Life

Ask the GP: The pain in my face makes teeth-brushing and shaving agony

Trigeminal neuralgia causes recurrent episodes of severe, electric-shock-like pains on one side of the face
Dr Martin Scurr

Q: FOR two years, I've suffered with trigeminal neuralgia, a most annoying and painful condition that makes it a struggle even to brush my teeth, shave and eat. It began after a tooth extraction.

My GP prescribed the nerve pain drug carbamazepine, and I've asked for the dose to be increased. Someone suggested I try acupuncture. What do you recommend?

KP

A: Trigeminal neuralgia causes recurrent episodes of severe, electric-shock-like pains on one side of the face. Each bout comes on suddenly and, while short-lived, can occur again and again in the space of minutes.

This can happen once or twice daily, or 50 times or more – a burdensome and ghastly experience. The pain occurs as a result of a blood vessel compressing the trigeminal nerve, which runs from the brain and through the skull, providing sensation in the face as well as sending signals to the muscles involved in chewing.

Diagnosis is based upon the intense bouts of stabbing pain across the face, and another identifying feature: where even lightly touching the area affected sets off the pain. Other movements, such as chewing, brushing teeth, or a puff of cold air, can have the same effect.

Trigeminal neuralgia is rare, affecting around 10 in 100,000 people a year in the UK, and some GPs will never see a patient for this condition. It usually occurs in middle age, with most cases beginning after the age of 50 – but we don't know why this is, nor why it can come on after tooth extraction, as happened in your case.

The first-line of treatment is with the drug you have been prescribed, carbamazepine. This is usually successful in stopping the attacks. Typically, the starting dose is 100mg twice daily. This is gradually increased until the pain is relieved. A usual daily maintenance dose is 600 mg to 800 mg (divided into two doses).

The side-effects – nausea, diarrhoea, rash, drowsiness and lethargy – are minimised by starting at the lowest dose and working upwards very gradually. Treatment may need to be long term.

There are other drug options for those who don't respond to carbamazepine. As a last resort, patients may undergo neurosurgery to remove the pressure caused by the blood vessel. However, let me reassure you that when the correct dose of carbamazepine is found it is very likely you will be pain-free and never have to undergo surgery.

While acupuncture hasn't been shown in research to help ease the pain of trigeminal neuralgia, there's nothing to lose by trying this – in addition to the medication – if you can see an experienced practitioner.

Q: I FOUND a lump in my groin last year, which caused my thigh to swell. Doctors thought it was possibly a psoas abscess. They drained the fluid, leaving a hole in my left thigh. I'd appreciate your thoughts on this.

JH

A: A psoas abscess is, in non-medical terms, essentially pus in the psoas muscle – the muscle that helps flex the hip.

It can be caused by the spread of infection, such as from an infected hip replacement (an operation you had 16 years ago, you say in your longer letter), so this would seem a plausible diagnosis.

However, tests haven't confirmed infection, and the fluid has continued to collect following attempts to clear it, so it's unlikely that it's pus, but could be lymph. This is the fluid that flows through the lymph vessels, which drain from the tissues back into the bloodstream via an entry point close to the heart.

If an obstruction occurs somewhere in these channels, fluid can pool in that area.

But you say scans (MRI and CT) haven't revealed any signs of a possible obstruction. Still, I believe this must be a continuing line of investigation.

Your specialists have recommended that you wait to see if the fluid reduces of its own accord. If it does not, then I'd suggest you ask for a magnetic resonance lymphangiogram, a type of scan that will outline the lymphatic channels of your leg and the flow of the lymph fluid into the pelvic and lower abdominal region.

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