|Facial Pain - Trigeminal Neuropathic Pains
RM Roddy McMillan
RM My name's Roddy McMillan. I'm the consultant in oral medicine and facial pain at the Eastman Dental Hospital in UCLH in London, and the talk today was about trigeminal neuropathic pains.
IV What are the causes of facial neuropathic pain?
RM There are several definite diagnoses within the umbrella term of trigeminal neuropathic pains. The most commonly known one is that of trigeminal neuralgia, which is a sharp paroxysmal type stabbing pain which affects one or more of the distributions of the trigeminal nerve. The other diagnoses include burning mouth syndrome, which is classically a burning, scalded, sore or altered taste affecting the lining of the mouth, which is usually persistent, present on a daily basis and can get worse as the day progresses. Another diagnosis is that of trigeminal neuropathic pains, which is more associated with trauma to the trigeminal nerve in some way which can be identified.
IV How does it usually present and how is it diagnosed?
RM In the case of trigeminal neuralgia, it's usually diagnosed from the history alone. There aren't really any investigations or scans which are particularly helpful to confirm the diagnosis. So classically, this is a short, stabbing, electric shock type pain affecting the trigeminal distribution which lasts for seconds. It very rarely lasts for any longer than a few seconds in duration, and there is never any background level of pain, at least in the initial onset of the condition.
In terms of burning mouth syndrome, that's diagnosed by exclusion of any other causes of a possible burning or uncomfortable symptom affecting the inside of the mouth. So classically, it will present with pain, usually around the front part of the mouth around the inside of the lips, possibly the tip of the tongue, but it can spread more widely in the mouth and possibly towards the back of the mouth and into the throat area. It's a continuous pain which is present on most days and very rarely goes completely. It's a condition which can sometimes affect the sense of taste, and occasionally it can be either made better by eating certain types of foods or it can be exacerbated by eating certain types of foods such as spicy food or acidic foods.
Trigeminal neuropathic pain is almost invariably a continuous background type of pain which doesn't usually have much variation, although sharp exacerbations can occur.
It's often described as a burning or a tingling characteristic, and it's usually localised to one area of the face, although over time this can sometimes change and develop and affect other portions of the face or the mouth. It often has an underlying cause or aetiology which quite often is associated with some form of trauma such as an infection of some description, a dental extraction, or a root canal treatment. But quite often, these types of neuropathic pains can develop without any obvious underlying cause and in that case, we would probably describe it more as persistent idiopathic facial pain or it used to be called atypical facial pain. In these patients... quite often, one can identify evidence of neuropathy in the trigeminal distribution in many of them.
IV Are there any important differential diagnoses or red flags?
RM In terms of trigeminal neuralgia, then trigeminal neuralgia can sometimes masquerade as toothache, and it's important to rule out a dental cause for this particular problem. So in the case of general practitioners, it may be worthwhile contacting the patient's dentist to get a dental assessment in order to rule out a potential dental cause, because many trigeminal neuralgia cases are actually misdiagnosed toothaches and that can be a problem in terms of management.
IV Are there any treatments possible in primary care?
RM So treatments in terms of trigeminal neuralgia... Certainly, if that is in the diagnosis you're considering, then first line treatments would be carbamazepine. So carbamazepine can be prescribed in primary care and can actually be quite helpful in helping to diagnose the condition of trigeminal neuralgia, because one would expect a very profound response to carbamazepine within about 72 hours of starting the prescription. So it can be a useful tool to help consider that as the diagnosis.
In terms of burning mouth syndrome, then we would normally recommend referral onwards to a secondary care setting prior to initiating any treatment. And in terms of the trigeminal neuropathic pain, that would probably follow a similar vein as the burning mouth syndrome. It's probably better to get secondary care involvement prior to starting any medications for those patients.
IV When should a GP refer on?
RM In the case of trigeminal neuralgia, it's probably worthwhile referring quite early on. So if you suspect that as a diagnosis and you ruled out a dental cause with communication with a dentist, it's probably worthwhile referring pretty quickly. In terms of acute managements, then your local oral and maxillofacial surgery units may be able to provide some support there. A facial pain service, if it's available to you, would be the best place to refer to. However, if that's not available, then a local oral maxillofacial surgeon or perhaps a neurologist may be more appropriate.
In terms of burning mouth syndrome, that's a diagnosis that often does require secondary care management, because it tends to be a prolonged chronic condition. So in that situation, then your local oral maxillofacial service probably would be the best place to refer to. If you have got access to an oral medicine clinic or a facial pain service locally, then that would probably be better.
With regards to trigeminal neuropathic pains, then a referral to a local oral maxillofacial surgery team would be appropriate, because they can investigate further with imaging and investigation inside the mouth. If the GP has got the ability to refer locally to an oral medicine unit or facial pain service, that may be appropriate in some circumstances.
IV What is the prognosis?
RM With regards to trigeminal neuralgia, it tends to be a chronic pain condition. Although the pain is episodic in nature, it does tend to recur and very rarely goes into complete remission without treatment. With regards to the surgical management of trigeminal neuralgia, then microvascular decompression can provide up to 80% complete pain resolution after a five-year period in many patients.
Burning mouth syndrome and trigeminal neuropathic pains tend to be more chronic, continuous type of pains. So the good thing we can say about these conditions is that they don't usually gradually worsen over time with regards to burning mouth syndrome and trigeminal neuropathic pain, but they very rarely completely go in spite of appropriate treatment.
IV Where can GPs find out more?
RM GPs have got access to the facial pain website which is part of the Eastman Dental Hospital at UCLH in London. That has got contact details for the department, details on how to refer, and also patient information leaflets which can be downloaded and distributed to patients in primary care.