Background

Tabes dorsalis is a late-stage manifestation of neurosyphilis, which is a complication of untreated or inadequately treated syphilis infection. It primarily affects the dorsal columns of the spinal cord, leading to a range of neurological symptoms and signs. Tabes dorsalis is characterized by progressive degeneration of the sensory neurons and their associated tracts in the spinal cord, resulting in various sensory, motor, and autonomic disturbances.

It is considered a rare condition due to the widespread use of antibiotics for treating syphilis. Tabes dorsalis typically develops years to decades after the initial syphilis infection. It is associated with the tertiary stage of syphilis, which occurs when the bacteria, Treponema pallidum, invade the nervous system. The exact mechanisms underlying the development of tabes dorsalis are not fully understood, but it is thought to be immune-mediated, with an inflammatory response leading to damage to the spinal cord.

Epidemiology

Tabes dorsalis is a rare condition that represents a late-stage complication of untreated or inadequately treated syphilis infection. The epidemiology of tabes dorsalis is closely tied to the epidemiology of syphilis itself. Here are some key points regarding the epidemiology of tabes dorsalis:

• Syphilis Incidence: The incidence of syphilis has fluctuated over time and varies between countries and regions. In recent years, there has been a resurgence of syphilis infections in several parts of the world, particularly in certain high-risk populations, including men who have sex with men, individuals engaged in sex work, and those with multiple sexual partners.
• Rare Condition: Tabes dorsalis is considered a rare condition due to the availability of effective antibiotics for treating syphilis. The widespread use of penicillin and other appropriate antibiotics has significantly reduced the incidence of late-stage neurosyphilis, including tabes dorsalis.
• Latency Period: Tabes dorsalis typically develops years to decades after the initial syphilis infection. The latency period between syphilis infection and the onset of tabes dorsalis can range from 10 to 30 years or more.
• Age and Gender: Tabes dorsalis can affect individuals of all ages, although it most commonly presents in middle-aged and older adults. There is no significant gender predilection, and both men and women can be affected.
• Impact of Treatment: Adequate and timely treatment of syphilis with appropriate antibiotics can prevent the development of tabes dorsalis. Regular screening, early diagnosis, and prompt treatment of syphilis infections are crucial in preventing the progression to late-stage neurosyphilis.
• Geographic Distribution: The global distribution of tabes dorsalis mirrors that of syphilis. It tends to be more prevalent in areas or populations with higher rates of syphilis infection. The incidence and prevalence of tabes dorsalis can vary between countries and regions depending on the local epidemiology of syphilis.

Anatomy

Pathophysiology

Tabes dorsalis is a late-stage manifestation of neurosyphilis, a condition caused by the invasion of the central nervous system (CNS) by the bacterium Treponema pallidum, which is responsible for syphilis. The pathophysiology of tabes dorsalis involves the progressive degeneration of the dorsal columns of the spinal cord, leading to various neurological manifestations. Here are the key pathophysiological mechanisms involved in tabes dorsalis:

• Infection of the Central Nervous System: Syphilis initially infects the body through sexual contact or exposure to syphilis-infected lesions. If left untreated or inadequately treated, the bacteria can penetrate the blood-brain barrier and invade the CNS, including the spinal cord.
• Inflammatory Response: In response to the presence of Treponema pallidum in the spinal cord, an inflammatory response is triggered. Immune cells, such as lymphocytes and plasma cells, infiltrate the affected areas.
• Demyelination and Neuronal Damage: The inflammatory process in tabes dorsalis leads to demyelination, which is the loss of myelin, the protective covering of nerve fibers in the dorsal columns of the spinal cord. Demyelination disrupts the transmission of sensory information.
• Loss of Sensory Neurons: Over time, the demyelination and inflammatory process in tabes dorsalis also result in the degeneration and loss of sensory neurons in the dorsal root ganglia, which are responsible for relaying sensory information to the spinal cord.
• Impaired Proprioception and Sensory Function: The degeneration of sensory neurons and loss of myelin in the dorsal columns lead to impaired proprioception (sense of body position) and vibration sense. This results in the characteristic sensory symptoms of tabes dorsalis, such as ataxia (loss of coordination), difficulty with balance, and abnormal gait.
• Neurovascular Changes: Tabes dorsalis can also affect the small blood vessels supplying the spinal cord. The inflammatory and vascular changes can lead to ischemia (lack of blood supply) and tissue damage in the affected areas.
• Complications: The progressive degeneration of the spinal cord in tabes dorsalis can lead to additional complications, such as neurogenic bladder (due to dysfunction of the bladder muscles), Charcot arthropathy (degenerative joint disease), and ocular abnormalities (including pupillary abnormalities).

Etiology

Tabes dorsalis is a late-stage complication of neurosyphilis, which is caused by the bacterium Treponema pallidum. The etiology of tabes dorsalis is directly related to the chronic infection and progression of syphilis. Here are the key points regarding the etiology of tabes dorsalis:

• Syphilis Infection: Tabes dorsalis arises as a result of untreated or inadequately treated syphilis infection. Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum. It can also be transmitted from an infected mother to her child during pregnancy (congenital syphilis).
• Progression to Neurosyphilis: If syphilis is left untreated or inadequately treated, the bacteria can spread throughout the body, including the central nervous system (CNS). This progression of syphilis into the CNS leads to a condition called neurosyphilis.
• Tertiary Stage of Syphilis: Tabes dorsalis is classified as a late manifestation of syphilis, occurring in the tertiary stage of the disease. The tertiary stage typically develops several years to decades after the initial infection.
• Chronic Infection and Inflammation: In tabes dorsalis, the bacterium Treponema pallidum invades the dorsal columns of the spinal cord, leading to chronic infection and inflammation in the affected areas. The chronic inflammatory response contributes to the tissue damage and degeneration seen in tabes dorsalis.
• Host Factors: While the presence of Treponema pallidum is necessary for the development of tabes dorsalis, the severity and progression of the disease can also be influenced by individual host factors, such as the immune response, genetic susceptibility, and other coexisting medical conditions.

Genetics

Prognostic Factors

The prognosis of tabes dorsalis, a late-stage manifestation of neurosyphilis, can vary depending on several factors, including the extent of neurological involvement, the duration of the disease, the response to treatment, and the presence of other medical conditions. Here are some key points regarding the prognosis of tabes dorsalis:

Neurological Damage: Tabes dorsalis is characterized by progressive degeneration of the sensory neurons in the spinal cord. The extent of neurological damage at the time of diagnosis greatly influences the prognosis. Individuals with advanced or severe neurological involvement may have more persistent and debilitating symptoms compared to those with milder forms of the disease.

Treatment Response: Timely and appropriate treatment with antibiotics can halt the progression of the underlying syphilis infection and prevent further neurological damage. However, treatment may not reverse the existing nerve damage. The response to treatment varies among individuals, and some may experience stabilization or improvement in their symptoms, while others may continue to have residual neurological deficits.

Symptomatic Management: The management of symptoms associated with tabes dorsalis, such as neuropathic pain, ataxia, and bladder dysfunction, can significantly impact the patient’s quality of life. Adequate pain management and rehabilitation efforts, including physical therapy, can help alleviate symptoms and improve functional outcomes.

Disease Progression: Without treatment, tabes dorsalis generally progresses slowly over many years, resulting in ongoing neurological deterioration. However, with appropriate treatment and management, the progression of the disease can be halted or slowed down. Regular monitoring and follow-up evaluations are essential to assess disease progression and adjust treatment strategies accordingly.

Coexisting Medical Conditions: The presence of other medical conditions or comorbidities can impact the overall prognosis and management of tabes dorsalis. Individuals with pre-existing medical conditions or complications related to syphilis, such as cardiovascular involvement, may have a less favorable prognosis and require additional medical interventions.

Individual Variability: The prognosis can vary significantly from person to person, depending on their overall health, response to treatment, and adherence to recommended management strategies. Some individuals may experience long periods of stability, while others may have a more progressive course with ongoing neurological decline.

Clinical History

Clinical history

The clinical history of tabes dorsalis, a late-stage manifestation of neurosyphilis, can provide important clues for diagnosis. The clinical history typically includes the following aspects:

• Previous Syphilis Infection: Patients with tabes dorsalis have a history of previous syphilis infection, usually several years to decades prior to the onset of symptoms. They may recall having primary syphilis (characterized by a painless genital sore called a chancre), secondary syphilis (involving skin rashes, mucous membrane lesions, and flu-like symptoms), or latent syphilis (asymptomatic stage without active signs or symptoms).
• Lack of Adequate Treatment: Tabes dorsalis develops as a consequence of untreated or inadequately treated syphilis infection. Patients may have a history of not receiving appropriate antibiotics, discontinuing treatment prematurely, or not completing the full course of treatment for syphilis.
• Latency Period: There is typically a long latency period between the initial syphilis infection and the development of tabes dorsalis. This period can range from 10 to 30 years or more, making it important to inquire about the duration of time since the syphilis infection.
• Presenting Symptoms: Tabes dorsalis is characterized by specific neurological symptoms, including:
• Sensory Disturbances: Patients may experience abnormal sensations such as pain, burning, tingling, or numbness. These sensations may be localized or involve large areas of the body. Sensory abnormalities often affect the lower limbs and progress upwards.
• Ataxia and Coordination Problems: Patients may have difficulties with balance, coordination, and gait. They may exhibit a wide-based, unsteady gait and a tendency to veer or sway while walking. Fine motor control may also be impaired.
• Bladder and Bowel Dysfunction: Tabes dorsalis can affect the autonomic nervous system, leading to bladder and bowel dysfunction. Patients may experience urinary urgency, incontinence, difficulty initiating or stopping urination, and bowel dysfunction such as constipation.
• Ocular Abnormalities: Some patients may present with ocular abnormalities, including impaired pupillary reflexes. One classic finding is the “Argyll Robertson pupil,” which refers to bilateral small pupils that do not react to light but constrict when focusing on a near object.
• Painful Paroxysms: Tabes dorsalis is often associated with severe neuropathic pain known as “lightning pains.” These are episodic, shooting or stabbing pains that can occur spontaneously or be triggered by touch or movement.
• Systemic Manifestations: In addition to neurological symptoms, patients with tabes dorsalis may have other manifestations of late-stage syphilis, such as cardiovascular abnormalities, gummatous lesions (nodular skin lesions), or other signs of organ involvement.

Physical Examination

Physical examination

During a physical examination of a patient suspected to have tabes dorsalis, healthcare professionals will assess various neurological signs and perform specific tests to evaluate the extent of sensory and motor abnormalities. Here are key components of the physical examination for tabes dorsalis:

• Gait and Coordination: The patient’s gait and coordination are evaluated for signs of ataxia, which is a characteristic feature of tabes dorsalis. Patients with tabes dorsalis often exhibit a wide-based, unsteady gait with a tendency to veer or sway while walking. The Romberg test, which involves asking the patient to stand with feet together and eyes closed, can be performed to assess balance and proprioception.
• Sensory Examination: Sensory disturbances are a hallmark of tabes dorsalis. The sensory examination typically involves assessing various modalities, including light touch, pinprick (pain), vibration sense, and joint position sense. The examiner may use a cotton swab, sharp object, or a tuning fork to evaluate the patient’s sensory responses in different areas of the body. The findings may include reduced or absent sensation, especially in a “stocking-glove” distribution (affecting the feet and hands).
• Deep Tendon Reflexes: Tabes dorsalis can lead to abnormalities in deep tendon reflexes. The deep tendon reflexes, such as the patellar reflex (knee jerk) and Achilles reflex, are tested using a reflex hammer. In tabes dorsalis, the deep tendon reflexes may be absent, diminished, or exhibit an abnormal response known as an “exaggerated” or “reversed” reflex response.
• Pupillary Reflexes: The pupillary reflexes are assessed during the physical examination of tabes dorsalis. One characteristic finding is the “Argyll Robertson pupil,” in which the pupils constrict when focusing on a near object (accommodation reflex) but do not react to light (light reflex). This pupillary abnormality is commonly associated with neurosyphilis and is suggestive of tabes dorsalis.
• Abdominal Reflexes: The abdominal reflexes, which involve the contraction of abdominal muscles in response to stimulation, may be diminished or absent in patients with tabes dorsalis. The examiner gently strokes the skin of the abdomen to assess the presence and symmetry of the reflex.
• Cranial Nerve Examination: As tabes dorsalis can involve the cranial nerves, a comprehensive cranial nerve examination may be performed to assess the function of various cranial nerves, including those involved in eye movement, facial sensation, hearing, and swallowing.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Differential diagnosis

Tabes dorsalis, a late-stage manifestation of neurosyphilis, can present with various neurological symptoms. The differential diagnosis of tabes dorsalis involves considering other conditions that can cause similar clinical features. Here are some conditions that may be included in the differential diagnosis of tabes dorsalis:

Multiple Sclerosis (MS): MS is an autoimmune disease that affects the central nervous system, including the spinal cord. It can present with symptoms such as ataxia, sensory disturbances, and bladder dysfunction. Clinical and imaging findings can help differentiate MS from tabes dorsalis.

Vitamin B12 Deficiency: Severe vitamin B12 deficiency can lead to neurological symptoms resembling those of tabes dorsalis, including ataxia, paresthesia, and sensory disturbances. A detailed medical history, blood tests to assess vitamin B12 levels, and response to vitamin B12 supplementation can aid in differentiating it from tabes dorsalis.

Peripheral Neuropathy: Various peripheral neuropathies can result in similar sensory symptoms as seen in tabes dorsalis. Diabetic neuropathy, for example, can present with sensory disturbances, pain, and autonomic dysfunction. A thorough evaluation, including nerve conduction studies and blood tests, can help differentiate peripheral neuropathy from tabes dorsalis.

Syringomyelia: Syringomyelia is a condition characterized by the presence of a fluid-filled cyst (syrinx) within the spinal cord. It can lead to sensory disturbances, loss of coordination, and motor deficits similar to those seen in tabes dorsalis. Imaging studies such as MRI can help identify syringomyelia and distinguish it from tabes dorsalis.

Subacute Combined Degeneration: Subacute combined degeneration of the spinal cord is caused by vitamin B12 deficiency, often associated with pernicious anemia. It can present with sensory ataxia, weakness, and paresthesia, resembling some of the symptoms of tabes dorsalis. Blood tests and imaging studies can help differentiate the two conditions.

Hereditary Ataxias: Certain hereditary ataxias, such as Friedreich’s ataxia, can exhibit similar symptoms to tabes dorsalis, including ataxia, sensory disturbances, and neurological deficits. Genetic testing and clinical evaluation can help differentiate hereditary ataxias from tabes dorsalis.

Other Causes of Spinal Cord Compression: Conditions that cause compression of the spinal cord, such as tumors or spinal stenosis, can present with symptoms similar to tabes dorsalis. Imaging studies can help identify spinal cord compression and distinguish it from tabes dorsalis.

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

Tabes dorsalis, as a late-stage manifestation of neurosyphilis, requires comprehensive treatment aimed at controlling the underlying syphilis infection and managing the associated neurological symptoms. The primary treatment approach for tabes dorsalis involves the following:

Antibiotic Therapy: The cornerstone of treatment for tabes dorsalis is antibiotic therapy to eradicate the underlying syphilis infection. The choice of antibiotics depends on the stage of syphilis and the individual patient’s clinical situation. Intravenous or intramuscular penicillin G is the most commonly used antibiotic for neurosyphilis. Other antibiotics, such as ceftriaxone or doxycycline, may be used if the patient has a penicillin allergy.

Pain Management: The neuropathic pain experienced by individuals with tabes dorsalis often requires effective pain management. Medications such as tricyclic antidepressants, anticonvulsants (e.g., gabapentin, pregabalin), or opioids may be prescribed to help alleviate the pain. However, the use of opioids should be carefully monitored due to the risk of dependence and side effects.

Symptomatic Treatment: Various symptoms associated with tabes dorsalis, such as ataxia, bladder dysfunction, and sensory disturbances, can be managed symptomatically to improve quality of life. Physical therapy and rehabilitation exercises can help improve balance and gait. Bladder dysfunction may require the use of medications to manage urinary symptoms or intermittent catheterization for bladder emptying.

Multidisciplinary Care: Given the complex nature of tabes dorsalis, a multidisciplinary approach involving neurologists, infectious disease specialists, pain specialists, physical therapists, and other healthcare professionals is often necessary. This ensures comprehensive evaluation, tailored treatment, and ongoing management of the condition.

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References

https://www.ncbi.nlm.nih.gov/books/NBK557891/