Postoperative trigeminal neuropathy outcomes following surgery for tumors involving the trigeminal nerve.

OBJECTIVE: To observe the evolution and outcomes of postoperative trigeminal neuropathy following surgery of tumor involving the trigeminal nerve. METHODS: A prospective observational study was conducted between October 2018 and February 2019 involving 25 patients with tumors confirmed to involve the trigeminal nerve during surgery by senior author. Pre- and postoperative trigeminal nerve function status and clinical data were recorded. RESULTS: This study included 18 cases of meningioma and seven of trigeminal schwannoma. Among the meningioma cases, 55.6% of the patients reported facial sensory dysfunction before surgery, 33.3% presented ocular discomfort, and 5.6% had masticatory muscle atrophy. Postoperatively, all patients experienced facial paresthesia, 94.4% complained of eye dryness, and one (5.56%) exhibited keratitis. Additionally, one patient (5.56%) showed new-onset masticatory weakness. During follow-up, 50.0% of patients reported improvement in facial paresthesia, and one (5.56%) experienced deterioration. Eye dryness resolved in 35.3% of patients, and keratitis remission was observed in one patient. However, one patient (5.56%) developed neurotrophic keratitis. Overall, 55.6% of patients displayed mild masticatory weakness without muscle atrophy. In the cases of schwannoma, 28.6% of patients had facial paresthesia before surgery, 42.9% showed ocular discomfort, and one (14.3%) complained of masticatory dysfunction. Postoperatively, 85.7% of patients reported facial paresthesia and eye dryness, with one patient (16.7%) experiencing keratitis. During follow-up, 66.7% of patients demonstrated improvement in facial paresthesia, 28.6% showed eye dryness remission, and one patient (16.7%) recovered from keratitis. However, one patient (16.7%) developed new-onset neurotrophic keratitis. One patient (16.7%) experienced relief of masticatory dysfunction, but 42.9% reported mild deterioration. Another patient (14.3%) had facial anesthesia that had not improved. CONCLUSION: Postoperative trigeminal neuropathy is a common complication with a high incidence rate and poor recovery outcomes after surgery for tumors involving the trigeminal nerve. When trigeminal nerve damage is unavoidable, it is essential to provide a multidisciplinary and careful follow-up, along with active management strategy, to mitigate the more severe effects of postoperative trigeminal neuropathy.

Utility of Dual Monitoring of the Lower Cranial Nerve Motor-Evoked Potentials Threshold Level Criterion to Predict Swallowing Function in Skull Base and Brainstem Surgery.

PURPOSE: Evaluate the value of bilateral final/baseline threshold level changes of lower cranial nerve MEPs in postoperative swallowing function deterioration prediction. METHODS: Bilateral lower cranial nerve motor-evoked potentials (MEPs) were recorded in 51 patients who underwent treatment for skull base and brainstem tumors. Corkscrew-like electrodes were positione 2 cm below C3/C4 and Cz. The MEPs were recorded from different muscle groups, including the posterior pharyngeal wall muscle, tongue muscle, genioglossus muscle, and cricothyroid muscle through paired needle electrodes. Swallowing function was assessed clinically using the Mann Assessment of Swallowing Ability score before and after the procedure at 7 days, 1 month, and 3 months. RESULTS: Bilateral final/baseline threshold level increases in lower cranial nerve MEPs under the dual monitoring were significantly correlated with postoperative swallowing function deterioration ( r = 0.660 at 7 days, r = 0.735 at 1 month, and r = 0.717 at 3 months; p < 0.05). Bilateral final/baseline threshold level changes of more than 20% were recorded in 23 of the 51 patients, with 21 patients experiencing swallowing function deterioration postoperatively. The other 28 patients had bilateral threshold level changes of less than 20%, with 26 patients maintaining or improving their swallowing function, and 12 of those patients presented transient deterioration of swallowing function in the early postoperative period. CONCLUSIONS: Dual monitoring of lower cranial nerves and their different muscle groups MEPs was a safe and effective way to predict postoperative swallowing function. An increase in bilateral final/baseline threshold level change of more than 20% was predictive of permanent swallowing deterioration, especially in patients with poor swallowing function preoperatively.

A clinical study of ocular motor nerve functions after petroclival meningioma resection.

BACKGROUND: Ocular motor dysfunction is one of the most common postoperative complications of petroclival meningioma. However, its incidence, recovery rate, and independent risk factors remain poorly explored. METHODS: A prospective analysis of 31 petroclival meningiomas was performed. Operative approaches were selected by utilizing a new 6-region classification of petroclival meningiomas we proposed. Two scores were used to evaluate the functions of the oculomotor and abducens nerves. Pearson correlation analysis and binary logistic regression analysis were used to identify independent risk factors for intraoperative oculomotor and abducens nerve injury. RESULTS: Postoperative new-onset dysfunctions in the pupillary light reflex and eye/eyelid movements as well as abducens paralysis were detected in eight (25.8%), ten (32.3%) and twelve (38.7%) cases, respectively. Their corresponding recovery rates after 6 months of follow-up were 75% (6/8), 80% (8/10), and 83.3% (10/12), respectively, and their mean times to start recovery were 4.03, 2.43, and 2.5 months, respectively. Tumor invasion into the suprasellar region/sphenoid sinus was the only risk factor for dysfunctions in both the pupillary light reflex (p = 0.001) and eye/eyelid movements (p = 0.002). Intraoperative utilization of the infratrigeminal interspace was the only risk factor for dysfunction in eyeball abduction movement (p = 0.004). CONCLUSIONS: Dysfunctions of the oculomotor and abducens nerves recovered within 6 months postoperatively. Tumor extension into the suprasellar region/sphenoid sinus was the only risk factor for oculomotor nerve paralysis. Eye/eyelid movements were more sensitive than the pupillary light reflex in reflecting nerve dysfunctions. Intraoperative utilization of the infratrigeminal interspace was the only risk factor for abducens nerve paralysis.