NEET-PG 2015 — Internal Medicine

Question 171: Locomotor ataxia, a late manifestation of syphilis due to parenchymatous involvement of the spinal cord, is called

• A. Tabes dorsalis (Correct Answer)
• B. Syphilitic amyotrophy
• C. Meningo vascular syphilis
• D. General paralysis of insane

Explanation: ***Tabes dorsalis*** - This condition is a **late manifestation of tertiary syphilis** caused by the demyelination and degeneration of the posterior columns and dorsal roots of the spinal cord [1], [2]. - It specifically leads to **locomotor ataxia** due to the loss of proprioception and vibration sense, characteristic of parenchymatous involvement [2]. *Syphilitic amyotrophy* - This is a rare form of neurosyphilis that presents with neurological symptoms primarily affecting **motor neurons**, leading to muscle weakness and atrophy. - It does not typically present as **locomotor ataxia** with sensory deficits as the primary feature. *Meningovascular syphilis* - This form of neurosyphilis predominantly affects the **blood vessels and meninges of the brain and spinal cord**, leading to infarcts and stroke-like symptoms. - While it can cause neurological deficits, it does not typically manifest as the specific sensory ataxia described as **tabes dorsalis**. *General paralysis of insane* - Also known as **general paresis**, this is another late manifestation of neurosyphilis primarily affecting the brain, leading to **dementia, personality changes, and psychiatric symptoms**. - While it involves parenchymatous brain damage, it does not present with **locomotor ataxia** as its defining feature.