Indications for LP: CNS infection, SAH, Guillian Barree, IIH Contraindications for LP: Space occupying lesion with mass effect ; severe thrombocytopenia and coagulopathy; cellulitis over LP site or concern for epidural abscess ; traumatic injury to spine Complications for LP: Post LP Headache, spinal hematoma, brainstem herniation Technique for LP: Positioning is everything.  Use US if necessary.  Check for CSF early and often.   When to CT before LP?: AMS; focal neuro deficit; new onset seizures, known CNS lesions; immunosuppression; papilledema