Laboratory Testing in the Diagnosis and Treatment of Dizziness

6 Laboratory Testing in the Diagnosis and Treatment of Dizziness

Mikhaylo Szczupak and Michael E. Hoffer

Introduction

The etiology of dizziness can be determined by history and physical examination alone in the majority of patients, ~ 75% in large series.1 For cases when the history and physical by themselves do not elucidate a cause, a variety of sophisticated auditory and vestibular tests are available, supplemented by established and emerging imaging techniques to help determine the diagnosis. It is reasonable, then, to ask if there continues to be a role for traditional laboratory testing in the diagnosis of patients presenting with complaints of dizziness.

Recent literature is largely devoid of specific guidelines regarding the use of laboratory tests in the diagnosis and treatment of dizziness. Hoffman et al, in a meta-analysis of over 4,000 patients, demonstrated that less than 1% had abnormal laboratory tests that identified a specific cause for dizziness.¹ Several standard textbooks address laboratory tests for dizziness under the heading for specific diseases or disorders in which the laboratory test would be applicable. Even less attention is directed to the judicious use of tests in the treatment of patients with vertigo. In this chapter, we examine several specific laboratory tests that may be helpful in some cases of dizziness. We provide information about the test and then discuss how we would use the test in the diagnosis and treatment of dizziness.

Treponema pallidum Serology

Treponema pallidum is the spirochete that causes syphilis. After entering the body, the spirochete can invade any organ system and manifest with a wide array of symptoms. This allows syphilis to closely mimic many other diseases, such as Meniere’s disease, autoimmune inner ear disease, and perilymphatic fistula. Audiovestibular symptoms of Treponema pallidum infection are known to develop in secondary, tertiary, and congenital forms of syphilis. In a series of 85 patients diagnosed with otosyphilis, patients presented with symptoms of dizziness ~ 53% of the time.² The diagnosis of otosyphilis is often delayed, so this is an important entity to consider in patients with fluctuating or sudden sensorineural hearing loss (SNHL) and/or vestibular symptoms.³

Syphilis can be diagnosed accurately with two different types of serologic tests, nontreponemal tests (Venereal Disease Research Laboratory [VDRL] or rapid plasma reagin [RPR]) and treponemal tests (fluorescent treponemal antibody-absorption [FTA-ABS], Treponema pallidum passive particle agglutination [TP-PA] assay, or treponemal enzyme immunoassay [EIA]/chemiluminescence immunoassays [CIA]). Nontreponemal tests usually correlate with disease activity and may be used to monitor treatment response. On the other hand, the majority of patients with reactive treponemal tests will remain positive after treatment, so a history must be taken for prior syphilis treatment. The Centers for Disease Control and Prevention (CDC) recommends initial screening by a nontreponemal test, with reactive samples undergoing reflex testing by a treponemal test for confirmation.⁴ Syphilis cannot be accurately diagnosed with only one serologic test due to the high rates of falsenegatives in persons with primary syphilis and falsepositives in persons without syphilis.⁴ For economic reasons, the advent of automated EIA/CIA testing in large-volume clinical laboratories has led to reverse sequence testing. This process is defined as initial screening with a treponemal test and reflex testing of reactive samples with a nontreponemal test.⁵ Issues arise in determining a diagnosis in patients with discordant results (i.e., reactive treponemal test with nonreactive subsequent nontreponemal test). The CDC continues to recommend the classical serologic testing sequence, but if reverse sequence testing is used, then discordant specimens should be reflexively tested by TP-PA.⁶ Discordant samples determined to be reactive by TP-PA testing are considered to indicate past or present syphilis infection, and if serology on TP-PA is nonreactive, then syphilis is unlikely.⁶

Dizziness secondary to syphilis can masquerade as almost any form of dizziness, including patients presenting with episodic vertigo, episodic unsteadiness, and constant unsteadiness while walking. Despite the fact that syphilis can cause any form of dizziness, we obtain syphilis serology only when we cannot make a definitive or even presumptive diagnosis with history, physical exam, or vestibular tests (i.e., when we are completely stumped), or when the individual has a history suggestive of syphilis infection (which can be difficult to obtain). The Tullio phenomenon (dizziness elicited with loud noises or pressure to the ear), which was once thought to be a diagnostic sign of syphilis, can occur with other disorders, such as superior canal dehiscence and Meniere’s disease, as well as in posttraumatic dizziness. Patients exhibiting dizziness with noise or pressure should undergo a work-up to rule out the known causes, and then one may think of ordering a syphilis serology more readily in these patients.