Congenital Neurosyphilis, Gumma of the Central Nervous System and Slow Virus Infections
The stigmata present at birth include hydrocephalus, mental retardation, seizures, chorioretinitis, optic atrophy, and nerve deafness. These may be associated with other evidences of congenital syphilis. Neurological involvement developing later in congenital syphilis may take the form of meningovascular lesions, optic atrophy, tabes dorsalis or GPI. The late parenchymal lesions occur at a much younger age (juvenile GPI, juvenile tabes).
Diagnosis: Neurosyphilis should be considered in the differential diagnosis of all neurological disorders. GPI should be differentiated from cerebrovascular disorders, primary dementias, intra-cranial space occupying lesions and progressive degenerative lesions. Tabes dorsalis has to be considered in the differential diagnosis of lesions such as diabetic, toxic and nutritional neuropatheis, heredofamilial, ataxias and syringomyelia. Presence of Argyll Robertson pupil is a very strong point to support the diagnosis of neurosyphilis.
Laboratory diagnosis; Blood serology is positive in 60-70% of cases. The CSF changes are present in many. These include lymphocytic pleocytosis, rise in proteins and a positive Lange’s colloidal gold curve (which may be tabetic or paretic). The CSF changes depend on the activity of the disease. Previous treatment tends to minimize the abnormalities.
Prognosis: Treatment may clear up meningovascular lesion completely. The results are poor in established cases of tabes and optc atrophy. In GPI considerable improvement may occur.
Treatment: Penicillin is given. Repeated courses may be required and this has to be decided depending upon blood and CSF serology repeated at 6 and 12 months after initial therapy. Tabetic pains may respond to analgesics and carbamazepine in a dose of 100mg thrice daily. Visceral crises are treated by sedation and supportive measures.
Gumma of the central nervous system
Gumma occurs in the third stage of syphilis. Pathologically, the gumma consist of collagen deposition forming an amorphouse matric with lymphocytes and plasma cells at the periphery and multinucleated giant cells in the center. T.Pallidum is not demonstrable in these lesions. Gumma may be seen in various situations cranial, dural, leptomeningeal, cerebral and spinal. These behave like space occupying lesions. response to antisyphilitic treatment is poor. Line of management is to excise the lesions and give antisyphilitic therapy.
Syphilitic deafness: Deafness may result from several reasons in the different stages of syphilis. It may result from affection of the cochlea, acoustic nerve, basal meninges or damage to the middle ear.
Slow virus infections
Some viruses are capable of remaining dormant in the nerve tissue for long periods and produce damage over several years. These are characterized by long incubation period, slow progressive course, and in many cases a fetal termination. The following two groups are distinguishable:
1. In the first group, the viral agents are identifiable e.g, subacute sclerosing panencephalitis and progressive multifocal leuconencephalopathy;
2. In the second group, the viruses have not been clearly identified, they are resistant to antiviral drugs and they do not evoke marked antibody response, e.g, Kuru and Jakob-Crutzfeldt disease.
Subacute sclerosing panencephalitis (SSPE) is caused by measles virus. It occurs in children. It causes gross abnormalities in intellectual functions and other motor and sensory disturbances. The disease runs a course of 3.9 months to end fatally. In Kuru and Jakob-Creutzfeldt disease, there is strong evidence of a viral etiology, though, the actual viruses have not been identified. Progressive multifocal leukoencephalopathy (PML) is caused by a Papoa virus (SV 40 Jc Virus). It leads to progressive demyelination occurring multifocally. PML is seen in association with immunosuppressed states and lymphomas.