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
Seepage of CSF
Fine needle
Toxic effects of the drugs
Traumatic damage to nerve roots
Anesthesia