Question

A patient undergoes the careful dissection of the anterior cervical neck due to advanced squamous cell carcinoma of the tongue with local invasion. The surgeon samples submandibular lymph nodes and resects a portion of the submandibular gland to do so. The patient tolerates the operation well and is taken to the ICU following the surgery due to the proximity of the surgery to the vocal cords and concern for edema. The patient is extubated on postoperative day 2 without difficulty, but their speech is dysarthric. The nurse calls the resident to bedside to evaluate for a possible stroke. The neurological exam is normal with the exception of tongue protrusion, which deviates to the left side.

What vessel courses through the submandibular space in proximity to the injured nerve?

Answer 1

The patient's leftward tongue deviation suggests an injury to the hypoglossal nerve (cranial nerve XII), which controls tongue movements and courses through the submandibular space. This is a peripheral nerve injury likely due to the surgery, rather than a central neurological event.

Step-by-step explanation:

The patient with dysarthric speech and a tongue deviation to the left side after a neck dissection for squamous cell carcinoma is likely experiencing a consequence of injury to a cranial nerve. Specifically, the hypoglossal nerve (cranial nerve XII), which courses through the submandibular space and innervates the muscles of the tongue, is responsible for tongue movements. Injury to this nerve causes weakness or paralysis on the same side of the tongue, leading to deviation towards the affected side when the tongue is protruded.

Tongue deviation is a classic sign of a hypoglossal nerve dysfunction, often evaluated during a physical examination by asking the patient to stick out their tongue. The genioglossus muscle, responsible for protruding the tongue, is innervated by the hypoglossal nerve. If there is a lesion affecting one side, the tongue will deviate toward the side of the lesion, as the stronger muscle on the unaffected side pushes the tongue towards the weaker side.

In this case, the nerve injury is not central but peripheral, as it occurred due to surgical intervention rather than a stroke, which would cause different symptoms. The absence of other neurological deficits in this patient further supports the conclusion that the issue is related to local trauma to the nerve rather than a central neurological event such as a stroke.