Approach Considerations
Studies have failed to yield a definitive guideline on the best treatment and escalation of treatment options for TN. The general consensus is to begin with medical therapy until it is ineffective or side effects of medication become prohibitive. For these patients it is reasonable to refer for surgical options without prolonged delay. [1]
Emergency Department Care
Care in the ED is generally limited to correct identification of trigeminal neuralgia (TN), consideration of alternative diagnosis, pain relief, and coordination of follow-up care.
Because of the time-limited character of pain with typical trigeminal neuralgia, patients often do not present to the ED for pain medication.
In some patients, the typically episodic pain becomes constant or so frequent as to be debilitating. Infusion of phenytoin is reportedly successful in interrupting such episodes, but the value of this therapy is anecdotal. [9, 10]
Coordinate therapy for refractory pain of trigeminal neuralgia with the primary care physician or consultants.
Consultations
Patients with a typical history and normal physical examination may be referred to their primary care physician for further care. Neurologic or neurosurgical consultations may be helpful, particularly if atypical features are present.
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Referral to a neurologist may be helpful if the diagnosis is in doubt or for medication management upon discharge.
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Comprehensive pain center follow-up care may be helpful. Pain specialists can inject local anesthetics that are used in the diagnosis and treatment of TN. These injections can provide relief from pain for a few months to years and help reduce the pain intensity and frequency in TN.
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Referral to a neurosurgeon may be indicated for patients whose conditions prove refractory to medical treatment. Percutaneous radiofrequency ablation of a portion of the trigeminal ganglion is commonly performed, as are anesthetic blocks of the trigeminal ganglion. Gamma knife radiosurgery is used at some centers. [11] Less commonly performed is decompression of the region of trigeminal root entry of impinging vascular structures. An MRI of a patient who has undergone gamma knife surgery is shown below.
MRI with high resolution on the pons demonstrating the trigeminal nerve root. In this case, the patient with trigeminal neuralgia has undergone gamma-knife therapy, and the left-sided treated nerve (arrow) is enhanced by gadolinium.
Medical Care
First-line treatment for trigeminal neuralgia (TN) is medication, and if the medication fails or severe side effects develop, surgical treatment may be offered. Approximately half of patients will fail medical thearpy. Carbamazepine (CBZ) and oxcarbazepine (OXC) are considered first-line therapy. Compared to CBZ, OXC showed a similar efficacy in controlling pain but a greater tolerability and less drug interactions. Second-line therapy is with add-on drugs of lamotrigine or monotherapy with lamotrigine or baclofen. [1]
In the ED, an acute exacerbation may benefit from intravenous hydration, management of hyponatraemia, titration of drugs, and, in certain cases, lidocaine or fosphenytoin intravenous infusion, under cardiac monitoring.
Less invasive options for pain relief are currently being researched. These include repeated peripheral alcohol injections with a variable pain relief duration. Repeated injections have been noted to be more difficult due to fibrosis and were also associated with a decreased duration of pain relief. Average duration of symptomatic improvement was 11–15 months. [12]
Subcutaneous or intradermal Botulinum toxin-A (Botox) injections work by blocking acetylcholine release at the neuromuscular junction with resultant muscle relaxation through eventual deactivation of sodium channels in the CNS. Relief of symptoms was reported to be between 3 and 24 months. Adverse reactions reported included development of hemotoma and mild facial asymmetry. [13] One study reported that the effectiveness of the injection faded after 60 days. [1]
There is a novel sodium channel blocker injection currently being investiaged for use in TN.
Surgical Care
Approximately half of trigeminal neuralgia (TN) patients will fail medical therapy and go on to require surgical management of their symptoms.
Neuromodulation is a treatment option when medication therapy has failed. Options include nerve stimulation at various locations along the trigeminal motor pathway including electrical Gasserian (trigeminal) ganglion stimulation, the peripheral nerve, as well as both non-invasive and invasive motor cortex stimulation. [1] Destruction of the sensory component of the trigeminal nerve can also be done. Gamma knife radiosurgery can be an option for patients who are poor surgical candidates.
Microvascular decompression is an invasive surgical option to reduce vascular compression on the trigeminal nerve or ganglion. This procedure requires a craniotomy in the posterior fossa and risks include infarcts, hematomas, cerebral spinal fluid leaks, meningitis, hearing loss, and sensory loss. [1] Pain relief following surgery can be immediate but can decrease over a time frame of years.
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Microscopic demonstration of demyelination in primary trigeminal neuralgia. A tortuous axon is surrounded by abnormally discontinuous myelin. Electron microscope, 3, 300 X.
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MRI with high resolution on the pons demonstrating the trigeminal nerve root. In this case, the patient with trigeminal neuralgia has undergone gamma-knife therapy, and the left-sided treated nerve (arrow) is enhanced by gadolinium.
