Asynchronous Cranial Neuralgia Syndromes: A Perspective on Approaches to Facial Pain through an Illustrative Case and Literature Review

Introduction: Facial pain comprises a heterogeneous and challenging spectrum of diseases. Although trigeminal neuralgia (TN) is the most common and well defined facial pain syndrome, many patients present with symptoms more consistent with glossopharyngeal or geniculate neuralgia (GPN/GN), while other patients describing multiple or ambiguous symptomatologies. Neurosurgical treatment of medication-refractory facial pain is variable. Microvascular decompression (MVD) is the standard first-line treatment for TN, but ablative procedures and stereotactic radiosurgery (SRS) are widespread; by contrast, many authors advocate for first-line nerve sectioning in GPN and GN, versus MVD alone. We report a patient who developed TN 7 years after successful GPN treatment, systematically review the literature on asynchronous facial pain syndromes, and highlight our approach to neurosurgically managed facial pain.

Methods: Case report and systematic literature review.

Results: A 55-year-old man presented with acute, intermittent, shock-like, pulsatile right pharyngeal pain with radiation to the right ear, intensely triggered by swallowing. Although he initially responded well to carbamazepine and gabapentin, severe pain recurred within months, and he underwent right retrosigmoid craniotomy, MVD of a compressive PICA loop, and sectioning of the glossopharyngeal nerve and upper vagal rootlets. Postoperatively, GPN symptoms resolved completely, and durable pain relief lasted 6 years. At that time, the patient developed new right-sided cheek and eye pain, worse over V2, with reproducible mechanical triggers and partial improvement on carbamazepine. The patient was returned to the OR, and via the same retrosigmoid craniotomy the trigeminal nerve was approached and noted to be under compression from both a large petrosal vein complex laterally an aberrant SCA loop superiorly. The venous branch in contact with the nerve was isolated, coagulated, and divided, and SCA loop were mobilized superiorly and buttressed with pledgets. The patient again made an excellent neurologic recovery, and remains pain-free as of 6-month follow-up.

In addition to our patient, systematic literature review identified 7 preceding cases of asynchronous TN and GPN with a true asymptomatic interval and unambiguously discrete symptomatologies. Overall, TN preceded GPN in 6 (75%), and median time to secondary syndrome was 24 months (range: 3–92). Symptoms were ipsilateral in 6 (75%) and contralateral in 2 (25%), with 63% of all symptoms occurring on the left. All patients achieved durable, complete pain relief, and 6 were able to discontinue all medications (75%). No major complications or mortalities were reported.

Conclusion: TN, GPN, and GN are complex and mutually confounding syndromes, each of which may respond to a range of treatments, including MVD, nerve section, ablative procedures, and SRS. Building on our experience with patients such as the present case, we’ve developed a comprehensive and reliable approach to planning facial pain treatment in accordance with both clinical and neuroanatomic features. In the presence of convincing symptoms, we plan an aggressive treatment—via MVD for TN, or nerve section for GPN and GN. At surgery, we thoroughly inspect the brainstem root entry zones and VII-VIII complex during all facial pain operations, and pro-actively MVD any compressive vessels, independent of symptomatology.

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