A 35-year-old woman from Delhi presents with a 6-month history of progressive cognitive decline, tremor, and personality changes. Her husband reports she has become irritable and withdrawn. On examination, she has a resting tremor, hyperreflexia, and positive Romberg sign. Pupillary examination shows irregular, dilated pupils that react better to accommodation than to light (Argyll Robertson pupils). Serum RPR is positive (1:32) and CSF VDRL is positive. CSF shows lymphocytic pleocytosis (80 cells/μL, predominantly lymphocytes) with elevated protein (120 mg/dL) and normal glucose. What is the most likely diagnosis?

Explanation

## Diagnosis: General Paresis of the Insane (GPI) — Neurosyphilis ### Clinical Presentation of GPI **Key Point:** GPI is a chronic meningoencephalitis caused by *Treponema pallidum* affecting the brain parenchyma, typically presenting 10–20 years after primary infection. **Classic Features of GPI:** 1. **Psychiatric symptoms** (personality change, irritability, withdrawal, dementia) 2. **Neurological signs** (tremor, hyperreflexia, Romberg sign, spasticity) 3. **Argyll Robertson pupils** — pathognomonic for neurosyphilis (irregular, dilated, react to accommodation but NOT to light) 4. **CSF findings** — lymphocytic pleocytosis, elevated protein, normal/low glucose 5. **Positive serology** — both serum (RPR/VDRL) AND CSF VDRL ### Differential Diagnosis: Neurosyphilis Variants | Feature | GPI | Tabes Dorsalis | Meningovascular | Gummatous | |---------|-----|---|---|---| | **Onset** | 10–20 years post-infection | 15–20 years | 5–10 years | Variable | | **Pathology** | Meningoencephalitis (brain parenchyma) | Dorsal root degeneration | Vasculitis of cerebral vessels | Granulomatous lesions | | **Psychiatric** | Prominent (dementia, personality change) | Minimal | Minimal | Minimal | | **Tremor** | Yes (coarse resting) | No | No | Possible | | **Argyll Robertson pupils** | Yes (>90%) | Yes (>90%) | Rare | Rare | | **Romberg sign** | Positive | Positive (severe) | Negative | Negative | | **Hyperreflexia** | Yes | Absent (areflexia) | Variable | Variable | | **Sensory loss** | Minimal | Severe (dorsal columns) | Minimal | Minimal | | **CSF protein** | Elevated (50–200) | Elevated (50–150) | Elevated (50–200) | Elevated | | **CSF glucose** | Normal/low | Normal | Low | Low | | **CSF cells** | Lymphocytic | Lymphocytic | Lymphocytic | Lymphocytic | ### Why This Is GPI, Not Tabes Dorsalis? **High-Yield Distinction:** - **GPI** = **Paresis** (weakness, tremor, hyperreflexia) + **Psychiatric decline** → Brain parenchyma affected - **Tabes** = **Ataxia** (loss of proprioception, Romberg sign) + **Areflexia** (loss of reflexes) → Dorsal roots/columns affected This patient has: - ✓ Cognitive decline + personality change (psychiatric → GPI) - ✓ Tremor + hyperreflexia (paresis → GPI) - ✓ Argyll Robertson pupils (both GPI and tabes, but combined with cognitive decline → GPI) - ✗ No dorsal column signs (no severe ataxia, no areflexia) **Clinical Pearl:** Argyll Robertson pupils are seen in both GPI and tabes dorsalis, but the **presence of cognitive decline, tremor, and hyperreflexia points to GPI**. In tabes, reflexes are typically absent (areflexia) due to dorsal root degeneration. ### Treatment of Neurosyphilis (GPI) **Key Point:** Neurosyphilis requires **aqueous penicillin G IV** (NOT benzathine penicillin) to achieve adequate CSF penetration. $$\text{Aqueous PCN G: 18–24 MU daily IV for 10–14 days}$$ Alternative (if penicillin allergy): Ceftriaxone 2 g IV BD for 10–14 days. **Mnemonic:** **NEURO-SYPHILIS = AQUEOUS** — **A**queous penicillin → **Q**uick CSF penetration → **U**rgent treatment → **E**arly intervention → **O**utcome improved → **U**nlike benzathine