Trigeminal neuralgia is a clinical pain syndrome now it's important to understand
that a patient can develop trigeminal neuralgia with a totally normal structural MRI scan.
So there's no diagnostic test for trigeminal neuralgia as such and as a clinician,
you're left dependent entirely on how the individual patient describes pain. Now that
can be a challenge because different patients can use words differently and in reality, the first
part of the clinical consultation for trigeminal neuralgia is to explore that pain history
and what you're trying to determine is whether you feel that the patient has classical trigeminal
neuralgia and then the expectation is very great that trigeminal neuralgia treatment should work
for them or whether the patient does not have trigeminal neuralgia in which case trigeminal
neuralgia treatments may be contraindicated or whether in some cases you're left not sure
and how you address that uncertainty. But I think it's important because if
you don't get the diagnosis right you won't get the treatment right and that's really the
first component of talking about the precision involved in trigeminal neuralgia management.
Well, the sort of pain that people describe is classically a very sharp shooting pain
but it's severe and debilitating but also it typically is aggravated by
small movements that shouldn't cause pain, triggers major episodes of pain.
This becomes quite a complicated set of issues because most trigeminal neuralgia is primary
or idiopathic without a clear risk factor. Although in some of those individuals,
a blood vessel compressing nerve seems to be a major provocative factor.
However, around 11 per cent of the normal population have blood vessels against the nerve
so having a blood vessel there does not mean that you've got trigeminal neuralgia.
There's a second group of patients where there is some other process going on.
It could be a skull-based deformity. It could be a typically benign skull-based tumor.
It could be conditions like multiple sclerosis that are particularly associated with trigeminal
neuralgia syndromes and teasing them out has implications because they have different
treatment strategies. Overall, in terms of risk factors there is a tendency for
trigeminal neuralgia to be more common in an older population so it does seem to be involved with
the ageing process but that doesn't mean that you cannot see younger patients with it.
Well, as I said in the first question,
essentially the diagnosis is clinical based on the patient's description of the pain. Now,
some of those times you'll get a patient who describes something so precisely, so clearly that
you'll feel that this must be trigeminal neuralgia but at times there will be more uncertainty
about the diagnosis and then knowing responses to previous treatments including drug treatments,
other factors can start to become useful in taking that management forward. If you've
made a clinical diagnosis that your patient has trigeminal neuralgia, I would always want to see
an MRI scan, mainly to rule out any other pathology that could present with that sort of
symptomotology or also to look and see whether there was evidence of a blood vessel compressing
a nerve because again, that changes the treatment options that may be open to the patient.
To answer that in reverse, trigeminal neuralgia has been associated with suicidal ideation.
Although the condition in its own is not life-threatening, it does make patients desperate
and patients quite typically are fearful of the neuralgia because it's that severe.
When it comes to the different treatments, I would always list four different sorts of treatment.
The first would be drug therapy and this is generally the first to be used and a positive
response to specific drug therapy can help confirm the diagnosis because you're saying that this pain
responds to things that trigeminal neuralgia responds to. The problem is that drug therapy
is not always tolerated because of side effects and there is always an impression that with time,
the pain gets worse and breaks through the drugs which is when other interventions are considered
and of those interventions, I would tend to list and consider three.
Injections into the nerve to deaden the nerve can be done in various ways. The problem with
that is that they tend not to last so they tend not to be a long-term management strategy
and they become increasingly difficult to repeat as a generalisation. Also, different territories
face may be more or less accessible to injection techniques. The second option is
open neurosurgery to try and decompress the nerve. Now, that's easier to undertake if there's clear
evidence of vascular compression on an MRI scan but it doesn't mean that there couldn't be a scan
with a small blood vessel tucked into the nerves that you can't see on the scan so again it's not a
complete answer. The problem is that that sort of surgery remains a major neurosurgical undertaking
with small but significant risks associated with it and as a generalisation,
I tend to avoid major cranial neurosurgery in an older age group because they are slower to
recuperate from that sort of surgery. That then leaves stereotactic radiosurgery
which remains attractive because it's a day case procedure done typically under local anaesthetic
and the steps of it involve fixation of a frame under local anaesthetic,
then precise radiological imaging to target the nerve and then, the delivery of a very focused
array of radiosurgical treatment. It's attractive because it's minimally invasive
but there is a recurrence rate and the more a nerve is treated with radiosurgery,
the more you can develop numbness in that part of the face. The thing about numbness
is that most of the time, probably 98 per cent of the time, if there's numbness patients are happy
because the numbness goes hand in hand with good pain relief
but the numbness can, in a small proportion of patients, perhaps up to two percent, be intrusive,
disabling or even perceived as being painful of its own so it is a significant
consideration that I would always discuss with patients on an individual basis.