To Map Human Lower Thoracic Dermatomes by Epidural Block
Condition: Urological Disease; Anesthesia
MeSH terms: Urologic Diseases
Study type: Interventional

Summary: 
      Significant differences exist among various dermatome maps. In addition, there were no
      anatomical landmarks to evaluate the dermatome at the back. The investigators aim to map the
      sensory innervations of lower thoracic nerves and find the dorsal landmarks to evaluate
      sensory innervations by epidural block. Patients undergoing urological surgery will receive
      epidural block. Fifty patients with superior border of complete sensory loss to ice from T9
      to T12 (anterior median line) will be included in this study. The sensory loss to ice will be
      evaluated at midclavicular line, anterior axillary line, posterior axillary line, scapular
      line and posterior median line. The level of vertebrae will be identified and marked by
      ultrasound. The superior border of complete sensory loss to ice from anterior median line to
      posterior median line will be recorded for every patient. The dermatome map of T9 to T12 will
      be drawn. The landmarks of sensory innervations at posterior median line will be established
      using vertebrae.
    

Detailed description: 
      Background: The tract for percutaneous nephrolithotomy is typically established in the 11th
      intercostal space or in the subcostal area. According to Keegan and Garrett's dermatome map,
      the somatic pain could be controlled if the 11th and 12th the spinal nerve been blocked.
      However, the investigators found that if the 11th and the 12th spinal nerve had been blocked
      by evaluating the landmarks of ventral landmarks (xiphoid process , umbilicus and pubic
      symphysis), the somatic pain of percutaneous nephrolithotomy could not be controlled. In
      order to find the reason, the investigators compared the four main dermatome maps created by
      Henry Head, Foerster, Keegan and Lee. There are significant differences of dermatome among
      these maps. In addition, there were no landmarks to evaluate the dermatome at the back.

      Objectives: To map the sensory innervations of lower thoracic nerves and find the dorsal
      landmarks to evaluate sensory innervations by epidural block.

      Methods: Adult patients undergoing elective percutaneous nephrolithotomy, ureteroscopic
      lithotripsy, transuretheral resection of prostate and transuretheral resection of bladder
      tumor will receive epidural block with 0.5% ropivacaine. Complete Sensory loss to ice will be
      evaluated at anterior median line as soon as the surgery was completed. The superior border
      of complete sensory loss to ice will be identified by ventral landmaks (xiphoid process ,
      umbilicus and pubic symphysis). Fifty patients with superior border of complete sensory loss
      to ice from T9 to T12 will be included in this study. The sensory loss to ice will be
      evaluated at anterior median line, midclavicular line, anterior axillary line, posterior
      axillary line, scapular line and posterior median line. The level of vertebrae will be
      identified and marked by ultrasound. The superior border of complete sensory loss to ice form
      anterior median line to posterior median line will be drawn and recorded for every patient.
      The dermatome map from T9 to T12 will be drawn. The landmarks of sensory innervations at
      posterior median line will be established using vertebrae..
    

Intervention name(s): cold sensation method
Intervention type(s): Other
Intervention description(s): Complete sensory loss to ice will be evaluated form anterior median line to posterior median line at the end of surgery.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: epidural block; dermatome; human; spinal nerve; thoracic