# Numb, burning feet in a 66-year-old: a neuropathy case to work up

> A neurology case for medical students: a 66-year-old with numb feet that burn at night and a cut he did not feel. History, red flags, how to examine sensation, first tests and the differential of neuropathy.

- Neurology · Beginner · about 20 minutes
- Web page: https://www.medikarya.in/case-studies/66-year-old-man-with-numb-feet
- Work up this patient: https://www.medikarya.in/case-studies/66-year-old-man-with-numb-feet

## How the patient presents

A 66-year-old man's feet have felt numb for a few months, and they burn at night. He recently cut his foot in the garden and did not feel it.

## Why numb, burning feet matters

Numb, burning feet are usually a peripheral neuropathy, and the cause is often found with a careful history and a few blood tests. The other half of the job is protecting feet that no longer feel injury, because an unnoticed wound can become an ulcer or an infection.

## What to ask in the history

- When it started, how it has spread, both sides or one
- Burning, tingling, worse at night
- Unsteadiness, falls, weakness; are the hands affected
- Diabetes, or thirst and passing a lot of urine
- Alcohol
- Diet, and medicines such as metformin, isoniazid or chemotherapy
- Kidney or thyroid disease; family history
- The cut: how it happened, whether it is healing, redness, discharge, fever
- Footwear and foot care

## Red flags

- Weakness that is getting worse quickly
- Symptoms on one side only, or mainly weakness
- Bladder or bowel symptoms
- A wound that is red, swollen, smelly or with fever
- A cold foot or missing pulses
- Weight loss

## What to examine

- The feet: skin, wounds, ulcers, deformity, temperature, pulses
- Light touch, pinprick, vibration and joint position, from the toes upwards
- Monofilament testing
- Ankle reflexes, power
- Romberg's test and gait
- The hands

## First investigations

- Glucose and HbA1c
- Vitamin B12 and folate, full blood count
- Kidney and liver function, thyroid function
- Further tests chosen by the history
- Wound swab and foot X-ray if the cut looks infected or deep
- Nerve conduction studies if the picture is unusual

## Differential diagnosis of numb, burning feet

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

### Other nerve diseases

- Inflammatory neuropathy
- Paraprotein-related neuropathy
- Inherited neuropathy

### Nutritional and toxic

- Vitamin B12 deficiency
- Alcohol
- Medicines

### Metabolic

- Diabetes
- Kidney disease
- Hypothyroidism

### Not the peripheral nerves

- Spinal cord disease
- Lumbar canal stenosis
- Peripheral arterial disease

## Common mistakes

- Forgetting to look at the feet themselves.
- Stopping at the first cause found: two can coexist.
- Sending him home without foot-care advice.

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