Study aim: Determining the effect of intravenous aminophylline in preventing headache caused by dural perforation following spinal anesthesia in elective orthopedic surgeries. Design: This is a two-group, double-blind, randomized clinical trial study conducted on 132 eligible patients using sealed envelopes for randomization. Settings and conduct: This study is conducted in the field of reducing and controlling headache following spinal anesthesia at Babol University of Medical Sciences and after obtaining informed consent from patients. Blinding of participants and outcome monitors is done using sealed envelopes and group numbering. Participants/Inclusion and exclusion criteria: Inclusion criteria: patients requiring elective orthopedic surgery with spinal anesthesia, having stable vital signs for the spinal anesthesia process (ASA class I and II); age range 15-75 years; and having informed consent to participate in the study. Exclusion criteria: presence of coagulation problems; presence of chronic heart and lung disease; presence of chronic liver disease; presence of allergy to specific drugs; especially anesthetic drugs; history of seizures; and presence of history of use of various opioids. Intervention groups: For patients in the intervention group, 10 mg of marcaine is injected into the L3-L4 or L4-L5 space, and after anesthesia is stabilized, aminophylline 1 mg/kg in 100 cc of normal saline is infused with cardiac monitoring. For patients in the control group, 10 mg of marcaine is injected into the L3-L4 or L4-L5 space, and after anesthesia is stabilized, only 100 cc of normal saline is infused with cardiac monitoring. Main outcome variables: Measuring the time of headache onset; measuring headache severity; and measuring the duration of headache