Pneumocephalus is the presence of air intracranially, this pathology is mostly seen in traumatic injury, however it remained exceptional in posterior spine surgery. In this study, we report a clinical case of a 66 years old woman who was operated for lumber spinal stenosis with spondylolisthesis presented a drowsiness, CT scan showed a compressive pneumocephalus (mount fuji sign) and pneumorrachis. A conservative treatment has been set up. The evolution was marked by improving its state of consciousness, the patient was discharged on day 10 post operatively with a brain CT that showed regression of PC.