Trigeminal Neuralgia and Hemifacial Spasm

Trigeminal Neuralgia

What is trigeminal neuralgia (TGN)?
‘Sudden, severe, brief stabbing pain which occurs in attacks, typically of a few seconds duration, usually on one side of the face and provoked by light touch’

What causes TGN?
Classical trigeminal neuralgia is caused by a blood vessel or vessels pressing on the nerve as it enters the brainstem. The pressure of the nerve over time damages the outer surface or ‘insulation’ of the nerve causing erratic messages to be transmitted along the nerve. These erratic impulses can cause a ‘short circuit’ between light touch and pain pathways. There are other causes of TGN symptoms aside from vascular compression however this is much less common.

Why has my doctor referred me to a neurosurgeon?
It is likely that your doctor has commenced you on medication to control your neuralgia symptoms such as carbamazepine, phenytoin or gabapentin. Although these drugs were first used to treat epilepsy, they also act to dull down the pain sensation in TGN. It is important that the dosages of these medications are controlled by your doctor and that you increase your dose very gradually under supervision since they also have side effects.

If your pain has persisted despite these medications or if you have not been able to tolerate these tablets due their side effects, your doctor may refer you to see a neurosurgeon to determine whether the pain you are suffering is actually TGN and to discuss surgical treatments.

Non-tablet treatment can be broadly classified into invasive surgery (microvascular decompression or MVD) and non-invasive (injections through the cheek into the nerve or gamma knife radiosurgery). I discuss with each patient the advantages and disadvantages of all options available and the likely success rate/recurrence rate of each.

In some cases (e.g. in the elderly patient) it has been shown that the risk of surgery outweighs any potential benefit, however, MVD surgery has been shown to provide the longest relief from pain of all procedures for TGN.

I perform a significant number of these surgeries every year. I work closely with the pain service who provide a comprehensive facial pain service including rhizolysis injections and lesioning.

Hemifacial Spasm

What is hemifacial spasm?
Hemifacial spasm (HFS) is characterised by intermittent, painless and involuntary contraction of the muscles innervated by the facial nerve. It affects one side of the face only and may start by only affecting the muscles around the eye which may progress to involved the entire half of the face. It may be associated with symptoms such as impaired balance (vertigo) and less commonly tinnitus.

What causes hemifacial spasm?
Like trigeminal neuralgia, hemifacial spasm is commonly caused by compression of the nerve which innervates the facial muscles as it exits the brainstem.

Why have I been referred to a neurosurgeon?
In some cases, HFS can be managed with injections of botulinum toxin (botox) into the affected muscle(s) however the most effective procedure for treating and in many cases curing HFS is microvascular decompression surgery.

When patients are referred to see me, I will determine whether you have HFS (this may involve having an MRI scan if you have not yet had a scan) and will discuss the risks and benefits of surgery if appropriate.