Tabes Dorsalis Health Article

Diagnosis

Diagnosis is mainly clinical. Syphilis has often been called "the great mimicker" and requires an astute physician to diagnose. There are three steps in diagnosis.

First, the physician has to suspect the diagnosis. The classic signs seen in tabes dorsalis are a triad of 3A's; Argyll-Robertson pupil, areflexia (absent tendon reflexes), and ataxia. Poor visual acuity, asymmetrical eye movement, deafness, clumsy hand and leg movements are other tell-tale signs.

Secondly, it has to be differentiated from other disorders that can present similarly. This is done with the help of CT scans, MRI scans, spinal tap and certain screening blood tests. The most common screening blood test is called the Venereal Disease Research Laboratory (VDRL) test. This measures the level of certain antibodies that are elevated in the blood in syphilis. It reflects disease activity and therefore may be falsely negative in very late "burnt out" cases of tabes. On the other hand, it maybe falsely elevated in a host of other medical conditions. Therefore, it is a sensitive but not a very specific test. It is only a screening test and any positive result has to be confirmed with other blood tests. The cerebrospinal fluid (CSF) circulates around the brain and spinal cord and reflects underlying inflammation. In tabes, the white cell count and protein level in the CSF are elevated. A positive VDRL test in the CSF is a definitive diagnostic test for tabes dorsalis.

Thirdly, confirmatory tests should be done on the spinal fluid and blood. There are two confirmatory tests for syphilis, namely the Fluorescent Treponemal Antibody Absorption (FTA-ABS) and Micro Hemagglutination of Treponema Pallidum (MHA-TP). These detect very specific antibodies in the blood that are present when the person has syphilis and not otherwise. FTA-ABS in the CSF is a very sensitive test and a negative result virtually rules out tabes dorsalis. It is mandatory that all patients with syphilis undergo testing for HIV.

Elevated white cells and protein in the CSF with a positive CSF VDRL test in a person with appropriate clinical findings is diagnostic for tabes dorsalis.

Treatment team

The team consists of a neurologist, an internist, an infectious disease specialist, psychiatrist and sometimes a pain management specialist. They will closely interact with physical therapists and occupational therapists.

Treatment

Treatment is aimed at curing the infection and hopefully halting the progression of neurologic damage. Treatment is unfortunately limited in reversing the damage already done and the degree of recovery depends on the extent of damage when therapy is started. Appropriate treatment however does reduce future nerve damage, reduces symptoms and normalizes the CSF abnormalities.

The CDC of the United States Department of Health and Human Services has extensive guidelines for treatment of tabes. It recommends antibiotic treatment with intravenous aqueous crystalline penicillin G for two weeks. If the patient has penicillin allergy, he should be desensitized first before treatment. Otherwise, the antibiotic Ceftriaxone can be used as an alternative but the adequacy of this has not been fully approved by the CDC. Serum VDRL titers are checked every three months till they start declining. CSF is checked at six and twelve months and if still abnormal, rechecked at two years. Re-treatment is recommended if neurological damage progresses, if CSF white cell count does not normalize in six months, VDRL titers do not decline or show a four-fold increase and if the first course of treatment was suboptimal. Symptomatic analgesic treatment is given for pain. This can range from simple over the counter medications like aspirin or Tylenol or more potent analgesics like narcotics. Certain anti-seizure medications like Phenytoin, Carbamazepine and Valproic acid are efficacious in treating resistant pain. If patients become demented and have behavioral issues, anti-psychotic medications can be given.

Primary and secondary prevention of syphilis is important to prevent development of tabes dorsalis. Safe sex (using a condom) is a way of primary prevention. Screening, detection and treatment of early syphilis are measures of secondary prevention. Sexually active people should consult a physician about any rash or sore in the genital area. Those who have been treated for another sexually transmitted infection like gonorrhea, should be tested for syphilis and HIV. Persons who have been exposed sexually to another person who has syphilis of any stage should be clinically evaluated, undergo testing and even be presumptively treated in certain instances.

Recovery and rehabilitation

Assistance or supervision may be needed for self-care activities like eating, showering, dressing etc. Patients may require assistive devices like a cane, walker or a wheelchair to overcome gait difficulty. Diapers or urinary catheters are used for urinary incontinence. Surgery can help replace joints destroyed by arthritis. Patients need a good bowel regimen to avoid constipation, which can trigger a visceral crisis. Since this is a chronic illness, respite care should be provided for the caregivers.