervous system

Central Nervous System (CNS): Consists of the brain and spinal cord.
Peripheral Nervous System (PNS): Includes peripheral nerves and nerve plexus.
Structure of the CNS:
- Cerebrum: Largest part of the brain responsible for higher brain functions.
- Cerebellum: Coordinates voluntary movements and balance.
- Brain Stem: Connects brain to spinal cord and controls involuntary functions.
- Spinal Cord: Contains neural pathways for communication.
Meninges: Protective membranes covering the brain and spinal cord. Includes:
- Dura Mater: Outer durable layer.
- Arachnoid Mater: Middle web-like layer.
- Pia Mater: Innermost delicate layer.

Types of Pathogenic Microbes:
- Infect cells in the nervous system (e.g., encephalitis, meningitis).
- Release toxins affecting neurons (e.g., botulism, tetanus).
Common Microbial Diseases:
- Encephalitis
- Meningitis
- Leprosy

Signs & Symptoms:
- Sudden high fever, severe headache, vomiting, light sensitivity.
- Stiff neck, altered muscle control, back spasms.
Pathogens & Virulence Factors:
- Streptococcus pneumoniae: Leading cause in adults; treated with penicillin.
- Neisseria meningitidis: Common in adolescents; transmission via droplets, prevented by vaccines (Menactra, Menomune).
- Haemophilus influenzae: Causes illness in children; prevented by Hib vaccine.
- Listeria monocytogenes: Affects fetuses & immunocompromised; found in undercooked foods.
- Streptococcus agalactiae (Group B): Causes neonatal meningitis; prevention via prophylactic antibiotics during birth.

Definition: Infection of the brain; can lead to severe behavioral changes or death.
Symptoms can develop rapidly, within hours to days.

Diagnosis: Based on symptoms and culturing bacteria from cerebrospinal fluid (CSF) during a spinal tap.
Prevention: Vaccinations available, such as for S. pneumoniae, H. influenzae, and N. meningitidis.

Forms:
- Tuberculoid leprosy: Non-progressive.
- Lepromatous leprosy: Progressive tissue destruction.
Pathogen: Caused by Mycobacterium leprae; transmitted via nasal secretions.
Symptoms: Loss of sensation, tissue loss, and disfigurement due to long-term infection.
Treatment: Long-term antimicrobial therapy (dapsone, rifampin).

Symptoms: Flaccid paralysis, diplopia, dysphagia.
Pathogen: Clostridium botulinum; causes intoxication from the toxin found in improperly stored foods.
Treatment: Involves washing the intestinal tract and administering botulism immune globulin (BIG).
Prevention: Proper food handling and storage.

Signs & Symptoms: Similar to bacterial meningitis but milder; usually self-limiting.
Pathogens: Enteroviruses most common; others include echovirus, herpesvirus.
Diagnosis: Lack of bacteria in CSF; specific treatment does not exist, prevention through hygiene.

Conditions: Asymptomatic, minor polio, nonparalytic, and paralytic forms exist.
Pathogen: Poliovirus; transmitted via contaminated water.
Vaccine: Salk vaccine introduced in 1954

Symptoms: Agitation, hallucinations, paralysis, aggressive outbursts.
Pathogen: Rabies virus spread through bites from infected animals.
Prevention: Immediate post-exposure prophylaxis with antibodies and vaccination.

Pathogen: Cryptococcus neoformans; affects immunocompromised individuals, predominantly.
Treatment: Amphotericin B and flucytosine.

Pathogen: Naegleria fowleri; enters through the skin or mucous membranes, especially during exposure to warm freshwater.
Treatment: Limited effectiveness; high fatality rate (90%).

Definition: Infectious proteins, causing spongiform encephalopathies (e.g., Mad Cow Disease).
Transmission: Can occur through consumption of infected meat.
Symptoms: Causes brain lesions leading to severe neurological decline.