Understanding Syphilis and Lues

Syphilis, also known as lues, is a chronic bacterial infection caused by Treponema pallidum. It is typically transmitted through sexual contact or from mother to child during pregnancy. The disease progresses through primary, secondary, latent, and tertiary stages. If left untreated, syphilis can involve multiple organ systems, including the nervous system and the ear.

What Is Otosyphilis?

Otosyphilis is a form of late syphilis that affects the inner ear and the auditory pathways. It can occur during any stage of the disease, but it is most often seen in the tertiary or latent phases. The bacterium invades the temporal bone and the eighth cranial nerve, leading to progressive damage. Otosyphilis is an important cause of reversible or preventable hearing loss and dizziness, especially in middle-aged and older adults.

Key Symptoms: Dizziness and hearing loss

The two most characteristic symptoms of otosyphilis are dizziness and hearing loss. These may appear separately or together, and their onset can be gradual or sudden.

• Hearing loss: Typically sensorineural, affecting both ears in most cases, although it may initially be unilateral. Hearing loss can progress rapidly over weeks or months. Tinnitus (ringing in the ears) frequently accompanies the hearing loss.
• Dizziness: Patients often experience episodes of vertigo, a spinning sensation, or persistent imbalance. The vertigo resembles that of Meniere's disease, with fluctuating hearing, a feeling of fullness in the ear, and attacks of dizziness.

Other symptoms may include unsteadiness when walking, nausea, and a sensation of motion intolerance. Because these symptoms overlap with other inner ear disorders, otosyphilis can be easily misdiagnosed.

How Otosyphilis Causes Ear Damage

The infection reaches the inner ear either through the bloodstream or by direct spread from the meninges surrounding the brain. Once inside the labyrinth, Treponema pallidum triggers an inflammatory response that damages the hair cells of the cochlea and the vestibular organs. This inflammation also affects the endolymphatic fluid, causing hydrops, which accounts for the Meniere-like attacks of dizziness. In some cases, gummatous lesions form in the temporal bone, further destroying auditory and vestibular structures.

Diagnosis of Otosyphilis

Diagnosis is based on a combination of clinical suspicion, serological tests, and audiovestibular testing. A history of syphilis, especially if previously untreated or inadequately treated, raises the likelihood of otosyphilis.

• Blood tests: Nontreponemal tests such as RPR and VDRL, followed by treponemal tests such as FTA-ABS or TP-PA, confirm exposure to syphilis.
• Audiometry: Reveals sensorineural hearing loss, often with poor speech discrimination out of proportion to the pure tone thresholds.
• Vestibular testing: Electronystagmography or caloric testing may show reduced vestibular response on the affected side.
• Imaging: High-resolution CT or MRI of the temporal bones can demonstrate inflammatory changes, bone erosion, or enhancement of the cochlea and vestibular labyrinth.

A lumbar puncture may be performed to look for neurosyphilis, as otosyphilis is often considered a form of neurosyphilis.

Treatment

Early treatment is essential to preserve hearing and reduce dizziness. The recommended regimen is similar to that for neurosyphilis and includes high-dose intravenous penicillin G for 10 to 14 days, sometimes followed by intramuscular benzathine penicillin once weekly for several weeks. For patients allergic to penicillin, desensitization is advised, as alternative antibiotics are less effective in the central nervous system.

In addition to antibiotics, corticosteroids (prednisone) are often prescribed to reduce inflammation and may help stabilize or improve hearing. Some patients require symptomatic treatment for vertigo, including vestibular suppressants or rehabilitation exercises. Hearing aids and cochlear implants are options for those with permanent hearing loss.

Prognosis

The outcome depends on the stage of the disease at diagnosis. Patients treated early may experience improvement in hearing and resolution of dizziness. Chronic cases can result in permanent damage, but treatment can halt progression in many individuals. Regular follow-up with audiometry and balance assessments is necessary to monitor the disease.