Infectious Diseases of the Brain PDF

Meningitis (most common) Despite vaccination, diagnosis, and treatment still millions of cases happen worldwide ○ 3 major signs: stiff neck, worst headache of their life, and fever ○ Signs of increased intracranial pressure and encephalitis: projectile vomiting...

Meningitis (most common) Despite vaccination, diagnosis, and treatment still millions of cases happen worldwide ○ 3 major signs: stiff neck, worst headache of their life, and fever ○ Signs of increased intracranial pressure and encephalitis: projectile vomiting and delirium Life-threatening disease ○ Patients who acquire meningitis have a risk of death ○ Evaluate ON, findings of papilledema, ddx encephalitis Most common causes: bacteria (#1) and viruses (#2) Less common: fungi and parasites, other autoimmune disorders ○ Chronic autoimmune after the use of corticosteroids can increase the risk of meningitis Definition: Inflammation of the meninges ○ Dura mater, arachnoid, pia mater; sub-arachnoid space ○ Line the vertebral canal and scull enclosing the brain and spinal cord Risk factors: ○ Chronic medical disorders (renal failure, diabetes, adrenal insufficiency, cystic fibrosis- lung disease that can appear in other organs and cause organ failure) Older patients have a higher risk of developing diseases from immunocompromised systems ○ Extremes of age less than 5 years or older than 65 years Too young and too old; age is also a risk ○ Undervaccination Must get the complete dosages of vaccinations; especially in children Higher risk for those who do not receive vaccines Perform cultures (lumbar puncture) for those who are not vaccinated Lumbar puncture is done after R/O a lot ○ Immunosuppressed states (iatrogenic, transplant recipients, congenital immunodeficiencies, AIDS) Have the highest risk  ○ Living in crowded conditions (military barracks, college dorms) ○ Exposures: Travel to endemic areas (Southwestern U.S. for cocci; Northeastern U.S. for Lyme disease- transmitted by ticks from deers and can complicate meningitis) Vectors (mosquitoes can be vectors for meningitis and transmit infection, ticks) Mosquitos are the #1 vector that kills people ○ Alcohol use disorder For those who intake alcohol and liver is not working; if they have cirrhosis it is worse ○ Presence of ventriculoperitoneal (VP) shunt Decrease the overproduction of CSF (hydrocephalus) or obstruction which is the common cause; the cerebra of the aqueduct is the common obstruction place It does not make lumen ○ Bacterial endocarditis Hematogenous spread ○ Malignancy (cancer; any type) ○ Dural defects ○ IV drug use (especially IV drug users who do not clean syringes; they use it multiple times & overuse the syringe- after so many uses it can become flat and they do not care) Very common reason to acquire infections ○ Sickle cell anemia Thrombosis increases risk of the meninges ○ Splenectomy Spleen is in charge of immunecomplements; we need the spleen to produce WBCs, immunoglobulins Most common causes: ○ Bacterial (#1) Streptococcus pneumoniae 50-60% Group B Streptococcus Neisseria meningitis 14-37% Hemophilus influenza 3-4% Listeria monocytogenes 4-11% ○ Viruses Enteroviruses 85% (very common to see if viral cause) Group B Coxsackievirus and Echovirus Herpes family viruses 4% HSV-2, HSV-1, VZV, EBV, CMV Other: Mumps, Measles, Influenza, HIV ○ Fungi Cryptococcus neoformans Coccidioides Aspergillus Candida Mucormycosis (Diabetes Mellitus and transplant recipients- have to use corticosteroids for a long period of time) Can also see in paranasal sinuses ○ Other rare causes Leptospirosis History of exposure to rodent, dog, or livestock urine, and often have associated jaundice and renal dysfunction Aggregation of water; rats were transmitting the egg or larvae that come from stool from cats or animals and leaving in places where someone can come into contact with the contaminated water ○ How it enters the skin is through small, small wounds Parasites Amebic disease secondary to Naegleria fowleri and Acanthamoeba species is fulminant and usually occurs in persons with exposure to freshwater lakes  Acanthamoeba: can also appear in the cornea; Severe pain is the common sign and does not heal after given tx for a long [period of time and suspect Acanthamoeba keratitis (ring as a characteristic) ○ Pathophysiology Hematogenous seeding Bacteria colonize the nasopharynx and enter the bloodstream after mucosal invasion, make their way to the subarachnoid space and bacteria cross the brain-blood barrier, causing inflammation and immune-mediated reactions Enters the nasopharynx** ○ Who is in charge of the brain barrier? Even in the retina? Tight junctions* when they are broken, allow inflammatory responses and the entrance of bacteria White and grey matter: parenchyma Direct contagious spread Organisms enter CSF via neighboring anatomic structures Otitis media, sinusitis Foreign objects (medical devices, penetrating trauma) Surgical procedures ○ Paranasal sinuses surgical procedures Viruses can penetrate CNS via retrograde transmission along neuronal pathways or by hematogenous seeding ○ Symptoms Fever Neck pain/stiffness Headache Photophobia Dizziness Confusion  Delirium Irritability Nausea/vomiting Petechiae* ○ Signs Increased intracranial pressure Altered mental status Neurologic deficit Seizures If these signs present, poor prognosis for the patient Important to treat asap Best culture for this is lumbar puncture ○ Clinical presentation Kerning’s Sign: unable to put the leg in 90 degrees If these are positive, we are highly suspecting meningitis ○ Evaluation CSF analysis by lumbar puncture  Blood cell count Glucose Protein Culture PCR CSF lumbar puncture findings ○ Decreased glucose levels in the CSF is a finding ○ R/O fungal infection if ??? ○ Severe WBCs elevated: decreased glucose in CSF, and intracranial pressure and culture will show pathogen Additional testing should be performed tailored to suspected etiology: Viral: multiplex and specific PCRs Fungal: CSF fungal culture, India ink stain for cryptococcus ○ WBCs are decreased ○ TB can also give you meningitis Mycobacterial: CSF Acid-fast bacilli smear and culture Syphilis: CSF VDRL Lyme Disease: CSF burgdorferi antibody ○ Diagnostic tests: localize the inflammatory place and make ddx with encephalitis and abscesses Encephalitis: The mass (parenchyma) is swollen versus abscess: localized lesion in the parenchyma Meningitis is more peripherally or spinal cord Brain CT scan  ○ Frontal empyema, and abscess formation in a patient with bacterial meningitis ○ MRI w/ and w/o contrast enhancement (appears on the thicker borders, white in color because of the inflammation) of meninges ○ CSF will change in color because of the contrast; ventricles are filled with contrast and appear thicker because absorb the dye more ○ Gallodium (most common dye to perform CT scan or MRI): contraindicated with patients using metformin; have to stop medication at least 3 days before scan Empyema or abscess Contrast Enhancement of Meninges Blood culture CT/MRI are better Serum glucose Complications: patients w/ diabetics have to control glucose levels Renal and liver function HIV test ○ Differential diagnosis Encephalitis  Distinguished by the absence of meningeal symptoms and the presence of diffuse neurologic deficits such as altered mentation, confusion, and seizures ○ Inflammation of the brain mass (parenchyma) and is in the enter versus meninges are surrounding Most common etiology of Herpes Simplex Virus (HSV1) Headache is meningitis is more severe; nausea and vomiting are more common in meningitis Encephalitis has more neurological conditions; the symptoms start at the beginning whereas complicated meningitis have delirium, seizures that come in the end Virus is the #1 cause of encephalitis Focal brain lesion (infectious or malignant) Are more likely to present with focal neurologic complaints and can be detected by CT imaging Abscesses will not have a stiff neck versus meningitis do Nausea, vomiting, seizures, delirium, papilledema are the common signs of increased intracranial pressure  ○ Non-bacterial meningitis treatment Viral Acyclovir (IV) Fungal Amphotericin B IV + Flucytosine PO ○ Bacterial meningitis treatment Vancomycin 2 years to 50 years (Vancomycin + either Cefotaxime or Ceftriaxone; add ampicillin if the patient at risk for L monocytogenes > 50 years (Vancomycin + Ampicillin + either Cefotaxime or Ceftriaxone) ○ 40 years or more should be recommended to take the pneumococcal vaccine Children usually receive from 9 months to 55 years (Menactra)