Severe hyponatremia and bilateral sequential facial palsy: A case report

Facial palsy (FP) is a known consequence of head trauma, manifesting either immediately at the time of injury or with delayed onset, typically occurring 2 days or more post-trauma. Unilateral FP is the more common presentation and is often attributed to partial or complete transection of facial nerves or delayed onset edema. Conversely, bilateral facial palsy is a rare occurrence, reported in only a small number of cases, accounting for approximately 3% of patients presenting with bilateral weakness. In this report, we present the case of a previously healthy 28-year-old female who suffered a closed head injury during the Beirut Port Blast. Four days following the incident, the patient exhibited right-sided peripheral FP, which was consistent with a right temporal bone fracture. Subsequently, on the fifth day, the right-sided FP worsened, accompanied by the development of new FP on the left side, characterized by sparing of the frontal region, indicating a central origin for the left-sided FP. Laboratory investigations revealed severe hypovolemic hyponatremia with a sodium level of 105 mmol/L. As isotonic saline fluid replacement was initiated, there was progressive improvement in the left-sided FP. The right-sided palsy also resolved gradually with the implementation of facial rehabilitation therapy. It is important to note that severe head trauma, particularly with a concussive injury, can lead to facial paralysis through various mechanisms. Furthermore, severe hyponatremia should be considered a potential cause of central facial palsy, particularly in the presence of bilateral facial involvement. A thorough evaluation is encompassing assessment of palsy patterns, comprehensive imaging studies, and metabolic investigations is crucial for accurate diagnosis and timely intervention, resulting in successful treatment.