CNS

• Neuron - principal functional unit of the CNS; incapable of cell division
• Glia - astrocytes and oligodendrocytes
• Motor neurons - control voluntary movement
• Sensory neurons -detect incoming light,

  sound, odor, taste, pressure and heat
• Hematogenous spread - most common; infectious agents ordinarily gain access through the arterial circulation
• Direct implantation - often traumatic
• Local extension-from infected adjacent

  structures
• Meningitis -inflammatory process of the leptomeninges & CSF w/in the subarachnoid space
• Meningoencephalitis -inflammation of the meninges and brain parenchyma
• Infectious meningitis -classified into acute pyogenic (bacterial), aseptic (acute or subacute viral), and chronic (tuberculous, spirochetal, or cryptococcal)
• Tuberculomas

  • well-circumscribed intraparenchymal masses that may cause significant mass effect
• Arachnoid fibrosis - Most serious complication
• Cerebral gummas - plasma cell-rich mass lesions
• Heubner arteritis -obliterative endarteritis
• Cowdry type A - intranuclear viral inclusions
• Herpes Simplex Virus Type 1

  • most commonly in children and young adults
  • alterations in mood, memory, and behavior
  • starts in and most severely involves the inferior and medial regions of the temporal lobes and the orbital gyri of the frontal lobes
• Herpes Simplex VirusType 2

  Adults= meningitis

  Neonates= encephalitis

  Active HIV infection= acute hemorrhagic and necrotizing encephalitis
• Varicella- Zoster Virus

  Primary infection= chickenpox

  Latent phase within sensory neurons

  Reactivation of infection= shingles or herpes zoster

  Postherpetic neuralgia syndrome
• Pathognomonic finding - Negri bodies
• Epilepsy

  • chronic noncommunicable disorder of the brain that affects people of all ages