Download Chapter 17 Serologic Studies

Chapter 17 Serologic Studies
I.
Dizziness can be psychogenic or organic
a. Organic dizziness can be nonvestibular or vestibular
b. Vestibular dizziness can be central or peripheral (inner ear)
c. Inner ear dizziness can be unilateral or bilateral
II.
Serologic tests for inner ear dizziness
a. Most helpful in dizzy patients with bilateral, progressive (i.e., recent) sensorineural hearing loss
because the percentage of true positive results is higher in this patient population
b. Rapid progression of hearing loss over days or weeks distinguishes these patients from those
with age-related or noise induced sensorineural hearing loss
c. A review of family history and medications helps rule out hereditary hearing loss and ototoxicity
d. Decision to obtain serologic testing in dizzy patients is based on audiometry results
III.
Inner Ear Disorders That Prompt Serologic Studies
a. Autoimmune Inner Ear Disease
i. Clinical hallmark is bilateral, rapidly progressive sensorineural hearing loss
ii. Dizziness occurs in ~ 50% of patients and consists of lightheadedness, vertigo, or ataxia.
iii. Immune laboratory tests are used to confirm a presumptive clinical diagnosis
1. Testing should be done when symptoms are acute
a. Hearing loss has progressed within the last 3 months
IV.
Types of Immune Tests
a. Antigen specific- use homologous or heterologous inner ear tissues and search for cellular or
humoral (antibody) activity as direct evidence of immune reactivity
b. Antigen-nonspecific- do not use inner ear tissues but instead search for soluble circulating
immune complexes as indirect evidence of immune reactivity
c. Laboratory techniques
i. Antigen specific cellular immune testing
1. Lymphocyte transformation test (LTT, blast proliferation)
ii. Antigen-specific humoral testing
1. indirect immunoflurorescence,
2. enzyme-linked immunoassay
3. Western blot immunoassay
d. Predictive Values
i. Western blot better than LTT
1. some patients have positive Western blots but negative LTTs
2. Others have negative Western blots but positive LTTs
3. May reflect different etiologies or the same disease entity or different entities
e. Treatment of autoimmune inner ear disease consists of prednisone 1 mg/kg/day for 30 days
followed by slow tapering and methotrexate or cyclophosphamide for maintenance or salvage
therapy
V.
Syphilis
a. Progressive bilateral sensorineural hearing loss, with or without dizziness
b. Meniere’s syndrome with episodic vertigo is also common
c. Serologic tests are used for diagnosis because most patients with late-onset or acquired otologic
syphilis will have a negative history for syphilis and normal physical exam
d. Types of serologic tests for syphilis
i. Nontreponemal- Veneral Disease Research Laboratory and rapid plasma regain
1. Generally not ordered because of low specificity and low sensitivity in late
syphilis (the most common form of otologic syphilis)
ii. Treponemal- fluorescent treponemal antibody absorption (FTA-abs) and
microhemaggluination assay for Treponema pallidum (MHA-TP)- can be used for luetic
inner ear disease
e. Treatment for inner ear syphilis
i. Benzathine penicillin G 2.4 million units intramuscularly weekly for 3 weeks, then 3
months or an oral agent daily for 3 months in the penicillin-allergic patient
ii. Other treatments- prednisone 60 mg daily for 30 days followed by a slow tapering and
maintenance therapy as needed
VI.
Lyme Disease
a. Caused by infection with Borrelia burgdorferi
b. Transmitted by several species of tick
c. Initial manifestations consist of
i. Arthralgia
ii. Neuropathy
iii. Meningitis
iv. Myocarditis
v. Facial paralysis
vi. Sudden hearing loss and Meniere’s syndrome have been reported
d. Sensorineural hearing loss and dizziness are not initial manifestations
e. Diagnosis is based on history, tick bite (often unnoticed) and elevated serum or cerebrospinal
fluid antibodies to the organism
f. Treatment: Oral doxycycline or B-lactamose penicillin
g. Parenteral antibiotics are required for severe cases
VII.
Miscellaneous
a. Serologic tests can be obtained for HIV (human immunodeficiency virus)
b. Dizziness from HIV can vary depending on the stage of disease
c. Hausler et al found that HIV-infected patients frequently had abnormal neurootologic findings.
i. Advanced stages1. central nervous system and inner ear deficits were noted
a. including sensorineural hearing loss and vertigo