A 28-year-old woman with borderline tuberculoid leprosy, diagnosed 3 months ago and on regular MDT, presents with sudden onset of pain and swelling in her left ulnar nerve at the elbow, along with weakness of intrinsic hand muscles. The lesions on her skin show increased erythema and edema. She has no fever or systemic symptoms. Slit-skin smear remains negative. What is the most appropriate immediate management?

Explanation

## Diagnosis: Type 1 Lepra Reaction (Reversal Reaction) with Neuritis ### Clinical Presentation **Key Point:** Type 1 lepra reaction (reversal reaction) is a cell-mediated (Type IV hypersensitivity) reaction that occurs in borderline forms of leprosy (BT, BL, LL) during or shortly after starting MDT. This patient has: - Borderline tuberculoid (BT) leprosy - Timing: 3 months into MDT (typical for Type 1) - Inflammation of existing skin lesions (erythema, edema) - **Acute nerve involvement** (ulnar nerve pain, swelling, motor weakness) - **No systemic symptoms** (no fever, constitutional signs) - Negative slit-skin smear (low bacillary load consistent with BT) ### Pathophysiology **High-Yield:** Type 1 lepra reaction is **delayed-type (cell-mediated) hypersensitivity** triggered by: 1. Immune reconstitution as bacillary load decreases 2. Shift from Th2 to Th1 response 3. Activation of CD4+ and CD8+ T cells against mycobacterial antigens 4. Inflammation of existing lesions and nerves ### Clinical Features of Type 1 Reaction | Feature | Details | |---------|----------| | **Leprosy types affected** | BT, BL, LL (borderline forms) | | **Timing** | During or shortly after starting MDT (weeks to months) | | **Skin manifestations** | Erythema, edema, ulceration of existing lesions | | **Nerve involvement** | Acute neuritis, nerve thickening, pain, motor/sensory loss | | **Systemic symptoms** | Absent or minimal | | **Bacillary load** | Usually low (slit-skin smear negative) | | **Histology** | Epithelioid granulomas with edema | ### Management of Type 1 Lepra Reaction **Key Point:** The cornerstone of treatment is **high-dose corticosteroids** (prednisolone 0.5–1 mg/kg/day, tapered over 12 weeks). **Clinical Pearl:** Nerve involvement in Type 1 reaction is a medical emergency because: - Acute inflammation can cause irreversible nerve damage - Early corticosteroid therapy prevents permanent disability - If no improvement in 2 weeks despite corticosteroids, **nerve decompression surgery** may be indicated to prevent permanent loss of function ### Treatment Algorithm for Type 1 Reaction with Neuritis ```mermaid flowchart TD A[Type 1 Lepra Reaction with Neuritis]:::outcome --> B[Start high-dose prednisolone<br/>0.5-1 mg/kg/day]:::action B --> C[Continue MDT without interruption]:::action C --> D[Reassess at 2 weeks]:::decision D -->|Improvement| E[Taper prednisolone over 12 weeks]:::action D -->|No improvement| F[Consider nerve decompression]:::urgent F --> G[Surgical intervention to prevent<br/>permanent disability]:::action ``` **Mnemonic for Type 1 management:** **"CORN"** — **C**orticosteroids, **O**ngoing MDT, **R**eassess at 2 weeks, **N**erve decompression if needed. ### Why MDT Should NOT Be Stopped **High-Yield:** MDT must continue during Type 1 reaction because: - The reaction is triggered by immune reconstitution, not drug toxicity - Stopping MDT allows bacillary regrowth and relapse - Corticosteroids control the inflammatory response while MDT continues ### Differential: Type 1 vs Type 2 Lepra Reactions | Feature | Type 1 (Reversal Reaction) | Type 2 (ENL) | |---------|---------------------------|---------------| | **Pathophysiology** | Cell-mediated (Type IV) | Immune complex (Type III) | | **Leprosy type** | BT, BL, LL | LL, BL | | **Timing** | During/shortly after MDT | 6–24 months into MDT | | **Skin signs** | Inflammation of existing lesions | Erythema nodosum (new lesions) | | **Neuritis** | Common, acute | Less common | | **Systemic symptoms** | Rare | Common (fever, arthritis) | | **Treatment** | Corticosteroids | Thalidomide (first-line) | [cite:Textbook of Dermatology, Valia & Valia Ch 28; WHO Guidelines on Leprosy]