Neurotization of oculomotor,trochlear and abducent nerves in skull base surgery

Objective To anatomically reconstruct the oculomotor nerve, trochlear nerve, and abducent nerve by skull base surgery. Methods Seventeen cranial nerves (three oculomotor nerves, eight trochlear nerves and six abducent nerves) were injured and anatomically reconstructed in thirteen skull base operations during a period from 1994 to 2000. Repair techniques included end-to-end neurosuture or fibrin glue adhesion, graft neurosuture or fibrin glue adhesion. The relationships between repair techniques and functional recovery and the related factors were analyzed.Results Functional recovery began from 3 to 8 months after surgery. During a follow-up period of 4 months to 6 years, complete recovery of function was observed in 6 trochlear nerves (75%) and 4 abducent nerves (67%), while partial functional recovery was observed in the other cranial nerves including 2 trochlear nerves, 2 abducent nerves, and 3 oculomotor nerves.Conclusions Complete or partial functional recovery could be expected after anatomical neurotization of an injured oculomotor, trochlear or abducent nerve. Our study demonstrated that, in terms of functional recovery, trochlear and abducent nerves are more responsive than oculomotor nerves, and that end-to-end reconstruction is more efficient than graft reconstruction. These results encourage us to perform reconstruction for a separated cranial nerve as often as possible during skull base surgery.

Validity and reliability of the Ocular Motor Nerve Palsy Scale

Objective and accurate assessment of the degree of ocular motor nerve palsy is helpful not only in the evaluation of prognosis, but also for the screening of treatment methods. However, there is currently no comprehensive measure of its severity. In this study, we designed the Ocular Motor Nerve Palsy Scale and investigated its validity and reliability. Six experts were invited to grade and evaluate the scale. The study recruited 106 patients with a definite diagnosis of unilateral isolated ocular motor nerve palsy. Three physicians evaluated the patients using the scale. One of the three physicians evaluated the patients again after 24 hours. The content validity index（CVI） and factor analysis were used to analyze the scale＇s construct validity. The intraclass correlation coefficient and Cronbach＇s alpha were used to evaluate the inter-rater and test-retest reliability and the internal consistency. The CVI results（I-CVI = 1.0, S-CVI = 0.9, Pc = 0.016, K＊ = 1） indicated good content validity. Factor analysis extracted two common factors that accounted for 85.2% of the variance. Furthermore, the load value of each component was above 0.8, indicating good construct validity. The Ocular Motor Nerve Palsy Scale was found to be highly reliable, with an inter-rater reliability intraclass correlation coefficient of 0.965（P 0.01）, a test-retest reliability intraclass correlation coefficient of 0.976（P 0.01）, and Cronbach＇s alpha values of 0.63–0.70. In conclusion, the Ocular Motor Nerve Palsy Scale with good validity and reliability can be used to quantify the severity of ocular motor nerve palsy. This study was registered at Chinese Clinical Trial Registry（registration number： Chi CTR-OOC-17010702）.