This type of neurosyphilis, described by Duchenne in his classic monograph L’ataxie locomotrice progressive (1858), usually develops 15 to 20 years after the onset of the infection. The major symptoms are lightning pains, ataxia, and urinary incontinence; the chief signs are absent tendon reflexes at knee and ankle, impaired vibratory and position sense in feet and legs, and a Romberg sign. The ataxia is purely a result of the sensory defect. Power, by contrast, is fully retained in most cases. The pupils are abnormal in more than 90 percent of cases, usually Argyll Robertson in type (see Chap. 13). Optic atrophy is frequent. The lancinating or lightning pains (present in more than 90 percent of cases) are, as their name implies, sharp, stabbing, and brief, like a flash of lightning. They are more frequent in the legs than elsewhere but roam over the body from face to feet, sometimes playing persistently on one spot “like the repeated twanging of a fiddle string,” as Wilson remarked. They may come in bouts lasting several hours or days. “Pins and needles” feelings, coldness, numbness, tingling, and other paresthesias are also present and are associated invariably with impairment of tactile, pain, and thermal sensation. The bladder is insensitive and hypotonic, resulting in unpredictable overflow incontinence. Constipation and megacolon as well as erectile dysfunction are other expressions of dysfunction of the sacral roots and ganglia.
In the late established phase of the disease, now seldom seen, ataxia is the most prominent feature. A Romberg sign is grossly manifest. The patient totters and staggers while standing and walking. In mild form, it is best seen as the patient walks between obstacles or along a straight line, turns suddenly, or halts. To correct the instability, the patient places his feet and legs wide apart, flexes his body slightly, and repeatedly contracts the extensor muscles of his feet as he sways (la danse des tendons). In moving forward, the patient flings his stiffened leg abruptly, and the foot strikes the floor with a resounding thump in a manner quite unlike that seen in the ataxia of cerebellar disease. The patient clatters along in this way with eyes glued to the floor. If his vision is blocked, he is rendered helpless. When the ataxia is severe, walking becomes impossible despite relatively normal strength of the leg muscles.
Trophic lesions, perforating ulcers of the feet, and Charcot joints are characteristic complications of the tabetic state. The deformity of deafferented Charcot joints occurs in less than 10 percent of tabetics (the most common cause nowadays is diabetic neuropathy, which is also a cause of lancinating pains). Most often the hips, knees, and ankles are affected, but occasionally also the lumbar spine or upper limbs are affected. The process generally begins as an osteoarthritis, which, with repeated injury to the insensitive joint, progresses to destruction of the articular surfaces. Osseous architecture disintegrates, with fractures, dislocations, and subluxations, only some of which occasion discomfort. The arthropathy has been observed to occur as frequently in the burned-out as in the active phase of tabes; hence it is only indirectly related to the syphilitic process. Although the basic abnormality appears to be repeated injury to an anesthetic joint, the process need not be painless. Presumably a deep and incomplete hypalgesia and loss of autonomic function are enough to interfere with protective mechanisms. The Charcot joint is addressed further in Chap. 43 in the context of sensory polyneuropathies.