Isolated oculomotor nerve palsy following mild traumatic brain injury: diagnostic challenges and insights from...

Isolated oculomotor nerve palsy (ONP) following mild traumatic brain injury (TBI) is rare and often presents diagnostic challenges. Typically associated with diffuse axonal injury and poor prognosis, ONP lacks comprehensive radiological documentation when no skull base fractures along the course of the 3rd Nerve or brainstem injuries are evident. This study explores the diagnostic utility of contrast-enhanced magnetic resonance imaging (CEMRI) in identifying ONP cases in mild TBI patients.

A retrospective analysis was conducted on six patients diagnosed with isolated ONP after mild TBI, with no evident skull base fractures along the course of the 3rd Nerve or brainstem findings. All patients underwent CE-MRI to identify structural or vascular anomalies along the course of the third cranial nerve. Clinical presentations, imaging findings, and outcomes were meticulously documented and reviewed by a neuroradiologist.

CE-MRI findings revealed consistent abnormalities in all cases. Thickening, blooming, and post-contrast enhancement of the cisternal portion of the third cranial nerve were observed, with two cases demonstrating extension into orbital segments. Despite the absence of fractures or direct injuries, partial recovery was noted in most cases, facilitated by targeted steroid therapy in some instances. These imaging patterns suggest indirect mechanisms such as traction, vascular compromise, or intraneural hemorrhage as potential causes of ONP.

High-resolution CE-MRI proves instrumental in diagnosing isolated ONP in mild TBI patients, even without conventional radiological indicators. Early imaging and intervention may improve recovery outcomes. This study underscores the significance of including CE-MRI in evaluation protocols for ONP. It highlights the importance of further research to unravel the underlying pathophysiology and optimize therapeutic approaches for these patients.