APPROACH TO DIAGNOSIS

Approach to Diagnosis

• Signs and Symptoms or Laboratory findings pathognomonic of a disease

• Signs and Symptoms or Laboratory findings pointing to an organ or part of an organ system

• Signs and Symptoms or Laboratory findings pointing to a group of diseases

• Signs and Symptoms or Laboratory findingsn whose mechanism is well understood

• Signs and Symptoms or Laboratory findings found in the least number of disease

Presenting Manifestations

• vomiting• drowsy but arousable• weak looking• Febrile • Seizures• Photophobia• Lymphocytosis on

lumbar tap

• CNS

• INFECTION

MENINGITIS

• Meningitis is an inflammation of the membranes (meninges) and cerebrospinal fluid surrounding your brain and spinal cord

• usually due to the spread of an infection.

• The swelling associated with meningitis often triggers the "hallmark" symptoms of this condition, including headache, fever and a stiff neck.

Common Symptoms• headache,• nausea, • vomiting,• anorexia, • restlessness, • altered state of

consciousness, • and irritability

Common signs

• fever, • photophobia, • neck pain and rigidity, • obtundation, • stupor, • coma, • seizures,• focal neurologic

Common Symptoms• headache,• nausea, • vomiting,• anorexia, • restlessness, • altered state of

consciousness, • and irritability

Common signs

• fever, • photophobia, • neck pain and rigidity, • obtundation, • stupor, • coma, • seizures,• focal neurologic deficits

CAUSES OF MENINGITIS

• Infection• Viral• Bacterial• Fungi• Parasites

• Chemical irritation• Drug allergies• Fungi• Tumors

Cerebrospinal Fluid Findings in Central Nervous System Disorders

CSF FINDINGS OF PATIENT

CSF FINDINGS OF PATIENT

CSF Gram’s Stain: 11/10No microorganisms seen

CSF C/S: 11/10:Positive for bacterial growth after 14 hours

of incubation

CSF C/S: 11/10Bacillus megaterium Sensitive to: Azithromycin, Gentamycin,

Clindamycin, Penicillin, Erythromycin and TMP-SMX

ACUTE VIRAL MENINGITIS

VIRAL MENINGITIS

• Viral infections are the most common cause of meningitis• Viral ("aseptic") meningitis is serious but rarely fatal in people with

normal immune systems. Usually, the symptoms last from 7 to 10 days and the patient recovers completely. 

• Viral meningitis is usually relatively mild. • It clears up in a week or two without specific treatment. • Viral meningitis is also called aseptic meningitis.

Centers for Disease Control and Prevention

Manifestations

• usually present with headache, fever, and signs of meningeal irritation coupled with an inflammatory CSF profile

• headache is usually frontal or retroorbital • often associated with photophobia and pain on moving the

eyes. • temperature is elevated, from 38 to 40C (100.4 to 104F). • Nuchal rigidity is present in most cases • Patients often have mild lethargy or drowsiness

Harrisons Principle of internal medicine 17th Ed

Viruses Causing Acute Meningitis and Encephalitis in North America

Viral Meningitis: CSF Examination

• The typical profile is a lymphocytic pleocytosis (25–500 cells/L),

• normal or slightly elevated protein concentration [0.2–0.8 g/L (20–80 mg/dL)]

• normal glucose concentration• normal or mildly elevated opening pressure (100–350

mmH2O).

COMMON VIRAL ETIOLOGIES

• Enteroviruses • are the most common cause of viral meningitis• incidence of enteroviral meningitis declines with increasing age, • Meningitis outside the neonatal period is usually benign• sudden onset of fever; headache; nuchal rigidity; and often

constitutional signs, including vomiting, anorexia, diarrhea, cough, pharyngitis, and myalgias.

• The physical examination • :exanthemata, hand-foot-mouth disease, herpangina, pleurodynia,

myopericarditis, and hemorrhagic conjunctivitis.

• The CSF : • lymphocytic pleocytosis (100–1000 cells/L)

• normal glucose and normal or mildly elevated protein concentration

• Treatment is supportive, and patients usually recover without sequelae

• Arbovirus • Arbovirus meningoencephalitis is typically associated with a CSF

lymphocytic pleocytosis, normal glucose concentration, and normal or mildly elevated protein concentration.

• Definitive diagnosis of arboviral meningoencephalitis: demonstration of viral-specific IgM in CSF or seroconversion.

• Mumps meningitis• occurs sporadically throughout the year,• Males are affected three times more frequently than females. • Other manifestations of mumps infection—parotitis, orchitis,

mastitis, oophoritis, and pancreatitis—may or may not be present.

TREATMENT

• Treatment of almost all cases of viral meningitis is primarily symptomatic and includes use of analgesics, antipyretics, and antiemetics

• Oral or intravenous acyclovir may be of benefit in patients with meningitis caused by HSV-1 or -2 • Seriously ill patients : intravenous acyclovir (15–30 mg/kg per day

in three divided doses), • which can be followed by an oral drug such as acyclovir (800 mg,

five times daily), famciclovir (500 mg tid), or valacyclovir (1000 mg tid) for a total course of 7–14 days.

ACUTE BACTERIAL MENINGITIS

ACUTE BACTERIAL MENINGITIS

• one of the most potentially serious infections occurring in infants and older children

• an acute purulent infection within the subarachnoid space• result in decreased consciousness, seizures, raised intracranial

pressure (ICP), and stroke• N. meningitidis accounts for 25% of all cases of bacterial meningitis

(0.6 cases per 100,000 persons per year) and for up to 60% of cases in children and young adults between the ages of 2 and 20

Harrisons Principle of internal medicine 17th Ed

Common Pathogens

• NEISSERIA MENINGITIDIS• Five serogroups of meningococcus, A, B, C, Y, and W-135• Nasopharyngeal carriage of N. meningitidis occurs in 1–15% of adults. • Colonization may last weeks to months; recent colonization places nonimmune

younger children at greatest risk for meningitis. The incidence of disease occurring in association with an index case in the family is 1%, a rate that is 1,000-fold the risk in the general population.

• Children younger than 5 yr have the highest rates of meningococcal infection.

• HAEMOPHILUS INFLUENZAE TYPE• Invasive infections occurred primarily in infants 2 mo–2 yr of age; peak incidence

was at 6–9 mo of age, and 50% of cases occurred in the 1st yr of life. • The risk to children was markedly increased among family or daycare center

contacts of patients with H. influenzae type b disease. • Incompletely vaccinated individuals, those in underdeveloped countries who are not

vaccinated, and those with blunted immunologic responses to vaccine (children with HIV infection) remain at risk for H. influenzae type b meningitis.

CLINICAL PRESENTATION

• acute fulminant illness • that progresses rapidly in a few hours

• subacute infection • progressively worsens over several days

• classic clinical triad • Fever• headache• nuchal rigidity

• A decreased level of consciousness occurs in >75% of lethargy to coma. • Nausea, vomiting, and photophobia

CLINICAL MANIFESTATION

• Headache, emesis• Increase ICP

• Decrease level of Consciousness• brain tissue may swell, with increasing pressure inside the

skull and a risk of swollen brain tissue getting trapped

• Seizures• common in the early stages of meningitis (30% of cases)

and do not necessarily indicate an underlying cause.•  result from increased pressure and from areas of

inflammation in the brain tissue

• Fever• Due to infection

TREATMENT

• Bacterial meningitis can be treated with a number of effective antibiotics. It is important that treatment be started early in the course of the disease. If bacterial meningitis is suspected, initial treatment with ceftriaxone and vancomycin is recommended. Appropriate antibiotic treatment of the most common types of bacterial meningitis should reduce the risk of dying from meningitis to below 15%, although the risk is higher among the elderly.

Fungal meningitis

• is rare, but can be life threatening.

• people at higher risk include those who have AIDS, leukemia, or other forms of immunodeficiency

• Cryptococcus• The most common cause of fungal meningitis for people with immune system

deficiencies, like HIV

• Candida, • The fungus that causes thrush, can lead to meningitis in rare cases, especially in

pre-mature babies with very low birth weight. 

• Histoplasma Meningitis • due to  can happen in anybody, but people with immunodeficiencies are at a higher

risk.  

• Coccidioides• Soil in Southwestern United States and northern Mexico contain the fungus  which can cause

fungal meningitis. 

• people at higher risk include African Americans, Filipinos, pregnant women in the third trimester, and immunocompromised persons.

Centers for Disease Control and Prevention

• Symptoms of fungal meningitis are similar to symptoms of other forms of meningitis;

• often appear more gradually.

• In addition to typical meningitis symptoms, like headache, fever, nausea, and stiffness of the neck, people with fungal meningitis may also experience:• Dislike of bright lights• Changes in mental status, confusion• Hallucinations• Personality changes

TREATMENT

• Fungal meningitis is treated with long courses of high dose antifungal medications. This is usually given using an IV line and is done in the hospital. The length of treatment depends on the status of the immune system and the type of fungus that caused the infection. For people with immune systems that do not function well because of other conditions, like AIDS, diabetes, or cancer, there is often a need for longer treatment.

TB MENINGITIS

• The incidence of CNS TB is related to the prevalence of TB in the community, and it is still the most common type of chronic CNS infection in developing countries

• Predisposing factors for the development of active TB include malnutrition, alcoholism, substance abuse, diabetes mellitus, corticosteroid use, malignancy, head trauma, and HIV infection.

• caused by Mycobacterium tuberculosis, • the bacteria that causes tuberculosis. The bacteria spreads to the

brain from another site in the body.

• Papilledema is the most common visual effect of TBM. • In children, papilledema may progress to primary optic atrophy and

blindness resulting from direct involvement of the optic nerves and chiasma by basal exudates

• CN VI is affected most frequently by TBM, followed by CNs III, IV, VII, and, less commonly, CNs II, VIII, X, XI, and XII

• Sudden onset of focal neurological deficits: monoplegia, hemiplegia, aphasia, and tetraparesis, has been reported.

• Vasculitis with resultant thrombosis and hemorrhagic infarction may develop in vessels that traverse the basilar or spinal exudate or lie within the brain substance. 

• Tremor is the most common movement disorder seen in the course of TBM.

• The best antimicrobial agents in the treatment of TBM include :• isoniazid (INH), • rifampin (RIF), • pyrazinamide (PZA)• streptomycin (SM)

• all of which enter CSF readily in the presence of meningeal inflammation.

• Ethambutol is less effective in meningeal disease unless used in high doses