From the Guidelines
After a thyroidectomy, it's crucial to check cranial nerves X (vagus) and XII (hypoglossal) to minimize morbidity, mortality, and improve quality of life. Here's what you need to know:
- Cranial Nerve X (Vagus):
- Test: Ask the patient to say "Ah" and observe for symmetrical palatal elevation, as recommended by the clinical practice guideline: improving voice outcomes after thyroid surgery 1.
- Reason: The recurrent laryngeal nerve, a branch of the vagus, can be injured during thyroid surgery, leading to vocal cord paralysis, which can significantly impact a patient's quality of life 1.
- Cranial Nerve XII (Hypoglossal):
- Test: Ask the patient to stick out their tongue and move it side to side.
- Reason: While less common, the hypoglossal nerve can be affected due to its proximity to the surgical site, and its injury can lead to difficulties in swallowing and speaking, ultimately affecting the patient's morbidity and mortality 1. Additionally, assess for:
- Voice changes (hoarseness, breathiness)
- Swallowing difficulties
- Neck swelling or hematoma Perform these checks immediately post-op and during follow-up visits, as early detection of nerve injury allows for prompt intervention, potentially improving outcomes, and reducing the risk of long-term complications, as highlighted in the study by Chandrasekhar et al 1. If any abnormalities are found, consult with an otolaryngologist for further evaluation and management, to ensure the best possible outcome for the patient in terms of morbidity, mortality, and quality of life.
From the Research
Cranial Nerves to be Assessed after Thyroidectomy
The cranial nerves that should be assessed after thyroidectomy are:
- Recurrent laryngeal nerve (RLN) 2, 3, 4, 5
- External branch of the superior laryngeal nerve (EBSLN) 2, 6, 5
Reasons for Assessment
These nerves are at risk of injury during thyroidectomy due to their close anatomical relationship with the thyroid gland and surrounding structures. Injury to these nerves can result in vocal cord paralysis, hoarseness, and other complications.
Key Points
- The RLN provides motor innervation to the intrinsic laryngeal muscles and sensory innervation to the larynx 2, 3, 4, 5
- The EBSLN provides motor innervation to the cricothyroid muscle, which is the tensor muscle of the vocal cord 2, 6, 5
- Intraoperative nerve monitoring (IONM) can be used to assess the functional integrity of the RLN and EBSLN 2, 5
- Visual control and gentle dissection of the RLN and EBSLN are imperative to prevent injury 2, 3, 5