Instructions for users • This slide presentation provides an overview of the clinical manifestations and diagnosis of encephalitis. • Below many of the slides, there are notes to explain the information in the slide. • You should adapt the presentation for your own use. • If you want to present this topic in a more in-depth way, useful resources are listed at the end of the presentation.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Instructions for users
• This slide presentation provides an overview of the clinical manifestations and diagnosis of encephalitis.
• Below many of the slides, there are notes to explain the information in the slide.
• You should adapt the presentation for your own use.
• If you want to present this topic in a more in-depth way, useful resources are listed at the end of the presentation.
Recognizing Encephalitis:Clinical Manifestations and Diagnosis
Participants will:• Identify common causes of encephalitis.
• Take a complete history from a patient with encephalitis.
• Conduct a thorough physical examination for a patient with encephalitis.
• Know the steps to conduct a successful lumbar puncture.
• Identify the appropriate laboratory investigations for a patient presenting with encephalitis.
Learning objectives
Raj is a 5-year-old previously healthy boy who is brought in to his local health clinic by his mother with complaints of fever, poor appetite, and drowsiness.
— What questions do you want to ask?
Clinical Case
Photo credit: Dr. Julie Jacobson
• The patient’s mother reports a 3 day history of not eating and high fevers at night. He started vomiting this morning and complained that his “tummy” and head hurt.
• Patient is not taking any medications. No one else is sick at home. Patient has received his routine immunizations.— What are important parts of your physical
Lymphocytes), glucose 80, protein 110— Anti-JEV IgM- pending
• Patient’s clinical presentation and findings on CSF are more consistent with encephalitis than meningitis. An IV is placed and Raj is started on antibiotics and IV hydration. He becomes more alert and responsive. His CSF is sent to the state lab and comes back later positive for Japanese encephalitis.
Clinical case- laboratory testing
• Encephalitis is an inflammation of the brain tissue due to infection.
• Most often caused by viruses that pass into blood stream and then into cerebral spinal fluid, leading to destruction of neural cells and inflammation of brain parenchyma.
— Primary or acute encephalitis
• May also result from a viral-mediated inflammatory response in the brain following an acute, systemic infection.
— Secondary or post-infectious encephalitis
What is encephalitis?
Viral infections of the Central Nervous System (CNS) result in the following clinical syndromes:
Note: A single infection can affect multiple locations of the CNS, making clinical diagnosis difficult (i.e., meningomyeloencephalitis)
Clinical syndrome Part of CNS affected
Encephalitis Brain Parenchyma
Aseptic meningitis Meninges
Myelitis Spinal Cord
Neuritis Peripheral Nerves
• Unfortunately, the clinical syndromes and results of routine laboratory tests are typically nonspecific and often do not help distinguish encephalitis and viral meningitis.
• Patients may have symptoms of both parenchymal and meningeal processes.
— i.e., A patient with stiff neck and photophobia, though classic signs of meningitis, could in fact also have encephalitis! (called meningoencephalitis)
• It is important to recognize other infectious and noninfectious causes, particularly those which are treatable
How to distinguish encephalitis from viral meningitis
Encephalitis vs. meningitisEncephalitis
Viral Meningitis
Constitutional symptoms
Fever Yes Yes
Headache, nausea, vomiting, lethargy Yes Yes
Photophobia, neck stiffness No Yes
Neurologic dysfunction
Seizures Yes Minimal
Cranial nerve palsies, paralysis Yes No
Altered mental status (i.e. confusion, coma)
Yes Minimal
Inflammation of brain parenchyma secondary to infection is known as?
a. Meningitis
b. Encephalitis
c. Neuritis
d. Epilepsy
QUIZ
• Viruses (most common)— More than 100 different viruses can cause acute
encephalitis— Seasonal and geographic distribution can help narrow
differential diagnosis— Examples of common viruses:
– Arboviruses
– Enteroviruses
– Mumps, Varicella
– Herpes simplex virus
– Influenza
– Rabies
What causes encephalitis?
*Note: A large number of reported cases of encephalitis are due to an unspecified cause
• Arboviruses or “arthropod-borne viruses” are the primary cause of encephalitis in many countries.
• Arthropods that transmit the viruses include mosquitoes and ticks.
• Common arboviruses include Japanese encephalitis, West Nile, and Dengue viruses.
Overview of physical exam (2)• Head, eyes, ears, nose and throat:
— pupils equal and reactive, corneal clouding, neck stiffness?
• Heart:— gallop rhythm, slow heart rate?
• Chest:— rales, crackles, signs of pneumonia, respiratory distress?
• Abdomen:— enlargement of liver or spleen?
The neurological exam
Remember:
The neurological exam in an encephalitis patient is part of the general physical examination. Thus, the neurologic exam should always be preceded by and interpreted in the context of a more general examination.
The neurologic exam
1. Mental status
— Level of alertness:– AVPU scale for rapid assessment: Alert / Responds to
voice / Reacts to pain / Unconscious– Glasgow Coma Scale or other coma scale
— Orientation, memory, speech, etc.
— Irritability, aphasia?
The neurologic exam (2)
3. Motor exam— Assess strength, tone of upper and lower extremities
– Compare sides— Abnormal movements or posturing?
4. Sensory system— Assess pain, vibration, temperature sensation
6. Coordination and Gait— Finger-to-nose test, Romberg test— Tandem (heel to toe) walking
Source: http://medicine.tamu.edu/neuro
Romberg Test
Source: http://medicine.tamu.edu/neuro/index.html
Tandem walking
Photo credit: Dr. Rao
Based on symptoms and signs:• Provide an initial assessment. • Determine which laboratory tests are required.• Develop a care plan.• Communicate the information with the parents or
caregiver.• Report suspected case of encephalitis to local
health authorities!
At completion of physical examination
Which of the following abnormalities in the neurological exam can be seen in a patient with encephalitis?
a. Decreased level of alertness
b. Abnormal movements of the lips
c. Paralysis of left arm
d. Abnormal finger-to-nose test
e. All of the above
QUIZ
Photo credit: Dr. Julie Jacobson
For surveillance purposes, WHO defines a case of acute encephalitis by:
— An acute febrile illness, AND— A change in mental status (such as confusion,
disorientation, inability to talk, coma) AND/OR— New onset seizures, excluding simple febrile seizures*
Acute encephalitis syndrome (AES):
* Simple febrile seizure: a single seizure lasting < 15 minutes with recovery of consciousness within 60 minutes, in a child aged 6 months to 5 years.
• For surveillance purposes, JE is also commonly reported under the heading of “acute encephalitis”.
• In WHO’s guidelines for JE surveillance, syndromic surveillance for JE is recommended. This means all cases of acute encephalitis syndrome (AES) should be reported.
• Laboratory confirmation of suspected cases is done where feasible.
Surveillance for cases of encephalitis
Which of the following is NOT part of the WHO case definition for acute encephalitis syndrome?
a. Fever
b. Change in mental status
c. Diffuse rash
d. New onset seizure
QUIZ
Laboratory studies of suspected encephalitis• Lumbar puncture
— CSF analysis and culture
• Blood, urine, secretion cultures
• Serum and CSF antibody testing
• Neurodiagnostic testing— Magnetic resonance imaging (MRI) or Computed
Tomography (CT) scan— Electroencephalogram (EEG)
Importance of performing a Lumbar Puncture (LP) in a patient with suspected encephalitis
• Collection and testing of spinal fluid are standard management for any patient with suspected CNS infection to direct treatment (e.g., if CSF profile suggests bacterial infection).
• An LP should be performed by a skilled healthcare provider.
• For detailed review of LP procedure and technique, see separate presentation.
Steps in performing a lumbar puncture
1. Obtain informed consent.
2. Gather materials.
3. Position patient.
4. Administer local anesthetic.
5. Insert needle with sterile technique.
6. Measure opening pressure.
7. Collect cerebrospinal fluid (CSF).
• Evidence of a space-occupying lesion such as a tumor or brain abscess.
Which of the following are possible complications of encephalitis infection?
a. Paralysis
b. Hearing loss
c. Seizure disorder
d. Decreased intelligence
e. All of the above
QUIZ
• Acute encephalitis is a medical emergency.
• Any patient presenting with fever and impaired mental status or neurological exam should be evaluated for encephalitis.
• The diagnosis of encephalitis is clinical.— Don’t forget the value of a good history and physical exam.
• All suspected cases of encephalitis should be reported to local authorities.
Important points to remember
Gutierrez, KM, Prober, CG. Encephalitis: identifying the specific cause is key to effective management. Postgraduate Medicine. 1998;103(3):123-125, 129-130, 140-143.
Huang, C, Chatterjee, NK, Grady, LJ. Diagnosis of viral infections of the central nervous system. New England Journal of Medicine. 1999;340(6):483-484.
Kabilan L, Rajendran R, et al. Japanese encephalitis in India: An overview. Indian Journal of Pediatrics. 2004;71:609-615.
Mandell GL, Bennett JE, Dolin R, editors. Principles and practice of infectious diseases. Philadelphia: Churchill Livingstone; 2000.
National Institute of Neurological Disorders and Strokes (NINDS). Encephalitis and meningitis [fact sheet]. Bethesda: National Institute of Health; 2004. Available at: http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm
Solomon, T, Dung, NM, Kneen, R, et al. Seizures and raised intracranial pressure in Vietnamese patients with Japanese encephalitis. Brain. 2002; 125:1084-1093.
U.S. Centers for Disease Control and Prevention (CDC). Japanese encephalitis [fact sheet]. Fort Collins: CDC; 2004. Available at: http://www.cdc.gov/ncidod/dvbid/jencephalitis
Whitley, RJ. Viral encephalitis. New England Journal of Medicine. 1990;323(4):242-250.