Uncommon Complication: Mandibular Branch Paralysis Following Carotid Endarterectomy – A Case Report

Case Diagnosis: Paralysis mandibular branch following a carotid endarterectomy

Case Description or Program Description: A 69-year-old male patient with a history of hyperlipidemia, type 2 diabetes, chronic kidney disease, past smoking, major depressive disorder, hypertension, and cerebrovascular accident underwent left carotid endarterectomy due to >70% carotid stenosis and a left medial carotid tear. He was referred to PM&R for suspected left marginal mandibular nerve paresis post-surgery. The patient reports left facial and neck hypersensitivity and pain (6/10 intensity), limiting his ability to shave and causing upper trapezius discomfort that restricts neck range of motion. He denies dysphagia or other neurological symptoms. He takes acetaminophen for pain relief.

Setting: Outpatient clinics

Assessment/Results: Physical exam remarkable for asymmetric smile with lip droop on left side, and hyperesthesia over inferior aspect of left facial side and left side of his neck. No other neurological deficits. House-Brackman scale II/III is mild; however, sensory disturbances affect daily functional activities. Patient was referred for physical therapy involving mimicking exercises, desensitization techniques, and electrical stimulation. Electrodiagnostic test pending to assess severity of nerve injury.

Discussion (relevance): Injury to the mandibular branch of the facial nerve is a rare complication of CEA. In contrast, injuries to the vagus and hypoglossal nerves are more commonly reported. The incidence of mandibular branch injuries during CEA is approximately 1.58%. This is significantly lower than the rates observed in orthodontic procedures, parotid dissection, or surgeries involving the submandibular triangle, where injuries can occur in nearly 30% of cases.

Conclusions: Although uncommon, paralysis of the marginal mandibular branch of the facial nerve can lead to bothersome and cosmetically undesirable effects. Early rehabilitation efforts can significantly improve quality of life and reduce pain. If physical therapy does not yield the desired results, promptly referring the patient for potential surgical correction is important.