A 14-year-old boy underwent emergency debridement surgery of right foot under spinal anaesthesia. Four hours after the surgery, the patient developed symptoms of cauda equina syndrome (CES). Postoperative magnetic resonance imaging of the patient's spine suggested underlying tubercular arachnoiditis. The boy was started on intravenous methylprednisolone and antitubercular therapy. He responded to the therapy and recovered completely in 2 weeks without any residual neurological deficits. We suggest that underlying pathological changes in the subarachnoid space due to tubercular arachnoiditis contributed to maldistribution of the local anaesthetic drug leading to CES.