From the Guidelines
Tabes dorsalis should be evaluated with MRI of the spine to assess the dorsal columns of the spinal cord, particularly in patients with chronic disequilibrium due to sensory ataxia and loss of proprioception, as recommended by the 2023 update of the ACR Appropriateness Criteria for Dizziness and Ataxia 1. When diagnosing tabes dorsalis, it is essential to consider the patient's medical history, including any previous syphilis infections, as the condition is a late complication of untreated syphilis. Key characteristics of tabes dorsalis include:
- Progressive sensory ataxia
- Lancinating pains
- Proprioceptive deficits
- Argyll Robertson pupils
- Loss of deep tendon reflexes
- Impaired position and vibration sense Treatment typically involves penicillin G, but for patients allergic to penicillin, alternative options such as doxycycline or tetracycline can be used after desensitization attempts. Some important points to consider when evaluating tabes dorsalis include:
- The use of MRI without IV contrast to evaluate the dorsal columns of the spinal cord, unless there is concern for an inflammatory or infectious neoplastic cause of sensory ataxia, in which case contrast-enhanced imaging should be included 1
- The importance of regular follow-up with CSF examinations to ensure treatment effectiveness
- The need to evaluate patients for other manifestations of tertiary syphilis, particularly cardiovascular involvement.
From the Research
Definition and Symptoms of Tabes Dorsalis
- Tabes dorsalis is a disease affecting the posterior columns of the spinal cord and dorsal roots, presenting as sensory ataxia and neuropathic pain, and less commonly as paresthesia and gastrointestinal disturbance 2.
- It is characterized by progressive ataxia, lightning pains, loss of proprioception, and urinary incontinence 3.
- The most frequent initial symptoms are limb numbness and lightning pains, with positive Romberg's sign and Argyll Robertson pupil being common physical signs 3.
Diagnosis and Treatment of Tabes Dorsalis
- The diagnosis of tabes dorsalis can be challenging due to the absence of a definitive diagnostic standard and non-specific clinical manifestations, leading to a significant rate of misdiagnoses 3.
- Serological tests, such as rapid plasma regain (RPR) and Treponema pallidum particle agglutination (TPPA), can help diagnose tabes dorsalis, with all CSF samples being TPPA-reactive 3.
- Magnetic resonance imaging (MRI) of the spinal cord can show intramedullary hyperintensity and cord atrophy, similar to changes seen in subacute combined degeneration 4.
- Penicillin G is the mainstay therapy of neurosyphilis and has been shown to improve and resolve spinal cord lesions associated with tertiary syphilis 2.
History and Etiology of Tabes Dorsalis
- Tabes dorsalis is a late manifestation of untreated syphilis, resulting from slow, progressive degeneration of the nerve cells in the spinal cord 4.
- The link between syphilis and tabes dorsalis was slowly established in the second part of the 19th century from epidemiologic observations 5.
- There was a heated debate in German neurology about the understanding of the etiology of tabes dorsalis, with some neurologists attributing it to social impoverishment, traumatic causes, or other factors, while others, such as Paul Julius Möbius, consistently stated that the only cause was a previous syphilitic infection 6.