Otosyphilis as a rare cause of secondary benign paroxysmal positional vertigo: a case report

Abstract

Otosyphilis is a rare cause of audiovestibular dysfunction that can easily be misdiagnosed. Here, we report a rare case in which a patient presented with secondary benign paroxysmal positional vertigo (BPPV) 2 weeks after symptoms of otosyphilis appeared. The Dix–Hallpike test showed a classical response in the head-hanging left position. The patient was treated with intravenous penicillin G and the canalith repositioning maneuver, which completely resolved the vertigo. The patient's audiovestibular symptoms resolved gradually. The elevated cerebrospinal fluid (CSF) white blood cell (WBC) count returned to normal and the results of the Treponema pallidum particle agglutination (TPPA) test were negative at the 3-month follow-up. This report suggests that otosyphilis should be considered in the differential diagnosis of audiovestibular dysfunction in patients at risk. Additionally, clinicians should remain vigilant about the possibility of secondary BPPV in patients with otosyphilis who report positional vertigo.

Introduction

Vertigo is one of the most frequent reasons for consultation in medical practice. It is a symptom of peripheral or central vestibular dysfunction and is related to a wide clinical spectrum.^1,2 Benign paroxysmal positional vertigo (BPPV) is one of the most common forms of vertigo, with a reported prevalence of 10.7 to 140 per 100,000 individuals. ³ BPPV is characterized by repeated episodes of positional vertigo with positional and/or positioning nystagmus, and the condition can be treated effectively using specific therapeutic maneuvers. ³ BPPV may be idiopathic or secondary, and secondary BPPV is frequently caused by otoconial dislodgement associated with Meniere’s disease, head injury, vestibular neuritis, and sensorineural hearing loss.^4–7

Syphilis is a sexually-transmitted infection caused by Treponema pallidum. The incidence of syphilis has been steadily increasing, especially in developing countries.^8–10 Syphilis is known as “the great imitator,” because it can imitate the symptoms of many other diseases. Otosyphilis is an uncommon type of syphilis,^11,12 with a prevalence of ocular manifestations of 0.4% among syphilis cases. ¹³ Otosyphilis mimics a variety of auditory and audiovestibular conditions and can be misdiagnosed. The symptoms are hearing loss, tinnitus, and vestibular abnormalities, such as vertigo, imbalance, and gait instability.^11,12 Otosyphilis is a rare cause of vertigo, ¹⁴ and its clinical manifestation in vertigo is not well understood. Secondary BPPV associated with otosyphilis has been reported rarely. Here, we present an unusual case of a woman with simultaneous BPPV and otosyphilis.

This case report was approved by the Ethics Committee of Zhejiang Hospital (2022-CA-23). Informed written consent was obtained from the patient for publication of this report and any accompanying images. The reporting of this study conforms to the CARE guidelines. ¹⁵

Case report

A 33-year-old healthy, heterosexual woman presented with acute-onset positional vertigo and autonomic symptoms (e.g., nausea and vomiting) and was admitted to the Emergency Department of our hospital. She reported experiencing a room-spinning sensation when she made quick head movements, rolled over in bed, and sat up from the supine position. Two weeks earlier, she had experienced right-side tinnitus and hearing loss. Audiography indicated severe right sensorineural deafness and normal hearing in the left ear. Methylprednisolone (40 mg/day for 1 week) was administered intravenously by an otolaryngologist after a diagnosis of sudden deafness, and the symptoms were partially relieved.

Physical examination revealed hearing loss and difficulty walking in a straight line. The results of the Dix–Hallpike test on the left side revealed downbeat nystagmus lasting approximately 15 s with a complaint of severe vertigo in the test position. No other neurological symptoms, such as ataxia and signs of meningeal irritation, were observed. Audiography indicated moderate-to-severe bilateral sensorineural deafness (Figure 1). Acoustic immittance measurements for both ears exhibited an A-type curve. The video head impulse test (vHIT) revealed that bilateral semicircular canal gains were obviously decreased and accompanied by saccade movement (Figure 2). The vestibulo-ocular reflex (VOR), brainstem evoked potentials (BSEP), brain magnetic resonance imaging (MRI), and auditory nerve MRI findings were unremarkable.

Figure 1.

Audiogram of the left and right ear obtained at admission. The audiograms show severe right sensorineural hearing loss and moderate left sensorineural hearing loss.

Figure 2.

Results of the video head pulse test. The data show an obvious decrease in gain in all three semicircular canals bilaterally (horizontal, posterior, and anterior semicircular canals), which was accompanied by saccade movement.

The results of the toluidine red unheated serum test (1:4) and Treponema pallidum particle agglutination (TPPA) test were positive (signal to cutoff ratio (S/CO): 14.17). The patient was negative for human immunodeficiency virus (HIV) antibodies. The cerebrospinal fluid (CSF) pressure was 150 mm H₂0, and the fluid appeared whitish and purulent. CSF analysis demonstrated lymphocytic pleocytosis with a white blood cell (WBC) count of 40 × 10⁶/L, glucose level of 2.50 mmol/L, and elevated protein level of 0.57 g/L. Additionally, the CSF was positive for TPPA (S/CO: 13.36). A cerebrospinal fluid smear for acid fast bacilli was negative, and antigen testing for Cryptococcus neoformans was also negative.

The patient was diagnosed with left posterior canal BPPV and otosyphilis. With the patient's consent, Epley’s maneuver was performed immediately. Based on the changes in the CSF, penicillin G (2.4 million units every 4 hours) was administered intravenously for 14 days, and vitamin B12 (0.5 mg three times daily) was administered orally for 3 months. The positional vertigo and autonomic symptoms resolved after Epley’s maneuver was performed. The symptoms of tinnitus, hearing loss, and imbalance were gradually alleviated over the course of 2 weeks. At the 3-month follow-up, the CSF WBC count had returned to normal, and the result of the TPPA test was negative.

Discussion

Here, we described a rare case of otosyphilis that was misdiagnosed during the initial consult. Moreover, the symptoms of BPPV appeared 2 weeks after the symptoms of otosyphilis, and the sequence of symptoms indicate that otosyphilis may predispose patients to BPPV. Fortunately, because of the early diagnosis and timely treatment, the patient showed a good response.

Hearing loss is the most common symptom of otosyphilis, and it occurs in 80.6% to 90.6% of cases.^11,16 Hearing loss can be unilateral or bilateral and often has a sudden onset and rapid progression. Patients who report unilateral hearing impairment may have bilateral disease on audiography. ¹² Otosyphilis generally leads to sensorineural hearing loss;^11,17,18 however, conductive hearing loss has also been reported.^19–21 The audiogram for our patient indicated moderate-to-severe bilateral sensorineural deafness, which is in accordance with the reported symptoms of otosyphilis.

Vestibular dysfunction has also been documented in otosyphilis; however, very few reports have investigated the prevalence and characteristics of vertigo in these patients. Reduced VOR and abnormal deviation in the subjective visual horizontal test were reported in two syphilitic basal meningitis patients. ²² In our case, vHIT showed decreased gain in all three semicircular canals bilaterally; however, no abnormalities were found for VOR, BSEP, or brain MRI. Although these findings indicated peripheral vestibular lesions, more research on vestibular dysfunction in otosyphilis is needed. Clinicians should also consider otosyphilis as a possible diagnosis in cases of vestibular lesions.

Otosyphilis involves structures such as the temporal bone, cochleovestibular apparatus, and neural pathway. ¹² Additionally, the CSF and subarachnoid space may be involved, as 57% to 67% of patients present with abnormal CSF findings.^11,23 Syphilis may lead to complete loss of the organ of Corti, significant loss of cochlear hair cells, and cochleosaccular hydrops. ²⁴ These pathological changes in the inner ear may increase the risk of secondary BPPV as there is an increased risk of BPPV after sudden sensorineural hearing loss and head injury.^5,6 The clinical symptoms may appear either concurrently or soon after the manifestation of the primary disease. Our patient presented with sensorineural hearing loss (a symptom of otosyphilis) before she developed BPPV, 2 weeks later. Thus, our findings confirm that pathological changes that cause sudden sensorineural hearing loss may increase the risk of BPPV.

Penicillin G is the main therapeutic agent for the treatment of otosyphilis, and early treatment may improve hearing. ¹⁸ As otosyphilis is a treatable disease, it should be diagnosed as early as possible. BPPV is another treatable disease that must be identified early, especially when it occurs with other diseases. In this case, the patient was successfully treated with the canalith repositioning maneuver and intravenous penicillin G.

In conclusion, otosyphilis is a rare cause of audiovestibular dysfunction, but it should be considered in the differential diagnosis of patients at risk. Additionally, given the simultaneous presentation of BPPV and otosyphilis in our patient, clinicians should remain vigilant about the possibility of BPPV in patients with otosyphilis who report positional vertigo.