Cranial Nerve Reconstruction

Introduction: Cranial nerves (CN) differ in several aspects from peripheral nerves. They are routinely encountered during skull base and cerebrovascular surgery. Not infrequently the suffer from approach related trauma and are lesioned iatrogenically. Repair methods are available and reported since long, however information on results is sparse. There are no common recommendations. We review current knowledge, and available literature on the basis of own experience and cases.

Findings: Cranial nerves differ in response to reconstruction in dependence on number of functions supplied by nerve (single vs multiple), axon number, nerve fiber type (mixed vs unmixed), and target muscle size. Surgical technique for intracranial nerve repair differs from extracranial repair. Some cranial nerves will have excellent results after instant intracranial repair. Different coaptation techniques are available. Reconstruction in a confined space and nerve coaptation within CSF necessitate an efficient time and tissue sparing approach. Experience with fast, local, or distant donor nerve harvest, graft alignment techniques and glue coaptation is necessary.

Good results can be expected for trochlear and abducent nerve, mediocre results for facial, and mediocre to bad results for oculomotor nerve. There is lack of reported experience and results with olfactory and lower cranial nerves, and especially so with glossopharyngeal nerve.

This in contrast to an abundance of literature regarding extracranial reconstruction of facial nerve, nerve transfers for facial reanimation and facial reanimation in general by direct and indirect means. Also well documented are favorable result of extracranial reconstruction of spinal accessory nerve.

Conclusion: Literature findings and own experience strengthened us to always attempt repair in acute situations. We make use of glue coaptation, as suture is not always practical and necessary for reinforcement, and if applicable we make use of autologous fat graft as mikro-bolster to reduce tension and pull.