|13.1.1||Classical trigeminal neuralgia [G50.00]||G44.847|
Trigeminal neuralgia is a unilateral disorder characterised by brief electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve. Pain is commonly evoked by trivial stimuli including washing, shaving, smoking, talking and/or brushing the teeth (trigger factors) and frequently occurs spontaneously. Small areas in the nasolabial fold and/or chin may be particularly susceptible to the precipitation of pain (trigger areas). The pains usually remit for variable periods.
- Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, affecting one or more divisions of the trigeminal nerve and fulfilling criteria B and C
- Pain has at least one of the following characteristics:
- intense, sharp, superficial or stabbing
- precipitated from trigger areas or by trigger factors
- Attacks are stereotyped in the individual patient
- There is no clinically evident neurological deficit
- Not attributed to another disorder
Classical trigeminal neuralgia usually starts in the second or third divisions, affecting the cheek or the chin. In <5% of patients the first division is affected. The pain never crosses to the opposite side but it may rarely occur bilaterally, in which case a central cause such as multiple sclerosis must be considered. Between paroxysms the patient is usually asymptomatic but a dull background pain may persist in some long-standing cases. Following a painful paroxysm there is usually a refractory period during which pain cannot be triggered. In some cases a paroxysm may be triggered from somatosensory stimuli outside the trigeminal area, such as a limb, or by other sensory stimulation such as bright lights, loud noises or tastes. The pain often evokes spasm of the muscle of the face on the affected side (tic douloureux).
The increasing frequency of posterior fossa exploration and magnetic resonance imaging has demonstrated that many, possibly most, patients with this condition have compression of the trigeminal root by tortuous or aberrant vessels.
Classical trigeminal neuralgia is usually responsive, at least initially, to pharmacotherapy.