How should I evaluate and treat peripheral numbness in a patient with leprosy?

Evaluation and Treatment of Peripheral Numbness in Leprosy

Peripheral numbness in leprosy patients requires immediate assessment for nerve damage using sensory testing (10-g monofilament, pinprick, temperature, vibration with 128-Hz tuning fork) and nerve palpation to detect thickening, followed by prompt initiation or optimization of multidrug therapy (rifampicin, clofazimine, dapsone) to prevent irreversible disability. 1, 2, 3

Clinical Assessment of Peripheral Numbness

Cardinal Signs to Confirm Leprosy-Related Neuropathy

• Hypopigmented or erythematous skin patches with definite sensory loss are diagnostic when present alongside numbness 3, 4
• Thickened peripheral nerves on palpation (ulnar, radial cutaneous, common peroneal, posterior tibial, great auricular) confirm leprosy neuropathy 2, 3
• Asymmetric or patchy distribution of numbness is typical in leprosy, distinguishing it from symmetric length-dependent neuropathies 2, 4

Neurological Examination Specifics

• Perform 10-g monofilament testing at multiple sites on hands and feet to detect loss of protective sensation 5, 6
• Test pinprick, temperature sensation, and vibration (128-Hz tuning fork) to characterize small versus large fiber involvement 5
• Assess motor function including grip strength, foot dorsiflexion, and intrinsic hand muscle strength, as motor involvement indicates more severe nerve damage 2, 4
• Palpate peripheral nerves systematically for thickening, tenderness, or nodularity—this finding is pathognomonic for leprosy among infectious neuropathies 3, 4

Pattern Recognition for Leprosy Classification

• Paucibacillary leprosy typically presents with 1-5 skin lesions and limited nerve involvement 3, 7
• Multibacillary leprosy presents with >5 skin lesions, multiple thickened nerves, and more extensive sensory loss 3, 7
• Borderline forms show intermediate features and are prone to immunological reactions causing acute nerve damage 1, 3

Diagnostic Confirmation

Essential Tests

• Skin smear for acid-fast bacilli from affected skin patches or earlobes to confirm diagnosis and classify disease burden 3, 4
• Skin biopsy from anesthetic patches showing granulomatous inflammation with loss of adnexal structures and nerve involvement 3, 4
• Nerve conduction studies are NOT routinely required for leprosy diagnosis, as clinical examination is sufficient 5, 2

Ruling Out Alternative Causes

• Check fasting glucose and HbA1c to exclude diabetic neuropathy, which presents with symmetric distal sensory loss rather than patchy distribution 5, 6
• Vitamin B12 level should be assessed, particularly if the patient has been on dapsone long-term or has other risk factors 6
• Consider vasculitic neuropathy if the pattern is truly multifocal/mononeuritis multiplex rather than the patchy but relatively symmetric pattern of leprosy 6

Treatment Approach

Multidrug Therapy Regimens

For paucibacillary leprosy (1-5 lesions):

• Rifampicin 600 mg once monthly (supervised) 3, 7
• Dapsone 100 mg daily (self-administered) 3, 7
• Duration: 6 months 3, 7

For multibacillary leprosy (>5 lesions):

• Rifampicin 600 mg once monthly (supervised) 3, 7
• Clofazimine 300 mg once monthly (supervised) plus 50 mg daily (self-administered) 3, 7
• Dapsone 100 mg daily (self-administered) 3, 7
• Duration: 12 months 3, 7

Nerve Damage Prevention and Management

• Early initiation of multidrug therapy is the ONLY proven intervention to prevent progression of nerve damage and disability 1, 4, 7
• Corticosteroids (prednisone 40-60 mg daily with gradual taper) should be added for acute neuritis or type 1 reactions causing rapid nerve function deterioration 4
• Monitor nerve function monthly during treatment using standardized sensory and motor testing to detect silent neuropathy progression 2, 4

Symptomatic Management of Neuropathic Pain

• Duloxetine 30 mg daily for 1 week, then 60 mg daily provides effective relief for burning pain and dysesthesias associated with nerve damage 8, 6
• Pregabalin or gabapentin are alternative agents for neuropathic pain if duloxetine is contraindicated 8, 6
• Topical agents have limited evidence in leprosy-specific neuropathy but may provide adjunctive benefit 8

Prevention of Disability

Foot Care Protocol

• Daily self-inspection of hands and feet for wounds, blisters, or signs of trauma that may go unnoticed due to sensory loss 5, 6
• Protective footwear is mandatory for patients with loss of protective sensation to prevent plantar ulceration 5
• Educate patients on avoiding repetitive trauma to anesthetic areas, as this is the primary cause of deformity in leprosy 1, 4

Monitoring Strategy

• Assess nerve function before each monthly rifampicin dose to detect acute neuritis requiring corticosteroid intervention 4
• Continue surveillance for 2 years after treatment completion, as late reactions can occur 4, 7
• Refer to specialized leprosy centers if nerve function deteriorates despite treatment or if surgical decompression is being considered 2, 4

Critical Pitfalls to Avoid

• Do not delay multidrug therapy while awaiting confirmatory tests—clinical diagnosis based on cardinal signs is sufficient to start treatment 3, 4
• Do not use corticosteroids without concurrent multidrug therapy, as this can worsen infection 4
• Do not assume symmetric distal numbness rules out leprosy—borderline forms can present with relatively symmetric patterns 2, 3
• Do not perform nerve biopsy routinely—it is rarely needed and risks further nerve damage 5, 2
• Do not stop treatment early even if symptoms improve—incomplete treatment leads to relapse and drug resistance 7