25 year old male with head injury comes walking, conscious oriented and then becomes unconsious. Diagnosis

.extradural haematoma is the collection of blood in the extradural space between the dura and skull. most common site is the temporoparietal region. usually, it is associated with fracture of temporoparietal region. immediately after injury , there is transient loss of consciousness and the patient soon becomes normal. later after 6-12hours , he again falls ill and the condition deteriorates. this is the time taken to increase the intracranial pressure,coning and its effects. this crucial time gap is called lucid interval (Ref : SRB&;s Manual of Surgery, 5th editin , pg no. 1095)