Tabes dorsalis

Tabes dorsalis is a late consequence of neurosyphilis, characterized by the slow degeneration (specifically, demyelination) of the neural tracts primarily in the dorsal root ganglia of the spinal cord (nerve root). These patients have lancinating nerve root pain which is aggravated by coughing, and features of sensory ataxia with ocular involvement. 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 sense of touch), 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).