This takes the form of progressive blindness beginning in one eye and then involving the other and may occur within months of the primary infection as part of meningovascular syphilis, or as a later manifestation. The usual finding is a constriction of the visual fields, but scotomata may occur in rare cases. The optic discs are gray-white. The CSF is almost invariably abnormal, although the degree of abnormality may be slight in some cases. The prognosis is poor if vision in both eyes is greatly reduced. If only one eye is badly affected, sight in the other eye can usually be saved. In exceptional cases, visual impairment may progress, even after the CSF becomes negative. The pathologic changes consist of perioptic meningitis (inflammatory reaction surrounding the optic nerves, chiasm and tracts), with subpial gliosis and fibrosis replacing degenerated optic nerve fibers. Exceptionally there are vascular lesions with infarction of central parts of the nerve.
There are several types of spinal syphilis other than tabes. Two of them, syphilitic meningomyelitis (formerly called Erb spastic paraplegia because of the predominance of bilateral corticospinal tract signs) and spinal meningovascular syphilis, are observed from time to time, although less often than tabes. Spinal meningovascular syphilis may occasionally take the form of an anterior spinal artery syndrome. In meningomyelitis, there is subpial loss of myelinated fibers and gliosis as a direct result of the chronic fibrosing meningitis. Gumma of the spinal meninges and cord seldom is found. It was not present in a single case in Merritt and Adams’ study of spinal syphilis. Progressive muscular atrophy (syphilitic amyotrophy) is a very rare disease of questionable syphilitic etiology; most cases are degenerative (see Chap. 38). Also rare is syphilitic hypertrophic pachymeningitis or arachnoiditis, which allegedly gives rise to radicular pain, amyotrophy of the hands, and signs of long tract involvement in the legs (syphilitic amyotrophy with spastic-ataxic paraparesis). In all these syndromes there is an abnormal CSF, unless, of course, the neurosyphilitic infection is burned out.
The prognosis in spinal neurosyphilis is uncertain. There is improvement or at least an arrest of the disease process in most instances, although a few patients may progress slightly after treatment is begun. A steady advance of the disease in the face of a negative CSF usually means that there has been a secondary constrictive myelopathy or that the original diagnosis was incorrect and the patient suffers from some other disease, for example, a spinal form of multiple sclerosis as a degenerative disease.
This may occur in either early or late syphilitic meningitis and may be combined with other syphilitic syndromes. Because this may produce a treatable vestibular syndrome of vertigo, with or without hearing loss, syphilis serology should be tested in patients with cryptic vestibular dysfunction. Some of the characteristics of vestibular neurosyphilis are identical to those of Ménière disease, including episodic loss of function (Baloh and Honrubia). Curiously, there is seldom a history of clear primary syphilitic infection. The pathology, mainly endarteritis in the cochlea and labyrinths, is identical to the more common congenital syphilitic deafness, which is described in Chap. 37.
Treatment of Neurosyphilis