post dural (Spinal) puncture headache is due to:
Headache is due to of CSF and can be treated with analgesics. Post-dural-puncture headache (PDPH) is a complication of puncture of the dura mater (one of the membranes that surround the brain and spinal cord). ... It is a common side-effect of spinal anesthesia and lumbarpuncture. From padmaja 4th edition Page no 205
Anesthesia
Seepage of CSF
Fine needle
Toxic effects of the drugs
Traumatic damage to nerve roots
Seepage of CSF