Otosyphilis

Otosyphyilis, otic syphilis or syphilitic labyrinthitis is a manifestation of neurosyphilis affecting the inner ear.

For a general discussion, and for links to other system-specific manifestations, please refer to the article on syphilis.

Pathology

The pathological features of syphilitic labyrinthitis consist of:

• severe endolymphatic hydrops
• degeneration of the membranous labyrinth
• diffuse osteitis

Electrocochleography of otosyphilis patients is similar to those of Meniere disease.

Diagnosis

The FTA-Abs assay reliably indicates a history of exposure to Treponema pallidum or cross-reacting antigen, however, does not distinguish between active and treated disease. Whilst FTA-Abs assays have high sensitivity and specificity (100% and 98% respectively) due to the very low levels of disease prevalence the positive predictive value is only 22%. Western blot assays are however able to confirm if the infection is active. Clinically, patients report vertigo that lasts minutes to hours, and the Tullio phenomenon may also be present, whereby motion of the tympanic membrane and ossicular chain (loud noise) can induce vertigo and nystagmus (Hennebert sign) in patients with otic syphilis, but may also occur in perilymph fistula and semicircular canal dehiscence.

Radiographic features

Radiographic features are best appreciated on MRI:

• gummas may be seen in the internal auditory canal
• there may be radiographic evidence of osteitis and osteolysis of the adjacent temporal bone

Furthermore, other manifestations of neurosyphilis may also be evident, in particular, those of acute syphilitic meningitis .