A man from Chhattisgarh presented with progressive muscle weakness and leg spasms. Pure motor paresis was seen on examination. What is the most appropriate history to be elicited in this patient?

Explanation

## Correct Answer: B. History of diet The clinical presentation of progressive muscle weakness, leg spasms, and pure motor paresis in a patient from Chhattisgarh (a region with high prevalence of nutritional deficiencies) points strongly to **lathyrism** or **nutritional neuropathy**. Lathyrism is caused by consumption of *Lathyrus sativus* (khesari dal), which contains β-N-oxalyl-L-α,β-diaminopropionic acid (ODAP), a neurotoxin that causes irreversible motor neuron damage. This condition is endemic in parts of central India, particularly during famine or food scarcity when inferior pulses are consumed. The pure motor paresis (sparing sensory function) and spasticity are pathognomonic. Nutritional deficiencies (B12, folate, thiamine) also present similarly with motor-predominant neuropathy. Detailed dietary history—specifically asking about consumption of khesari dal, other inferior pulses, or prolonged malnutrition—is the single most discriminating and appropriate history to elicit. This directly identifies the causative agent and confirms the diagnosis, guiding management (cessation of exposure, supportive care, and rehabilitation). The geographic location and clinical phenotype make dietary history the cornerstone of diagnosis in this case. ## Why the other options are wrong **A. History of vaccination** — While vaccination history is relevant for polio (which also causes motor paresis), the clinical picture here—progressive weakness with spasticity and leg spasms in a Chhattisgarh resident—is far more consistent with lathyrism or nutritional neuropathy than vaccine-preventable polio. Polio typically presents with acute flaccid paralysis, not progressive spasticity. This is an NBE distractor leveraging the motor paresis feature. **C. History of similar illness in the past** — This would be relevant for recurrent or familial conditions (e.g., hereditary spastic paraplegia), but lathyrism and nutritional neuropathy are acquired, exposure-based disorders. A past history of identical illness would not help differentiate the cause or guide management. This option misses the acute/subacute nutritional or toxin exposure context. **D. History of fever** — Fever history would be pertinent for infectious causes (e.g., poliomyelitis, transverse myelitis, or Guillain-Barré syndrome), but lathyrism and nutritional deficiencies are non-inflammatory, non-infectious conditions. The absence of fever in the stem and the pure motor phenotype argue against infection. This is a common NBE trap pairing motor weakness with infection. ## High-Yield Facts - **Lathyrism** is caused by *Lathyrus sativus* (khesari dal) and presents with progressive spastic paraparesis and pure motor paresis, endemic in central India during food scarcity. - **Nutritional neuropathy** (B12, folate, thiamine deficiency) causes motor-predominant peripheral neuropathy with spasticity, common in India due to vegetarian diets and malabsorption. - **Pure motor paresis** with spasticity in a Chhattisgarh resident is pathognomonic for lathyrism or nutritional deficiency—dietary history is the key discriminator. - **ODAP toxin** in khesari dal causes irreversible motor neuron degeneration; cessation of exposure halts progression but does not reverse damage. - **Geographic clustering** of lathyrism in central India (Chhattisgarh, Madhya Pradesh, Uttar Pradesh) during droughts makes dietary history the most appropriate first question. ## Mnemonics **LATHYR for Lathyrism Features** **L**ower limb spasticity | **A**cute/progressive onset | **T**oxin (ODAP) from khesari dal | **H**istory of diet crucial | **Y**ield to cessation of exposure | **R**eversible only if caught early **Motor Paresis + Spasticity = Dietary History** When you see pure motor paresis with spasticity in an Indian patient from endemic region (central India), think **lathyrism first**, ask about khesari dal and inferior pulses immediately. This memory hook saves time in exams. ## NBE Trap NBE pairs motor paresis with vaccination (polio) and fever (infection) to distract from the nutritional/toxin exposure angle. The geographic clue (Chhattisgarh) and pure motor phenotype are the keys to recognizing this as a lathyrism/nutritional case, not an infectious one. ## Clinical Pearl In rural Chhattisgarh and central India, during drought or food scarcity, families resort to consuming khesari dal (Lathyrus sativus) as a cheap protein source. A single focused dietary history question—"Have you or your family eaten khesari dal or inferior pulses recently?"—can clinch the diagnosis and prevent further exposure, halting disease progression. This is why dietary history is the most appropriate and actionable history in this case. _Reference: Park's Textbook of Preventive and Social Medicine (Nutritional Disorders & Lathyrism section); Harrison's Principles of Internal Medicine Ch. 379 (Nutritional Neuropathies)_