Tabes dorsalis, also known as syphilitic myelopathy, is a slow degeneration (specifically, demyelination) of the sensory neurons that carry information to the brain. The degenerating nerves are in the dorsal columns (posterior columns) of the spinal cord (the portion closest to the back of the body). They help maintain a person's sense of position (proprioception), vibration, and discriminative touch.
Tabes dorsalis is caused by demyelination secondary to an untreated syphilis infection.
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
Symptoms may not appear for some 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 ocular pain, lacrimation and photophobia. 
"Tabes dorsalgia" is a related back pain.
"Tabetic gait" is a characteristic high-stepping gait of untreated syphilis where the patient's feet slap the ground as they strike the floor due to loss of proprioception.
Left untreated, tabes dorsalis can lead to paralysis, dementia, and blindness. Existing nerve damage cannot be reversed.
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.
Penicillin, administered intravenously, is the treatment of choice. Associated pain can be treated with opiates, valproate, or carbamazepine. Patients 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.
Notable researchers 
Sir Arthur Conan Doyle, author of the Sherlock Holmes stories, completed his doctorate on tabes dorsalis in 1885.
Notable sufferers 
- German storywriter E.T.A. Hoffmann appears to have suffered and died from tabes dorsalis.
- The French novelist Alphonse Daudet kept a journal of the pain he experienced from this condition which was posthumously published as La Doulou (1930) and translated into English as In the Land of Pain (2002) by Julian Barnes.
- Charles Baudelaire contracted syphilis in 1839 and resorted to opium to help alleviate the pain of tabes dorsalis ascending his spine.
See also