Nervous System Diseases PDF

Diseases of the Nervous System Structure and Function of the Nervous System Central nervous system (CNS): brain and spinal cord Peripheral nervous system (PNS): nerves that branch from the CNS Meninges protect the brain and spinal cord Dura, arachnoid and pia mater: outer,...

Diseases of the Nervous System Structure and Function of the Nervous System Central nervous system (CNS): brain and spinal cord Peripheral nervous system (PNS): nerves that branch from the CNS Meninges protect the brain and spinal cord Dura, arachnoid and pia mater: outer, middle and innermost layers, respectively Subarachnoid space contains cerebrospinal fluid (CSF) Blood–brain barrier Meningitis An infection of the CSF surrounding the brain and spinal cord It is caused by bacteria and viruses. Viral meningitis Generally less severe Resolves without specific treatment Bacterial meningitis Severe May result in brain damage, hearing loss, or learning disability modification of work by National Institutes of Health Meningitis (a) A normal human brain removed during an autopsy. (b) The brain of a patient who died from bacterial meningitis. Note the pus under the dura mater (being retracted by the forceps) and the red hemorrhagic foci on the meninges. (credit b: modification of work by the Centers for Disease Control and Prevention) Bacterial Meningitis Causative agent: Before the 1990s → Haemophilus influenzae → HiB vaccine young children Also causes pneumonia, otitis media and epiglotitis Streptococcus pneumoniae and Neisseria meningitidis Today → leading causes of bacterial meningitis General public credit: modification of work by CDC Bacterial Meningitis Transmission: Neisseria meningitidis: direct person- person (schools, military camps, prisons) H. influenzae: respiratory droplets S. pneumoniae: respiratory droplets Signs/Symptoms: High fever, headache, and stiff neck in anyone over the age of 2 years. Nausea, vomiting, discomfort looking into bright lights, confusion, and sleepiness. CDC As the disease progresses, patients of any age may have seizures. Bacterial Meningitis Diagnosis: Culturing CSF → Lumbar puncture Treatment: Penicillin, cefotaxime, ceftriaxone Prevention: Vaccines against H. influenzae and some strains of N. meningitidis and many types of Streptococcal pneumoniae. N. meningitidis vaccine against serogroups A and B are now recommended in the USA. Tetanus An acute often fatal disease characterized by skeletal muscles rigidity and convulsive spasms 37 reported cases in 2001 Causative agent: Clostridium tetani Transmission: puncture wounds, handling bedpans, dirty diapers, or other objects contaminated CDC with feces Tetanus Vegetative cells produce exotoxin tetanospasmin into the bloodstream. Tetanospasmin toxin blocks release of GABA from inhibitory neurons at the NMJ Blocks the relaxation pathway in muscles Inhibition is irreversible; new axon terminals must grow to relieve inhibition The toxin reaches the nervous system through the bloodstream as the bacteria multiply. Tetanus-Signs/Symptoms Early symptoms: Lockjaw, stiffness in the neck and abdomen, and difficulty swallowing. Later symptoms: fever elevated blood pressure severe muscle contractions Tetanus Complications: 11% of cases result in death, especially people > 60 Treatment: IV penicillin, tetanus IgG, tetanus antitoxin Prevention: DTaP Toxoid: Inactivated Toxin 1933: development of tetanus vaccine decreased the incidence of tetanus in the U.S. Botulism In the US, an average of 110 cases of botulism each year. Causative agent: Clostridium botulinum The disease occurs in three forms: Foodborne Infant Wound Disease is toxin mediated Blocks release of acetylcholine Used for many purposes Most acutely lethal toxin known to mankind L.D.50 is