The hypoglossal nerve, also known as the twelfth cranial nerve (CNXII), is responsible for innervating the intrinsic and extrinsic muscles of the tongue, with the exception of the palatoglossus muscle. Injuries to this nerve can significantly impact a patient’s speech and swallowing abilities. While the hypoglossal nerve is resilient, it can be damaged during trauma or surgery, or in rare cases, due to iatrogenic causes such as tonsillectomy, laryngoscopy, or tooth extraction.
Surgical Repair Options for Hypoglossal Nerve Injury
When a hypoglossal nerve injury is diagnosed, surgical exploration and repair should be considered. The ideal management involves establishing a tension-free anastomosis, similar to facial nerve repairs. This can be achieved through end-to-end anastomosis if possible, or the use of interposition grafts if necessary.
One surgical technique, known as the hypoglossal-facial nerve transfer, involves partially cutting the hypoglossal nerve on its side and connecting it to the facial nerve. This procedure aims to restore facial symmetry and tone at rest, typically within one year after the surgery. However, it is important to note that this technique does not provide restoration of smile.
Another surgical option is the hypoglossal-facial graft procedure, which involves transecting the donor hypoglossal nerve. While this method can lead to improved facial reanimation, it may also result in hemiglottic paralysis, potentially causing speech and swallowing difficulties. To avoid these complications, a modified technique called the “XII-VII interposition jump grafts” has been developed, which preserves hypoglossal nerve function while still providing facial reinnervation.
In cases of bilateral hypoglossal nerve paralysis, the treatment is more complex. Patients with total loss of tongue movement face significant challenges with speech and voluntary swallowing initiation. In such cases, a multidisciplinary approach involving a speech language pathologist is crucial to help the patient adapt to their condition and develop compensatory strategies.