Trigeminal Neuralgia
- thought due to vascular compression of Trigeminal N, most commonly by superior cerebellar & anterior inferior cerebellar arteries, possibly leading to demyelination
- type 1 and type 2.
- TN type 1 (TN1) - intense, stabbing pain affecting the mouth, cheek, nose, and/or other areas on one side of the face.
- TN type 2 (TN2) - less intense pain, but a constant dull aching or burning pain.
- pain often completely resolves between attacks
- triggers can include touch, cleaning teeth, cold, wind
- rare during sleep
- TN2 tends to be more of an ache but over broader area
- women>men, age esp >50yrs (rare <40yrs), Right side 5x> Left
- idiopathic TN - clinical exam should be normal apart from triggering of pain with touch
- course varies but can last years
Strict criteria for Trigeminal neuralgia as defined by the International Headache Society (IHS) (International Classification of Headache Disorders, 2nd ed) in 2004 are:
- Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, affecting 1 or more divisions of the trigeminal nerve and fulfilling criteria B and C
- Pain has at least 1 of the following characteristics: (1) intense, sharp, superficial or stabbing; or (2) precipitated from trigger areas or by trigger factors
- Attacks stereotyped in the individual patient
- No clinically evident neurologic deficit
- Not attributed to another disorder
other classifications do exist but there is no universal agreement
Management
- Carbamazepine 200mg tds-qid usually sufficient
- Other anti-convulsants prescribed frequently include phenytoin, gabapentin, lamotrigine, oxcarbazepine, and topiramate.
- Baclofen (GABA derivative muscle relaxant) - alone or in combination with other drugs. The only muscle relaxant with supporting evidence
- surgery - microvascular decompression
2019 European Academy of Neurology (EAN) guidelines:
- all TN patients should undergo MRI
- carbamazepine and oxcarbazepine should be used as first-line prophylactic treatments
- lamotrigine, gabapentin, botulinum toxin type A, pregabalin, baclofen, and phenytoin may be used either alone or as add-on therapy
- patients should be offered surgery if pain is not sufficiently controlled medically or if medical treatment is poorly tolerated
- in patients with classical TN, microvascular decompression is recommended as first-line surgery