# Weak legs four days after a stomach upset, a 48-year-old: a case to work up

> A neurology case for medical students: a 48-year-old whose legs have weakened over four days. Nerve versus cord, the breathing checks that matter, first tests and the differential of acute weakness.

- Neurology · Intermediate · about 20 minutes
- Web page: https://www.medikarya.in/case-studies/48-year-old-man-with-weak-legs-after-a-stomach-upset
- Work up this patient: https://www.medikarya.in/case-studies/48-year-old-man-with-weak-legs-after-a-stomach-upset

## How the patient presents

A 48-year-old supermarket worker can barely stand. His feet started feeling wrong four days ago, walking became difficult the next day, and now his feet hurt too. He had a stomach upset a month ago.

## Why rapidly progressive leg weakness matters

Weakness that climbs over days can reach the breathing muscles without much warning. Tell a nerve problem from a spinal cord problem, and measure breathing early and repeatedly rather than waiting for the oxygen to fall.

## What to ask in the history

- How it started and how it has spread: feet first, upwards, arms, face, swallowing
- Numbness, tingling, pain
- Bladder and bowel
- Back pain
- Recent infection: gut or chest, and vaccinations
- Breathlessness, weak cough
- Palpitations, dizziness on standing
- Diet, alcohol, medicines

## Red flags

- Breathlessness or a weak cough
- Trouble swallowing or pooling saliva
- Swinging blood pressure or heart rate
- Rapid worsening
- A sensory level, or bladder and bowel loss

## What to examine

- Tone, power and reflexes in legs and arms
- Sensation, and a sensory level on the trunk
- Cranial nerves: face, eye movements, swallowing
- Breathing: rate, use of neck muscles, counting in one breath
- Blood pressure and heart rate

## First investigations

- Vital capacity, measured repeatedly
- Electrolytes including potassium, creatine kinase, glucose
- Nerve conduction studies
- Lumbar puncture
- MRI of the spine if the cord is a possibility
- ECG and monitoring

## Differential diagnosis of rapidly progressive leg weakness

Grouped, not ranked. Which one fits this patient is for you to work out in the case.

### Spinal cord

- Transverse myelitis
- Cord compression

### In the blood

- Low or high potassium

### Peripheral nerves

- Guillain-Barre syndrome
- Toxic or vasculitic neuropathy

### Junction and muscle

- Myasthenia gravis
- Botulism
- Myositis

## Common mistakes

- Relying on oxygen saturation to judge breathing: it falls late.
- Missing a cord problem because the sensory level was not looked for.
- Forgetting that blood pressure and heart rate can become unstable.

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A study guide for medical students, not medical advice. Follow your institution's protocols in practice.