Trigeminal neuralgia

trigeminal neuralgiaAlthough rare, trigeminal neuralgia can have a huge impact on a patient’s quality of life. This useful BMJ review gives us guidance on how to spot it and treat it effectively, something your patients with trigeminal neuralgia will no doubt thank you for! (BMJ 2014;348:g474).

What is trigeminal neuralgia?

  • A facial pain syndrome which usually presents with episodic, unilateral electric shock-like facial pain in the two lower branches of the trigeminal nerve.
  • It is most common between 50-60 years of age and commoner in men than women.
  • Most cases (95%) are classed as idiopathic and may relate to vascular compression of the trigeminal nerve by a blood vessel.
  • The remaining 5% are associated with abnormalities such as a brain tumour, vascular abnormality or multiple sclerosis.

Diagnosis

This is usually clinical, imaging is only required if there are red flags or atypical features.

Typical features of pain Red flags/atypical features
Unilateral, electric shock-likeAffects lower two branches of trigeminal nerveEpisodic and sudden onsetNo pain between attacksAttacks gradually become closer togetherProvoked by light touch, eating, cold winds, vibration Occurrence <40 years ageBilateral symptomsOphthalmic division only affectedSensory lossHearing lossSkin or oral lesionsNo response to treatment

If the diagnosis can be made clinically, start treatment in primary care. If red flags/atypical features are present, refer for neurological assessment and possible MRI.

Medical treatment

Trigeminal neuralgia does not respond to conventional painkillers including opiates.

Carbamazepine seems to be the most effective treatment, though this is on the basis of small imperfect RCTs. NICE guidance from 2013 on neuropathic pain (CG173) recommends carbamazepine as first line and the only treatment for trigeminal neuralgia in primary care.

  • Start carbamazepine treatment at 100mg 1-2 times daily then titrate up slowly every 3-7 days according to response (usual maintenance dose is 200mg 3-4 times daily, up to maximum 1.6g/day).
  • Remember carbamazepine is an enzyme inducer and has multiple drug interactions.
  • Routine blood monitoring is not required but carbamazepine can cause leucopenia, liver dysfunction and skin rashes. Baseline FBC, LFT and U&E may be useful.
  • 10% of patients will not respond to this. NICE do not recommend any alternatives in primary care and suggest referral at this point.
  • Specialists may undertake MRI imaging to rule out underlying demyelination or lesions in referred patients. Other treatment options include phenytoin, baclofen or lamotrigine. Injection of local anaesthetic into trigger points may also help.

Surgical treatment

If medical treatments fail and symptoms remain distressing, surgery may be considered. The two options are:

  • Palliative partial destruction of the trigeminal nerve root.
  • Microvascular surgery to decompress the nerve.

Take Home Messages

  • Diagnosis is clinical – consider it in unilateral episodic sharp/electric shock-like facial pain.
  • Prescribe carbamazepine as first line treatment in primary care.
  • If no response to treatment or red flags/atypical features, refer to Neurology for MRI and consideration of alternative medical or surgical treatment.

 

Aimee Lettis

Aimee Lettis from the GP Update team gives us short, sharp nuggets of clinical information for sessional GPs. The GP Update team run one-day courses, bringing GPs up to date with all the latest evidence and guidelines.

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