A man, a teenage victim of an assault to the head, presented to the emergency department, in Baghdad, with a Glasgow Coma Score of 4/15 (E1 M2 V1) and total right-sided paralysis. CT of the brain revealed a large-left sided frontotemporoparietal extradural haematoma with the presence of an ipsilateral sylvian arachnoid cyst deep to the haematoma. Urgent surgical evacuation of the haematoma was performed, leaving the arachnoid cyst intact. The patient improved and gained full consciousness within 4 days.Three years after the initial trauma, the patient has remained well. This case required a thorough discussion of the surgical options, in particular whether to intervene with the associated cyst, and whether any intervention with the cyst should be performed in the same or future operations. This dilemma forms the basis of the discussion in the following report.