Dual Impact: Coup-Contrecoup Brain Injury in a Young Cyclist-A Case Report.

INTRODUCTION: Coup-contrecoup brain injury occurs when trauma produces focal damage both at the site of impact (coup) and at the contralateral side (contrecoup) due to intracranial pressure (ICP) dynamics and rotational forces. These injuries are frequently seen in high-velocity accidents and often demand staged neurosurgical intervention.

CASE PRESENTATION: We report a case of a 14-year-old boy presenting with altered sensorium following a road traffic accident. Initial CT revealed a large left frontal extradural hematoma (EDH) with mass effect and contralateral right frontotemporoparietal contusion. He underwent emergency left frontal craniotomy and evacuation of ~150 mL of EDH. Despite initial improvement, the patient developed neurological deterioration with anisocoria on postoperative day three. Repeat CT revealed worsening contralateral contusion with subdural hematoma (SDH) and midline shift. A right frontotemporoparietal decompressive craniectomy with lax duraplasty was performed, resulting in resolution of mass effect. The patient showed progressive neurological recovery, was decannulated, discharged on postoperative day 18, and later underwent elective cranioplasty with good functional outcome.

CONCLUSION: Coup-contrecoup injuries are mechanistically linked to rotational acceleration, ICP gradients, and skull deformation, rather than simple rebound forces. Frontal and temporal lobes are most commonly involved. Clinical predictors of outcome include Glasgow coma scale (GCS), pupillary reactivity, presence of SDH, and systemic secondary insults. These injuries are dynamic, with contralateral lesion progression often necessitating vigilant monitoring and timely intervention. Management requires repeat neuroimaging, control of ICP, and staged surgical procedures when indicated.