RESUMO
Acute interhemispheric subdural haematoma (AISH) was considered extremely rare until identification with imaging studies. Interhemispheric subdural hematoma in adults is a rare complication of head injury with no more than 100 cases reported since 1940. The classical presentation of this disorder is a contralateral monoparesis of the leg or a hemiparesis more pronounced in the leg1. Treatment may consist of conservative observation or craniotomy and is dictated by the clinical course. Conservative management is the treatment of choice for patients without disturbances of consciousness and for patients with stable clinical conditions. Surgical treatment is necessary in patients with progressive neurological deterioration. We describe the case of traumatic AISH in a 31-year-old patient who presented a contralateral monoparesis of the leg.