|Axial section of the spinal cord showing syphilitic destruction (whitened area, upper center) of the posterior columns which carry sensory information from the body to the brain|
Tabes dorsalis, also known as syphilitic myelopathy, is a slow degeneration (specifically, demyelination) of the neural tracts primarily in the dorsal columns (posterior columns) of the spinal cord (the portion closest to the back of the body) & dorsal roots. These nerves normally help maintain a person's sense of position (proprioception), vibration, and discriminative touch.
Signs and symptoms may not appear for decades after the initial infection and include weakness, diminished reflexes, paresthesias (shooting and burning pains, pricking sensations, and formication), hypoesthesias (abnormally diminished cutaneous, especially tactile, sensory modalities), tabetic gait (locomotor ataxia), progressive degeneration of the joints, loss of coordination, episodes of intense pain and disturbed sensation (including glossodynia), personality changes, urinary incontinence, dementia, deafness, visual impairment, positive Romberg's test, and impaired response to light (Argyll Robertson pupil). The skeletal musculature is hypotonic due to destruction of the sensory limb of the spindle reflex. The deep tendon reflexes are also diminished or absent; for example, the "knee jerk" or patellar reflex may be lacking (Westphal's sign). A complication of tabes dorsalis can be transient neuralgic paroxysmal pain affecting the eyes and the ophthalmic areas, previously called "Pel's crises" after Dutch physician P.K. Pel. Now more commonly called "tabetic ocular crises", an attack is characterized by sudden, intense eye pain, tearing of the eyes and sensitivity to light.
"Tabes dorsalgia" is a related lancinating back pain.
"Tabetic gait" is a characteristic ataxic gait of untreated syphilis where the person's feet slap the ground as they strike the floor due to loss of proprioception. In daylight the person can avoid some unsteadiness by watching their own feet.
Tabes dorsalis is caused by demyelination by advanced syphilis infection (tertiary syphilis), when the primary infection by the causative spirochete bacterium, Treponema pallidum, is left untreated for an extended period of time (past the point of blood infection by the organism).. The spirochete invades large myelinated fibers, leading to the involvement of the dorsal column medial leminiscus pathway rather than the spinothalamic tract.
Intravenously administered penicillin is the treatment of choice. Associated pain can be treated with opiates, valproate, or carbamazepine. Those with tabes dorsalis may also require physical therapy to deal with muscle wasting and weakness. Preventive treatment for those who come into sexual contact with an individual with syphilis is important.
The disease is more frequent in males than in females. Onset is commonly during mid-life. The incidence of tabes dorsalis is rising, in part due to co-associated HIV infection.
Although there were earlier clinical accounts of this disease, and descriptions and illustrations of the posterior columns of the spinal cord, it was the Berlin neurologist Romberg whose account became the classical textbook description, first published in German and later translated into English.