Nelson Textbook of Pediatrics 22nd Edition β Peripheral neuropathies caused by drugs (vincristine, isoniazid, metronidazole, linezolid, amiodarone, colchicine), heavy metals (lead, arsenic, mercury, thallium), chemotherapy agents (cisplatin, paclitaxel, oxaliplatin), industrial toxins (organophosphates, acrylamide), and biologic toxins. Diagnosis: history of exposure, NCS/EMG (axonal vs demyelinating), heavy metal levels. Treatment: removal of toxin, supportive care, chelation (for certain metals).
π paeds.online β Pakistan's Pediatric Platform| Drug | Type | Key Features | Prevention/Treatment |
|---|---|---|---|
| Vincristine | Axonal sensorimotor, autonomic | Distal weakness (foot drop), areflexia, constipation, jaw pain. Dose-dependent. | Reduce dose, monitor; pyridoxine? not proven; gabapentin for pain. |
| Cisplatin | Axonal, primarily sensory | Sensory ataxia, numbness, Lhermitte sign, ototoxicity. Coasting (progression afterεθ―). | Avoid cumulative dose; amifostine? limited. |
| Oxaliplatin | Sensory, acute cold-induced paresthesias | Acute dysesthesias triggered by cold (pharyngeal, perioral), jaw spasm, chronic sensory ataxia. | Calcium/magnesium (controversial), avoid cold. |
| Paclitaxel | Sensory predominant, painful | Burning pain, numbness, arthralgias, myalgias. Dose-dependent. | Gabapentin, duloxetine. |
| Isoniazid | Axonal sensory | Distal numbness, paresthesias. Risk: slow acetylators, malnutrition (B6 deficiency). | Pyridoxine (B6) prophylaxis 25-50 mg/day. |
| Metronidazole | Axonal sensory, ataxia, encephalopathy | Painful distal neuropathy, dose-dependent, prolonged courses (>4 weeks). | Discontinue; monitor neurologic status. |
| Linezolid | Axonal sensory, optic neuropathy | Burning pain, numbness, visual loss (optic neuritis). Dose- and duration-dependent. | Monitor for >28 days; discontinue if symptoms. |
| Amiodarone | Mixed axonal + demyelinating, tremor, ataxia | Sensorimotor neuropathy, may mimic GBS. Dose-dependent. | Discontinue; slow resolution. |
| Colchicine | Axonal sensory, myopathy | Neuropathy + myopathy (CK elevation). Renal impairment increases risk. | Discontinue; supportive. |
| Nitrous oxide | Axonal, myelopathy (B12 inactivation) | Subacute combined degeneration, neuropathy, B12 deficiency pattern. | B12 supplementation; avoid recreational use. |
| Metal | Exposure | Clinical Features | Diagnosis | Treatment |
|---|---|---|---|---|
| Lead | Paint, batteries, pottery, water | Motor > sensory, wrist drop, foot drop (mononeuritis multiplex), basophilic stippling, lead lines on X-ray. | Blood lead level, free erythrocyte protoporphyrin. | Remove source, chelation (BAL, EDTA, succimer). |
| Arsenic | Insecticides, herbicides, contaminated water | Acute: GI, encephalopathy. Subacute: painful burning paresthesias, distal weakness, Mees lines (white nail bands), hyperkeratosis, rice-water stools. | Urine arsenic (24h), hair/nail analysis. | BAL (dimercaprol), succimer. |
| Mercury | Fish (methylmercury), broken thermometers, dental amalgams | Paresthesias, ataxia, tremor, erethism (emotional lability), visual constriction. | Blood/urine mercury. | Removal, chelation (BAL, DMSA). |
| Thallium | Rodenticides (banned) | Acute GI, painful ascending neuropathy, alopecia (3-4 weeks), Mees lines. | Urine thallium. | Prussian blue, hemodialysis. |
| Zinc (excess) | Dietary supplements, denture creams | Neuropathy, myelopathy due to copper deficiency (secondary). | Low serum copper, high zinc. | Stop zinc, copper supplementation. |
Nitrous oxide inactivates vitamin B12 (methionine synthase). Causes subacute combined degeneration of the spinal cord (myelopathy) and peripheral neuropathy. History: recreational use (whippets), prolonged anesthesia. Treat with high-dose B12 (cyanocobalamin).
Coasting phenomenon: Neuropathy may worsen for 2-3 months after discontinuation of the offending agent (e.g., cisplatin, vincristine).
First-line test for suspected toxic neuropathy: Nerve conduction studies/EMG (distinguish axonal from demyelinating).