Tabes dorsalis
Related Subjects:
|Dementias
|Abbreviated Mental Test Score (AMTS)
|Syphilis
|Treponema
🧠 Tabes dorsalis is a late complication of untreated syphilis, usually developing 10–35 years after the initial infection.
It is now rare in the post-antibiotic era but remains an important classic neurological syndrome.
📖 About
- Represents a form of tertiary neurosyphilis affecting the dorsal roots and posterior columns of the spinal cord.
- Leads to progressive sensory loss, ataxia, and characteristic clinical signs such as Argyll Robertson pupils and Charcot joints.
🧬 Aetiology
- Neurosyphilis: Damage to dorsal (sensory) nerve roots + posterior columns → impaired proprioception & ataxia.
- General Paresis: Cortical involvement → cortical atrophy, psychiatric changes (delusions of grandeur, dementia), epilepsy.
- Meningovascular Syphilis: Endarteritis and fibrosis affecting cranial nerves (II, III, IV) → stroke-like syndromes.
🩺 Clinical Features
- ⚡ Shooting lancinating pains: Severe, sudden pains due to dorsal root irritation.
- 👣 Positive Romberg’s sign: Loss of balance when eyes closed (posterior column loss).
- 🚶 Ataxic gait: Broad-based, stamping gait from sensory ataxia.
- 👀 Argyll Robertson pupil: Small, irregular pupils that accommodate but do not react to light.
- 🦴 Charcot joints: Painless joint destruction from loss of pain sensation.
- 🧑⚕️ Other neurosyphilis signs: Optic atrophy, impaired deep pain, cognitive/psychiatric changes from general paresis.
🔍 Differential Diagnosis
- Subacute combined degeneration (Vitamin B12 deficiency)
- Multiple sclerosis
- HIV myelopathy
- Nitrous oxide abuse
- Copper deficiency
- Sarcoidosis
🧪 Investigations
- CSF analysis: Raised protein, WCC, ± oligoclonal bands.
- Syphilis serology: TPHA and FTA-ABS positive (VDRL may become negative after treatment).
- Nerve conduction: Motor conduction usually normal (sensory involvement).
- MRI spine: High T2 signal in dorsal cord, possible spinal cord atrophy.
💊 Management
- IV Benzylpenicillin: Standard therapy for neurosyphilis.
- Jarisch–Herxheimer reaction: Acute worsening after antibiotics (fever, rigors, symptom flare) due to spirochaete lysis. Managed with supportive care ± steroids.
📉 Prognosis
- Progression may halt with treatment, but neurological damage is often irreversible.
- Early recognition of syphilis and treatment in earlier stages prevents this complication.
