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

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.

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.