Ultrasound-Guided Landmark and Epidural Site Pain

Few studies have examined how epidural placement changes localized sensation at the epidural insertion site. This study will be the first study to quantitatively measure sensation at the epidural insertion site. The investigator will assess localized pressure sensitivity with an algometer. An algometer is a hand-held device commonly used by neurologist to detect sensory deficits and measures the pressure sensitivity threshold in a 1-cm diameter circular area. Ultrasound (US) pre-procedural examination provides more accurate landmarks for the placement of epidural catheters. The investigator will determine if an US examination prior to epidural placement reduces localized pressure sensitivity. The investigator will also determine if there are correlations between the participants characteristics and/or comorbidities and increased pressure sensitivity at the insertion site.