Tabes Dorsalis

This article or area is currently under construction and may only be partially complete. Please come back soon to see the finished work! (6/08/2021)

Original Editor - Innocent Abugu
Top Contributors - Innocent Abugu, Kirenga Bamurange Liliane, Kim Jackson and Oyemi Sillo

Introduction

Tabes dorsalis is a slowly progressive degenarative disorder of the dorsal column and dorsal root of the spinal cord. Tabes dorsalis is caused by demyelination as a result of an untreated syphilis infection caused by Treponema pallidum. Treponema pallidum infection, if left untreated or partially treated, can lead to late neurosyphilis which has two forms, general paresis (also known as "syphilitic dementia," "dementia paralytica" or "paretic neurosyphilis") and tabes dorsalis (also known as "locomotor ataxia"). It is more common in males than in females.

Clinically Relevant Anatomy

Sensory information is transmitted through the dorsal (posterior) column of the spinal cord and through the medial lemniscus in the brainstem. The dorsal column-medial lemniscal pathway is responsible for conveying sensations of vibration, proprioception and fine touch (tactile sensation).

Pathological Process

Treponemes are spirochetes, which are thin, delicate, helically coiled organisms measuring 5-20 µm in length.Treponema pallidum can be transferred vertically from mother to fetus and through sexual intercourse.

The disease usually involves three phases. The primary infection follows the inoculation of an individual with about 500–1000 bacteria. Within 36 hours these replicate and result in a painless ulceration called a chancre. These typically occur in the genital areas. After 2–6 weeks the second stage of the disease continues, with wide infiltration throughout the body and nervous system. Afterward, during the latent stage of disease, patients are frequently asymptomatic for many years. About 10% of patients with untreated syphilis develop neurological symptoms called neurosphyilis, or tabes dorsalis, 10–15 years later.

Clinical Presentation

The neurologic presentation is one of ongoing loss of pain sensation, loss of peripheral reflexes, impairment of vibration and position senses, and progressive ataxia. The earliest stages of neurosyphilis involve inflammation of the meninges presenting with headache, nausea, vomiting, and, occasionally, seizures. There may be chronic destructive changes in the large joints of the affected limbs in far-advanced cases (i.e., Charcot's joints). Incontinence of the bladder and impotence are common. Sudden and severely painful crises of uncertain origin are a characteristic part of the syndrome.

Diagnostic Procedure

Diagnosis of syphilis is made using two types of tests: (1) non-treponemal serum screening tests, such as the rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL) test; and (2) treponemal-specific tests such as the fluorescent treponemal antibody absorption test (FTA-ABS), T. pallidum particle agglutination assay (TP-PA), and microhemagglutination test for antibodies to T. pallidum (MHA-TP). In patients with suspected neurosyphilis and stroke, a negative CSF FTA-ABS effectively rules out the disease and a positive VDRL effectively confirms it. In patients with a positive CSF FTA-ABS and a negative VDRL, CSF protein and cell count and clinical judgment might be needed to decide on the treatment.

Management / Interventions

Medical treatment

Medical treatment involves penicillin, administered intravenously. Opiates, valproate and carbamazepine are some of the analgesics used in treating pain associated with Tabes dorsalis.

Physiotherapy management

Physiotherapy management includes Frenkel's exercise, strengthening exercises, balance retraining and use of assistive devices. Aims of physiotherapy management include:

• Improve coordination
• Improve muscle strength.
• Improve muscle endurance.
• Improve balance.
• Improve posture.
• Retrain normal movement pattern.
• Educate the patient about sensory loss and precautions to be taken.

Preventive management

Preventive drug therapy should be given to those who have sexual contact with an individual with syphilis.

Differential Diagnosis

Given the protean manifestations of the various forms and stages of neurosyphilis, the differential diagnostic possibilities are broad. If the presentation is that of cranial nerve palsy, other basal meningitides should be considered, such as tubercular involvement. Acute meningitis due to other organisms is also possible.

Meningovascular syphilis can manifest as a strokelike phenomenon, in which case all causes of vaso-occlusive or ischemic infarction must be reviewed.

If gummata are present, other space-occupying lesions are included in the differential diagnosis, such as primary or metastatic neoplasms with mass effect.

General paresis can manifest with a multitude of psychiatric symptoms, including delirium, dementia, mania, psychosis, personality change, and/or depression.

Tabes dorsalis can appear consistent with subacute combined degeneration of the spinal cord.

Multiple sclerosis must also always remain in the differential. The presence of an Argyll Robertson pupil indicates the possibility of the differential diagnosis mentioned under tabes dorsalis.

Prognosis

Prognosis is good after treatment, but Tabes dorsalis may lead to paralysis, blindness and dementia if left untreated.